Category Archives: radio-sensitizing

Akt, angiogenesis, Anti-angiogenic, Anti-cancer, anti-inflammatory, Anti-metastatic, AP-1, apoptosis, BAX, Bcl-2, c-Fos, c-Jun, c-Myc, cell-cycle arrest, Cervical cancer, Chapter 7 Isolates and Cancer Research, Chemo-sensitizer, cytotoxic, ERK, G0/G1, G1, G2/M, IAP, IKK, IL-2, IL-6, Immune, Immunomodulatory, induces apoptosis, Lung cancer, Ovarian cancer, p16, p21, p53, PARP, pro-oxidative, Radio-sensitizer, radio-sensitizing, ROS, TIMP-2, TNF, XIAP

Saikosaponin

April 21, 2014 brian

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.

A549, anti-tumor, anti-tumor activity, apoptosis, Apoptotic, BAX, Bcl-2, Breast cancer, CDC2, cell-cycle arrest, Chapter 7 Isolates and Cancer Research, COX-2, G2/M, induces apoptosis, Lung cancer, MCF-7, p21, p53, Panc-28, Pancreatic cancer, PC3, Pro-apoptotic, pro-apoptotic with 5-FU, Prostate cancer, Radio-sensitizer, radio-sensitizing, ROS

Oleanolic Acid (OA)

April 20, 2014 brian

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.

anti-tumor, anti-tumor activity, apoptosis, Chapter 7 Isolates and Cancer Research, cytotoxic, Melanoma, PC3, PC3 and DU145, Prostate cancer, Prostate cancer cell lines, Radio-sensitizer, radio-sensitizing, U251

Oleandrin

April 20, 2014 brian

Cancer: Prostate, glioma, melanoma

Action: Radio-sensitizer

Anvirzel is an extract of Nerium oleander (L.) currently undergoing, as Anvirzelª Phase I clinical evaluation as a potential treatment for cancer. Two of the active components of Anvirzel are the cardiac glycosides, oleandrin and oleandrigenin.

Prostate Cancer

In continuing research on the anti-tumor activity of this novel plant extract, the relative abilities of oleandrin and oleandrigenin to inhibit FGF-2 export from two human prostate cancer cell lines, DU145 and PC3, were examined. An ELISA assay was utilized to determine the FGF-2 concentration in the cell culture medium before and after exposure to cardiac glycosides or the parent extract material Anvirzel.

Studies also were conducted with Anvirzel (a hot water extract of Nerium oleander, known as Anvirzelª) and ouabain (found in the ripe seeds of African plants Strophanthus gratus). Oleandrin (0.1 ng/mL) produced a 45.7% inhibition of FGF-2 release from PC3 cells and a 49.9% inhibition from DU145 cells. Non-cytotoxic concentrations (100 ng/mL) of Anvirzel produced a 51.9% and 30.8% inhibition of FGF-2 release, respectively, in the two cell lines. These results demonstrate that Anvirzel, like oleandrin, inhibited FGF-2 export in vitro from PC3 and DU145 prostate cancer cells in a concentration- and time-dependent fashion and may, therefore, contribute to the anti-tumor activity of this novel treatment for cancer (Smith et al., 2001).

Radio-sensitizers; Prostate Cancer

In the present study Nasu et al. (2002) explored the relative radio-sensitization potential of oleandrin, a cardiac glycoside contained within the plant extract known as Anvirzelª. The data show that oleandrin produces an enhancement of sensitivity of PC-3 human prostate cells to radiation; at a cell survival of 0.1, the enhancement factor was 1.32. The magnitude of radio-sensitization depended on duration of exposure of cells to drug prior to radiation treatment.

While a radio-sensitizing effect of oleandrin was evident with only 1 hour of cell exposure to drug, the effect greatly increased with 24 hours of oleandrin pre-treatment.

