Category Archives: p53

Wogonin

Cancer:
Breast, lung (NSCLC), gallbladder carcinoma, osteosarcoma, colon, cervical

Action: Neuro-protective, anti-lymphangiogenesis, anti-angiogenic, anti-estrogenic, chemo-sensitizer, pro-oxidative, hypoxia-induced drug resistance, anti-metastatic, anti-tumor, anti-inflammatory

Wogonin is a plant monoflavonoid isolated from Scutellaria rivularis (Benth.) and Scutellaria baicalensis (Georgi).

Breast Cancer; ER+ & ER-

Effects of wogonin were examined in estrogen receptor (ER)-positive and -negative human breast cancer cells in culture for proliferation, cell-cycle progression, and apoptosis. Cell growth was attenuated by wogonin (50-200 microM), independently of its ER status, in a time- and concentration-dependent manner. Apoptosis was enhanced and accompanied by up-regulation of PARP and Caspase 3 cleavages as well as pro-apoptotic Bax protein. Akt activity was suppressed and reduced phosphorylation of its substrates, GSK-3beta and p27, was observed. Suppression of Cyclin D1 expression suggested the down-regulation of the Akt-mediated canonical Wnt signaling pathway.

ER expression was down-regulated in ER-positive cells, while c-ErbB2 expression and its activity were suppressed in ER-negative SK-BR-3 cells. Wogonin feeding to mice showed inhibition of tumor growth of T47D and MDA-MB-231 xenografts by up to 88% without any toxicity after 4 weeks of treatment. As wogonin was effective both in vitro and in vivo, our novel findings open the possibility of wogonin as an effective therapeutic and/or chemo-preventive agent against both ER-positive and -negative breast cancers, particularly against the more aggressive and hormonal therapy-resistant ER-negative types (Chung et al., 2008).

Neurotransmitter Action

Kim et al. (2011) found that baicalein and wogonin activated the TREK-2 current by increasing the opening frequency (channel activity: from 0.05 ± 0.01 to 0.17 ± 0.06 in baicalein treatment and from 0.03 ± 0.01 to 0.29 ± 0.09 in wogonin treatment), while leaving the single-channel conductance and mean open time unchanged. Baicalein continuously activated TREK-2, whereas wogonin transiently activated TREK-2. Application of baicalein and wogonin activated TREK-2 in both cell attached and excised patches, suggesting that baicalein and wogonin may modulate TREK-2 either directly or indirectly with different mechanisms. These results suggest that baicalein- and wogonin-induced TREK-2 activation help set the resting membrane potential of cells exposed to pathological conditions and thus may give beneficial effects in neuroprotection.

Anti-metastasic

The migration and invasion assay was used to evaluate the anti-metastasis effect of wogonin. Wogonin at the dose of 1–10 µM, which did not induce apoptosis, significantly inhibited the mobility and invasion activity of human gallbladder carcinoma GBC-SD cells. In addition, the expressions of matrix metalloproteinase (MMP)-2, MMP-9 and phosphorylated extracellular regulated protein kinase 1/2 (ERK1/2) but not phosphorylated Akt were dramatically suppressed by wogonin in a concentration-dependent manner. Furthermore, the metastasis suppressor maspin was confirmed as the downstream target of wogonin.

These findings suggest that wogonin inhibits cell mobility and invasion by up-regulating the metastasis suppressor maspin. Together, these data provide novel insights into the chemo-protective effect of wogonin, a main active ingredient of Chinese medicine Scutellaria baicalensis (Dong et al., 2011).

Anti-tumor and Anti-metastatic

Kimura & Sumiyoshi (2012) examined the effects of wogonin isolated from Scutellaria baicalensis roots on tumor growth and metastasis using a highly metastatic model in osteosarcoma LM8-bearing mice. Wogonin (25 and 50mg/kg, twice daily) reduced tumor growth and metastasis to the lung, liver and kidney, angiogenesis (CD31-positive cells), lymphangiogenesis (LYVE-1-positive cells), and TAM (F4/80-positive cell) numbers in the tumors of LM8-bearing mice. Wogonin (10–100µM) also inhibited increases in IL-1β production and cyclooxygenase (COX)-2 expression induced by lipopolysaccharide in THP-1 macrophages. The anti-tumor and anti-metastatic actions of wogonin may be associated with the inhibition of VEGF-C-induced lymphangiogenesis through a reduction in VEGF-C-induced VEGFR-3 phosphorylation by the inhibition of COX-2 expression and IL-1β production in Tumor-associated macrophages (TAMs).

Anti-inflammatory

Wogonin extracted from Scutellariae baicalensis and S. barbata is a cell-permeable and orally available flavonoid that displays anti-inflammatory properties. Wogonin is reported to suppress the release of NO by iNOS, PGE2 by COX-2, pro-inflammatory cytokines, and MCP-1 gene expression and NF-kB activation (Chen et al., 2008).

Hypoxia-Induced Drug Resistance (MDR)

Hypoxia-induced drug resistance is a major obstacle in the development of effective cancer therapy. The reversal abilities of wogonin on   hypoxia resistance were examined and the underlying mechanisms discovered. MTT assay revealed that hypoxia increased maximal 1.71-, 2.08-, and 2.15-fold of IC50 toward paclitaxel, ADM, and DDP in human colon cancer cell lines HCT116, respectively. Furthermore, wogonin showed strong reversal potency in HCT116 cells in hypoxia and the RF reached 2.05. Hypoxia-inducible factor-1α (HIF-1α) can activate the expression of target genes involved in glycolysis. Wogonin decreased the expression of glycolysis-related proteins (HKII, PDHK1, LDHA), glucose uptake, and lactate generation in a dose-dependent manner.

In summary, wogonin could be a good candidate for the development of a new multi-drug resistance (MDR) reversal agent and its reversal mechanism probably is due to the suppression of HIF-1α expression via inhibiting PI3K/Akt signaling pathway (Wang et al., 2013).

NSCLC

Wogonin, a flavonoid originated from Scutellaria baicalensis Georgi, has been shown to enhance TRAIL-induced apoptosis in malignant cells in in vitro studies. In this study, the effect of a combination of TRAIL and wogonin was tested in a non-small-cell lung cancer xenografted tumor model in nude mice. Consistent with the in vitro study showing that wogonin sensitized A549 cells to TRAIL-induced apoptosis, wogonin greatly enhanced TRAIL-induced suppression of tumor growth, accompanied with increased apoptosis in tumor tissues as determined by TUNEL assay.

The down-regulation of these antiapoptotic proteins was likely mediated by proteasomal degradation that involved intracellular reactive oxygen species (ROS), because wogonin robustly induced ROS accumulation and ROS scavengers butylated hydroxyanisole (BHA) and N-acetyl-L-cysteine (NAC) and the proteasome inhibitor MG132 restored the expression of these antiapoptotic proteins in cells co-treated with wogonin and TRAIL.

These results show for the first time that wogonin enhances TRAIL's anti-tumor activity in vivo, suggesting this strategy has an application potential for clinical anti-cancer therapy (Yang et al., 2013).

Colon Cancer

Following treatment with baicalein or wogonin, several apoptotic events were observed, including DNA fragmentation, chromatin condensation and increased cell-cycle arrest in the G1 phase. Baicalein and wogonin decreased Bcl-2 expression, whereas the expression of Bax was increased in a dose-dependent manner compared with the control. Furthermore, the induction of apoptosis was accompanied by an inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt in a dose-dependent manner.

The administration of baicalein to mice resulted in the inhibition of the growth of HT-29 xenografts without any toxicity following 5 weeks of treatment. The results indicated that baicalein induced apoptosis via Akt activation in a p53-dependent manner in the HT-29 colon cancer cells and that it may serve as a chemo-preventive or therapeutic agent for HT-29 colon cancer (Kim et al., 2012).

Breast

The involvement of insulin-like growth factor-1 (IGF-1) and estrogen receptor α (ERα) in the inhibitory effect of wogonin on the breast adenocarcinoma growth was determined. Moreover, the effect of wogonin on the angiogenesis of chick chorioallantoic membrane (CAM) was also investigated. The results showed wogonin and ICI182780 both exhibited a potent ability to blunt IGF-1-stimulated MCF-7 cell growth. Either of wogonin and ICI182780 significantly inhibited ERα and p-Akt expressions in IGF-1-treated cells. The inhibitory effect of wogonin showed no difference from that of ICI182780 on IGF-1-stimulated expressions of ERα and p-Akt. Meanwhile, wogonin at different concentrations showed significant inhibitory effect on CAM angiogenesis.

These results suggest the inhibitory effect of wogonin on breast adenocarcinoma growth via inhibiting IGF-1-mediated PI3K-Akt pathway and regulating ERα expression. Furthermore, wogonin has a strong anti-angiogenic effect on CAM model (Ma et al., 2012).

Chemoresistance; Cervical Cancer, NSCLC

Chemoresistance to cisplatin is a major limitation of cisplatin-based chemotherapy in the clinic. The combination of cisplatin with other agents has been recognized as a promising strategy to overcome cisplatin resistance. Previous studies have shown that wogonin (5,7-dihydroxy-8-methoxyflavone), a flavonoid isolated from the root of the medicinal herb Scutellaria baicalensis Georgi, sensitizes cancer cells to chemotheraputics such as etoposide, adriamycin, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and TNF.

In this study, the non-small-cell lung cancer cell line A549 and the cervical cancer cell line HeLa were treated with wogonin or cisplatin individually or in combination. It was found for the first time that wogonin is able to sensitize cisplatin-induced apoptosis in both A549 cells and HeLa cells as indicated by the potentiation of activation of caspase-3, and cleavage of the caspase-3 substrate PARP in wogonin and cisplatin co-treated cells.

Results provided important new evidence supporting the potential use of wogonin as a cisplatin sensitizer for cancer therapy (He et al., 2012).

References

Chen LG, Hung LY, Tsai KW, et al. (2008). Wogonin, a bioactive flavonoid in herbal tea, inhibits inflammatory cyclooxygenase-2 gene expression in human lung epithelial cancer cells. Mol Nutr Food Res. 52:1349-1357.


Chung H, Jung YM, Shin DH, et al. (2008). Anti-cancer effects of wogonin in both estrogen receptor-positive and -negative human breast cancer cell lines in vitro and in nude mice xenografts. Int J Cancer, 122(4):816-22.


Dong P, Zhang Y, Gu J, et al. (2011). Wogonin, an active ingredient of Chinese herb medicine Scutellaria baicalensis, inhibits the mobility and invasion of human gallbladder carcinoma GBC-SD cells by inducing the expression of maspin. J Ethnopharmacol, 137(3):1373-80. doi: 10.1016/j.jep.2011.08.005.


He F, Wang Q, Zheng XL, et al. (2012). Wogonin potentiates cisplatin-induced cancer cell apoptosis through accumulation of intracellular reactive oxygen species. Oncology Reports, 28(2), 601-605. doi: 10.3892/or.2012.1841.


Kim EJ, Kang D, Han J. (2011). Baicalein and wogonin are activators of rat TREK-2 two-pore domain K+ channel. Acta Physiologica, 202(2):185–192. doi: 10.1111/j.1748-1716.2011.02263.x.


Kim SJ, Kim HJ, Kim HR, et al. (2012). Anti-tumor actions of baicalein and wogonin in HT-29 human colorectal cancer cells. Mol Med Rep, 6(6):1443-9. doi: 10.3892/mmr.2012.1085.


Kimura Y & Sumiyoshi M. (2012). Anti-tumor and anti-metastatic actions of wogonin isolated from Scutellaria baicalensis roots through anti-lymphangiogenesis. Phytomedicine, 20(3-4):328-336. doi:10.1016/j.phymed.2012.10.016


Ma X, Xie KP, Shang F, et al. (2012). Wogonin inhibits IGF-1-stimulated cell growth and estrogen receptor α expression in breast adenocarcinoma cell and angiogenesis of chick chorioallantoic membrane. Sheng Li Xue Bao, 64(2):207-12.


Wang H, Zhao L, Zhu LT, et al. (2013). Wogonin reverses hypoxia resistance of human colon cancer HCT116 cells via down-regulation of HIF-1α and glycolysis, by inhibiting PI3K/Akt signaling pathway. Mol Carcinog. doi: 10.1002/mc.22052.


Yang L, Wang Q, Li D, et al. (2013). Wogonin enhances anti-tumor activity of tumor necrosis factor-related apoptosis-inducing ligand in vivo through ROS-mediated down-regulation of cFLIPL and IAP proteins. Apoptosis, 18(5):618-26. doi: 10.1007/s10495-013-0808-8.

Subamolide A

Cancer: Lung, urothelial carcinoma

Action: Increases cellular reactive oxygen species (ROS) production, decreases glutathione level

Lung Cancer

Subamolide A is isolated from Cinnamomum subavenium (Miq.). The anti-cancer effects of subamolide A (Sub-A) were investigated on human nonsmall cell lung cancer cell lines A549 and NCI-H460. Treatment of cancer cells with Sub-A resulted in decreased cell viability of both lung cancer cell lines. Sub-A induced lung cancer cell death by triggering mitotic catastrophe with apoptosis. It triggered oxidant stress, indicated by increased cellular reactive oxygen species (ROS) production and decreased glutathione level.

Therefore, Sub-A may be a novel anti-cancer agent for the treatment of non-small-cell lung cancer. Human lung cancer cells A549 and NCI-H460 are highly sensitive to Sub-A-induced mitotic catastrophe and apoptosis, mainly via ROS elevation that induces ATM and ATF3 activation, subsequently leading to p53-mediated cell death. Sub-A also causes cell growth inhibition in an in vivo xenograft model. The elucidated molecular bases and processes may provide a new strategy for developing more effective chemotherapeutic regimens for lung cancer treatment (Hung et al., 2013).

Urothelial Carcinoma

A study by Liu et al. (2011) demonstrated that subamolide A triggered the mitochondria-dependent apoptotic pathways and p53 and ERK1/2 activation in the human urothelial carcinoma cell line NTUB1. In addition, subamolide A synergistically enhanced cytotoxic effect of CDDP and Gem in NTUB1. These data suggested that subamolide A exhibited a potent anti-proliferation activity.

Subamolide A selectively induced apoptosis in two cancerous human urothelial carcinoma cell lines (NTUB1 and T24) in comparison with normal immortalized uroepithelial cells (SV-HUC-1). Subamolide A reduced mitochondrial membrane potential (Δψm) and caused apoptosis of NTUB1 cells. Subamolide A increased Bax/Bcl-2 ratios, the amount of cytochrome c released from the mitochondria, caspase-3 and PARP cleavage, activated p53 and ERK1/2 and ultimately led to apoptosis in NTUB1 cells. Furthermore, a higher dose (10µM) of subamolide A synergistically enhanced the cytotoxicity of cisplatin and gemcitabine in NTUB1 cells.

References

Hung JY, Wen CW, Hsu YL, et al. (2013). Subamolide A Induces Mitotic Catastrophe Accompanied by Apoptosis in Human Lung Cancer Cells. Evidence-Based Complementary and Alternative Medicine, 2013: 828143. doi:10.1155/2013/828143.


Liu CH, Chen CY, Huang AM, Li JH. (2011) Subamolide A, a component isolated from Cinnamomum subavenium, induces apoptosis mediated by mitochondria-dependent, p53 and ERK1/2 pathways in human urothelial carcinoma cell line NTUB1. J Ethnopharmacol,137(1):503-11. doi: 10.1016/j.jep.2011.06.001.

Sophoridine (See also oxymatrine,Matrine)

Cancer: Colorectal, lung

Action: Cell-cycle arrest

Cell-cycle Arrest

Matrine, sophoridine and oxymatrine are isolates from Sophora Flavescens (Aiton).

