Category Archives: HER-2

Piperine

Cancer: Breast, prostate

Action: Autophagy inhibitor, anti-proliferative effect

Breast Cancer Stem Cells

Mammosphere formation assays were performed after curcumin, piperine and control treatment in unsorted normal breast epithelial cells and normal stem and early progenitor cells, selected by ALDH positivity. Wnt signaling was examined using a Topflash assay. Both curcumin and piperine inhibited mammosphere formation, serial passaging and percent of ALDH+ cells, by 50% at 5 µM and completely at 10 µM concentration in normal and malignant breast cells. Curcumin and piperine separately, and in combination, inhibit breast stem cell self-renewal but do not cause toxicity to differentiated cells. These compounds could be potential cancer-preventive agents. Mammosphere formation assays may be a quantifiable biomarker to assess cancer-preventive agent efficacy and Wnt signaling assessment a mechanistic biomarker for use in human clinical trials (Kakarala et al., 2010).

HER-2 Overexpressing Breast Cancer

Results showed that piperine strongly inhibited proliferation and induced apoptosis of HER2-overexpressing breast cancer cells through caspase-3 activation and PARP cleavage. Furthermore, piperine inhibited HER2 gene expression at the transcriptional level.   Piperine pre-treatment enhanced sensitization to paclitaxel killing in HER2-overexpressing breast cancer cells. Our findings suggest that piperine may be a potential agent for the prevention and treatment of human breast cancer with HER2 overexpression (Do et al., 2013).

Prostate Cancer

Piperine treatment resulted in a dose-dependent inhibition of the proliferation of prostate cancer DU145, PC-3 and LNCaP cell lines. Cell-cycle arrest at G₀/G₁ was induced and cyclin D1 and cyclin A were down-regulated upon piperine treatment. Notably, the level of p21(Cip1) and p27(Kip1) was increased dose-dependently by piperine treatment in both LNCaP and DU145 but not in PC-3 cells, in line with more robust cell-cycle arrest in the former two cell lines than the latter one. The piperine-induced autophagic flux was further confirmed by assaying LC3-II accumulation and LC3B puncta formation in the presence of chloroquine, a well-known autophagy inhibitor. Taken together, these results indicated that piperine exhibited anti-proliferative effect in human prostate cancer cells by inducing cell-cycle arrest and autophagy (Ouyang et al., 2013).

References

Do MT, Kim HG, Choi JH, et al. (2013). Anti-tumor efficacy of piperine in the treatment of human HER2-overexpressing breast cancer cells. Food Chem, 141(3):2591-9. doi: 10.1016/j.foodchem.2013.04.125.


Kakarala M, Brenner DE, Korkaya H, et al. (2010). Targeting breast stem cells with the cancer-preventive compounds curcumin and piperine. Breast Cancer Res Treat, 122(3): 777–785.


Ouyang DY, Zeng LH, Pan H, et al. (2013). Piperine inhibits the proliferation of human prostate cancer cells via induction of cell-cycle arrest and autophagy. Food Chem Toxicol, 60:424-30. doi: 10.1016/j.fct.2013.08.007.

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.

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

Antrodia camphorata

 

Cancer: Leukemia, colorectal., ER+ ovarian cancer

Action: Anti-cancer

Antrodia Camphorata [(M. Zang & C.H. Su) Sheng H. Wu, Ryvarden & T.T.] is a native Taiwanese mushroom which is used in Asian folk medicine. It is also known as Ganoderma camphoratum (M. Zang & C.H. Su) and Taiwanofungus camphoratus [(M. Zang & C.H. Su) Sheng H. Wu, Z.H. Yu, Y.C. Dai & C.H. Su].

Anti-tumor

Mycotherapy is defined as the study of the use of extracts and compounds obtained from mushrooms as medicines or health-promoting agents. An increasing number of studies in the past few years have revealed mushroom extracts as potent anti-tumor agents. Also, numerous studies have been conducted on bioactive compounds isolated from mushrooms reporting the heteropolysaccharides, β-glucans, α-glucans, proteins, complexes of polysaccharides with proteins, fatty acids, nucleoside antagonists, terpenoids, sesquiterpenes, lanostanoids, sterols and phenolic acids, as promising anti-tumor agents (Popović et al., 2013).