Activation was greatest when cells were exposed simultaneously to oleandrin and radiation. Inhibition of caspase-3 activation with Z-DEVD-FMK abrogated the oleandrin-induced enhancement of radiation response suggesting that both oleandrin and radiation share a caspase-3 dependent mechanism of apoptosis in the PC-3 cell line.

Glioma, Melanoma

Twelve human tumor cell lines were chosen to examine determinants of human tumor cell sensitivity to cardiac glycosides. In vitro cell culture models of human glioma HF U251 and U251 cells as well as human parental and modified melanoma BRO cells were also included in these studies. Cardiac glycosides such as oleandrin, ouabain and bufalin increased expression of Na+, K+ -ATPase alpha 1 and therefore total Na+, K+ -ATPase activity, which is associated with increased cellular levels of glutathione. Additionally, an increased colony-forming ability was noted in cells with high levels of Na+, K+ -ATPase alpha 1 expression, suggesting that Na+, K+ -ATPase alpha 1 isoform may be actively involved in tumor growth and cell survival (Lin, Ho, & Newman, 2010)

References

Lin Y, Ho DH, Newman RA. (2010). Human tumor cell sensitivity to oleandrin is dependent on relative expression of Na+, K+ -ATPase subunitst. J Exp Ther Oncol, 8(4):271-86.

Nasu S, Milas L, Kawabe S, Raju U, Newman R. (2002). Enhancement of radiotherapy by oleandrin is a caspase-3 dependent process. Cancer Letters, 185(2):145–151. doi:10.1016/S0304-3835(02)00263-X

Smith JA, Madden T, Vijjeswarapu M, Newman RA. (2001). Inhibition of export of fibroblast growth factor-2 (FGF-2) from the prostate cancer cell lines PC3 and DU145 by anvirzel and its cardiac glycoside component, oleandrin. Biochemical Pharmacology, 62(4):469-472. doi:10.1016/S0006-2952(01)00690-6.

Anti-cancer, Anti-cancer effect, apoptosis, Apoptotic, BAX, Breast cancer, CDC2, cell-cycle arrest, Chapter 7 Isolates and Cancer Research, chemo-prevention, chemo-preventive, chemo-sensitizing, Chemotherapy, Cytostatic, ER, G1, G2/M, Glioblastoma, H460, Liver cancer, Lung cancer, Oral cancer, p21, p53, PARP, PKC, radio-sensitizing, S, U87

Aloe-emodin (See also Emodin)

April 18, 2014 brian

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.

anti-tumor, apoptosis, Apoptotic, AT6.3, Breast cancer, Chapter 7 Isolates and Cancer Research, Enhances tamoxifen, PARP, Prostate cancer, Radio-sensitizer, radio-sensitizing

Daidzein & S-(-)-equol

March 27, 2014 brian

Cancer: Breast, prostate

Action: Enhances tamoxifen, radio-sensitizer

Daidzein & Genistein Concentrations; Breast Cancer

A systematic search by Mário L de Lemos (2001) through primary English-language literature on MEDLINE (1966–January 2001), EMBASE (1982–January 2001) and Current Contents (1998–January 2001) found that genistein and daidzein at low concentrations were found to stimulate breast tumor growth in in vitro and in vivo animal studies, and antagonize the anti-tumor effect of tamoxifen in vitro. However, at high concentrations, genistein inhibited tumor growth and enhanced the effect of tamoxifen in vitro.

At concentrations below 10 µmol/L, phytoestrogens can stimulate breast tumor growth and antagonize the anti-tumor effects of tamoxifen, particularly in an environment of low endogenous estrogen. In contrast, phytoestrogens inhibit breast tumor growth and enhance the anti-tumor effects of tamoxifen at concentrations above 10 µmol/L (de Lemos, 2002; Akaza et al., 2004).