Sophoridine (SRI) inhibited the growth of SW620 cells significantly in a dose-and time-dependent manner, and morphological characteristics of apoptosis were observed with condensation of the nucleus, cytoplasmic bubbling, and DNA fragmentation. A DNA ladder pattern of inter-nucleosomal fragmentation was observed. Compared with that of the control group, the percentage of the G0/G1 phase and the S phase cells increased after treatment by SRI. Apoptosis was induced in SW620 cells and underwent G0/G1 arrest with exposure to SRI as evidenced by flow cytometry results. Sophoridine could induce the inhibition of cell growth by means of apoptosis in a dose-and time-dependent manner, and cellcycle arrest at G0/G1 (Liang et al., 2008).

Colorectal Cancer

The anti-proliferation of sophoridine (SRI) in human colorectal cells SW480 was detected by3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The pathology and ultrastructure of xenograft tumors treated with SRI were also observed. SRI significantly inhibited the growth of SW480 cells, and the administration of SRI significantly inhibited the growth of xenograft tumors without apparent toxicity. SRI's mechanism of action involved the induction of apoptosis.

These results suggest that SRI produces obvious anti-tumor effects in vitro and in vivo. It supports the viability of developing SRI as a novel therapeutic prodrug for colorectal cancer treatment, as well as providing a method for identifying new anti-tumor drugs in traditional Chinese medicine (Liang et al., 2012).

Sophoridine can inhibit the growth of transplanted solid tumor of human colon cancer SW480 cell line, the mechanism of which involves the inhibition of p53 and VEGF expression. The volume and weight of the tumor xenograft in sophoridine group decreased in comparison with those in the control group. Sophoridine treatment resulted in lowered expressions of p53 and VEGF at both the protein and mRNA levels in the tumor explants as compared with the control group, with a tumor inhibition rate of 34.07% in nude mice (Wang et al., 2010).

References

Liang L, Zhang XH, Wang XY, Chen Y, Deng HZ. (2008). Effect of sophoridine on proliferation and apoptosis of human colon adenocarcinoma cells (SW620). Zhong Guo Yao Li Xue Tong Bao, 24(6): 782-787.


Liang W, Wang XY, Zhang XH, et al. (2012). Sophoridine exerts an anti-colorectal carcinoma effect through apoptosis induction in vitro and in vivo. Life Sciences, 91(25–26):1295–1303


Wang QR, Li CH, Fu XQ, et al. (2010). Effects of sophoridine on the growth and expressions of p53 and vascular endothelial growth factor of transplanted solid tumor SW480 in nude mice. Nan Fang Yi Ke Da Xue Xue Bao, 30(7):1593-6.

Salvianolic acid-B / Salvinal

Cancer:
Head and neck squamous cell carcinoma, oral squamous cell carcinoma, glioma

Action: MDR, reduction of cardiotoxicity, COX-2 inhibitor, inflammatory-associated tumor development, anti-cancer

Salvia miltiorrhiza contains a variety of anti-tumor active ingredients, such as the water-soluble components, salvianolic acid A, salvianolic acid B, salvinal, and liposoluble constituents, tanshinone I, tanshinone IIA, dihydrotanshinone I, miltirone, cryptotanshinone, ailantholide, neo-tanshinlactone, and nitrogen-containing compounds. These anti-tumor active components play important roles in the different stages of tumor evolution, progression and metastasis (Zhang & Lu, 2010).

Anti-cancer/MDR

Aqueous extracts of Salvia miltiorrhizae Bunge have been extensively used in the treatment of cardiovascular disorders and cancer in Asia. Recently, a compound, 5-(3-hydroxypropyl)-7-methoxy-2-(3'-methoxy-4'-hydroxyphenyl)-3-benzo[b]furancarbaldehyde (salvinal), isolated from this plant showed inhibitory activity against tumor cell growth and induced apoptosis in human cancer cells. In the present study, we investigated the cytotoxic effect and mechanisms of action of salvinal in human cancer cell lines. Salvinal caused inhibition of cell growth (IC50 range, 4-17 microM) in a variety of human cancer cell lines.

In particular, salvinal exhibited similar inhibitory activity against parental KB, P-glycoprotein-overexpressing KB vin10 and KB taxol-50 cells, and multi-drug resistance-associated protein (MRP)-expressing etoposide-resistant KB 7D cells.

Taken together, our data demonstrate that salvinal inhibits tubulin polymerization, arrests cell-cycle at mitosis, and induces apoptosis. Notably, Salvinal is a poor substrate for transport by P-glycoprotein and MRP. Salvinal may be useful in the treatment of human cancers, particularly in patients with drug resistance (Chang et al., 2004).

Glioma

Salvianolic acid B (SalB) has been shown to exert anti-cancer effect in several cancer cell lines. SalB increased the phosphorylation of p38 MAPK and p53 in a dose-dependent manner. Moreover, blocking p38 activation by specific inhibitor SB203580 or p38 specific siRNA partly reversed the anti-proliferative and pro-apoptotic effects, and ROS production induced by SalB treatment.

These findings extended the anti-cancer effect of SalB in human glioma cell lines, and suggested that these inhibitory effects of SalB on U87 glioma cell growth might be associated with p38 activation mediated ROS generation. Thus, SalB might be concerned as an effective and safe natural anti-cancer agent for glioma prevention and treatment (Wang et al., 2013).

Reduced Cardiotoxicity

Clinical attempts to reduce the cardiotoxicity of arsenic trioxide (ATO) without compromising its anti-cancer activities remain an unresolved issue. In this study, Wang et al., (2013b) determined that Sal B can protect against ATO-induced cardiac toxicity in vivo and increase the toxicity of ATO toward cancer cells.

The combination treatment significantly enhanced the ATO-induced cytotoxicity and apoptosis of HepG2 cells and HeLa cells. Increases in apoptotic marker cleaved poly (ADP-ribose) polymerase and decreases in procaspase-3 expressions were observed through Western blot. Taken together, these observations indicate that the combination treatment of Sal B and ATO is potentially applicable for treating cancer with reduced cardiotoxic side effects.

Oral Cancer

Sal B has inhibitory effect on oral squamous cell carcinoma (OSCC) cell growth. The anti-tumor effect can be attributed to anti-angiogenic potential induced by a decreased expression of some key regulator genes of angiogenesis. Sal B may be a promising modality for treating oral squamous cell carcinoma.

Sal B induced growth inhibition in OSCC cell lines but had limited effects on premalignant cells. A total of 17 genes showed a greater than 3-fold change when comparing Sal B treated OSCC cells to the control. Among these genes, HIF-1α, TNFα and MMP9 are specifically inhibited; expression of THBS2 was up-regulated (Yang et al., 2011).

Head and Neck Cancer

Overexpression of cyclooxygenase-2 (COX-2) in oral mucosa has been associated with increased risk of head and neck squamous cell carcinoma (HNSCC). Celecoxib is a non-steroidal anti-inflammatory drug, which inhibits COX-2 but not COX-1. This selective COX-2 inhibitor holds promise as a cancer-preventive agent. Concerns about the cardiotoxicity of celecoxib limit its use in long-term chemo-prevention and therapy. Salvianolic acid B (Sal-B) is a leading bioactive component of Salvia miltiorrhiza Bge, which is used for treating neoplastic and chronic inflammatory diseases in China.

Tumor volumes in Sal-B treated group were significantly lower than those in celecoxib treated or untreated control groups (p < 0.05). Sal-B inhibited COX-2 expression in cultured HNSCC cells and in HNSCC cells isolated from tumor xenografts. Sal-B also caused dose-dependent inhibition of prostaglandin E(2) synthesis, either with or without lipopolysaccharide stimulation. Taking these results together, Sal-B shows promise as a COX-2 targeted anti-cancer agent for HNSCC prevention and treatment (Hao et al., 2009).

Inflammatory-associated tumor development

A half-dose of daily Sal-B (40 mg/kg/d) and celecoxib (2.5 mg/kg/d) significantly inhibited JHU-013 xenograft growth relative to mice treated with a full dose of Sal-B or celecoxib alone. The combination was associated with profound inhibition of COX-2 and enhanced induction of apoptosis. Taken together, these results strongly suggest that a combination of Sal-B, a multifunctional anti-cancer agent, with low-dose celecoxib holds potential as a new preventive strategy in targeting inflammatory-associated tumor development (Zhao et al., 2010).

Squamous Cell Carcinoma

The results showed that Sal B significantly decreased the squamous cell carcinoma (SCC) incidence from 64.7 (11/17) to 16.7% (3/18) (P=0.004); angiogenesis was inhibited in dysplasia and SCC (P<0.01), with a simultaneous decrease in the immunostaining of hypoxia-inducible factor 1alpha and vascular endothelium growth factor protein (P<0.05). The results suggested that Sal B had inhibitory effect against the malignant transformation of oral precancerous lesion and such inhibition may be related to the inhibition of angiogenesis (Zhou, Yang, & Ge, 2006).

References

Chang JY, Chang CY, Kuo CC, et al. (2004). Salvinal, a novel microtubule inhibitor isolated from Salvia miltiorrhizae Bunge (Danshen), with antimitotic activity in Multi-drug-sensitive and -resistant human tumor cells. Mol Pharmacol, 65(1):77-84.


Hao Y, Xie T, Korotcov A, et al. (2009). Salvianolic acid B inhibits growth of head and neck squamous cell carcinoma in vitro and in vivo via cyclooxygenase-2 and apoptotic pathways. Int J Cancer, 124(9):2200-9. doi: 10.1002/ijc.24160.


Wang ZS, Luo P, Dai SH, et al., (2013a). Salvianolic acid B induces apoptosis in human glioma U87 cells through p38-mediated ROS generation. Cell Mol Neurobiol, 33(7):921-8. doi: 10.1007/s10571-013-9958-z.


Wang M, Sun G, Wu P, et al. (2013b). Salvianolic Acid B prevents arsenic trioxide-induced cardiotoxicity in vivo and enhances its anti-cancer activity in vitro. Evid Based Complement Alternat Med, 2013:759483. doi: 10.1155/2013/759483.


Yang Y, Ge PJ, Jiang L, Li FL, Zhum QY. (2011). Modulation of growth and angiogenic potential of oral squamous carcinoma cells in vitro using salvianolic acid B. BMC Complement Altern Med, 11:54. doi: 10.1186/1472-6882-11-54.


Zhang W, Lu Y. (2010). Advances in studies on anti-tumor activities of compounds in Salvia miltiorrhiza. Zhongguo Zhong Yao Za Zhi, 35(3):389-92.


Zhao Y, Hao Y, Ji H, Fang Y, et al. (2010). Combination effects of salvianolic acid B with low-dose celecoxib on inhibition of head and neck squamous cell carcinoma growth in vitro and in vivo. Cancer Prev Res (Phila), 3(6):787-96. doi: 10.1158/1940-6207.CAPR-09-0243.


Zhou ZT, Yang Y, Ge JP. (2006). The preventive effect of salvianolic acid B on malignant transformation of DMBA-induced oral premalignant lesion in hamsters. Carcinogenesis, 27(4):826-32.

Saikosaponin

Cancers:
Cervical, colon, liver, lung, ovarian, liver, breast, hepatocellular

Action: Anti-angiogenic, anti-metastatic, chemo-sensitizer, pro-oxidative, cell-cycle arrest

T cell-mediated autoimmune, induces apoptosis, immune regulating, radio-sensitizer

Induces Apoptosis

Long dan xie gan tang, a well known Chinese herbal formulation, is commonly used by patients with chronic liver disease in China. Accumulated anecdotal evidence suggests that Long dan tang may have beneficial effects in patients with hepatocellular carcinoma. Long dan tang is comprised of five herbs: Gentiana root, Scutellaria root, Gardenia fruit, Alisma rhizome, and Bupleurum root. The cytotoxic effects of compounds from the five major ingredients isolated from the above plants, i.e. gentiopicroside, baicalein, geniposide, alisol B acetate and saikosaponin-d, respectively, on human hepatoma Hep3B cells, were investigated.

Annexin V immunofluorescence detection, DNA fragmentation assays and FACScan analysis of propidium iodide-staining cells showed that gentiopicroside, baicalein, and geniposide had little effect, whereas alisol B acetate and saikosaponin-d profoundly induced apoptosis in Hep3B cells. Alisol B acetate, but not saikosaponin-d, induced G2/M arrest of the cell-cycle as well as a significant increase in caspase-3 activity. Interestingly, baicalein by itself induced an increase in H(2)O(2) generation and the subsequent NF-kappaB activation; furthermore, it effectively inhibited the transforming growth factor-beta(1) (TGF-beta(1))-induced caspase-3 activation and cell apoptosis.

Results suggest that alisol B acetate and saikosaponin-d induced cell apoptosis through the caspase-3-dependent and -independent pathways, respectively. Instead of inducing apoptosis, baicalein inhibits TGF-beta(1)-induced apoptosis via increase in cellular H(2)O(2) formation and NF-kappaB activation in human hepatoma Hep3B cells (Chou, Pan, Teng & Guh, 2003).

Breast

Saikosaponin-A treatment of MDA-MB-231 for 3 hours and of MCF-7 cells for 2 hours, respectively, caused an obvious increase in the sub G1 population of cell-cycles.

Apoptosis in MDA-MB-231 cells was independent of the p53/p21 pathway mechanism and was accompanied by an increased ratio of Bax to Bcl-2 and c-myc levels and activation of caspase-3. In contrast, apoptosis of MCF-7 cells may have been initiated by the Bcl-2 family of proteins and involved p53/p21 dependent pathway mechanism, and was accompanied by an increased level of c-myc protein. The apoptosis of both MDA-MB-231 and MCF-7 cells showed a difference worthy of further research (Chen, Chang, Chung, & Chen, 2003).

Hepatocellular Carcinoma

The signaling pathway mediating induction of p15(INK4b) and p16(INK4a) during HepG2 growth inhibition triggered by the phorbol ester tumor promoter TPA (12-O-tetradecanoylphorbol 13-acetate) and the Chinese herbal compund Saikosaponin A was investigated.

Expressions of proto-oncogene c-jun, junB and c-fos were induced by TPA and Saikosaponin A between 30 minutes to 6 hours of treatment. Pre-treatment of 20 microg/ml PD98059, an inhibitor of MEK (the upstream kinase of ERK), prevents the TPA and Saikosaponin A triggered HepG2 growth inhibition by 50% and 30%, respectively. In addition, AP-1 DNA-binding assay, using non-isotopic capillary electrophoresis and laser-induced fluorescence (CE/LIF), demonstrated that the AP-1-related DNA-binding activity was significantly induced by TPA and Saikosaponin A, which can be reduced by PD98059 pre-treatment.

Results suggest that activation of ERK, together with its downstream transcriptional machinery, mediated p15(INK4b) and p16(INK4a) expression that led to HepG2 growth inhibition (Wen-Sheng, 2003).

The effects of Saikosaponin D (SSd) on syndecan-2, matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases-2 (TIMP-2) in livers of rats with hepatocellular carcinoma (HCC) was investigated.

The model group had more malignant nodules than the SSd group. Model-group HCC cells were grade III; SSd-group HCC cells were grades I-II. Controls showed normal hepatic cell phenotypes and no syndecan-2+ staining. Syndecan-2+ staining was greater in the model group (35.2%, P < or = 0.001) than in controls or the SSd group (16.5%, P < or = 0.001). The model group had more intense MMP-2+ staining than controls (0.37 vs 0.27, P< or =0.01) or the SSd group (0.31 vs 0.37, P< or =0.05); and higher MMP-13+ staining (72.55%) than in controls (12.55%, P< or =0.001) and SSd group (20.18%, P< or =0.01).

The model group also had more TIMP-2+ staining (57.2%) than controls (20.9%, P< or =0.001) and SSd group (22.7%, P< or=0.001). Controls and SSd group showed no difference in TIMP-2+ rates.

