Breast Cancer

Evid Based Complement Alternat Med.2011;2011:562187. doi: 10.1093/ecam/nep093. Epub 2011 Feb 14.

Suppression of Heregulin-β1/HER2-Modulated Invasive and Aggressive Phenotype of Breast Carcinoma by Pterostilbene via Inhibition of Matrix Metalloproteinase-9, p38 Kinase Cascade and Akt Activation.

Pan MH¹, Lin YT, Lin CL, Wei CS, Ho CT, Chen WJ.

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Abstract

Invasive breast cancer is the major cause of death among females and its incidence is closely linked to HER2 (human epidermal growth factor receptor 2) overexpression. Pterostilbene, a natural analog of resveratrol, exerts its cancer chemopreventive activity similar to resveratrol by inhibiting cancer cell proliferation and inducing apoptosis. However, the anti-invasive effect of pterostilbene on HER2-bearing breast cancer has not been evaluated. Here, we used heregulin-β1 (HRG-β1), a ligand for HER3, to transactivate HER2 signaling. We found that pterostilbene was able to suppress HRG-β1-mediated cell invasion, motility and cell transformation of MCF-7 human breast carcinoma through down-regulation of matrix metalloproteinase-9 (MMP-9) activity and growth inhibition. In parallel, pterostilbene also inhibited protein and mRNA expression of MMP-9 driven by HRG-β1, suggesting that pterostilbene decreased HRG-β1-mediated MMP-9 induction via transcriptional regulation. Examining the signaling pathways responsible for HRG-β1-associated MMP-9 induction and growth inhibition, we observed that pterostilbene, as well as SB203580 (p38 kinase inhibitor), can abolish the phosphorylation of p38 mitogen-activated protein kinase (p38 kinase), a downstream HRG-β1-responsive kinase responsible for MMP-9 induction. In addition, HRG-β1-driven Akt phosphorylation required for cell proliferation was also suppressed by pterostilbene. Taken together, our present results suggest that pterostilbene may serve as a chemopreventive agent to inhibit HRG-β1/HER2-mediated aggressive and invasive phenotype of breast carcinoma through down-regulation of MMP-9, p38 kinase and Akt activation.

PMID: 19617202

J Surg Res.2010 Jun 15;161(2):195-201. doi: 10.1016/j.jss.2009.07.027. Epub 2009 Aug 18.

Pterostilbene inhibits breast cancer in vitro through mitochondrial depolarization and induction of caspase-dependent apoptosis.

Alosi JA¹,McDonald DE, Schneider JS, Privette AR, McFadden DW.

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Abstract

BACKGROUND: Epidemiologic studies suggest that diets high in fruits and vegetables reduce cancerrisk. Resveratrol, a compound present in grapes, has been shown to inhibit a variety of primary tumors. Pterostilbene, an analogue of resveratrol found in blueberries, has both antioxidant and antiproliferative properties. We hypothesized that pterostilbenewould induce apoptosis and inhibit breast cancercell growth in vitro.

METHODS: Breast cancercells were treated with graduated doses of pterostilbene. Cell viability was measured by MTT assay. Apoptosis was evaluated via DNA fragmentation assay and TUNEL assay. Apo-ONE caspase-3/7 assay was used to evaluate caspase activity. Flow cytometry was used to evaluate mitochondrial depolarization, superoxide formation, and cell cycle. Student’s t-test and two-way ANOVA with Bonferroni posttests were utilized for statistical analysis.

RESULTS: Pterostilbene decreased breast cancercell viability in a concentration- and time-dependent manner. Pterostilbenetreatment increased caspase-3/7 activity and apoptosis in both cell lines. Caspase-3/7 inhibitors completely reversed pterostilbene’s effects on cell viability. Pterostilbenetreatment triggered mitochondrial depolarization, increased superoxide anion, and caused alteration in cell cycle.

CONCLUSIONS: Pterostilbene treatment inhibits the growth of breast cancerin vitro through caspase-dependent apoptosis. Mitochondrial membrane depolarization and increased superoxide anion may contribute to the activation downstream effector caspases. Caspase inhibition leads to complete reversal of pterostilbene’s effect on cell viability. Further in vitro mechanistic studies and in vivo experiments are warranted to determine its potential for the treatment of breast cancer.

PMID: 20031172

Am J Surg.2010 Nov;200(5):577-80. doi: 10.1016/j.amjsurg.2010.07.022.