Breast cancer

Daidzein or its major metabolite equol at a dose molar equivalent to tamoxifen [1.0 mg(2.7 µmol)/kg or 10 mg (27 µmol)/kg/day] was treated orally to rats bearing 7,12-dimethylbenz(a)anthracene(DMBA)-induced mammary tumors or ovariectomized athymic nude mice implanted with human MCF-7 breast cancer xenograft and an estrogen pellet. The growth of tumors was monitored for several weeks after the treatment. The cell-cycle and apoptotic stages in mammary tumors collected from rats were analyzed by flow cytometry. Immunohistochemistry analysis was also used to determine the expression of caspase-3.

Oral treatment with daidzein or equol at a human equivalent dose suppressed the growth of both DMBA-induced mammary tumors and human MCF-7 breast cancer xenografts in rodents, the inhibitory activity being superior to that of genistein or tamoxifen. Strong apoptosis induced by daidzein or equol contributes to the anti-tumor potential.

Daidzein and its metabolite equol showed the potential of inhibiting the growth of mammary tumors in rodents. Daidzein or equol could be used as a core structure to design new drugs for breast cancer therapy. Our results indicate that consumption of daidzein may protect against breast cancer (Liu et al., 2012).

Equol Production

S-(-)-equol is a metabolite of the soy isoflavone daidzein and is produced by intestinal bacteria in some, but not in all, humans after soy consumption (Setchell & Clerici, 2010). The ability of S-equol to play a role in the treatment of estrogen or androgen-mediated diseases or disorders was first proposed in 1984 (Setchell et al., 1984). The ability to do so depends on two things: soy and bacteria. First, the soy must contain the soy isoflavone daidzein and the amount may influence equol production. Second, the human must have certain strains of bacteria living within the intestine. Twenty-one different strains of intestinal bacteria cultured from humans have the ability to transform daidzein into S-equol or a related intermediate compound (Setchell & Clerici, 2010).

Several studies indicate that only 25 to 30 percent of the adult population of Western countries produces S-equol after eating soy foods containing isoflavones, (Rowland et al., 2000; Atkinson et al., 2005) significantly lower than the reported 50–60% frequency of equol-producers in adults from Japan, Korea, or China (Song et al., 2006).

Equol Production; Prostate Cancer

Akaza et al. (2004) recently conducted a case-controlled study on those who are able to degrade daidzein, a soybean isoflavone, to equol and those without this ability. The incidence of prostate cancer is known to be lower in residents in Japan. On the other hand, American residents in the United States have a markedly higher incidence of prostate cancer.

The number of subjects was 295 in Japan (133 patients and 162 controls), 122 in Korea (61 patients and 61 controls) and 45 in the United States (24 patients and 21 controls). The percentage of equol producers among patients and controls was 29% and 46% in Japan (P = 0.004) and 30% and 59% in Korea (P = 0.001), respectively. The active isoflavone level was markedly lower and the percentage of equol producers was also lower (17% for patients and 14% for controls) for Americans as compared to the Japanese and Koreans.

These results suggest that the ability to produce equol, or equol itself, is closely related to the lower incidence of prostate cancer. The results also suggest that a diet based on soybean isoflavones will be useful in preventing prostate cancer.

Prostate cancer

The age-adjusted incidence rate of prostate cancer (PCa) has been reported to be lower among Asians than Western populations. A traditional Japanese meal., high in soybean products or isoflavones, may be associated with a decreased risk of PCa. Equol, which is converted from daidzein by human intestinal flora, is biologically more active than any other isoflavone aglycone.

Five out of 6 articles showed significant association of isoflavones with a decreased risk of PCa, and two of them consistently showed that equol-producers carry a significantly reduced risk of PCa. Furthermore, 5 human intestinal bacteria that can convert daidzein into equol were identified in the last 5 years. If equol can reduce risk of PCa, a possible strategy for reducing the risk of PCa may be to increase the proportion of equol-producers by changing the intestinal flora to carry an equol-producing bacterium, with dietary alteration or probiotic technology (Sugiyama et al., 2013).