SSd inhibited HCC development, and downregulated expression of syndecan-2, MMP-2, MMP-13 and TIMP-2 in rat HCC liver tissue (Jia et al., 2012).

T Cell-mediated Autoimmune

Saikosaponin-d (Ssd) is a triterpene saponin derived from the medicinal plant, Bupleurum falcatum L. (Umbelliferae). Previous findings showed that Ssd exhibits a variety of pharmacological and immunomodulatory activities including anti-inflammatory, anti-bacterial, anti-viral and anti-cancer effects.

Results demonstrated that Ssd not only suppressed OKT3/CD28-costimulated human T cell proliferation, it also inhibited PMA, PMA/Ionomycin and Con A-induced mouse T cell activation in vitro. The inhibitory effect of Ssd on PMA-induced T cell activation was associated with down-regulation of NF-kappaB signaling through suppression of IKK and Akt activities. In addition, Ssd suppressed both DNA binding activity and the nuclear translocation of NF-AT and activator protein 1 (AP-1) of the PMA/Ionomycin-stimulated T cells. The cell surface markers, such as IL-2 receptor (CD25), were also down-regulated along with decreased production of pro-inflammatory cytokines of IL-6, TNF-alpha and IFN-gamma.

Results indicate that the NF-kappaB, NF-AT and AP-1 (c-Fos) signaling pathways are involved in the T cell inhibition evoked by Ssd. Ssd could be a potential candidate for further study in treating T cell-mediated autoimmune conditions (Wong, Zhou, Cheung, Li, & Liu, 2009).

Cervical Cancer

Saikosaponin-a and -d, two naturally occurring compounds derived from Bupleurum radix, have been shown to exert anti-cancer activity in several cancer cell lines. However, the effect of a combination of saikosaponins with chemotherapeutic drugs have never been addressed. Investigated as to whether these two saikosaponins have chemo-sensitization effect on cisplatin-induced cancer cell cytotoxicity was carried out.

Two cervical cancer cell lines, HeLa and Siha, an ovarian cancer cell line, SKOV3, and a non-small-cell lung cancer cell line, A549, were treated with saikosaponins or cisplatin individually or in combination. Cell death was quantitatively detected by the release of lactate dehydrogenase (LDH) using a cytotoxicity detection kit. Cellular ROS was analyzed by flow cytometry. Apoptosis was evaluated by AO/EB staining, flow cytometry after Anexin V and PI staining, and Western blot for caspase activation. ROS scavengers and caspase inhibitor were used to determine the roles of ROS and apoptosis in the effects of saikosaponins on cisplatin-induced cell death.

Both saikosaponin-a and -d sensitized cancer cells to cisplatin-induced cell death in a dose-dependent manner, which was accompanied with induction of reactive oxygen species (ROS) accumulation.

Results suggest that saikosaponins sensitize cancer cells to cisplatin through ROS-mediated apoptosis, and the combination of saikosaponins with cisplatin could be an effective therapeutic strategy (Wang et al., 2010).

Colon Cancer

Saikosaponin-a (SSa)-induced apoptosis of HCC cells was associated with proteolytic activation of caspase-9, caspase-3, and PARP cleavages and decreased levels of IAP family members, such as XIAP and c-IAP-2, but not of survivin. SSa treatment also enhanced the activities of caspase-2 and caspase-8, Bid cleavage, and the conformational activation of Bax. Moreover, inhibition of caspase-2 activation by the pharmacological inhibitor z-VDVAD-fmk, or by knockdown of protein levels using a si-RNA, suppressed SSa-induced caspase-8 activation, Bid cleavage, and the conformational activation of Bax. Although caspase-8 is an initiator caspase like caspase-2, the inhibition of caspase-8 activation by knockdown using a si-RNA did not suppress SSa-induced caspase-2 activation.

Results suggest that sequential activation of caspase-2 and caspase-8 is a critical step in SSa-induced apoptosis (Kim & Hong, 2011).

Immune Regulating

Tumor necrosis factor-alpha (TNF- α ) was reported as an anti-cancer therapy due to its cytotoxic effect against an array of tumor cells. However, its undesirable responses of TNF- α on activating NF- κB signaling and pro-metastatic property limit its clinical application in treating cancers. Therefore, sensitizing agents capable of overcoming this undesirable effect must be valuable for facilitating the usage of TNF- α -mediated apoptosis therapy for cancer patients. Previously, saikosaponin-d (Ssd), a triterpene saponin derived from the medicinal plant, Bupleurum falcatum L. (Umbelliferae), exhibited a variety of pharmacological activities such as anti-inflammatory, anti-bacterial, anti-viral and anti-cancer.

Investigation found that Ssd could potentially inhibit activated T lymphocytes via suppression of NF- κ B, NF-AT and AP-1 signaling. Ssd significantly potentiated TNF- α -mediated cell death in HeLa and HepG2 cancer cells via suppression of TNF- α -induced NF- κ B activation and its target genes expression involving cancer cell proliferation, invasion, angiogenesis and survival. Also, Ssd revealed a significant potency in abolishing TNF- α -induced cancer cell invasion and angiogenesis in HUVECs while inducing apoptosis via enhancing the loss of mitochondrial membrane potential in HeLa cells.

Collectively, findings indicate that Ssd has significant potential to be developed as a combined adjuvant remedy with TNF- α for cancer patients (Wong et al., 2013).

Radio-sensitizer

Saikosaponin-d (SSd), a monomer terpenoid purified from the Chinese herbal drug Radix bupleuri, has multiple effects, including anti-cancer properties. Treatment with SSd alone and radiation alone inhibited cell growth and increased apoptosis rate at the concentration used. These effects were enhanced when SSd was combined with radiation. Moreover, SSd potentiated the effects of radiation to induce G0/G1 arrest in SMMC-7721 hepatocellular carcinoma cells, and reduced the G2/M-phase population under hypoxia. SSd potentiates the effects of radiation on SMMC-7721 cells; thus, it is a promising radio-sensitizer. The radio-sensitizing effect of SSd may contribute to its effect on the G0/G1 and G2/M checkpoints of the cell-cycle (Wang et al., 2013).

References

Chen JC, Chang NW, Chung JG, Chen KC. (2003). Saikosaponin-A induces apoptotic mechanism in human breast MDA-MB-231 and MCF-7 cancer cells. The American Journal of Chinese Medicine, 31(3), 363-77.


Chou CC, Pan SL, Teng CM, Guh JH. (2003). Pharmacological evaluation of several major ingredients of Chinese herbal medicines in human hepatoma Hep3B cells. European Journal of Pharmaceutical Sciences, 19(5), 403-12.


Jia X, Dang S, Cheng Y, et al. (2012). Effects of saikosaponin-d on syndecan-2, matrix metalloproteinases and tissue inhibitor of metalloproteinases-2 in rats with hepatocellular carcinoma. Journal of Traditional Chinese Medicine, 32(3), 415-22.


Kim BM, Hong SH. (2011). Sequential caspase-2 and caspase-8 activation is essential for saikosaponin a-induced apoptosis of human colon carcinoma cell lines. Apoptosis, 16(2), 184-197. doi: 10.1007/s10495-010-0557-x.


Wang BF, Dai ZJ, Wang XJ, et al. (2013). Saikosaponin-d increases the radiosensitivity of smmc-7721 hepatocellular carcinoma cells by adjusting the g0/g1 and g2/m checkpoints of the cell-cycle. BMC Complementary and Alternative Medicine, 13:263. doi:10.1186/1472-6882-13-263


Wang Q, Zheng XL, Yang L, et al. (2010). Reactive oxygen species-mediated apoptosis contributes to chemo-sensitization effect of saikosaponins on cisplatin-induced cytotoxicity in cancer cells. Journal of Experimental & Clinical Cancer Research, 9(29), 159. doi: 10.1186/1756-9966-29-159.


Wen-Sheng, W. (2003). ERK signaling pathway is involved in p15INK4b/p16INK4a expression and HepG2 growth inhibition triggered by TPA and Saikosaponin A. Oncogene, 22(7), 955-963.


Wong VK, Zhang MM, Zhou H, et al. (2013). Saikosaponin-d Enhances the Anti-cancer Potency of TNF- α via Overcoming Its Undesirable Response of Activating NF-Kappa B Signaling in Cancer Cells. Evidence-based Complementary and Alternative Medicine, 2013(2013), 745295. doi: 10.1155/2013/745295.


Wong VK, Zhou H, Cheung SS, Li T, Liu L. (2009). Mechanistic study of saikosaponin-d (Ssd) on suppression of murine T lymphocyte activation. Journal of Cellular Biochemistry, 107(2), 303-15. doi: 10.1002/jcb.22126.

RG3 (See also Ginsenosides)

Cancer: Glioblastoma, prostate, breast, colon

Action: Anti-angiogenesis, MDR, enhances chemotherapy, MDR, enhanced paclitaxel absorption, anti-metastatic

RG3 is a ginsenoside isolated from red ginseng (Panax ginseng (L.)), after being peeled, heated, and dried.

Angiosuppressive Activity

Aberrant angiogenesis is an essential step for the progression of solid tumors. Thus anti-angiogenic therapy is one of the most promising approaches to control tumor growth.

Rg3 was found to inhibit the proliferation of human umbilical vein endothelial cells (HUVEC) with an IC50 of 10 nM in Trypan blue exclusion assay.

Rg3 (1-10(3) nM) also dose-dependently suppressed the capillary tube formation of HUVEC on the Matrigel in the presence or absence of 20 ng/ml vascular endothelial growth factor (VEGF). The Matrix metalloproteinases (MMPs), such as MMP-2 and MMP-9, which play an important role in the degradation of basement membrane in angiogenesis and tumor metastasis present in the culture supernatant of Rg3-treated aortic ring culture were found to decrease in their gelatinolytic activities. Taken together, these data underpin the anti-tumor properties of Rg3 through its angiosuppressive activity (Yue et al., 2006).

Glioblastoma

Rg3 has been reported to exert anti-cancer activities through inhibition of angiogenesis and cell proliferation. The mechanisms of apoptosis by ginsenoside Rg3 were related with the MEK signaling pathway and reactive oxygen species. Our data suggest that ginsenoside Rg3 is a novel agent for the chemotherapy of glioblastoma multiforme (GBM) (Choi et al., 2013).

Sin, Kim, & Kim (2012) report that chronic treatment with Rg3 in a sub-lethal concentration induced senescence-like growth arrest in human glioma cells. Rg3-induced senescence was partially rescued when the p53/p21 pathway was inactivated. Data indicate that Rg3 induces senescence-like growth arrest in human glioma cancer through the Akt and p53/p21-dependent signaling pathways.

MDR/Enhanced Paclitaxel Absorption

The penetration of paclitaxel through the Caco-2 monolayer from the apical side to the basal side was facilitated by 20(s)-ginsenoside Rg3 in a concentration-dependent manner. Rg3 also inhibited P-glycoprotein (P-gp), and the maximum inhibition was achieved at 80 µM (p < 0.05). The relative bioavailability (RB)% of paclitaxel with 20(s)-ginsenoside Rg3 was 3.4-fold (10 mg/kg) higher than that of the control. Paclitaxel (20 mg/kg) co-administered with 20(s)-ginsenoside Rg3 (10 mg/kg) exhibited an effective anti-tumor activity with the relative tumor growth rate (T/C) values of 39.36% (p <0.05).

The results showed that 20(s)-ginsenoside Rg3 enhanced the oral bioavailability of paclitaxel in rats and improved the anti-tumor activity in nude mice, indicating that oral co-administration of paclitaxel with 20(s)-ginsenoside Rg3 could provide an effective strategy in addition to the established i.v. route (Yang et al., 2012).

Prostate Cancer

The anti-proliferation effect of Rg3 on prostate cancer cells has been well reported. Rg3 treatment triggered the activation of p38 MAPK; and SB202190, a specific inhibitor of p38 MAPK, antagonized the Rg3-induced regulation of AQP1 and cell migration, suggesting a crucial role for p38 in the regulation process. Rg3 effectively suppresses migration of PC-3M cells by down-regulating AQP1 expression through p38 MAPK pathway and some transcription factors acting on the AQP1 promoter (Pan et al., 2012).

Enhances Chemotherapy

The clinical use of cisplatin (cis-diamminedichloroplatinum II) has been limited by the frequent emergence of cisplatin-resistant cell populations and numerous other adverse effects. Therefore, new agents are required to improve the therapy and health of cancer patients. Oral administration of ginsenoside Rg3 significantly inhibited tumor growth and promoted the anti-neoplastic efficacy of cisplatin in mice inoculated with CT-26 colon cancer cells. In addition, Rg3 administration remarkably inhibited cisplatin-induced nephrotoxicity, hepatotoxicity and oxidative stress.

Rg3 promotes the efficacy of cisplatin by inhibiting HO-1 and NQO-1 expression in cancer cells and protects the kidney and liver against tissue damage by preventing cisplatin-induced intracellular ROS generation (Lee et al., 2012).

Colon Cancer

Rg3-induced apoptosis in HT-29 cells is mediated via the AMPK signaling pathway, and that 20(S)-Rg3 is capable of inducing apoptosis in colon cancer. Rg3-treated cells displayed several apoptotic features, including DNA fragmentation, proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) and morphological changes. 20(S)-Rg3 down-regulated the expression of anti-apoptotic protein B-cell CLL/lymphoma 2 (Bcl2), up-regulated the expression of pro-apoptotic protein of p53 and Bcl-2-associated X protein (Bax), and caused the release of mitochondrial cytochrome c, PARP, caspase-9 and caspase-3 (Yuan et al., 2010).

Anti-metastatic

Studies have linked Rg3 with anti-metastasis of cancer in vivo and in vitro and the CXC receptor 4 (CXCR4) is a vital molecule in migration and homing of cancer to the docking regions. At a dosage without obvious cytotoxicity, Rg3 treatment elicits a weak CXCR4 stain color, decreases the number of migrated cells in CXCL12-elicited chemotaxis and reduces the width of the scar in wound healing and Rg3 is a new CXCR4 inhibitor (Chen et al., 2011).

References

Chen XP, Qian LL, Jiang H, Chen JH. (2011). Ginsenoside Rg3 inhibits CXCR4 expression and related migrations in a breast cancer cell line. Int J Clin Oncol, 16(5):519-23. doi: 10.1007/s10147-011-0222-6.


Choi YJ, Lee HJ, Kang DW, et al. (2013). Ginsenoside Rg3 induces apoptosis in the U87MG human glioblastoma cell line through the MEK signaling pathway and reactive oxygen species. Oncol Rep. doi: 10.3892/or.2013.2555.


Lee CK, Park KK, Chung AS, Chung WY. (2012). Ginsenoside Rg3 enhances the chemosensitivity of tumors to cisplatin by reducing the basal level of nuclear factor erythroid 2-related factor 2-mediated heme oxygenase-1/NAD(P)H quinone oxidoreductase-1 and prevents normal tissue damage by scavenging cisplatin-induced intracellular reactive oxygen species. Food Chem Toxicol, 50(7):2565-74. doi: 10.1016/j.fct.2012.01.005.


Pan XY, Guo H, Han J, et al. (2012). Ginsenoside Rg3 attenuates cell migration via inhibition of aquaporin 1 expression in PC-3M prostate cancer cells. Eur J Pharmacol, 683(1-3):27-34. doi: 10.1016/j.ejphar.2012.02.040.


Sin S, Kim SY, Kim SS. (2012). Chronic treatment with ginsenoside Rg3 induces Akt-dependent senescence in human glioma cells. Int J Oncol., 41(5):1669-74. doi: 10.3892/ijo.2012.1604.


Yang LQ, Wang B, Gan H, et al. (2012). Enhanced oral bioavailability and anti-tumor effect of paclitaxel by 20(s)-ginsenoside Rg3 in vivo. Biopharm Drug Dispos., 33(8):425-36. doi: 10.1002/bdd.1806.