Pterostilbene and tamoxifen show an additive effect against breast cancerin vitro.

Mannal P¹,McDonald D, McFadden D.

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Abstract

BACKGROUND: Tamoxifen is widely used for the treatment of breast cancer. Pterostilbene, a bioavailable stilbenoid found in blueberries, has been found to inhibit breast cancergrowth in vitro. It was hypothesized that combining pterostilbenewith tamoxifen would produce additive effects on estrogen receptor-positive breast cancercells.

METHODS: Two estrogen receptor-positive breast cancercell lines, MCF7 and ZR-751, were pretreated with graduated doses of pterostilbenefor 24 hours, followed by 5 μmol/L tamoxifen. MTT proliferation assays and Cell Death Detection ELISA(PLUS) tests evaluated cell viability and apoptosis.

RESULTS: MCF7 cells showed inhibition (10 and 20 μmol/L, P < .001; 30 μmol/L, P < .05) at all time points when combined with tamoxifen. ZR-751 cells showed additive reductions in cell viability (P < .001). Cell Death Detection ELISA(PLUS) indicated increased apoptosis (P < .01).

CONCLUSIONS: Pterostilbene shows an additive inhibitory effect on breast cancercells when combined with tamoxifen, most likely from augmented cancercellapoptosis.

PMID: 21056131

Am J Surg.2011 Nov;202(5):541-4. doi: 10.1016/j.amjsurg.2011.06.020. Epub 2011 Sep 23.

The antiproliferative effects of pterostilbene on breast cancer in vitro are via inhibition of constitutive and leptin-induced Janus kinase/signal transducer and activator of transcription activation.

McCormack D¹,Schneider J, McDonald D, McFadden D.

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Abstract

BACKGROUND: The hormone leptin is implicated in breast carcinogenesis in obese women. One mechanism is through its activation of Janus kinase/signal transducer and activator of transcription (JAK/STAT3) and apoptosis dysregulation. We have shown that the antioxidant pterostilbene inhibits proliferation and induces apoptosis in breast cancer. Therefore, the goal of this study was to evaluate the effect of pterostilbene on cell proliferation and JAK/STAT3 signaling in leptin-stimulated breast cancer.

METHODS: Breast cancer cells were treated with leptin alone or in combination with pterostilbene. Detection of cell proliferation and JAK/STAT3 signaling were performed using enzyme-linked immunosorbent assay protocols. Statistical analysis was performed with analysis of variance and Tukey post hoc analysis.

RESULTS: Pterostilbene suppresses constitutive as well as leptin-induced JAK/STAT3 activation. Pterostilbene treatment also inhibited leptin-induced cell proliferation.

CONCLUSIONS: Pterostilbene has an inhibitory effect on leptin-stimulated breast cancer in vitro through reduction of cell proliferation and JAK/STAT3 signaling, a critical regulatory component of tumorigenesis in obesity-related breast cancer.

PMID: 21944294

Mol Cell Endocrinol.2012 May 15;355(1):25-40. doi: 10.1016/j.mce.2012.01.009. Epub 2012 Jan 16.

Long term induction by pterostilbene results in autophagy and cellular differentiation in MCF-7 cells via ROS dependent pathway.

Chakraborty A¹, Bodipati N, Demonacos MK, Peddinti R, Ghosh K, Roy P.

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Abstract

This study shows the effect of pterostilbene on intracellular neutral lipid accumulation in MCF-7 breast cancer cells leading to growth arrest and autophagy. On exposing the breast cancer cells with 30 μM pterostilbene for 72 h there was almost 2-folds increase in neutral lipids and triglycerides. Also the phytochemical caused a 4-folds increase in the expression of adipogenic differentiation marker c/EBPα. Further, pterostilbene inhibited 3β-hydroxylsterol-Δ(7)-reductase, the enzyme which catalyzes the last step conversion of 7-dehydrocholesterol to cholesterol, and thereby causes the intracellular accumulation of the former sterol. These results were associated with over-expression of oxysterol binding protein homologue and liver X receptor (LXR) by ~7-folds. Pterostilbene also caused a simultaneous increase in the expression autophagic marker proteins Beclin 1 and LC3 II (microtubule-associated protein 1 light chain 3) by approximately 6-folds, which leads to an alternative pathway of autophagy. These effects were observed in association with the loss of mitotic and metastatic potential of MCF-7 cells which was abolished in the presence of catalase (ROS scavenger) or 3MA (autophagic inhibitor). Thus the present data shows that the long term exposure to pterostilbene causes growth arrest in MCF-7 cells which may be due to differentiation of the mammary carcinoma cells into normal epithelial cell like morphology and activation of autophagy.