Leukemia

Antrodia camphorata (AC) is a native Taiwanese mushroom, which is used in Asian folk medicine as a chemo-preventive agent. The triterpenoid-rich fraction (FEA) was obtained from the ethanolic extract of AC and characterized by high performance liquid chromatography (HPLC). FEA caused DNA damage in leukemia HL60 cells which was characterized by phosphorylation of H2A.X and Chk2. It also exhibited apoptotic effect which was correlated to the enhancement of PARP cleavage and to the activation of caspase 3.

Taken together, these results provide the first evidence that pure AC component inhibits tumor growth in an in vivo model, thereby backing the traditional anti-cancer use of AC in Asian countries (Du et al., 2012).

Colon Cancer

Antrodia camphorata (AC) grown on germinated brown rice (CBR) was studied in HT-29 human colon cancer cells. CBR 80% ethanol EtOAc fraction showed the strongest inhibitory activity against HT-29 cell proliferation. Induction of G0/G1 cell-cycle arrest on human colon carcinoma cell was observed in CBR EtOAc fraction-treated cells. We found that CBR decreased the level of proteins involved in G0/G1 cell-cycle arrest and apoptosis. CBR EtOAc fraction inhibited the β-catenin signaling pathway, supporting its suppressive activity on the level of cyclin D1 (Park, Lim, & Park, 2013).

A new enynyl-benzenoid, antrocamphin O (1,4,7-dimethoxy-5-methyl-6-(3'-methylbut-3-en-1-ynyl)benzo[d][1,3]dioxide), and the known benzenoids antrocamphin A and 7-dimethoxy-5-methyl-1,3-benzodioxole, were isolated from the fruiting bodies of Antrodia camphorata (Taiwanofungus camphoratus). The benzenoids were tested successfully for cytotoxicity against the HT29, HTC15, DLD-1, and COLO 205 colon cancer cell lines (Chen et al., 2013).

ER+ Ovarian Cancer

MTT and colony formation assays showed that Antrodia camphorata (AC) induced a dose-dependent reduction in SKOV-3 cell growth. Immunoblot analysis demonstrated that HER-2/neu activity and tyrosine phosphorylation were significantly inhibited by AC. Furthermore, AC treatment significantly inhibited the activation of PI3K/Akt and their downstream effector β-catenin (Yang et al., 2013).

References

Chen PY, Wu JD, Tang KY, et al. (2013). Isolation and synthesis of a bioactive benzenoid derivative from the fruiting bodies of Antrodia camphorata. Molecules, 18(7):7600-8. doi: 10.3390/molecules18077600.


Du YC, Chang FR, Wu TY, et al. (2012). Anti-leukemia component, dehydroeburicoic acid from Antrodia camphorata induces DNA damage and apoptosis in vitro and in vivo models. Phytomedicine. doi:10.1016/j.phymed.2012.03.014


Park DK, Lim YH, Park HJ. (2013). Antrodia camphorata Grown on Germinated Brown Rice Inhibits HT-29 Human Colon Carcinoma Proliferation Through Inducing G0/G1 Phase Arrest and Apoptosis by Targeting the β -Catenin Signaling. J Med Food, 16(8):681-91. doi: 10.1089/jmf.2012.2605.


Popovi ć V, Zivkovi ć J, Davidovi ć S, et al. (2013). Mycotherapy Of Cancer: An Update On Cytotoxic And Anti-tumor Activities Of Mushrooms, Bioactive Principles And Molecular Mechanisms Of Their Action. Curr Top Med Chem.


Yang HL, Lin KY, Juan YC, et al. (2013). The anti-cancer activity of Antrodia camphorata against human ovarian carcinoma (SKOV-3) cells via modulation of HER-2/neu signaling pathway. J Ethnopharmacol, 148(1):254-65. doi: 10.1016/j.jep.2013.04.023.

Emodin (See also Aloe-Emodin)

Cancer:
Breast, colon, liver, chemotherapy, myeloma, oral., pancreatic, hepatocellular carcinoma, lung, leukemia

Action: MDR-1, cell-cycle arrest

Emodin is an active natural anthraquinone derivative component of a traditional Chinese and Japanese medicine isolated from the root and rhizomes of Rheum palmatum L., Senna obtusifolia [(L.) H.S.Irwin & Barneby], Fallopia japonica [Houtt. (Ronse Decr.)], Kalimeris indica (L.) Sch.Bip., Ventilago madraspatana (Gaertn.), Rumex nepalensis (Spreng.), Fallopia multiflora [(Thunb.) Haraldson], Cassia occidentalis [(L.) Link], Senna siamea [(Lam.) Irwin et Barneby] and Acalypha australis (L.).