Equol Enhances Tamoxifen

Charalambous, Pitta, & Constantinou (2013) found that equol (>50 µM) and 4-hydroxy-tamoxifen (4-OHT; >100 nM) significantly reduced the breast cancer MCF-7 cell viability. Furthermore, the combination of equol (100 µM) and 4-OHT (10 µM) induced apoptosis more effectively than each compound alone. Subsequent treatment of MCF-7 cells with the pan-caspase inhibitor Z-VAD-FMK inhibited equol- and 4-OHT-mediated apoptosis, which was accompanied by PARP and α-fodrin cleavage, indicating that apoptosis is mainly caspase-mediated.

Equol may be used therapeutically in combination treatments and clinical studies to enhance tamoxifen's effect by providing additional protection against estrogen-responsive breast cancers.

Radio-sensitizer

Sensitivity of cells to equol, radiation and a combination of both was determined by colonogenic assays. Induction of apoptosis by equol, radiation and the combination of both was also determined by acridine orange/ethidium bromide double staining fluorescence microscopy. DNA strand breaks were assessed by Comet assay.

MTT assay showed that equol (0.1-350 µM) inhibited MDA-MB-231 and T47D cell growth in a time- and dose-dependent manner. Treatment of cells with equol for 72 hours (MDA-MB-231) and 24 hours (T47D) was found to inhibit cell growth with IC50 values of 252 µM and 228 µM, respectively. Furthermore, pre-treatment of cells with 50 µM equol for 72 hours (MDA-MB-231) and 24 hours (T47D) sensitized the cells to irradiation. Equol was also found to enhance radiation-induced apoptosis. Comet assay results showed that the radio-sensitizing effect of equol was accompanied by increased radiation-induced DNA damage.

These results suggest for the first time that equol can be considered as a radio-sensitizing agent and its effects may be due to increasing cell death following irradiation, increasing the remaining radiation-induced DNA damage and thus reducing the surviving fraction of irradiated cells (Taghizadeh et al., 2013).

References

Akaza H, Miyanaga N, Takashima N, Naito S, et al. (2004). Comparisons of percent equol producers between prostate cancer patients and controls: case-controlled studies of isoflavones in Japanese, Korean and American residents. Japanese Journal of Clinical Oncology, 34(2): 86–9.

Atkinson, C., Frankenfeld, C.L., Lampe, J.W. (2005). Gut bacterial metabolism of the soy isoflavone daidzein: exploring the relevance to human health. Experimental Biology and Medicine (Maywood, N.J.), 230(3):155–70.

Charalambous C, Pitta CA, Constantinou AI. (2013). Equol enhances tamoxifen's anti-tumor activity by induction of caspase-mediated apoptosis in MCF-7 breast cancer cells. BMC Cancer, 13:238. doi: 10.1186/1471-2407-13-238.

de Lemos ML. (2001). Effects of soy phytoestrogens genistein and daidzein on breast cancer growth. Ann Pharmacother, 35(9):1118-21.

de Lemos ML. (2002). Safety Issues of Soy Phytoestrogens in Breast Cancer Patients. JCO, 20(13):3040-3042.

Liu X, Suzuki N, Santosh Laxmi YR, Okamoto Y, Shibutani S. (2012). Anti-breast cancer potential of daidzein in rodents. Life Sci, 91(11-12):415-9.

Rowland IR, Wiseman H, Sanders TA, Adlercreutz H, Bowey EA. (2000). Interindividual variation in metabolism of soy isoflavones and lignans: influence of habitual diet on equol production by the gut microflora. Nutrition and Cancer, 36(1):27–32. doi:10.1207/S15327914NC3601_5.

Setchell KD, Borriello SP, Hulme P, Kirk DN, Axelson M. (1984). Nonsteroidal estrogens of dietary origin: possible roles in hormone-dependent disease. The American Journal of Clinical Nutrition, 40(3):569–78.