PMID: 22273805

Am J Transl Res.2012;4(1):44-51. Epub 2012 Jan 5.

Pterostilbene simultaneously induces apoptosis, cell cycle arrest and cyto-protective autophagy in breast cancer cells.

Wang Y, Ding L, Wang X, Zhang J, Han W, Feng L, Sun J, Jin H, Wang XJ.

Abstract

As a nature phytoalexin found in grapes, resveratrol has been proposed as a potential drug for cancerchemoprevention and treatment. However, its poor bioavailability limits its potential clinical application. Pterostilbene, the natural dimethylated analog of resveratrol with greater bioavailability, was confirmed to inhibit tumor growth both in vivo and in vitro, demonstrating its potential for further clinical application. In the current study, we found that pterostilbenecouldmarkedly inhibit the growth of two independent breast cancercell lines. Both apoptosis and cell cycle arrest as well as the inhibition of wnt singling was induced by pterostilbene. The dominant-active mutant of β-catenin could reverse the growth inhibitory effect of pterostilbene, indicating that the inhibition of wnt signaling is important to the growth inhibitory effect of pterostilbene. Interestingly, pterostilbene induced autophagy and blockage of autophagy augmented pterostilbene-induced growth inhibition, suggesting that the combination of autophagy inhibitors with pterostilbene and other therapeutics such as endocrine drugs could serve as a new and promising strategy for the treatment of breast cancer cells.

KEYWORDS: Pterostilbene; apoptosis; phytoalexins; tumor growth inhibition; wnt singling

PMID: 22347521

J Surg Res.2013 Apr;180(2):208-15. doi: 10.1016/j.jss.2012.04.027. Epub 2012 Apr 29.

Pterostilbene induces mitochondrially derived apoptosis in breast cancer cells in vitro.

Moon D¹,McCormack D, McDonald D, McFadden D.

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Abstract

BACKGROUND: The ability of a breast cancercell to evade apoptosis has a key role in tumor progression and sensitivity to treatment. High levels of Bcl-2-associated X protein (Bax) in tumor cells have been found to promote apoptosis and sensitize cells to anti-cancertherapies. Bcl-2-associated X protein redistribution to the mitochondrial membrane results in the release of proapoptotic factors including cytochrome C, second-mitochondrial-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low PI (Smac/DIABLO), and Ca(2+). We aimed to explore this pathway in cancerous breast cell lines treated with the naturally occurring antioxidant 3,5-dimethoxy-4-hydroxystilbene (pterostilbene).

METHODS: We used whole cell lysates +/- Bax SiRNA from the cell lines MCF-7 and MDA-MB-231 in an enzyme-linked immunosorbent assay to quantify Bax, cytochrome C, Smac/DIABLO expression, and manganese superoxide dismutase (MnSOD) activity after treatment with pterostilbene. We quantified cell death using histone-related DNA complexes from cytosolic and mitochondrial fractions and used methylthiazol tetrazolium assay to analyze cell proliferation, in the presence of Bax-silencing or scrambled RNA. We measured changes in cytosolic calcium using the ratiometric calcium-sensitive dye fura-2-AM using an inverted ratiometric monochromator microscope.

RESULTS: Treatment of MCF-7 and MDA-MB-231 (MDA) cells with pterostilbenecaused concentration-dependent increases in intracellular Bax at all doses tested. RNA silencing of Bax resulted in reduced rates of apoptosis in both cells types and increased cell survival when treated with pterostilbene. We observed an increase in cytochrome C in MDA cells after treatment with pterostilbene. The MCF-7 cells showed a net increase in cytosolic cytochrome C, with a corresponding reduction in mitochondrial cytochrome C after treatment with 50 and 75 μmol/L pterostilbene. We observed this again in Smac/DIABLO expression in both cell types. In MCF-7 cells, pterostilbene treatment caused an increase in cytosolic but a decrease in mitochondrial Smac/DIABLO protein concentrations. Pterostilbene significantly increase MnSOD activity in MDA-MB-231 cells. Finally, pterostilbene resulted in significant increases in cytosolic calcium concentrations.