Aloe-emodin is an active natural anthraquinone derivative, and is found in the roots and rhizomes of numerous Chinese medicinal herbs (including Rheum palmatum L) and exhibits anti-cancer effects on many types of human cancer cell lines.

Administration of rhubarb (Emodin) can effectively reverse severe acute pancreatitis (SAP) by regulating the levels of IL-15 and IL-18 (Yu & Yang, 2013).

Pancreatic Cancer

Emodin is a tyrosine kinase inhibitor that has an inhibitory effect on mammalian cell-cycle modulation in specific oncogene-overexpressing cells. Recently, there has been great progress in the preclinical study of the anti-cancer mechanisms of emodin. A recent study revealed that emodin has therapeutic effects on pancreatic cancer through various anti-tumor mechanisms. Notably, the therapeutic efficacy of emodin in combination with chemotherapy was found to be higher than the comparable single chemotherapeutic regime, and the combination therapy also exhibited fewer side-effects (Wei et al., 2013).

Hepatocellular Carcinoma, Pancreatic, Breast, Colorectal and Lung Cancers, and Leukemia

Emodin is found as an active ingredient in different Chinese herbs including Rheum palmatum and Polygonam multiflorum, and has diuretic, vasorelaxant, anti-bacterial., anti-viral., anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. The anti-inflammatory effects of emodin have been exhibited in various in vitro as well as in vivo models of inflammation including pancreatitis, arthritis, asthma, atherosclerosis and glomerulonephritis. As an anti-cancer agent, emodin has been shown to suppress the growth of various tumor cell lines including hepatocellular carcinoma, pancreatic, breast, colorectal., leukemia, and lung cancers. Emodin is a pleiotropic molecule capable of interacting with several major molecular targets including NF-κB, casein kinase II, HER2/neu, HIF-1α, AKT/mTOR, STAT3, CXCR4, topoisomerase II, p53, p21, and androgen receptors which are involved in inflammation and cancer (Shrimali et al., 2013).

Hepatocellular Carcinoma

It has been found that emodin induces apoptotic responses in the human hepatocellular carcinoma cell lines (HCC) Mahlavu, PLC/PRF/5 and HepG2. The addition of emodin to these three cell lines led to inhibition of growth in a time-and dose-dependent manner. Emodin generated reactive oxygen species (ROS) in these cells which brought about a reduction of the intracellular mitochondrial transmembrane potential (ΔΨ m), followed by the activation of caspase–9 and caspase–3, leading to DNA fragmentation and apoptosis.

Preincubation of hepatoma cell lines with the hydrogen peroxide-scavenging enzyme, catalase (CAT) and cyclosporin A (CsA), partially inhibited apoptosis. These results demonstrate that enhancement of generation of ROS, DeltaPsim disruption and caspase activation may be involved in the apoptotic pathway induced by emodin (Jing et al., 2002).

Colon Cancer

In in vitro study, emodin induced cell morphological changes, decreased the percentage of viability, induced G2/M phase arrest and increased ROS and Ca(2+) productions as well as loss of mitochondrial membrane potential (ΔΨ(m)) in LS1034 cells. Emodin-triggered apoptosis was also confirmed by DAPI staining and these effects are concentration-dependent.

In in vivo study, emodin effectively suppressed tumor growth in tumor nude mice xenografts bearing LS1034. Overall, the potent in vitro and in vivo anti-tumor activities of emodin suggest that it might be developed for treatment of colon cancer in the future (Ma et al., 2012).

Myeloid Leukemia

It has been shown that emodin significantly induces cytotoxicity in the human myeloma cells through the elimination of myeloid cell leukemia 1 (Mcl-1). Emodin inhibited interleukin-6–induced activation of Janus-activated kinase 2 (JAK2) and phosphorylation of signal transducer and activator of transcription 3 (STAT3), followed by the decreased expression of Mcl-1. Activation of caspase-3 and caspase-9 was triggered by emodin, but the expression of other anti-apoptotic Bcl-2 family members, except Mcl-1, did not change in the presence of emodin. To clarify the importance of Mcl-1 in emodin-induced apoptosis, the Mcl-1 expression vector was introduced into the human myeloma cells by electroporation. Induction of apoptosis by emodin was almost abrogated in Mcl-1–overexpressing myeloma cells as the same level as in parental cells, which were not treated with emodin. Emodin therefore inhibits interleukin-6–induced JAK2/STAT3 pathway selectively and induces apoptosis in myeloma cells via down-regulation of Mcl-1, which is a good target for treating myeloma. Taken together, these results show emodin as a new potent anti-cancer agent for the treatment of multiple myeloma patients (Muto et al., 2007).