Yuan HD, Quan HY, Zhang Y, et al. (2010). 20(S)-Ginsenoside Rg3-induced apoptosis in HT-29 colon cancer cells is associated with AMPK signaling pathway. Mol Med Rep., 3(5):825-31. doi: 10.3892/mmr.2010.328.


Yue PY, Wong DY, Wu PK, et al. (2006). The angiosuppressive effects of 20 (R)-ginsenoside Rg3. Biochem Pharmacol, 72(4):437-45.

Oleanolic Acid (OA)

Cancer:
Pancreatic, hepatocellular carcinoma, prostate, lung, gastric, breast

Action: Radio-sensitizer, pro-apoptotic with 5-FU

Oleanolic acid (OA), a pentacyclic triterpenoid isolated from several plants, including Rosa woodsii (Lindl.), Prosopis glandulosa (Torr.), Phoradendron juniperinum (Engelm. ex A. Gray), Syzygium claviflorum (Roxburgh), Hyptis capitata (Jacq.) and Ternstromia gymnanthera (L.) exhibits potential anti-tumor activity against many tumor cell lines. Mistletoe contains water-insoluble triterpenoids, mainly oleanolic acid, that have anti-tumorigenic effects (StrŸh et al., 2013).

Pancreatic Cancer

Results of a study by Wei et al. (2012) showed that the proliferation of Panc-28 cells was inhibited by OA in a concentration-dependent manner, with an IC50 (The half maximal inhibitory concentration) value of 46.35 µg ml−1. The study also showed that OA could induce remarkable apoptosis and revealed that OA could induce Reactive Oxygen Species (ROS) generation, mitochondrial depolarization, release of cytochrome C, lysosomal membrane permeabilization and leakage of cathepin B. Further study confirmed that ROS scavenger vitamin C could reverse the apoptosis induced by OA in Panc-28 cells.

These results provide evidence that OA arrests the cell-cycle and induces apoptosis, possibly via ROS-mediated mitochondrial and a lysosomal pathway in Panc-28 cell.

The effects of the combination of OA and 5-fluorouracil (5-FU) on Panc-28 human pancreatic cells showed that combined use synergistically potentiated cell death effects on these cells, and that the pro-apoptotic effects were also increased. The expression of apoptosis related proteins was also affected in cells treated with the combination of OA and 5-FU, including activation of caspases-3 and the expression of Bcl-2/Bax, survivin and NF-κB (Wei et al., 2012).

Radio-sensitizer

The combined treatment of radiation with OA significantly decreased the clonogenic growth of tumor cells and enhanced the numbers of intracellular MN compared to irradiation alone. Furthermore, it was found that the synthesis of cellular GSH was inhibited concomitantly with the down-regulation of γ-GCS activity. Therefore, the utilization of OA as a radio-sensitizing agent for irradiation-inducing cell death offers a potential therapeutic approach to treat cancer (Wang et al., 2013).

Prostate Cancer, Lung Cancer, Gastric Cancer, Breast Cancer

Twelve derivatives of oleanolic acid (OA) have been synthesized and evaluated for their inhibitory activities against the growth of prostate PC3, breast MCF-7, lung A549, and gastric BGC-823 cancer cells by MTT assays. Within these series of derivatives, compound 17 exhibited the most potent cytotoxicity against PC3 cell line (IC50=0.39 µM) and compound 28 displayed the best activity against A549 cell line (IC50=0.22 µM). SAR analysis indicates that H-donor substitution at C-3 position of oleanolic acid may be advantageous for improvement of cytotoxicity against PC3, A549 and MCF-7 cell lines (Hao et al., 2013).

Hepatocellular Carcinoma

OA induced G2/M cell-cycle arrest through p21-mediated down-regulation of cyclin B1/cdc2. Cyclooxygenase-2 (COX-2) and p53 were involved in OA-exerted effect, and extracellular signal-regulated kinase-p53 signaling played a central role in OA-activated cascades responsible for apoptosis and cell-cycle arrest. OA demonstrated significant anti-tumor activities in hepatocellular carcinoma (HCC) in vivo and in vitro models. These data provide new insights into the mechanisms underlying the anti-tumor effect of OA (Wang et al., 2013).

References

Hao J, Liu J, Wen X, Sun H. (2013). Synthesis and cytotoxicity evaluation of oleanolic acid derivatives. Bioorg Med Chem Lett, 23(7):2074-7. doi: 10.1016/j.bmcl.2013.01.129.


StrŸh CM, JŠger S, Kersten A, et al. (2013). Triterpenoids amplify anti-tumoral effects of mistletoe extracts on murine B16.f10 melanoma in vivo. PLoS One, 8(4):e62168. doi: 10.1371/journal.pone.0062168.


Wang J, Yu M, Xiao L, et al. (2013). Radio-sensitizing effect of oleanolic acid on tumor cells through the inhibition of GSH synthesis in vitro. Oncol Rep, 30(2):917-24. doi: 10.3892/or.2013.2510.


Wang X, Bai H, Zhang X, et al. (2013). Inhibitory effect of oleanolic acid on hepatocellular carcinoma via ERK-p53-mediated cell-cycle arrest and mitochondrial-dependent apoptosis. Carcinogenesis, 34(6):1323-30. doi: 10.1093/carcin/bgt058.


Wei JT, Liu M, Liuz, et al. (2012). Oleanolic acid arrests cell-cycle and induces apoptosis via ROS-mediated mitochondrial depolarization and lysosomal membrane permeabilization in human pancreatic cancer cells. Journal of Applied Toxicology, 33(8):756–765. doi: 10.1002/jat.2725


Wei J, Liu H, Liu M, et al. (2012). Oleanolic acid potentiates the anti-tumor activity of 5-fluorouracil in pancreatic cancer cells. Oncol Rep, 28(4):1339-45. doi: 10.3892/or.2012.1921.

Nomilin

Cancer: Melanoma, breast cancer

Action: Anti-angiogenic

Nomilin is a triterpenoid present in common edible citrus fruits (Citrus grandis [(L.) Osb.], Citrus unshiu [(Swingle) Marcow.] and Citrus reticulata (Blanco)) with putative anti-cancer properties.

Melanoma

Nomilin possess anti-metastatic action, inducing metastasis in C57BL/6 mice through the lateral tail vein using highly metastatic B16F-10 melanoma cells. Administration of nomilin inhibited tumor nodule formation in the lungs (68%) and markedly increased the survival rate of the metastatic tumor–bearing animals. Nomilin showed an inhibition of tumor cell invasion and activation of matrix metalloproteinases. Treatment with nomilin induced apoptotic response.

Nomilin treatment also exhibited a down-regulated Bcl-2 and cyclin-D1 expression and up-regulated p53, Bax, caspase-9, caspase-3, p21, and p27 gene expression in B16F-10 cells. Pro-inflammatory cytokine production and gene expression were found to be down-regulated in nomilin-treated cells. The study also reveals that nomilin could inhibit the activation and nuclear translocation of anti-apoptotic transcription factors such as nuclear factor (NF)-κB, CREB, and ATF-2 in B16F-10 cells (Pratheeshkumar et al., 2011).

Breast Cancer; ER+

A panel of 9 purified limonoids, including limonin, nomilin, obacunone, limonexic acid (LNA), isolimonexic acid (ILNA), nomilinic acid glucoside (NAG), deacetyl nomilinic acid glucoside (DNAG), limonin glucoside (LG) and obacunone glucoside (OG) as well as 4 modified compounds such as limonin methoxime (LM), limonin oxime (LO), defuran limonin (DL), and defuran nomilin (DN), were screened for their cytotoxicity on estrogen receptor (ER)-positive (MCF-7) or ER-negative (MDA-MB-231) human breast cancer cells. Findings indicated that the citrus limonoids may have potential for the prevention of estrogen-responsive breast cancer (MCF-7) via caspase-7 dependent pathways (Lin et al., 2013).

Blocks Angoigenesis

Nomilin significantly inhibited tumor-directed capillary formation. Serum pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α and GM-CSF and also serum NO levels were significantly reduced by the treatment of nomilin. Administration of nomilin significantly reduced the serum level of VEGF, a pro-angiogenic factor and increased the anti-angiogenic factors IL-2 and TIMP-1. Nomilin significantly retarded endothelial cell proliferation, migration, invasion and tube formation. These data clearly demonstrate the anti-angiogenic potential of nomilin by down-regulating the activation of MMPs, production of VEGF, NO and pro-inflammatory cytokines as well as up-regulating IL-2 and TIMP (Pratheeshkumar et al., 2011).

References

Kim J, Jayaprakasha GK, Patil BS. (2013). Limonoids and their anti-proliferative and anti-aromatase properties in human breast cancer cells. Food Funct, 4(2):258-65. doi: 10.1039/c2fo30209h.


Pratheeshkumar P, Raphael TJ & Kuttan G. (2011). Nomilin Inhibits Metastasis via Induction of Apoptosis and Regulates the Activation of Transcription Factors and the Cytokine Profile in B16F-10 Cells. Integr Cancer Ther. doi: 10.1177/1534735411403307


Pratheeshkumar P, Kuttan G. (2011). Nomilin inhibits tumor-specific angiogenesis by down-regulating VEGF, NO and pro-inflammatory cytokine profile and also by inhibiting the activation of MMP-2 and MMP-9. Eur J Pharmacol, 668(3):450-8. doi: 10.1016/j.ejphar.2011.07.029.

Magnolol

Cancer:
Bladder, breast, colon, prostate, glioblastoma, ovarian, leukemia, lung

Action: Anti-inflammatory, apoptosis, inhibits angiogenesis, anti-metastatic

Magnolol (Mag), an active constituent isolated from the Chinese herb hou po (Magnolia officinalis (Rehder & Wilson)) has long been used to suppress inflammatory processes. It has anti-cancer activity in colon, hepatoma, and leukemia cell lines.

Anti-inflammatory

Magnolol (Mag) suppressed IL-6-induced promoter activity of cyclin D1 and monocyte chemotactic protein (MCP)-1 for which STAT3 activation plays a role. Pre-treatment of ECs with Mag dose-dependently inhibited IL-6-induced Tyr705 and Ser727 phosphorylation in STAT3 without affecting the phosphorylation of JAK1, JAK2, and ERK1/2. Mag pre-treatment of these ECs dose-dependently suppressed IL-6-induced promoter activity of intracellular cell adhesion molecule (ICAM)-1 that contains functional IL-6 response elements (IREs).

In conclusion, our results indicate that Mag inhibits IL-6-induced STAT3 activation and subsequently results in the suppression of downstream target gene expression in ECs. These results provide a therapeutic basis for the development of Mag as an anti-inflammatory agent for vascular disorders including atherosclerosis (Chen et al., 2006).

Bladder Cancer; Inhibits Angiogenesis

In the present study, Chen et al. (2013) demonstrated that magnolol significantly inhibited angiogenesis in vitro and in vivo, evidenced by the attenuation of hypoxia and vascular endothelial growth factor (VEGF)-induced tube formation of human umbilical vascular endothelial cells, vasculature generation in chicken chorioallantoic membrane, and Matrigel plug.

In hypoxic human bladder cancer cells (T24), treatment with magnolol inhibited hypoxia-stimulated H2O2 formation, HIF-1α induction including mRNA, protein expression, and transcriptional activity as well as VEGF secretion. Interestingly, magnolol also acts as a VEGFR2 antagonist, and subsequently attenuates the downstream AKT/mTOR/p70S6K/4E-BP-1 kinase activation both in hypoxic T24 cells and tumor tissues. As expected, administration of magnolol greatly attenuated tumor growth, angiogenesis and the protein expression of HIF-1α, VEGF, CD31, a marker of endothelial cells, and carbonic anhydrase IX, an endogenous marker for hypoxia, in the T24 xenograft mouse model.

Collectively, these findings strongly indicate that the anti-angiogenic activity of magnolol is, at least in part, mediated by suppressing HIF-1α/VEGF-dependent pathways, and suggest that magnolol may be a potential drug for human bladder cancer therapy.

Colon Cancer; Induces Apoptosis

Emerging evidence has suggested that activation of AMP-activated protein kinase (AMPK), a potential cancer therapeutic target, is involved in apoptosis in colon cancer cells. However, the effects of magnolol on human colon cancer through activation of AMPK remain unexplored.

Magnolol displayed several apoptotic features, including propidium iodide labeling, DNA fragmentation, and caspase-3 and poly(ADP-ribose) polymerase cleavages. Park et al. (2012) showed that magnolol induced the phosphorylation of AMPK in dose- and time-dependent manners.

Magnolol down-regulated expression of the anti-apoptotic protein Bcl2, up-regulated expression of pro-apoptotic protein p53 and Bax, and caused the release of mitochondrial cytochrome c. Magnolol-induced p53 and Bcl2 expression was abolished in the presence of compound C. Magnolol inhibited migration and invasion of HCT-116 cells through AMPK activation. These findings demonstrate that AMPK mediates the anti-cancer effects of magnolol through apoptosis in HCT-116 cells.

Ovarian Cancer

Treatment of HER-2 overexpressing ovarian cancer cells with magnolol down-regulated the HER-2 downstream PI3K/Akt signaling pathway, and suppressed the expression of downstream target genes, vascular endothelial growth factor (VEGF), matrix metalloproteinase 2 (MMP2) and cyclin D1. Consistently, magnolol-mediated inhibition of MMP2 activity could be prevented by co-treatment with epidermal growth factor. Migration assays revealed that magnolol treatment markedly reduced the motility of HER-2 overexpressing ovarian cancer cells. These findings suggest that magnolol may act against HER-2 and its downstream PI3K/Akt/mTOR-signaling network, thus resulting in suppression of HER-2mediated transformation and metastatic potential in HER-2 overexpressing ovarian cancers. These results provide a novel mechanism to explain the anti-cancer effect of magnolol (Chuang et al., 2011).

Lung Cancer

Magnolol has been found to inhibit cell growth, increase lactate dehydrogenase release, and modulate cell cycle in human lung carcinoma A549 cells. Magnolol induced the activation of caspase-3 and cleavage of Poly-(ADP)-ribose polymerase, and decreased the expression level of nuclear factor-κB/Rel A in the nucleus. In addition, magnolol inhibited basic fibroblast growth factor-induced proliferation and capillary tube formation of human umbilical vein endothelial cells. These data indicate that magnolol is a potential candidate for the treatment of human lung carcinoma (Seo et al., 2011).

Prostate Cancer; Anti-metastatic

Matrix metalloproteinases (MMPs) are enzymes involved in various steps of metastasis development. The objective of this study was to study the effects of magnolol on cancer invasion and metastasis using PC-3 human prostate carcinoma cells. Magnolol inhibited cell growth in a dose-dependent manner. In an invasion assay conducted in Transwell chambers, magnolol showed 33 and 98% inhibition of cancer cell at 10 microM and 20 microM concentrations, respectively, compared to the control. The protein and mRNA levels of both MMP-2 and MMP-9 were down-regulated by magnolol treatment in a dose-dependent manner.

These results demonstrate the anti-metastatic properties of magnolol in inhibiting the adhesion, invasion, and migration of PC-3 human prostate cancer cells (Hwang et al., 2010).

Glioblastoma Cancer

Magnolol has been found to concentration-dependently (0-40 microM) decrease the cell number in a cultured human glioblastoma cancer cell line (U373) and arrest the cells at the G0/G1 phase of the cell-cycle.

Pre-treatment of U373 with p21/Cip1 specific antisense oligodeoxynucleotide prevented the magnolol-induced increase of p21/Cip1 protein levels and the decrease of DNA synthesis. Magnolol at a concentration of 100 microM induced DNA fragmentation in U373. These findings suggest the potential applications of magnolol in the treatment of human brain cancers (Chen et al. 2011).