CONCLUSIONS: The natural dietary compound pterostilbenehas an anti-proliferative effect and induces apoptosis in breast cancercells in vitro via Bax activation and overexpression, resulting in increased MnSOD, Smac/DIABLO, and cytochrome C activity and cytosolic Ca(2+) overload.

PMID: 22572619

Mol Nutr Food Res.2013 May;57(5):886-95. doi: 10.1002/mnfr.201200715. Epub 2013 Feb 18.

Invadopodia-associated proteins blockade as a novel mechanism for 6-shogaol and pterostilbene to reduce breast cancer cell motility and invasion.

Hong BH¹,Wu CH, Yeh CT, Yen GC.

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Abstract

SCOPE: Invadopodia are actin-rich membrane protrusions of tumor cells that are thought to initiate the local migration and invasion during cancer metastasis. The blockade of invadopodia-associated proteins has been reported as a promising approach for prevention of tumor metastasis. The aim of this study was to investigate the modulatory effects of 6-shogaol and pterostilbene on invadopodia in aggressive breast cancer cells.

METHODS AND RESULTS: By wound-healing, transwell, and gelatin zymography assays, we found that 6-shogaol and pterostilbene effectively attenuated the motility and invasion of MDA-MB-231 cells, and suppressed the activities of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). Further investigation into the underlying molecular mechanisms revealed that the levels of key modulators of invadopodium maturation, including c-Src kinase, cortactin, and membrane type 1-matrix metalloproteinase (MT1-MMP) decreased when cells were treated with 6-shogaol or pterostilbene.

CONCLUSION: These data suggest that the repression of these factors might affect the maturation of invadopodia, inhibiting the metastasis of MDA-MB-231 cells. In conclusion, the present study demonstrates for the first time that 6-shogaol and pterostilbene can inhibit invadopodium formation and MMP activity in highly invasive breast cancer cells. We suggest that these compounds may be clinically useful in chemopreventive treatments for metastatic breast cancer.

PMID: 23417847

Food Funct.2014 Aug;5(8):1856-65. doi: 10.1039/c4fo00145a.

The anti-tumor efficiency of pterostilbene is promoted with a combined treatment of Fas signaling or autophagy inhibitors in triple negative breast cancer cells.

Chen WC¹, Hsu KY, Hung CM, Lin YC, Yang NS, Ho CT, Kuo SC, Way TD.

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Abstract

High expression of vimentin, a canonical mesenchymal marker, is linked with poor prognosis in triple negative breast cancer (TNBC), implying that vimentin may be a potential biomarker in the application of TNBC therapy. Pterostilbene (PTE) has shown anti-invasion activity, and thus, we investigated whether PTE inhibited the epithelial-mesenchymal transition (EMT) in TNBC. Here, we show that PTE decreases the vimentin expression, but that the effect was transient. PTE stimulated Fas signaling, which drives EMT by the ERK1/2 and GSK3β/β-catenin pathways, supporting Fas signaling induction involved in EMT regulation. PTE also triggered autophagy in TNBC. The treatment of TNBC with 3-methyladenine an autophagy inhibitor, not only sustained PTE-inhibited EMT but also significantly promoted anti-proliferation, which indicates that autophagy plays a cyto-protective role and is associated with EMT. Taken together, these data showed that Fas signaling and autophagy accelerated the aggressiveness of TNBC. Inhibition of autophagy or Fas signaling may provide novel targets for TNBC therapy.

PMID: 24944076

PLoS One.2014 Aug 15;9(8):e104459. doi: 10.1371/journal.pone.0104459. eCollection 2014.

Estrogen receptor-α36 is involved in pterostilbene-induced apoptosis and anti-proliferation in in vitro and in vivo breast cancer.

Pan C¹, Hu Y², Li J³, Wang Z⁴, Huang J⁵, Zhang S¹, Ding L⁵.