Breast Cancer; Block HER-2

The mechanism by which emodin prevents breast cancer is unknown; however the product of the HER-2/neu proto-oncogene, HER2 has been proposed to be involved. The product of the HER-2/neu proto-oncogene, HER2, is the second member of the human epidermal growth factor receptor (HER) family of tyrosine kinase receptors and has been suggested to be a ligand orphan receptor. Amplification of the HER2 gene and overexpression of the HER2 protein induces cell transformation and has been demonstrated in 10% to 40% of human breast cancer. HER2 overexpression has been suggested to associate with tumor aggressiveness, prognosis and responsiveness to hormonal and cytotoxic agents in breast cancer patients. These findings indicate that HER2 is an appropriate target for tumor-specific therapies.

A number of approaches have been investigated: (1) a humanized monoclonal antibody against HER2, rhuMAbHER2 (trastuzumab), which is already approved for clinical use in the treatment of patients with metastatic breast cancer; (2) tyrosine kinase inhibitors, such as emodin, which block HER2 phosphorylation and its intracellullar signaling; (3) active immunotherapy, such as vaccination; and (4) heat shock protein (Hsp) 90-associated signal inhibitors, such as radicicol derivatives, which induce degradation of tyrosine kinase receptors, such as HER2 (Kurebayashi, 2001).

MDR

The effects of emodin on the nucleoside transport and multi-drug resistance in cancer cells has also been investigated. Nucleoside transport inhibition was determined by thymidine incorporation assay. The cytotoxicity to cancer cells was determined by MTT assay. The pump efflux activity and the expression of P glycoprotein were examined by flow cytometric assay. Emodin was active in the inhibition of nucleoside transport, with an IC 50 value of 9 9 µmol·L -1. Emodin markedly enhanced the cytotoxicity of 5 FU, MMC and MTX against human hepatoma BEL 7402 cells and partly reversed the multi-drug resistance in human breast cancer MCF 7/Adr cells.

Emodin inhibited P-gp pump efflux activity and reduced the expression of P gp in MCF 7/Adr cells. These findings provide a biological basis for the application of emodin as a biochemical modulator to potentiate the effects of anti-tumor drugs and reverse the multi-drug resistance in cancer cells (Jiang et al., 2009).

Cell-cycle Arrest

Large quantities of emodin were isolated from the roots of Rheum emodi and a library of novel emodin derivatives 2–15 were prepared to evaluate their anti-proliferative activities against HepG2, MDA-MB-231 and NIH/3T3 cells lines. The derivatives 3 and 12 strongly inhibited the proliferation of HepG2 and MDA-MB-231 cancer cell line with an IC50 of 5.6, 13.03 and 10.44, 5.027, respectively, which is comparable to marketed drug epirubicin (III). The compounds 3 and 12 were also capable of inducing cell-cycle arrest and caspase dependent apoptosis in HepG2 cell lines and exhibit DNA intercalating activity. These emodin derivatives hold promise for developing safer alternatives to the marketed epirubicin (Narender et al., 2013).

Cell-cycle Arrest; MDR1 & AZT

3'-azido-3'-deoxythymidine (AZT) and emodin altered the cell-cycle distribution and led to an accumulation of cells in S phase. Meanwhile, the expression of MDR1 mRNA/p-gp protein was markedly decreased. These results show a synergistic growth-inhibitory effect of AZT and emodin in K562/ADM cells, which is achieved through S phase arrest. MDR1 might ultimately be responsible for these phenomena (Chen et al., 2013).

References

Chen P, Liu Y, Sun Y, et al. (2013). AZT and emodin exhibit synergistic growth-inhibitory effects on K562/ADM cells by inducing S phase cell-cycle arrest and suppressing MDR1 mRNA/p-gp protein expression. Pharm Biol.


Garg AK, Buchholz TA, Aggarwal BB. (2005). Chemo-sensitization and Radiosensitization of Tumors by Plant Polyphenols. Antioxid Redox Signal., 7(11-12):1630-47.