Inhibits Angiogenesis

Magnolol inhibited VEGF-induced Ras activation and subsequently suppressed extracellular signal-regulated kinase (ERK), phosphatidylinositol-3-kinase (PI3K)/Akt and p38, but not Src and focal adhesion kinase (FAK). Interestingly, the knockdown of Ras by short interfering RNA produced inhibitory effects that were similar to the effects of magnolol on VEGF-induced angiogenic signaling events, such as ERK and Akt/eNOS activation, and resulted in the inhibition of proliferation, migration, and vessel sprouting in HUVECs.

In combination, these results demonstrate that magnolol is an inhibitor of angiogenesis and suggest that this compound could be a potential candidate in the treatment of angiogenesis-related diseases (Kim et al., 2013).

References

Chen LC, Liu YC, Liang YC, Ho YS, Lee WS. (2009). Magnolol inhibits human glioblastoma cell proliferation through up-regulation of p21/Cip1. J Agric Food Chem, 57(16):7331-7. doi: 10.1021/jf901477g.


Chen MC, Lee CF, Huang WH, Chou TC. (2013). Magnolol suppresses hypoxia-induced angiogenesis via inhibition of HIF-1 α /VEGF signaling pathway in human bladder cancer cells. Biochem Pharmacol, 85(9):1278-87. doi: 10.1016/j.bcp.2013.02.009.


Chen SC, Chang YL, Wang DL, Cheng JJ. (2006). Herbal remedy magnolol suppresses IL-6-induced STAT3 activation and gene expression in endothelial cells. Br J Pharmacol, 148(2): 226–232. doi: 10.1038/sj.bjp.0706647


Chuang TC, Hsu SC, Cheng YT, et al. (2011). Magnolol down-regulates HER2 gene expression, leading to inhibition of HER2-mediated metastatic potential in ovarian cancer cells. Cancer Lett, 311(1):11-9. doi: 10.1016/j.canlet.2011.06.007.


Hwang ES, Park KK. (2010). Magnolol suppresses metastasis via inhibition of invasion, migration, and matrix metalloproteinase-2/-9 activities in PC-3 human prostate carcinoma cells. Biosci Biotechnol Biochem, 74(5):961-7.


Kim KM, Kim NS, Kim J, et al. (2013). Magnolol Suppresses Vascular Endothelial Growth Factor-Induced Angiogenesis by Inhibiting Ras-Dependent Mitogen-Activated Protein Kinase and Phosphatidylinositol 3-Kinase/Akt Signaling Pathways. Nutr Cancer.


Park JB, Lee MS, Cha EY, et al. (2012). Magnolol-induced apoptosis in HCT-116 colon cancer cells is associated with the AMP-activated protein kinase signaling pathway. Biol Pharm Bull, 35(9):1614-20.


Seo JU, Kim MH, Kim HM, Jeong HJ. (2011). Anti-cancer potential of magnolol for lung cancer treatment. Arch Pharm Res, 34(4):625-33. doi: 10.1007/s12272-011-0413-8.

Hispolon

Cancer: Bladder, breast, liver, gastric

Action: Anti-inflammatory, cytostatic, cytotoxic, pro-oxidative, anti-proliferative

Hispolon is an active phenolic compound of Phellinus igniarius , a mushroom that has recently been shown to have anti-oxidant, anti-inflammatory, and anti-cancer activities.

Liver Cancer

Hispolon inhibited cellular growth of Hep3B cells in a time-dependent and dose-dependent manner, through the induction of cell-cycle arrest at S phase measured using flow cytometric analysis and apoptotic cell death, as demonstrated by DNA laddering. Exposure of Hep3B cells to hispolon resulted in apoptosis as evidenced by caspase activation, PARP cleavage, and DNA fragmentation. Hispolon treatment also activated JNK, p38 MAPK, and ERK expression. Inhibitors of ERK (PB98095), but not those of JNK (SP600125) and p38 MAPK (SB203580), suppressed hispolon-induced S-phase arrest and apoptosis in Hep3B cells.

These findings establish a mechanistic link between the MAPK pathway and hispolon-induced cell-cycle arrest and apoptosis in Hep3B cells (Huang et al., 2011).

Gastric Cancer, Breast Cancer, Bladder Cancer

Hispolon extracted from Phellinus species was found to induce epidermoid and gastric cancer cell apoptosis. Hispolon has also been found to inhibit breast and bladder cancer cell growth, regardless of p53 status. Furthermore, p21(WAF1), a cyclin-dependent kinase inhibitor, was elevated in hispolon-treated cells. MDM2, a negative regulator of p21(WAF1), was ubiquitinated and degraded after hispolon treatment.

Lu et al. (2009) also found that activated ERK1/2 (extracellular signal-regulated kinase1/2) was recruited to MDM2 and involved in mediating MDM2 ubiquitination. The results indicated that cells with higher ERK1/2 activity were more sensitive to hispolon. In addition, hispolon-induced caspase-7 cleavage was inhibited by the ERK1/2 inhibitor, U0126.

In conclusion, hispolon ubiquitinates and down-regulates MDM2 via MDM2-recruited activated ERK1/2. Therefore, hispolon may be a potential anti-tumor agent in breast and bladder cancers.

Gastric Cancer

The efficacy of hispolon in human gastric cancer cells and cell death mechanism was explored. Hispolon induced ROS-mediated apoptosis in gastric cancer cells and was more toxic toward gastric cancer cells than toward normal gastric cells, suggesting greater susceptibility of the malignant cells.

The mechanism of hispolon-induced apoptosis was that hispolon abrogated the glutathione anti-oxidant system and caused massive ROS accumulation in gastric cancer cells. Excessive ROS caused oxidative damage to the mitochondrial membranes and impaired the membrane integrity, leading to cytochrome c release, caspase activation, and apoptosis. Furthermore, hispolon potentiated the cytotoxicity of chemotherapeutic agents used in the clinical management of gastric cancer.

These results suggest that hispolon could be useful for the treatment of gastric cancer either as a single agent or in combination with other anti-cancer agents (Chen et al., 2008).

Anti-proliferative Activity

Hispolon, which lacks one aromatic unit in relation to curcumin, exhibits enhanced anti-inflammatory and anti-proliferative activities. Dehydroxy hispolon was least potent for all three activities. Overall the results indicate that the substitution of a hydroxyl group for a methoxy group at the meta positions of the phenyl rings in curcumin significantly enhanced the anti-inflammatory activity, and the removal of phenyl ring at the 7(th) position of the heptadiene back bone and addition of hydroxyl group significantly increased the anti-proliferative activity of curcumin and hispolon (Ravindran et al., 2010).

References

Chen W, Zhao Z, Li L, et al. (2008). Hispolon induces apoptosis in human gastric cancer cells through a ROS-mediated mitochondrial pathway. Free Radic Biol Med, 45(1):60-72. doi: 10.1016/j.freeradbiomed.2008.03.013.


Huang GJ, Deng JS, Huang SS, Hu ML. (2011). Hispolon induces apoptosis and cell-cycle arrest of human hepatocellular carcinoma Hep3B cells by modulating ERK phosphorylation. J Agric Food Chem, 59(13):7104-13. doi: 10.1021/jf201289e.


Lu TL, Huang GJ, Lu TJ, et al. (2009). Hispolon from Phellinus linteus has anti-proliferative effects via MDM2-recruited ERK1/2 activity in breast and bladder cancer cells. Food Chem Toxicol, 47(8):2013-21. doi: 10.1016/j.fct.2009.05.023.


Ravindran J, Subbaraju GV, Ramani MV, et al. (2010). Bisdemethylcurcumin and structurally related hispolon analogues of curcumin exhibit enhanced prooxidant, anti-proliferative and anti-inflammatory activities in vitro. Biochem Pharmacol, 79(11):1658-66. doi: 10.1016/j.bcp.2010.01.033.

Geniposide –Penta-acetyl Geniposide (Ac)5GP

Cancers:
Glioma, melanoma, liver, hepatocarcinogenesis, hepatoma, prostate, cervical

Action: Cytostatic, induces apoptosis

Gardenia, the fruit of Gardenia jasminoides Ellis, has been widely used to treat liver and gall bladder disorders in Chinese medicine. It has been shown recently that geniposide, the main ingredient of Gardenia fructus , exhibits anti-tumor effect.

Hepatocarcinogenesis, Glioma

It has been demonstrated that (Ac)5GP plays more potent roles than geniposide in chemoprevention. (Ac)5GP decreased DNA damage and hepatocarcinogenesis, induced by aflatoxin B1 (AFB1), by activating the phase II enzymes glutathione S-transferase (GST) and GSH peroxidase (GSH-Px). It reduced the growth and development of inoculated C6 glioma cells, especially in pre-treated rats. In addition to the preventive effect, (Ac)5GP exerts its actions on apoptosis and growth arrest.

Treatment of (Ac)5GP caused DNA fragmentation of glioma cells. (Ac)5GP induced sub- G1 peak through the activation of apoptotic cascades PKCdelta/JNK/Fas/caspase8 and caspase 3. It arrested the cell-cycle at G0/ G1 by inducing the expression of p21, thus suppressing the cyclin D1/cdk4 complex formation and the phosphorylation of E2F.

Data from in vivo experiments indicated that (Ac)5GP is not harmful to the liver, heart and kidney. (Ac)5GP is strongly suggested to be an anti-tumor agent for development in the future (Peng, Huang, & Wang, 2005).

Induces Apoptosis

Previous studies have demonstrated the apoptotic cascades protein kinase C (PKC) delta/c-Jun NH2-terminal kinase (JNK)/Fas/caspases induced by penta-acetyl geniposide [(Ac)5GP]. However, the upstream signals mediating PKCdelta activation have not yet been clarified. Ceramide, mainly generated from the degradation of sphingomyelin, was hypothesized upstream above PKCdelta in (Ac)5GP-transduced apoptosis.

After investigation, (Ac)5GP was shown to activate neutral sphingomyelinase (N-SMase) immediately, with its maximum at 15 min. The NGF and p75 enhanced by (Ac)5GP was inhibited when combined with GW4869, the N-SMase inhibitor, indicating NGF/p75 as the downstream signals of N-SMase/ceramide. To evaluate whether N-SMase is involved in (Ac)5GP-transduced apoptotic pathway, cells were treated with (Ac)5GP, alone or combined with GW4869. It was demonstrated that N-SMase inhibition blocked FasL expression and caspase 3 activation. Similarly, p75 antagonist peptide attenuated the FasL/caspase 3 expression. It indicated that N-SMase activation is pivotal in (Ac)5GP-mediated apoptosis.

SMase and NGF/p75 are suggested to mediate upstream above PKCdelta, thus transducing FasL/caspase cascades in (Ac)5GP-induced apoptosis (Peng, Huang, Hsu, & Wang, 2006).

Glioma

Penta-acetyl geniposide [(Ac)(5)GP], an acetylated geniposide product from Gardenia fructus, has been known to have hepato-protective properties and recent studies have revealed its anti-proliferative and apoptotic effect on C6 glioma cells. The anti-metastastic effect of (Ac)(5)GP in the rat neuroblastoma line C6 glioma cells were investigated.

Further (Ac)(5)GP also exerted an inhibitory effect on phosphoinositide 3-kinase (PI3K) protein expression, phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and inhibition of activation of transcription factor nuclear factor kappa B (NF-kappaB), c-Fos, c-Jun.

Findings suggest (Ac)(5)GP is highly likely to be an inhibiting cancer migration agent to be further developed in the future (Huang et al., 2009).

Melanoma

A new iridoid glycoside, 10-O-(4'-O-methylsuccinoyl) geniposide, and two new pyronane glycosides, jasminosides Q and R, along with nine known iridoid glycosides, and two known pyronane glycosides, were isolated from a MeOH extract of Gardeniae Fructus, the dried ripe fruit of Gardenia jasminoides (Rubiaceae).

The structures of new compounds were elucidated on the basis of extensive spectroscopic analyzes and comparison with literature. Upon evaluation of these compounds on the melanogenesis in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), three compounds, i.e., 6-O-p-coumaroylgeniposide (3), 7, and 6'-O-sinapoyljasminoside (12), exhibited inhibitory effects with 21.6-41.0 and 37.5-47.7% reduction of melanin content at 30 and 50 µM, respectively, with almost no toxicity to the cells (83.7-106.1% of cell viability at 50 µM) (Akisha et al., 2012).

Hepatoma, Prostate Cancer, Cervical Cancer

Genipin is a metabolite of geniposide isolated from an extract of Gardenia fructus. Some observations suggested that genipin could induce cell apoptosis in hepatoma cells and PC3 human prostate cancer cells. Genipin could remarkably induce cytotoxicity in HeLa cells and inhibit its proliferation. Induction of the apoptosis by genipin was confirmed by analysis of DNA fragmentation and induction of sub-G(1) peak through flow cytometry.

The results also showed that genipin-treated HeLa cells cycle was arrested at G(1) phase. Western blot analysis revealed that the phosphorylated c-Jun NH(2)-terminal kinase (JNK) protein, phospho-Jun protein, p53 protein and bax protein significantly increased in a dose-dependent manner after treatment of genipin for 24 hours; the activation of JNK may result in the increase of the p53 protein level; the increase of the p53 protein led to the accumulation of bax protein; and bax protein further induced cell apoptotic death eventually (Cao et al., 2010).

References

Akihisa T, Watanabe K, Yamamoto A, et al. (2012). Melanogenesis inhibitory activity of monoterpene glycosides from Gardeniae Fructus. Chemistry & Biodiversity, 9(8), 1490-9. doi: 10.1002/cbdv.201200030.


Cao H, Feng Q, Xu W, et al. (2010). Genipin induced apoptosis associated with activation of the c-Jun NH2-terminal kinase and p53 protein in HeLa cells. Biol Pharm Bull, 33(8):1343-8.


Huang HP, Shih YW, Wu CH, et al. (2009). Inhibitory effect of penta-acetyl geniposide on C6 glioma cells metastasis by inhibiting matrix metalloproteinase-2 expression involved in both the PI3K and ERK signaling pathways. Chemico-biological Interactions, 181(1), 8-14. doi: 10.1016/j.cbi.2009.05.009.


Peng CH, Huang CN, Hsu SP, Wang CJ. (2006). Penta-acetyl geniposide induce apoptosis in C6 glioma cells by modulating the activation of neutral sphingomyelinase-induced p75 nerve growth factor receptor and protein kinase Cdelta pathway. Molecular Pharmacology, 70(3), 997-1004.


Peng CH, Huang CN, Wang CJ. (2005). The anti-tumor effect and mechanisms of action of penta-acetyl geniposide. Current Cancer Drug Targets, 5(4), 299-305.

Eugenol

Cancer:
Melanoma, osteosarcoma, leukemia, gastric, colon, liver, oral., lung

Action: Radio-protective

Eugenol is a natural compound available in honey and various plants extracts; in particular, cloves (Syzygium aromaticum (L.) Merrill & Perry).

Melanoma, Skin Tumors, Osteosarcoma, Leukemia, Gastric Cancer

Eugenol (4-allyl-2-methoxyphenol), a phenolic phytochemicals, is the active component of Syzigium aromaticum (cloves). Aromatic plants like nutmeg, basil, cinnamon and bay leaves also contain eugenol. Eugenol has a wide range of applications like perfumeries, flavorings, essential oils and in medicine as a local antiseptic and anesthetic. Increasing volumes of literature show eugenol possesses anti-oxidant, anti-mutagenic, anti-genotoxic, anti-inflammatory and anti-cancer properties.

The molecular mechanism of eugenol-induced apoptosis in melanoma, skin tumors, osteosarcoma, leukemia, gastric and mast cells has been well documented and highlights the anti-proliferative activity and molecular mechanism of eugenol-induced apoptosis against the cancer cells and animal model (Jaganathan et al., 2012).