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Abstract

Pterostilbene (trans-3,5-dimethoxy-4′-hudroxystilbene) is an antioxidant primarily found in blueberries. It also inhibits breast cancer regardless of conventional estrogen receptor (ER-α66) status by inducing both caspase-dependent and caspase-independent apoptosis. However, the pterostilbene-induced apoptosis rate in ER-α66-negative breast cancer cells is much higher than that in ER-α66-positive breast cancer cells. ER-α36, a variant of ER-α66, is widely expressed in ER-α66-negative breast cancer, and its high expression mediates the resistance of ER-α66-positive breast cancer patients to tamoxifen therapy. The aim of the present study is to determine the relationship between the antiproliferation activity of pterostilbene and ER-α36 expression in breast cancer cells. Methyl-thiazolyl-tetrazolium (MTT) assay, apoptosis analysis, and an orthotropic xenograft mouse model were used to examine the effects of pterostilbene on breast cancer cells. The expressions of ER-α36 and caspase 3, the activation of ERK and Akt were also studied through RT-PCR, western blot analysis, and immunohistochemical (IHC) staining. ER-α36 knockdown was found to desensitize ER-α66-negative breast cancer cells to pterostilbene treatment both in vitro and in vivo, and high ER-α36 expression promotes pterostilbene-induced apoptosis in breast cancer cells. Western blot analysis data indicate that MAPK/ERK and PI3K/Akt signaling in breast cancer cells with high ER-α36 expression are mediated by ER-α36, and are inhibited by pterostilbene. These results suggest that ER-α36 is a therapeutic target in ER-α36-positive breast cancer, and pterostilbene is an inhibitor that targets ER-α36 in the personalized therapy against ER-α36-positive breast cancer.

PMID: 25127034

J Nutr Biochem.2015 Jun;26(6):675-85. doi: 10.1016/j.jnutbio.2015.01.005. Epub 2015 Mar 6.

Pterostilbene inhibits triple-negative breast cancer metastasis via inducing microRNA-205 expression and negatively modulates epithelial-to-mesenchymal transition.

Su CM¹,Lee WH², Wu AT³, Lin YK⁴, Wang LS⁵, Wu CH⁶, Yeh CT⁷.

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Abstract

Breast canceris the leading cause of cancer-related deaths among females in economically developing countries. Greater than 95% of breast malignancies are of epithelial origin; the induction of epithelial-to-mesenchymal transition (EMT) has been shown to initiate the metastatic process in breast carcinoma and remains the key target for drug development. Here, we examine the anti-metastatic potential of pterostilbene in modulating EMT process in breast cancercells both in vitro and in vivo. The differential invasive ability among MCF7, Hs578t and MDA-MB-231 breast cancercell lines were closely correlated with the expression of EMT markers, determined by Western blots and Matrigel-coated transwells assay. Pterostilbene inhibited the migratory and invasive potential of triple-negative MDA-MB-231 and Hs578t cells, accompanied by the up-regulation of E-cadherin and down-regulation of Snail, Slug, vimentin and ZEB1. Mechanistic investigations revealed a significant up-regulation of miR-205, which resulted in the reduction of Src expression in pterostilbene-treated breast cancer cells. Importantly, pterostilbene suppressed tumor growth and metastasis in MDA-MB-231-bearing NOD/SCID mice by reducing Src/Fak signaling; this observation was consistent with the negative correlations between miR-205 and Src expression in both normal and malignant breast tissues. Our findings provide supports for the usage of pterostilbene as an inhibitor of EMT process and potential candidate for adjuvant therapy.

KEYWORDS: Epithelial-to-mesenchymal transition (EMT); Metastasis; Pterostilbene; Triple-negative breast cancer; miR-205

PMID: 25792283

BMC Cancer.2015 Oct 12;15:672. doi: 10.1186/s12885-015-1693-z.

Epigenetic-based combinatorial resveratrol and pterostilbenealters DNA damage response by affecting SIRT1 and DNMT enzyme expression, including SIRT1-dependent γ-H2AX and telomerase regulation in triple-negative breast cancer.

Kala R¹,Shah HN², Martin SL³, Tollefsbol TO^4,5,6,7,8.

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Abstract

BACKGROUND: Nutrition is believed to be a primary contributor in regulating gene expression by affecting epigenetic pathways such as DNA methylation and histone modification. Resveratrol and pterostilbeneare phytoalexins produced by plants as part of their defense system. These two bioactive compounds when used alone have been shown to alter genetic and epigenetic profiles of tumor cells, but the concentrations employed in various studies often far exceed physiologically achievable doses. Triple-negative breast cancer(TNBC) is an often fatal condition that may be prevented or treated through novel dietary-based approaches.

METHODS: HCC1806 and MDA-MB-157 breast cancercells were used as TNBC cell lines in this study. MCF10A cells were used as control breast epithelial cells to determine the safety of this dietary regimen. CompuSyn software was used to determine the combination index (CI) for drug combinations.