Jiang XF & Zhen YS. (1999). Reversal of Multi-drug resistance by emodin in cancer cells. Acta Pharmaceutica Sinica, 1999-03.


Jing X, Ueki N, Cheng J, Imanishi H, Hada T. (2002). Induction of apoptosis in hepatocellular carcinoma cell lines by emodin. Cancer Science, 93(8):874–882.


Kurebayashi J. (2001). Biological and clinical significance of HER2 overexpression in breast cancer. Breast Cancer, 8(1):45-51


Ma YS, Weng SW, Lin MW, et al. (2012). Anti-tumor effects of emodin on LS1034 human colon cancer cells in vitro and in vivo: Roles of apoptotic cell death and LS1034 tumor xenografts model. Food Chem Toxicol, 50(5): 1271–1278. doi: 10.1016/j.fct.2012.01.033.


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Curcumin

Cancer: Colorectal., prostate, pancreatic

Action: MDR, chemo-preventive activity, anti-inflammatory, attenuation of immune suppression

Chemo-preventive Activity

Curcumin is a naturally occurring, dietary polyphenolic phytochemical that is under preclinical trial evaluation for cancer-preventive drug development. It is derived from the rhizome of Curcuma longa L. and has both anti-oxidant and anti-inflammatory properties; it inhibits chemically-induced carcinogenesis in the skin, forestomach, and colon when it is administered during initiation and/or postinitiation stages. Chemo-preventive activity of curcumin is observed when it is administered prior to, during, and after carcinogen treatment as well as when it is given only during the promotion/progression phase (starting late in premalignant stage) of colon carcinogenesis (Kawamori et al., 1999)

Anti-inflammatory

With respect to inflammation, in vitro, it inhibits the activation of free radical-activated transcription factors, such as nuclear factor κB (NFκB) and AP-1, and reduces the production of pro-inflammatory cytokines such as tumor necrosis factor-α (TNFα), interleukin-1β (IL-1β), and interleukin-8 (Chan et al., 1998)

Prostate Cancer

In addition, NF-kappaB and AP-1 may play a role in the survival of prostate cancer cells, and curcumin may abrogate their survival mechanisms (Mukhopadhyay et al., 2001).

Pancreatic Cancer

In patients suffering from pancreatic cancer, orally-administered curcumin was found to be well-tolerated and despite limited absorption, had a reasonable impact on biological activity in some patients. This was attributed to its potent nuclear factor-kappaB (NF-kappaB) and tumor-inhibitory properties, against advanced pancreatic cancer (Dhillon et al., 2008)

MDR

Curcumin, the major component in Curcuma longa (Jianghuang), inhibited the transport activity of all three major ABC transporters, i.e. Pgp, MRP1 and ABCG2 (Ganta et al., 2009).

Curcumin reversed MDR of doxorubicin or daunorubicin in K562/DOX cell line and decreased Pgp expression in a time-dependent manner (Chang et al., 2006). Curcumin enhanced the sensitivity to vincristine by the inhibition of Pgp in SGC7901/VCR cell line (Tang et al., 2005). Moreover, curcumin was useful in reversing MDR associated with a decrease in bcl-2 and survivin expression but an increase in caspase-3 expression in COC1/DDP cell line (Ying et al., 2007).

The cytotoxicity of vincristine and paclitaxel were also partially restored by curcumin in resistant KBV20C cell line. Curcumin derivatives reversed MDR by inhibiting Pgp efflux (Um et al., 2008). A chlorine substituent at the meta-or para-position on benzamide improved MDR reversal [72]. Bisdemethoxycurcumin modified from curcumin resulted in greater inhibition of Pgp expression (Limtrakul et al., 2004).

Attenuation of Immune Suppression

Curcumin (a chalcone) exhibited toxicity to human neural stem cells (hNSCs). Although oridonin (a diterpene) showed a null toxicity toward hNSCs, it repressed the enzymatic function only marginally in contrast to its potent cytotoxicity in various cancer cell lines. While the mode of action of the enzyme-polyphenol complex awaits to be investigated, the sensitivity of enzyme inhibition was compared to the anti-proliferative activities toward three cancer cell lines.

The IC50s obtained from both sets of the experiments indicate that they are in the vicinity of micromolar concentration with the enzyme inhibition slightly more active.

These results suggest that attenuation of immune suppression via inhibition of IDO-1 enzyme activity may be one of the important mechanisms of polyphenols in chemoprevention or combinatorial cancer therapy (Chen et al., 2012).