Colon Cancer

Since most of the drugs used in cancer are apoptosis-inducers, the apoptotic effect and anti-cancer mechanism of eugenol were investigated against colon cancer cells. MTT assay signified the anti-proliferative nature of eugenol against the tested colon cancer cells. PI staining indicated increasing accumulation of cells at sub-G1-phase. Eugenol treatment resulted in reduction of intracellular non-protein thiols and increase in the earlier lipid layer break. Further events like dissipation of MMP and generation of ROS (reactive oxygen species) were accompanied in the eugenol-induced apoptosis. Augmented ROS generation resulted in the DNA fragmentation of treated cells as shown by DNA fragmentation and TUNEL assay. Further activation of PARP (polyadenosine diphosphate-ribose polymerase), p53 and caspase-3 were observed in Western blot analyzes.

These results demonstrate the molecular mechanism of eugenol-induced apoptosis in human colon cancer cells. This research will further enhance eugenol as a potential chemo-preventive agent against colon cancer (Jaganathan et al., 2011).

Radio-protective, Skin Cancer, Liver Cancer, Oral Cancer, Lung Cancer

Ocimum sanctum L. or Ocimum tenuiflorum L , commonly known as Holy Basil in English or Tulsi in the various Indian languages, is an important medicinal plant in the various traditional and folk systems of medicine in Southeast Asia, and another plant from which eugenol is extracted. Scientific studies have shown it to possess anti-inflammatory, analgesic, anti-pyretic, anti-diabetic, hepato-protective, hypolipidemic, anti-stress, and immunomodulatory activities. Preclinical studies have also shown that Ocimum and some of its phytochemicals including eugenol prevented chemical-induced skin, liver, oral., and lung cancers and to mediate these effects by increasing the anti-oxidant activity, altering the gene expressions, inducing apoptosis, and inhibiting angiogenesis and metastasis.

The aqueous extract of Ocimum and its flavanoids, orintin and vicenin, are shown to protect mice against γ-radiation-induced sickness and mortality and to selectively protect the normal tissues against the tumoricidal effects of radiation. This action is related to the important phytochemicals it contains like eugenol, which are also shown to prevent radiation-induced DNA damage.

References

Baliga MS, Jimmy R, Thilakchan KR, et al. (2013). Ocimum sanctum L (Holy Basil or Tulsi) and its phytochemicals in the prevention and treatment of cancer. Nutr Cancer, 65(1):26-35. doi: 10.1080/01635581.2013.785010.


Jaganathan SK, Mazumdar A, Mondhe D, Mandal M. (2011). Apoptotic effect of eugenol in human colon cancer cell lines. Cell Biol Int, 35(6):607-15. doi: 10.1042/CBI20100118.


Jaganathan SK, Supriyanto E. (2012). Anti-proliferative and Molecular Mechanism of Eugenol-Induced Apoptosis in Cancer Cells. Molecules, 17(6):6290-6304. doi:10.3390/molecules17066290.

Diosgenin

Cancer: Breast, colon, prostate, leukemia, stomach

Action: HER-2, apoptosis, chemo-enhancing

Diosgenin is a plant-derived steroid isolated from Trigonella foenum-graecum (L.).

Breast Cancer; Chemo-enhancing

Diosgenin preferentially inhibited proliferation and induced apoptosis in HER2-overexpressing cancer cells. Furthermore, diosgenin inhibited the phosphorylation of Akt and mTOR, and enhanced phosphorylation of JNK.

The use of pharmacological inhibitors revealed that the modulation of Akt, mTOR and JNK phosphorylation was required for diosgenin-induced FAS suppression. Finally, it was shown that diosgenin could enhance paclitaxel-induced cytotoxicity in HER2-overexpressing cancer cells. These results suggested that diosgenin has the potential to advance as chemo-preventive or chemotherapeutic agent for cancers that overexpress HER2 (Chiang et al., 2007).

Colon Cancer

On 24 hours exposure to diosgenin, MTT cytotoxicity activity reduced by ³50% was achieved at the higher concentrations (i.e., ³80 µmol/L). However, compared with the control, 20 to 60 µmol/L diosgenin reduced the MTT activity only by 5% to 30%. Diosgenin caused a significant time-dependent and dose-dependent decrease in the proliferation of HT-29 cells. Twenty four hours exposure to diosgenin (20 to 100 µmol/L) inhibited cell proliferation compared with untreated cell growth. The in vitro experiment results indicated that diosgenin inhibits cell growth and induces apoptosis in the HT-29 human colon cancer cell line in a dose-dependent manner.

Furthermore, diosgenin induces apoptosis in HT-29 cells at least in part by inhibition of bcl-2 and by induction of caspase-3 protein expression (Raju et al., 2004).

Breast Cancer

The electrochemical behavior of breast cancer cells was studied on a graphite electrode by cyclic voltammetry (CV) and potentiometric stripping analysis (PSA) in unexposed and diosgenin exposed cells. In both cases, only one oxidative peak at approximately +0.75 V was observed. The peak area in PSA was used to study the growth of the cells and the effect of diosgenin on MCF-7 cells. The results showed that diosgenin can effectively inhibit the viability and proliferation of the breast cancer cells (Li et al., 2005).

Leukemia

Cell viability was assessed via an MTT assay. Apoptosis was investigated in terms of nuclear morphology, DNA fragmentation, and phosphatidylserine externalization. Cell cycle analysis was performed via PI staining and flow cytometry (FCM). Western blotting and immunofluorescence methods were used to determine the levels of p53, cell-cycle-related proteins and Bcl-2 family members. Cell cycle analysis showed that diosgenin caused G2/M arrest independently of p53. The levels of cyclin B1 and p21Cip1/Waf1 were decreased, whereas cdc2 levels were increased. The anti-apoptotic Bcl-2 and Bcl-xL proteins were down-regulated, whereas the pro-apoptotic Bax was upregulated.

Diosgenin was hence found to inhibit K562 cell proliferation via cell-cycle G2/M arrest and apoptosis, with disruption of Ca2+ homeostasis and mitochondrial dysfunction playing vital roles (Liu et al., 2005).

In recent years, Akt signaling has gained recognition for its functional role in more aggressive, therapy-resistant malignancies. As it is frequently constitutively active in cancer cells, several drugs are being investigated for their ability to inhibit Akt signaling. Diosgenin (fenugreek), a dietary compound, was examined for its action on Akt signaling and its downstream targets on estrogen receptor positive (ER+) and estrogen receptor negative (ER-) breast cancer (BCa) cells. Additionally, in vivo tumor studies indicate diosgenin significantly inhibits tumor growth in both MCF-7 and MDA-231 xenografts in nude mice. Thus, these results suggest that diosgenin might prove to be a potential chemotherapeutic agent for the treatment of BCa (Srinivasan et al., 2009).

Leukemia, Stomach Cancer

Protodioscin (PD) was purified from fenugreek (Trigonella foenumgraecum L.) and identified by mass spectrometry, and 1H- and 13C-NMR. The effects of PD on cell viability in human leukemia HL-60 and human stomach cancer KATO III cells were investigated. PD displayed strong growth-inhibitory effect against HL-60 cells, but weak growth-inhibitory effect on KATO III cells.

These findings suggest that growth inhibition by PD of HL-60 cells results from the induction of apoptosis by this compound in HL-60 cells (Hibasami et al., 2003).

References

Chiang CT, Way TD, Tsai SJ, Lin JK. (2007). Diosgenin, a naturally occurring steroid, suppresses fatty acid synthase expression in HER2-overexpressing breast cancer cells through modulating Akt, mTOR and JNK phosphorylation. FEBS letters, 581(30), 5735-42. doi:     10.1016/j.febslet.2007.11.021.


Hibasami H, Moteki H, Ishikawa K, et al. (2003). Protodioscin isolated from fenugreek (Trigonella foenumgraecum L.) induces cell death and morphological change indicative of apoptosis in leukemic cell line H-60, but not in gastric cancer cell line KATO III. Int J Mol Med, 11(1):23-6.


Li J, Liu X, Guo M, et al. (2005). Electrochemical Study of Breast Cancer Cells MCF-7 and Its Application in Evaluating the Effect of Diosgenin. Analytical Sciences, 21(5), 561. doi:10.2116/analsci.21.561


Liu MJ, Wang Z, Ju Y, Wong RNS, Wu QY. (2005). Diosgenin induces cell-cycle arrest and apoptosis in human leukemia K562 cells with the disruption of Ca2+ homeostasis. Cancer Chemotherapy and Pharmacology, 55(1), 79-90, doi: 10.1007/s00280-004-0849-3


Raju J, Patlolla JMR, Swamy MV, Rao CV. (2004). Diosgenin, a Steroid Saponin of Trigonella foenum graecum (Fenugreek), Inhibits Azoxymethane-Induced Aberrant Crypt Foci Formation in F344 Rats and Induces Apoptosis in HT-29 Human Colon Cancer Cells. Cancer Epidemiol Biomarkers Prev, 13; 1392.


Srinivasan S, Koduru S, Kumar R, et al. (2009). Diosgenin targets Akt-mediated prosurvival signaling in human breast cancer cells. International Journal of Cancer, 125(4), 961–967. doi: 10.1002/ijc.24419

Cucurbitacin D (CuD) (See also Trichosanthin)

Cancer: Hepatocellular carcinoma, pancreatic, breast

Action: Apoptosis

Breast Cancer

Cucurbitacin D (CuD) isolated from Trichosanthes kirilowii induces apoptosis in several cancer cells. Constitutive signal transducer and activator of transcription 3 (STAT3), which is an oncogenic transcription factor, is often observed in many human malignant tumors, including breast cancer. Kim et al. (2013) tested whether Trichosanthes kirilowii ethanol extract (TKE) or CuD suppresses cell growth and induces apoptosis through inhibition of STAT3 activity in breast cancer cells.

They found that both TKE and CuD suppressed proliferation and induced apoptosis and G2/M cell-cycle arrest in MDA-MB-231 breast cancer cells by inhibiting STAT3 phosphorylation. In addition, both TKE and CuD inhibited nuclear translocation and transcriptional activity of STAT3. Taken together, our results indicate that TKE and its derived compound, CuD, could be potent therapeutic agents for breast cancer, blocking tumor cell proliferation and inducing apoptosis through suppression of STAT3 activity.

Hepatocellular Carcinoma

Takahashi et al. (2009) found that the anti-tumor components isolated from the extract of trichosanthes (EOT) are cucurbitacin D and dihydrocucurbitacin D, and suggest that cucurbitacin D induces apoptosis through caspase-3 and phosphorylation of JNK in hepatocellular carcinoma cells. These results suggest that cucurbitacin D isolated from Trichosanthes kirilowii could be a valuable candidate for an anti-tumor drug.

Pancreatic Cancer

Dose-response studies showed that the drug inhibited 50% growth of seven pancreatic cancer cell lines at 10−7 mol/L, whereas clonogenic growth was significantly inhibited at 5 × 10−8 mol/L. Cucurbitacin B caused dose- and time-dependent G2-M-phase arrest and apoptosis of pancreatic cancer cells. This was associated with inhibition of activated JAK2, STAT3, and STAT5, increased level of p21WAF1 even in cells with nonfunctional p53, and decrease of expression of cyclin A, cyclin B1, and Bcl-XL with subsequent activation of the caspase cascade.

Cucurbitacin B has profound in vitro and in vivo anti-proliferative effects against human pancreatic cancer cells, and the compound may potentate the anti-proliferative effect of the chemotherapeutic agent gemcitabine. Further clinical studies are necessary to confirm our findings in patients with pancreatic cancer (Thoennissen et al., 2009).

References

Kim SR, Seo HS, Choi H-S, et al. (2013). Trichosanthes kirilowii Ethanol Extract and Cucurbitacin D Inhibit Cell Growth and Induce Apoptosis through Inhibition of STAT3 Activity in Breast Cancer Cells. Evidence-Based Complementary and Alternative Medicine, 2013. http://dx.doi.org/10.1155/2013/975350


Thoennissen NH, Iwanski GB, Doan NB, et al. (2009). Cucurbitacin B Induces Apoptosis by Inhibition of the JAK/STAT Pathway and Potentiates Anti-proliferative Effects of Gemcitabine on Pancreatic Cancer Cells.   Cancer Res, 69; 5876 doi: 10.1158/0008-5472.CAN-09-0536


Takahashi N, Yoshida Y, Sugiura T, et al. (2009). Cucurbitacin D isolated from Trichosanthes kirilowii induces apoptosis in human hepatocellular carcinoma cells in vitro. International Immunopharmacology, 9(4):508–513.

Concanavalin A

Cancer: Melanoma

Action: Autophagy

Concanavalin A (ConA) is isolated from Canavalia ensiformis [(L.) DC.].

Autophagy

Plant lectins, a group of highly diverse carbohydrate-binding proteins of non-immune origin, are ubiquitously distributed through a variety of plant species, and have recently drawn rising attention due to their remarkable ability to kill tumor cells using mechanisms implicated in autophagy. Plant lectins concanavalin A, Polygonatum cyrtonema lectin and mistletoe lectins can target autophagy by modulating BNIP-3, ROS-p38-p53, Ras-Raf and PI3KCI-Akt pathways, as well as Beclin-1, in many types of cancer cells (Liu et al., 2013).

Melanoma

Con A possesses a remarkable anti-proliferative effect on human melanoma A375 cells, and there is a link between the anti-proliferative activity of Con A and its sugar-binding activity. Subsequently, Con A can induce human melanoma A375 cell apoptosis in a caspase-dependent manner. It has been demonstrated that there may be a close correlation between the anti-proliferative activity of Con A and its sugar-binding activity. More importantly, Con A can induce human melanoma A375 cell death in a caspase-dependent manner as well as via a mitochondrial apoptotic pathway (Liu et al.,2009).

References

Liu B, Min MW, Bao JK. (2009). Induction of apoptosis by Concanavalin A and its molecular mechanisms in cancer cells. Autophagy, 5(3):432-3. doi: 10.1016/j.abb.2008.12.003


Liu Z, Luo Y, Zhou TT, Zhang WZ. (2013). Could plant lectins become promising anti-tumor drugs for causing autophagic cell death? Cell Prolif, 46(5):509-15. doi: 10.1111/cpr.12054.

Camptothecin

Cancer: Breast, colon

Action: Cytostatic

Breast Cancer

Recently, natural product DNA topoisomerase I inhibitors 10-hydroxycamptothecin (HCPT) and camptothecin (CPT) have been shown to have therapeutic effects in both in vitro and in vivo models of human breast cancer. After evaluation, the apoptotic pathways were characterized in vitro and in vivo in the human breast cancer cell lines MCF-7 and MDA-MB-468.

The elevation of p53 protein levels in MCF-7 cells treated with CPT was significantly inhibited by preincubation with DNA breaks inhibitor aphidicolin, while the elevation of p21WAF1/CIP1 protein levels was not inhibited. The elevation of p21WAF1/CIP1 in MDA-MB-468 cells treated with CPT was not inhibited by aphidicolin. Using Northern blot analysis, the transcription of p21WAF1/CIP1 was shown to increase in a dose-dependent manner in MCF-7 and MDA-MB-468 cells treated with HCPT or CPT.

Results suggest that treatment with HCPT and CPT results in increased levels of p21WAF1/CIP1 protein and mRNA, and that they induce apoptosis in human breast cancer cells through both p53-dependent and -independent pathways. Findings may be significant in further understanding the mechanisms of actions of camptothecins in the treatment of human cancers (Liu & Zhang, 1998).