Setchell KD, Clerici C. (2010). Equol: history, chemistry, and formation. The Journal of Nutrition, 140 (7): 1355S–62S. doi:10.3945/jn.109.119776.

Song KB, Atkinson C, Frankenfeld CL, Jokela T, et al. (2006). Prevalence of daidzein-metabolizing phenotypes differs between Caucasian and Korean American women and girls. The Journal of Nutrition, 136(5):1347–51.

Sugiyama Y, Masumori N, Fukuta F, et al. (2013). Influence of isoflavone intake and equol-producing intestinal flora on prostate cancer risk. Asian Pac J Cancer Prev, 14(1):1-4.

Taghizadeh B, Ghavami L, Nikoofar A, Goliaei B. (2013). Equol as a potent radiosensitizer in estrogen receptor-positive and -negative human breast cancer cell lines. Breast Cancer.

A549 and CH27, angiogenesis, Anti-angiogenic, Anti-cancer, anti-depressant, anti-inflammatory, Anti-metastatic, anti-tumor, Antibiotic, anxiolytic, apoptosis, Apoptotic, B-CLL, Breast cancer, Chapter 7 Isolates and Cancer Research, Chemo-sensitizer, Chemotherapy, Colon Cancer or Colorectal cancer, cytotoxic, Depression or Anxiety, HL-60, induces apoptosis, inflammation, inhibits angiogenesis, inhibits VEGF, Lung cancer, MCF-7/ADR, MDR, Multi-Drug Resistance, Multi-drug resistance, Multi-drug resistance reversal, Ovarian cancer, Pancreatic cancer, Prostate cancer, radio-sensitizing, RKO, Sarcoma, STAT, Uterine cancer, VEGF, VEGF

Honokiol (See also Injectables)

March 27, 2014 brian

Cancer:
Lung, breast, prostate, leukemia, colorectal., esophageal., ovarian, myeloma, pancreatic, stomach, uterine

Action: Anti-angiogenic, chemo-sensitizer, multi-drug resistance reversal., anti-inflammatory, anxiolytic, anti-depressant, inhibits VEGF, anti-metastatic, synergistic effects with other cancer treatments

Honokiol is a phenolic compound purified from plants of the Magnolia genus, including Magnolia officinalis (Rehder & Wilson) and Magnolia grandiflora (L.), that exhibits anti-cancer effects in experimental models with various types of cancer cells, including esophageal., ovarian, breast, and lung cancer, as well as myeloma and leukemia. It is speculated that this compound causes cancer cell death in part through targeting mitochondria (Munroe et al., 2007; Chen et al., 2009; Fried & Arbiser, 2009).

Inhibits Angiogenesis, MDR, Anti-inflammatory, Inhibits VEGF

Honokiol is one of two dominant biphenolic compounds isolated from Magnolia spp. bark, and is the most widely researched active constituent of the bark. In vivo studies suggest that honokiol's greatest value is in its multiple anti-cancer actions. In vitro research suggests honokiol has potential to enhance current anti-cancer regimens by inhibiting angiogenesis, promoting apoptosis, providing direct cytotoxic activity, down-regulating cancer cell signaling pathways, regulating genetic expression, enhancing the effects of specific chemotherapeutic agents, radio-sensitizing cancer cells to radiation therapy, and inhibiting multi-drug resistance.

Honokiol also shows potential in preventive health by reducing inflammation and oxidative stress, providing neurological protection, and regulating glucose; in mental illness by its effects against anxiety and depression; and in helping regulate stress response signaling. Its anti-microbial effects demonstrate potential for partnering with anti-viral/antibiotic therapy, and treating secondary infections.

Honokiol may occupy a distinct therapeutic niche because of its unique characteristics: the ability to cross the blood brain barrier (BBB) and blood cerebrospinal fluid barrier (BCSFB), high systemic bioavailability, and its actions on a multiplicity of signaling pathways and genomic activity. There is a need for research on honokiol to progress to human studies and on into clinical use.