Cancer Stem Cells

In cancers that appear to follow the stem cell model, pathways such as Wnt, Notch and Hedgehog may be targeted with natural compounds such as curcumin or drugs to reduce the risk of initiation of new tumors. Disease progression of established tumors could also potentially be inhibited by targeting the tumorigenic stem cells alone, rather than aiming to reduce overall tumor size.

Cancer treatments could be evaluated by assessing stem cell markers before and after treatment. Targeted stem cell specific treatment of cancers may not result in 'complete' or 'partial' responses radiologically, as stem cell targeting may not reduce the tumor bulk, but eliminate further tumorigenic potential. These changes are discussed using breast, pancreatic, and lung cancer as examples (Reddy et al., 2011).

Multiple Cancer Effects; Cell-signaling

Curcumin has been shown to interfere with multiple cell signaling pathways, including cell-cycle (cyclin D1 and cyclin E), apoptosis (activation of caspases and down-regulation of anti-apoptotic gene products), proliferation (HER-2, EGFR, and AP-1), survival (PI3K/AKT pathway), invasion (MMP-9 and adhesion molecules), angiogenesis (VEGF), metastasis (CXCR-4) and inflammation (NF- κB, TNF, IL-6, IL-1, COX-2, and 5-LOX).

The activity of curcumin reported against leukemia and lymphoma, gastrointestinal cancers, genitourinary cancers, breast cancer, ovarian cancer, head and neck squamous cell carcinoma, lung cancer, melanoma, neurological cancers, and sarcoma reflects its ability to affect multiple targets (Anand et al., 2008).

Anti-inflammatory; Cell-signaling

Curcumin, a liposoluble polyphenolic pigment isolated from the rhizomes of Curcuma longa L. (Zingiberaceae), is another potential candidate for new anti-cancer drug development. Curcumin has been reported to influence many cell-signaling pathways involved in tumor initiation and proliferation. Curcumin inhibits COX-2 activity, cyclin D1 and MMPs overexpresion, NF-kB, STAT and TNF-alpha signaling pathways and regulates the expression of p53 tumor suppressing gene.

Curcumin is well-tolerated but has a reduced systemic bioavailability. Polycurcumins (PCurc 8) and curcumin encapsulated in biodegradable polymeric nanoparticles showed higher bioavailability than curcumin together with a significant tumor growth inhibition in both in vitro and in vivo studies (Cretu et al., 2012). Curcumin also sensitizes tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis through reactive oxygen species-mediated up-regulation of death receptor 5 (DR5) (Jung et al., 2005).

Curcumin and bioavailability

Curcumin, a major constituent of the spice turmeric, suppresses expression of the enzyme cyclooxygenase 2 (Cox-2) and has cancer chemo-preventive properties in rodents. It possesses poor systemic availability. Marczylo et al. (2007) explored whether formulation with phosphatidylcholine increases the oral bioavailability or affects the metabolite profile of curcumin. Their results suggest that curcumin formulated with phosphatidylcholine furnishes higher systemic levels of parent agent than unformulated curcumin.

Curcuminoids are poorly water-soluble compounds and to overcome some of the drawbacks of curcuminoids, Aditya et al. (2012) explored the potential of liposomes for the intravenous delivery of curcuminoids. The curcuminoids-loaded liposomes were formulated from phosphatidylcholine (soy PC). Curcumin/curcuminoids were encapsulated in phosphatidylcholine vesicles with high yields. Vesicles in the size range around 200 nm were selected for stability and cell experiments. Liposomal curcumin were found to be twofold to sixfold more potent than corresponding curcuminoids. Moreover, the mixture of curcuminoids was found to be more potent than pure curcumin in regard to the anti-oxidant and anti-inflammatory activities (Basnet et al., 2012). Results suggest that the curcumin-phosphatidylcholine complex improves the survival rate by increasing the anti-oxidant activity (Inokuma et al., 2012). Recent clinical trials on the effectiveness of phosphatidylcholine formulated curcumin in treating eye diseases have also shown promising results, making curcumin a potent therapeutic drug candidate for inflammatory and degenerative retinal and eye diseases (Wang et al., 2012). Data demonstrate that treatment with curcumin dissolved in sesame oil or phosphatidylcholine curcumin improves the peripheral neuropathy of R98C mice by alleviating endoplasmic reticulum stress, by reducing the activation of unfolded protein response (Patzk- et al., 2012).

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