Colon Cancer

10-Hydroxycamptothecin (10-HCPT), an indole alkaloid isolated from a Chinese tree, Camptotheca acuminate , inhibits the activity of topoisomerase I and has a broad spectrum of anti-cancer activity in vitro and in vivo. 10-HCPT significantly repressed the proliferation of Colo 205 cells at a relatively low concentration (5-20 nM). Flow cytometry analysis and Western blot and apoptosis assays demonstrated that low-dose 10-HCPT arrested Colo 205 cells in the G2 phase of the cell-cycle and triggered apoptosis through a caspase-3-dependent pathway. No acute toxicity was observed after an oral challenge of 10-HCPT in BALB/c-nude mice every 2 days.

Results suggest that a relatively low dose of 10-HCPT (p.o.) is able to inhibit the growth of colon cancer, facilitating the development of a new protocol of human trials with this anti-cancer drug (Ping et al., 2006).

References

Liu W, & Zhang R (1998). Up-regulation of p21WAF1/CIP1 in human breast cancer cell lines MCF-7 and MDA-MB-468 undergoing apoptosis induced by natural product anti-cancer drugs 10-hydroxycamptothecin and camptothecin through p53-dependent and independent pathways. International Journal of Oncology, 12(4), 793-804.


Ping YH, Lee HC, Lee JY, et al. (2006). Anti-cancer effects of low-dose 10-hydroxycamptothecin in human colon cancer. Oncology Reports, 15(5), 1273-9.

Betulin and Betulinic acid

Cancer:
Neuroblastoma, medulloblastoma, glioblastoma, colon, lung, oesophageal, leukemia, melanoma, pancreatic, prostate, breast, head & neck, myeloma, nasopharyngeal, cervical, ovarian, esophageal squamous carcinoma

Action: Anti-angiogenic effects, induces apoptosis, anti-oxidant, cytotoxic and immunomodifying activities

Betulin is a naturally occurring pentacyclic triterpene found in many plant species including, among others, in Betula platyphylla (white birch tree), Betula X caerulea [Blanch. (pro sp.)], Betula cordifolia (Regel), Betula papyrifera (Marsh.), Betula populifolia (Marsh.) and Dillenia indica L . It has anti-retroviral., anti-malarial., and anti-inflammatory properties, as well as a more recently discovered potential as an anti-cancer agent, by inhibition of topoisomerase (Chowdhury et al., 2002).

Betulin is found in the bark of several species of plants, principally the white birch (Betula pubescens ) (Tan et al., 2003) from which it gets its name, but also the ber tree (Ziziphus mauritiana ), selfheal (Prunella vulgaris ), the tropical carnivorous plants Triphyophyllum peltatum and Ancistrocladus heyneanus, Diospyros leucomelas , a member of the persimmon family, Tetracera boiviniana , the jambul (Syzygium formosanum ) (Zuco et al., 2002), flowering quince (Chaenomeles sinensis ) (Gao et al., 2003), rosemary (Abe et al., 2002) and Pulsatilla chinensis (Ji et al., 2002).

Anti-cancer, Induces Apoptosis

The in vitro characterization of the anti-cancer activity of betulin in a range of human tumor cell lines (neuroblastoma, rhabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukaemia and multiple myeloma), and in primary tumor cultures isolated from patients (ovarian carcinoma, cervical carcinoma and glioblastoma multiforme) was carried out to probe its anti-cancer effect. The remarkable anti-proliferative effect of betulin in all tested tumor cell cultures was demonstrated. Furthermore, betulin altered tumor cell morphology, decreased their motility and induced apoptotic cell death. These findings demonstrate the anti-cancer potential of betulin and suggest that it may be applied as an adjunctive measure in cancer treatment (Rzeski, 2009).

Lung Cancer

Betulin has also shown anti-cancer activity on human lung cancer A549 cells by inducing apoptosis and changes in protein expression profiles. Differentially expressed proteins explained the cytotoxicity of betulin against human lung cancer A549 cells, and the proteomic approach was thus shown to be a potential tool for understanding the pharmacological activities of pharmacophores (Pyo, 2009).

Esophageal Squamous Carcinoma

The anti-tumor activity of betulin was investigated in EC109 cells. With the increasing doses of betulin, the inhibition rate of EC109 cell growth was increased, and their morphological characteristics were changed significantly. The inhibition rate showed dose-dependent relation.

Leukemia

Betulin hence showed potent inhibiting effects on EC109 cells growth in vitro (Cai, 2006).

A major compound of the methanolic extract of Dillenia indica L. fruits, betulinic acid, showed significant anti-leukaemic activity in human leukaemic cell lines U937, HL60 and K562 (Kumar, 2009).

Betulinic acid effectively induces apoptosis in neuroectodermal and epithelial tumor cells and exerts little toxicity in animal trials. It has been shown that betulinic acid induced marked apoptosis in 65% of primary pediatric acute leukemia cells and all leukemia cell lines tested. When compared for in vitro efficiency with conventionally used cytotoxic drugs, betulinic acid was more potent than nine out of 10 standard therapeutics and especially efficient in tumor relapse. In isolated mitochondria, betulinic acid induced release of both cytochrome c and Smac. Taken together, these results indicated that betulinic acid potently induces apoptosis in leukemia cells and should be further evaluated as a future drug to treat leukemia (Ehrhardt, 2009).

Multiple Myeloma

The effect of betulinic acid on the induction apoptosis of human multiple myeloma RPMI-8226 cell line was investigated. The results showed that within a certain concentration range (0, 5, 10, 15, 20 microg/ml), IC50 of betulinic acid to RPMI-8226 at 24 hours was 10.156+/-0.659 microg/ml, while the IC50 at 48 hours was 5.434+/-0.212 microg/ml, and its inhibiting effect on proliferation of RPMI-8226 showed both a time-and dose-dependent manner.

It is therefore concluded that betulinic acid can induce apoptosis of RPMI-8226 within a certain range of concentration in a time- and dose-dependent manner. This phenomenon may be related to the transcriptional level increase of caspase 3 gene and decrease of bcl-xl. Betulinic acid also affects G1/S in cell-cycle which arrests cells at phase G0/G1 (Cheng, 2009).

Anti-angiogenic Effects, Colorectal Cancer

Betulinic acid isolated from Syzygium campanulatum Korth (Myrtaceae) was found to have anti-angiogenic effects on rat aortic rings, matrigel tube formation, cell proliferation and migration, and expression of vascular endothelial growth factor (VEGF). The anti-tumor effect was studied using a subcutaneous tumor model of HCT 116 colorectal carcinoma cells established in nude mice. Anti-angiogenesis studies showed potent inhibition of microvessels outgrowth in rat aortic rings, and studies on normal and cancer cells did not show any significant cytotoxic effect.

In vivo anti-angiogenic study showed inhibition of new blood vessels in chicken embryo chorioallantoic membrane (CAM), and in vivo anti-tumor study showed significant inhibition of tumor growth due to reduction of intratumor blood vessels and induction of cell death. Collectively, these results indicate betulinic acid as an anti-angiogenic and anti-tumor candidate (Aisha, 2013).

Nasopharyngeal Carcinoma Melanoma, Leukemia, Lung, Colon, Breast,Prostate, Ovarian Cancer

Betulinic acid is an effective and potential anti-cancer chemical derived from plants. Betulinic acid can kill a broad range of tumor cell lines, but has no effect on untransformed cells. The chemical also kills melanoma, leukemia, lung, colon, breast, prostate and ovarian cancer cells via induction of apoptosis, which depends on caspase activation. However, no reports are yet available about the effects of betulinic acid on nasopharyngeal carcinoma (NPC), a widely spread malignancy in the world, especially in East Asia.

In a study, Liu & Luo (2012) showed that betulinic acid can effectively kill CNE2 cells, a cell line derived from NPC. Betulinic acid-induced CNE2 apoptosis was characterized by typical apoptosis hallmarks: caspase activation, DNA fragmentation, and cytochrome c release.

These observations suggest that betulinic acid may serve as a potent and effective anti-cancer agent in NPC treatment. Further exploration of the mechanism of action of betulinic acid could yield novel breakthroughs in anti-cancer drug discovery.

Cervical Carcinoma

Betulinic acid has shown anti-tumor activity in some cell lines in previous studies. Its anti-tumor effect and possible mechanisms were investigated in cervical carcinoma U14 tumor-bearing mice. The results showed that betulinic acid (100 mg/kg and 200 mg/kg) effectively suppressed tumor growth in vivo. Compared with the control group, betulinic acid significantly improved the levels of IL-2 and TNF-alpha in tumor-bearing mice and increased the number of CD4+ lymphocytes subsets, as well as the ratio of CD4+/CD8+ at a dose of 200 mg/kg.

Furthermore, treatment with betulinic acid induced cell apoptosis in a dose-dependent manner in tumor-bearing mice, and inhibited the expression of Bcl-2 and Ki-67 protein while upregulating the expression of caspase-8 protein. The mechanisms by which BetA exerted anti-tumor effects might involve the induction of tumor cell apoptosis. This process is also related to improvement in the body's immune response (Wang, 2012).

Anti-oxidant, Cytotoxic and Immunomodifying Activities

Betulinic acid exerted cytotoxic activity through dose-dependent impairment of viability and mitochondrial activity of rat insulinoma m5F (RINm5F) cells. Decrease of RINm5F viability was mediated by nitric oxide (NO)-induced apoptosis. Betulinic acid also potentiated NO and TNF-α release from macrophages therefore enhancing their cytocidal action. The rosemary extract developed more pronounced anti-oxidant, cytotoxic and immunomodifying activities, probably due to the presence of betulinic acid (Kontogianni, 2013).

Pancreatic Cancer

Lamin B1 is a novel therapeutic target of Betulinic Acid in pancreatic cancer. The role and regulation of lamin B1 (LMNB1) expression in human pancreatic cancer pathogenesis and betulinic acid-based therapy was investigated. Lamin proteins are thought to be involved in nuclear stability, chromatin structure and gene expression. Elevation of circulating LMNB1 marker in plasma could detect early stages of HCC patients, with 76% sensitivity and 82% specificity. Lamin B1 is a clinically useful biomarker for early stages of HCC in tumor tissues and plasma (Sun, 2010).

It was found that lamin B1 was significantly down-regulated by BA treatment in pancreatic cancer in both in vitro culture and xenograft models. Overexpression of lamin B1 was pronounced in human pancreatic cancer and increased lamin B1 expression was directly associated with low grade differentiation, increased incidence of distant metastasis and poor prognosis of pancreatic cancer patients.

Furthermore, knockdown of lamin B1 significantly attenuated the proliferation, invasion and tumorigenicity of pancreatic cancer cells. Lamin B1 hence plays an important role in pancreatic cancer pathogenesis and is a novel therapeutic target of betulinic acid treatment (Li, 2013).

Multiple Myeloma, Prostate Cancer

The inhibition of the ubiquitin-proteasome system (UPS) of protein degradation is a valid anti-cancer strategy and has led to the approval of bortezomib for the treatment of multiple myeloma. However, the alternative approach of enhancing the degradation of oncoproteins that are frequently overexpressed in cancers is less developed. Betulinic acid (BA) is a plant-derived small molecule that can increase apoptosis specifically in cancer but not in normal cells, making it an attractive anti-cancer agent.

Results in prostate cancer suggest that BA inhibits multiple deubiquitinases (DUBs), which results in the accumulation of poly-ubiquitinated proteins, decreased levels of oncoproteins, and increased apoptotic cell death. In the TRAMP transgenic mouse model of prostate cancer, treatment with BA (10 mg/kg) inhibited primary tumors, increased apoptosis, decreased angiogenesis and proliferation, and lowered androgen receptor and cyclin D1 protein.

BA treatment also inhibited DUB activity and increased ubiquitinated proteins in TRAMP prostate cancer but had no effect on apoptosis or ubiquitination in normal mouse tissues. Overall, this data suggests that BA-mediated inhibition of DUBs and induction of apoptotic cell death specifically in prostate cancer but not in normal cells and tissues may provide an effective non-toxic and clinically selective agent for chemotherapy (Reiner, 2013).

Melanoma

Betulinic acid was recently described as a melanoma-specific inducer of apoptosis, and it was investigated for its comparable efficacy against metastatic tumors and those in which metastatic ability and 92-kD gelatinase activity had been decreased by introduction of a normal chromosome 6. Human metastatic C8161 melanoma cells showed greater DNA fragmentation and growth arrest and earlier loss of viability in response to betulinic acid than their non-metastatic C8161/neo 6.3 counterpart.

These effects involved induction of p53 without activation of p21WAF1 and were synergized by bromodeoxyuridine in metastatic Mel Juso, with no comparable responses in non-metastatic Mel Juso/neo 6 cells. These data suggest that betulinic acid exerts its inhibitory effect partly by increasing p53 without a comparable effect on p21WAF1 (Rieber, 1998).

As a result of bioassay–guided fractionation, betulinic acid has been identified as a melanoma-specific cytotoxic agent. In follow-up studies conducted with athymic mice carrying human melanomas, tumor growth was completely inhibited without toxicity. As judged by a variety of cellular responses, anti-tumor activity was mediated by the induction of apoptosis. Betulinic acid is inexpensive and available in abundant supply from common natural sources, notably the bark of white birch trees. The compound is currently undergoing preclinical development for the treatment or prevention of malignant melanoma (Pisha, 1995).

Betulinic acid strongly and consistently suppressed the growth and colony-forming ability of all human melanoma cell lines investigated. In combination with ionizing radiation the effect of betulinic acid on growth inhibition was additive in colony-forming assays.

Betulinic acid also induced apoptosis in human melanoma cells as demonstrated by Annexin V binding and by the emergence of cells with apoptotic morphology. The growth-inhibitory action of betulinic acid was more pronounced in human melanoma cell lines than in normal human melanocytes.

The properties of betulinic acid make it an interesting candidate, not only as a single agent but also in combination with radiotherapy. It is therefore concluded that the strictly additive mode of growth inhibition in combination with irradiation suggests that the two treatment modalities may function by inducing different cell death pathways or by affecting different target cell populations (Selzer, 2000).

Betulinic acid has been demonstrated to induce programmed cell death with melanoma and certain neuroectodermal tumor cells. It has been demonstrated currently that the treatment of cultured UISO-Mel-1 (human melanoma cells) with betulinic acid leads to the activation of p38 and stress activated protein kinase/c-Jun NH2-terminal kinase (a widely accepted pro-apoptotic mitogen-activated protein kinases (MAPKs)) with no change in the phosphorylation of extracellular signal-regulated kinases (anti-apoptotic MAPK). Moreover, these results support a link between the MAPKs and reactive oxygen species (ROS).

These data provide additional insight in regard to the mechanism by which betulinic acid induces programmed cell death in cultured human melanoma cells, and it likely that similar responses contribute to the anti-tumor effect mediated with human melanoma carried in athymic mice (Tan, 2003).

Glioma

Betulinic acid triggers apoptosis in five human glioma cell lines. Betulinic acid-induced apoptosis requires new protein, but not RNA, synthesis, is independent of p53, and results in p21 protein accumulation in the absence of a cell-cycle arrest. Betulinic acid-induced apoptosis involves the activation of caspases that cleave poly(ADP ribose)polymerase.

Betulinic acid induces the formation of reactive oxygen species that are essential for BA-triggered cell death. The generation of reactive oxygen species is blocked by BCL-2 and requires new protein synthesis but is unaffected by caspase inhibitors, suggesting that betulinic acid toxicity sequentially involves new protein synthesis, formation of reactive oxygen species, and activation of crm-A-insensitive caspases (Wolfgang, 1999).

Head and Neck Carcinoma

In two head and neck squamous carcinoma (HNSCC) cell lines betulinic acid induced apoptosis, which was characterized by a dose-dependent reduction in cell numbers, emergence of apoptotic cells, and an increase in caspase activity. Western blot analysis of the expression of various Bcl-2 family members in betulinic acid–treated cells showed, surprisingly, a suppression of the expression of the pro-apoptotic protein Bax but no changes in Mcl-1 or Bcl-2 expression.