The preclinical research on honokiol's broad-ranging capabilities shows its potential as a therapeutic compound for numerous solid and hematological cancers, including its effectiveness in combating multi-drug resistance (MDR) and its synergy with other anti-cancer therapies. Research thus far shows no toxicity or serious adverse effects in animal models.

Honokiol has also been shown to inhibit spread of cancer cells through the lymph system by inhibiting one of the primary pathways involved in growth stimulation related to vascular endothelial growth factor (VEGF) (Wen et al., 2009).

Inhibits Angiogenesis, Gastric Cancer

A 2012 in vivo study in PLoS One showed that honokiol, by inhibiting angiogenic pathways such as STAT-3, dampened peritoneal dissemination of gastric cancer in mice (5 mg/kg delivered intraperitoneally) (Liu et al., 2012).

Induces Apoptosis; Leukemia

Honokiol induces cell apoptosis in several cell lines, such as leukemia cell lines HL-60, colon cancer cell lines RKO, lung cancer cell lines A549 and CH27 (Hirano et al., 1994; Wang et al., 2004; Hibasami et al., 1998; Konoshima et al., 1991;Yang et al., 2002; Kong et al., 2005). It also has remarkable in vivo anti-tumor activities in tumor mouse models (Bai et al., 2003). Honokiol has demonstrated potent anti-angiogenic and anti-tumor properties against aggressive angiosarcoma by blocking of VEGF-induced VEGF receptor 2 autophosphorylation (Konoshima et al., 1991; Yang et al., 2002).

MDR

Honokiol has also been found to down-regulate the expression of P-glycoprotein at mRNA and protein levels in MCF-7/ADR, a human breast MDR cancer cell line. The down-regulation of P-glycoprotein is accompanied with a partial recovery of the intracellular drug accumulation (Xu et al., 2006).

Prostate Cancer

In addition, it has been shown that prostate cancer cells that failed to respond to hormone withdrawal responded to honokiol-induced apoptosis. It was found to significantly induce death in cells surrounding primary and metastatic prostate cancers, the prostate stromal fibroblasts, marrow stromal cells, and bone marrow-associated endothelial cells. Honokiol is hence a promising nontoxic agent that could be used as an adjuvant with low-dose docetaxel for the treatment of hormone-refractory prostate cancer and its distant bone metastases (Shigemura et al., 2007).

Anti-metastatic

Honokiol inhibited the activity of MMP-9, which may be responsible, in part, for the inhibition of tumor cell invasiveness (Nagase et al., 2001).

Breast Cancer

The development of more targeted and low toxic drugs from traditional Chinese medicines for breast cancer are needed due to most of the anti-breast cancer drugs often being limited because of drug resistance and serious adverse reactions. Results have shown that honokiol inhibited the rate of breast cancer MDA-MB-231 cell growth (Nagalingam et al., 2012).

Synergistic Effects with Other Cancer Treatments

One of the most promising benefits of honokiol is its ability to synergize with other cancer treatments. Clinical trials are desperately needed to validate the potential synergy that has been demonstrated in vitro and in vivo.

Chemotherapy

• A 2013 in vitro study published in the International Journal of Oncology showed that honokiol synergized chemotherapy drugs in Multi-drug-resistant breast cancer (Tian et al., 2013). A 2011 in vitro study published in PLoS One found that honokiol enhanced the apoptotic effects of the anti-cancer drug gemcitabine against pancreatic cancer (Arora et al., 2011).

• In vivo research published in Oncology Letters in 2011 found honokiol enhanced the action of cisplatin against colon cancer (Cheng et al., 2011).

• A 2010 in vitro study from the Journal of Biological Regulators and Homeostatic Agents showed that honokiol resensitized cancer cells to doxorubicin in Multi-drug-resistant uterine cancer (Angelini et al., 2010).