These data clearly demonstrate for the first time that betulinic acid has apoptotic activity against HNSCC cells (Thurnher et al., 2003).

References

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Ehrhardt H, Fulda S, FŸhrer M, Debatin KM & Jeremias I. (2004). Betulinic acid-induced apoptosis in leukemia cells. Leukemia, 18:1406–1412. doi:10.1038/sj.leu.2403406


Gao H, Wu L, Kuroyanagi M, et al. (2003). Anti-tumor-promoting constituents from Chaenomeles sinensis KOEHNE and their activities in JB6 mouse epidermal cells. Chemical & Pharmaceutical Bulletin, 51(11):1318–21. doi:10.1248/cpb.51.1318. PMID 14600382.


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Reiner T, Parrondo R, de Las Pozas A, Palenzuela D, Perez-Stable C. (2013). Betulinic Acid Selectively Increases Protein Degradation and Enhances Prostate Cancer-Specific Apoptosis: Possible Role for Inhibition of Deubiquitinase Activity. PLoS One, 8(2):e56234. doi: 10.1371/journal.pone.0056234.


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Selzer E, Pimentel E, Wacheck V, et al. (2000). Effects of Betulinic Acid Alone and in Combination with Irradiation in Human Melanoma Cells. Journal of Investigative Dermatology, 114:935–940; doi:10.1046/j.1523-1747.2000.00972.x


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Artemisinin

Cancer: Breast, leukemia, gastric

Action: Anti-cancer

Artemisinin is isolated from Artemisia annua (L.).

Anti-cancer

Artemisinin and related compounds (artemisinins) is a frontline treatment for malaria. According to experimental evidence from more than 400 literature studies, 558 key proteins were derived and the artemisinins-rewired protein interaction network was constructed. Topological properties were analyzed to show that the protein network was a scale-free biological system. Five key pathways including PI3K-Akt, T cell receptor, Toll-like receptor, TGF-beta and insulin signaling pathways were involved in artemisinins-mediated anti-cancer effects (Huang et al., 2013).

Breast Cancer

Artemisinin has previously been shown to have selective toxicity towards cancer cells in vitro. The potential of artemisinin to prevent breast cancer development has been investigated in rats treated with a single oral dose (50 mg/kg) of 7,12-dimethylbenz[a]anthracene (DMBA), known to induce multiple breast tumors. Starting from the day immediately after DMBA treatment, one group of rats was provided with a powdered rat-chow containing 0.02% artemisinin, whereas a control group was provided with plain powdered food. For 40 weeks, both groups of rats were monitored for breast tumors.

Oral artemisinin significantly delayed (P<.002) and in some animals prevented (57% of artemisinin-fed versus 96% of the controls developed tumors, P<.01) breast cancer development in the monitoring period. In addition, breast tumors in artemisinin-fed rats were significantly fewer (P<.002) and smaller in size (P<.05) when compared with controls. Since artemisinin is a relatively safe compound that causes no known side-effects even at high oral doses, the present data indicate that artemisinin may be a potent chemoprevention agent (Lai, 2006).

Leukemia

Artemisinin is also a well-known anti-leukemic agent. The effect of artemisinin on cellular differentiation in the human promyelocytic leukemia HL-60 cell culture system has been investigated. Artemisinin markedly increased the degree of HL-60 leukemia cell differentiation when simultaneously combined with low doses of 1α,25-dihydoxyvitamin D3 [1,25-(OH)2D3] or all-trans retinoic acid (all-trans RA).

Extracellular-regulated kinase (ERK) inhibitors markedly inhibited HL-60 cell differentiation induced by artemisinin in combination with 1,25-(OH)2D3 or all-trans RA, whereas phosphatidylinositol 3-kinase (PI3-K) inhibitors did not. Particularly, protein kinase C (PKC) inhibitors inhibited HL-60 cell differentiation induced by artemisinin in combination with 1,25-(OH)2D3 but not with all-trans RA. Artemisinin enhanced PKC activity and protein level of PKCβI isoform in only 1,25-(OH)2D3-treated HL-60 cells.

Taken together, these results indicate that artemisinin strongly enhances the action of low doses of 1α,25-dihydoxyvitamin D3 [1,25-(OH)2D3] and all-trans retinoic acid in leukemia cell differentiation (Kim, 2003).

Gastric Cancer

Zhang et al. (2013) found that artemisinin inhibited growth and modulated expression of cell-cycle regulators in gastric cancer cells (AGS and MKN74 cells). Treatment with artemisinin was also associated with induction of p27kip1 and p21kip1, two negative cell-cycle regulators. Furthermore, we revealed that artemisinin treatment led to an increased expression of p53.

The side-effects from the artemisinin class of medications are similar to the symptoms of malaria: nausea, vomiting, anorexia, and dizziness. Mild blood abnormalities have also been noted. A rare but serious adverse effect is allergic reaction (Leonardi et al., 2001).

References

Huang C, Ba Q, Yue Q, et al. (2013). Artemisinin rewires the protein interaction network in cancer cells: network analysis, pathway identification, and target prediction. Mol Biosyst. Kim SH, Kim HJ, Kim TS. (2003). Differential involvement of protein kinase C in human promyelocytic leukemia cell differentiation enhanced by artemisinin. European Journal of Pharmacology, 482(1–3):67–76. doi:10.1016/j.ejphar.2003.09.057.


Lai H, Singh NP. (2006). Oral artemisinin prevents and delays the development of 7, 12-dimethylbenz [a] anthracene (DMBA)-induced breast cancer in the rat. Cancer Letters, 231(1):43–48. doi: 10.1016/j.canlet.2005.01.019.


Leonardi E, Gilvary G, White NJ, Nosten F. (2001). Severe allergic reactions to oral artesunate: a report of two cases'. Trans. R. Soc. Trop. Med. Hyg, 95(2):182–3. doi:10.1016/S0035-9203(01)90157-9.


Sun H, Meng X, Han J, et al. (2013) Anti-cancer activity of DHA on gastric cancer-an in vitro and in vivo study. Tumor Biol.


Zhang HT, Wang YL, Zhang J, Zhang QX. (2013). Artemisinin inhibits gastric cancer cell proliferation through up-regulation of p53. Tumor Biol.

Aloe-emodin (See also Emodin)

Cancer:
Nasopharyngeal., ER α degradation, Lung, breast, oral., glioblastoma, liver cancer prevention

Action: Cytostatic, radio-sensitizing, chemo-sensitizing

Nasopharyngeal Carcinoma

Aloe-emodin (AE), a natural., biologically active compound from Aloe vera leaves has been shown to induce apoptosis in several cancer cell lines in vitro. Investigation showed that AE induced G2/M phase arrest by increasing levels of cyclin B1 bound to Cdc2, and also caused an increase in apoptosis of nasopharyngeal carcinoma (NPC) cells, which was characterized by morphological changes, nuclear condensation, DNA fragmentation, caspase-3 activation, cleavage of poly (ADP-ribose) polymerase (PARP) and increased sub-G(1) population. Treatment of NPC cells with AE also resulted in a decrease in Bcl-X(L) and an increase in Bax expression.

Collectively, results indicate that the caspase-8-mediated activation of the mitochondrial death pathway plays a critical role in AE-induced apoptosis of NPC cells (Lin et al., 2010).

Glioblastoma

Aloe emodin arrested the cell-cycle in the S phase and promoted the loss of mitochondrial membrane potential in glioblastoma U87 cells that indicated the early event of the mitochondria-induced apoptotic pathway. It plays an important role in the regulation of cell growth and death (Ismail et al., 2013).

Breast Cancer

The anthraquinones emodin and aloe-emodin are also abundant in the rhizome Rheum palmatum and can induce cytosolic estrogen receptor α (ER α) degradation; it primarily affected nuclear ER α distribution similar to the action of estrogen when protein degradation was blocked. In conclusion, our data demonstrate that emodin and aloe-emodin specifically suppress breast cancer cell proliferation by targeting ER α protein stability through distinct mechanisms (Huang et al., 2013).

Lung Cancer

Photoactivated aloe-emodin induced anoikis and changes in cell morphology, which were in part mediated through its effect on cytoskeleton in lung carcinoma H460 cells. The expression of protein kinase Cδ (PKCδ) was triggered by aloe-emodin and irradiation in H460 cells. Furthermore, the photoactivated aloe-emodin-induced cell death and translocation of PKCδ from the cytosol to the nucleus was found to be significantly inhibited by rottlerin, a PKCδ-selective inhibitor (Chang et al., 2012).

Oral Cancer; Radio-sensitizing, Chemo-sensitizing

The treatment of cancer with chemotherapeutic agents and radiation has two major problems: time-dependent development of tumor resistance to therapy (chemoresistance and radioresistance) and nonspecific toxicity toward normal cells. Many plant-derived polyphenols have been studied intensively for their potential chemo-preventive properties and are pharmacologically safe.

These compounds include genistein, curcumin, resveratrol, silymarin, caffeic acid phenethyl ester, flavopiridol, emodin, green tea polyphenols, piperine, oleandrin, ursolic acid, and betulinic acid. Recent research has suggested that these plant polyphenols might be used to sensitize tumor cells to chemotherapeutic agents and radiation therapy by inhibiting pathways that lead to treatment resistance. These agents have also been found to be protective from therapy-associated toxicities.

Treatment with aloe-emodin at 10 to 40 microM resulted in cell-cycle arrest at G2/M phase. The alkaline phosphatase (ALP) activity in KB cells increased upon treatment with aloe-emodin when compared to controls. This is one of the first studies to focus on the expression of ALP in human oral carcinomas cells treated with aloe-emodin. These results indicate that aloe-emodin has anti-cancer effect on oral cancer, which may lead to its use in chemotherapy and chemo-prevention of oral cancer (Xiao et al., 2007).

Liver Cancer Prevention

In Hep G2 cells, aloe-emodin-induced p53 expression and was accompanied by induction of p21 expression that was associated with a cell-cycle arrest in G1 phase. In addition, aloe-emodin had a marked increase in Fas/APO1 receptor and Bax expression. In contrast, with p53-deficient Hep 3B cells, the inhibition of cell proliferation of aloe-emodin was mediated through a p21-dependent manner that did not cause cell-cycle arrest or increase the level of Fas/APO1 receptor, but rather promoted aloe-emodin-induced apoptosis by enhancing expression of Bax.

These findings suggest that aloe-emodin may be useful in liver cancer prevention (Lian et al., 2005).

References

Chang WT, You BJ, Yang WH, et al. (2012). Protein kinase C delta-mediated cytoskeleton remodeling is involved in aloe-emodin-induced photokilling of human lung cancer cells. Anti-cancer Res, 32(9):3707-13.

Huang PH, Huang CY, Chen MC, et al. (2013). Emodin and Aloe-Emodin Suppress Breast Cancer Cell Proliferation through ER α Inhibition. Evid Based Complement Alternat Med, 2013:376123. doi: 10.1155/2013/376123.

Ismail S, Haris K, Abdul Ghani AR, et al. (2013). Enhanced induction of cell-cycle arrest and apoptosis via the mitochondrial membrane potential disruption in human U87 malignant glioma cells by aloe emodin. J Asian Nat Prod Res.

Lian LH, Park EJ, Piao HS, Zhao YZ, Sohn DH. (2005). Aloe Emodin‐Induced Apoptosis in Cells Involves a Mitochondria‐Mediated Pathway. Basic & Clinical Pharmacology & Toxicology, 96(6):495–502.

Lin, ML, Lu, YC, Chung, JG, et al. (2010). Aloe-emodin induces apoptosis of human nasopharyngeal carcinoma cells via caspase-8-mediated activation of the mitochondrial death pathway. Cancer Letters, 291(1), 46-58. doi: 10.1016/j.canlet.2009.09.016.

Xiao B, Guo J, Liu D, Zhang S. (2007). Aloe-emodin induces in vitro G2/M arrest and alkaline phosphatase activation in human oral cancer KB cells. Oral Oncol, 43(9):905-10.

Acetyl-keto-beta-boswellic acid (AKBA)

Cancer: Colorectal, prostate, gastric

Action: Anti-cancer

Apoptotic

Acetyl-keto-beta-boswellic acid (AKBA), a triterpenoid isolated from Boswellia carterri Birdw and Boswellia serrata, has been found to inhibit tumor cell growth and to induce apoptosis. Boswellic acids trigger apoptosis via a pathway dependent on caspase-8 activation, and independent of Fas/Fas ligand interaction in colon cancer HT-29 cells (Liu et al., 2002).

Colon Cancer

Although there is increasing evidence showing that boswellic acid might be a potential anti-cancer agent, the mechanisms involved in its action are unclear. It has been shown that acetyl-keto-beta-boswellic acid (AKBA) inhibits cellular growth in several colon cancer cell lines. Cell cycle analysis by flow cytometry showed that cells were arrested at the G1 phase after AKBA treatment.

These results demonstrate that AKBA inhibits cellular growth in colon cancer cells. These findings may have implications for the use of boswellic acids as potential anti-cancer agents in colon cancer (Liu et al., 2006).

AKBA significantly inhibited human colon adenocarcinoma growth, showing arrest of the cell-cycle in G1-phase and induction of apoptosis. AKBA administration in mice effectively delayed the growth of HT-29 xenografts without signs of toxicity (Yuan et al., 2013).

Gastric Cancer

AKBA exhibited anti-cancer activity in vitro and in vivo. With oral application in mice, AKBA significantly inhibited gastric cancer cells line SGC-7901 and MKN-45 xenografts without toxicity.

This effect might be associated with its roles in cell-cycle arrest and apoptosis induction. The results also showed activation of p21(Waf1/Cip1) and p53 in mitochondria and increased cleaved caspase-9, caspase-3, and PARP and Bax/Bcl-2 ratio after AKBA treatment. Upon AKBA treatment, β-catenin expression in nuclei was inhibited, and membrane β-catenin was activated (Zhang et al., 2013).

Prostate

The apoptotic effects and the mechanisms of action of AKBA were studied in LNCaP and PC-3 human prostate cancer cells. AKBA induced apoptosis in both cell lines at concentrations above 10 microg/mL. AKBA-induced apoptosis was correlated with the activation of caspase-3 and caspase-8 as well as with poly(ADP)ribose polymerase (PARP) cleavage.

AKBA treatment increased the levels of CAAT/enhancer binding protein homologous protein (CHOP) and activated a DR5 promoter reporter but did not activate a DR5 promoter reporter with the mutant CHOP binding site. These results suggest that AKBA induces apoptosis in prostate cancer cells through a DR5-mediated pathway, which probably involves the induced expression of CHOP (Lu et al., 2008).

References

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Liu JJ, Huang B, Hooi SC. (2006). Acetyl-keto-beta-boswellic acid inhibits cellular proliferation through a p21-dependent pathway in colon cancer cells. Br J Pharmacol, 148(8):1099-107.

 

Lu M, Xia L, Hua H, Jing Y. (2008). Acetyl-keto-beta-boswellic acid induces apoptosis through a death receptor 5-mediated pathway in prostate cancer cells. Cancer Res, 68(4):1180-6. doi: 10.1158/0008-5472.CAN-07-2978.

 

Yuan Y, Cui SX, Wang Y, et al. (2013). Acetyl-11-keto-beta-boswellic acid (AKBA) prevents human colonic adenocarcinoma growth through modulation of multiple signaling pathways. Biochim Biophys Acta, 1830(10):4907-16. doi: 10.1016/j.bbagen.2013.06.039.

 

Zhang YS, Xie JZ, Zhong JL, et al. (2013) Acetyl-11-keto-β-boswellic acid (AKBA) inhibits human gastric carcinoma growth through modulation of the Wnt/β -catenin signaling pathway. Biochim Biophys Acta, 1830(6):3604-15. doi: 10.1016/j.bbagen.2013.03.003.