• A 2010 in vitro study published in Toxicology Mechanisms and Methods showed honokiol performed synergistically with the drug imatinib against human leukemia cells (Wang et al., 2010).

• 2008 in vivo research published in the International Journal of Gynecological Cancer showed honokiol to potentiate the activity of cisplatin in murine models of ovarian cancer (Liu et al., 2008).

• 2005 in vitro research published in Blood showed honokiol enhanced the cytotoxicity induced by fludarabine, cladribine, and chlorambucil, indicating it is a potent inducer of apoptosis in B-CLL cells (Battle et al., 2005).

Radiation treatment

• 2012 in vitro research published in Molecular Cancer Therapeutics showed that honokiol was able to sensitize cancer cells to radiation treatments (Ponnurangam et al., 2012).

• A 2011 in vitro study published in American Journal of Physiology Gastrointestinal and Liver Physiology showed honokiol sensitized treatment-resistant colon cancer cells to radiation therapy (He et al., 2011).

Inhibition of multi-drug resistance

Honokiol has been shown to interact with genes that are involved with mechanisms of drug efflux, thus reversing MDR in experimental models. The exact mechanisms of action in this regard are thought to be related to effects of blocking of NF-kB activity, but other mechanisms may also be involved (Xu et al., 2006).

References

Angelini A, Di Ilio C, Castellani ML, Conti P, Cuccurullo F. (2010). Modulation of Multi-drug resistance p-glycoprotein activity by flavonoids and honokiol in human doxorubicin-resistant sarcoma cells (MES-SA/DX-5): Implications for natural sedatives as chemosensitizing agents in cancer therapy. Journal of Biological Regulators & Homeostatic Agents, 24(2). 197-205.

Arora S, Bhardwaj A, Srivastava SK, et al. (2011). Honokiol arrests Cell-cycle, induces apoptosis, and potentiates the cytotoxic effect of gemcitabine in human pancreatic cancer cells. PLoS One, 6(6), e21573. doi: 10.1371/journal.pone.0021573.

Bai X, Cerimele F, Ushio-Fukai M, et al. (2003). Honokiol, a small molecular weight natural product, inhibits angiogenesis in vitro and tumor growth in vivo. J Biol Chem, 278: 35501–7.

Battle TE, Arbiser J, Frank DA. (2005). The natural product honokiol induces caspase-dependent apoptosis in B-cell chronic lymphocytic leukemia (B-CLL) cells. Blood, 106(2), 690-697.

Chen G, Izzo J, Demizu Y, et al. (2009). Different redox states in malignant and nonmalignant esophageal epithelial cells and differential cytotoxic responses to bile acid and honokiol. Antioxid. Redox Signal., 11(5):1083–1095

Cheng N, Xia T, Han Y, et al. (2001). Synergistic anti-tumor effects of liposomal honokiol combined with cisplatin in colon cancer models. Oncology Letters, 2(5), 957-962.

Eliaz I. (2013). Honokiol research review: A promising extract with multiple applications. Natural Medicine Journal., 5(7).

Fried LE, Arbiser JL. (2009). Honokiol, a multifunctional anti-angiogenic and anti-tumor agent. Antioxid. Redox Signal., 1(5):1139–1148. doi: 10.1089/ARS.2009.2440.

He Z, Subramaniam D, Ramalingam S, et al. (2011). Honokiol radiosensitizes colorectal cancer cells: enhanced activity in cells with mismatch repair defects. American Journal of Physiology: Gastrointest and Liver Physiology, 301(5):G929-937.

Hibasami H, Achiwa Y, Katsuzaki H, et al. (1998). Honokiol induces apoptosis in human lymphoid leukemia Molt 4B cells. Int J Mol Med, 2:671–3.

Hirano T, Gotoh M, Oka K. (1994). Natural flavonoids and lignans are potent cytostatic agents against human leukemic HL-60 cells. Life Sci, 55:1061–9.