RESULTS: Combinatorial resveratrol and pterostilbeneadministered at close to physiologically relevant doses resulted in synergistic (CI <1) growth inhibition of TNBCs. SIRT1, a type III histone deacetylase (HDAC), was down-regulated in response to this combinatorial treatment. We further explored the effects of this novel combinatorial approach on DNA damage response by monitoring γ-H2AX and telomerase expression. With combination of these two compounds there was a significant decrease in these two proteins which might further resulted in significant growth inhibition, apoptosis and cell cycle arrest in HCC1806 and MDA-MB-157 breast cancercells, while there was no significant effect on cellular viability, colony forming potential, morphology or apoptosis in control MCF10A breast epithelial cells. SIRT1 knockdown reproduced the effects of combinatorial resveratrol and pterostilbene-induced SIRT1 down-regulation through inhibition of both telomerase activity and γ-H2AX expression in HCC1806 breast cancercells. As a part of the repair mechanisms and role of SIRT1 in recruiting DNMTs, the effects of this combination treatment was also explored on DNA methyltransferases (DNMTs) expression. Interestingly, the compounds resulted in a significant down-regulation of DNMT enzymes with no significant effects on DNMT enzyme expression in MCF10A control cells.

CONCLUSION: Collectively, these results provide new insights into the epigenetic mechanisms of a novel combinatorial nutrient control strategy that exhibits synergy and may contribute to future recalcitrant TNBC prevention and/or therapy.

PMID: 26459286

PLoS One.2016 May 9;11(5):e0155057. doi: 10.1371/journal.pone.0155057. eCollection 2016.

A Novel Combinatorial Epigenetic Therapy Using Resveratrol and Pterostilbene for Restoring Estrogen Receptor-α (ERα) Expression in ERα-Negative Breast Cancer Cells.

Kala R¹, Tollefsbol TO^1,2,3,4,5.

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Abstract

Breast cancer is the second most common cancer and a leading cause of cancer death in women. Specifically, estrogen receptor-α (ERα)-negative breast cancers are clinically more aggressive and normally do not respond to conventional hormone-directed therapies such as tamoxifen. Although epigenetic-based therapies such as 5-aza-2′-deoxycytidine and/or trichostatin A as DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, respectively, can regulate the expression of ERα, this can often lead to a number of side effects. Plant-based dietary compounds such as resveratrol and pterostilbene in novel combinatorial therapy provides new avenues to target these side effects and provide similar results with a higher level of safety. Here, we report that combinatorial resveratrol and pterostilbene leads to the reactivation of ERα expression in ERα-negative breast cancer cells in a time-dependent manner. Chromatin immunoprecipitation analysis of the ERα promoter in each cell type revealed an increase in enrichment of acetyl-H3, acetyl-H3lysine9 (H3K9) and acetyl-H4 active chromatin markers in the ERα promoter region after combinatorial treatment. This treatment also resulted in a significant change in HDAC and histone acetyl transferase (HAT) enzyme activity in these cells after 3 days of treatments. The combination resulted in a significant decrease in DNMT enzyme activity and 5-methylcytosine levels in MDA-MB-157 breast cancer cells. Moreover, reactivation of ERα expression by resveratrol combined with pterostilbene was found to sensitize ERα-dependent response to 17β-estradiol (E2)-mediated cellular proliferation and antagonist 4-hydroxytamoxifen (4-OHT)-mediated inhibition of cellular proliferation in ERα-negative breast cancer cells. E2 and 4-OHT further affected the ERα-responsive downstream progesterone receptor (PGR) gene in ERα reactivated MDA-MB-157 cells. Collectively, our findings provide a new and safer way of restoring ERα expression by regulating epigenetic mechanisms with the use of phytochemicals in combinatorial therapy. This combination can further provide effective treatment options for hormonal refractory breast cancer with available anti-hormonal therapy.

PMID: 27159275

Carcinogenesis.2016 Jul;37(7):656-68. doi: 10.1093/carcin/bgw048. Epub 2016 Apr 28.

Stilbenoids remodel the DNA methylation patterns in breast cancer cells and inhibit oncogenic NOTCH signaling through epigenetic regulation of MAML2 transcriptional activity.

Lubecka K¹, Kurzava L¹, Flower K², Buvala H¹, Zhang H³, Teegarden D⁴, Camarillo I⁵, Suderman M⁶, Kuang S⁷, Andrisani O⁸, Flanagan JM², Stefanska B⁹.

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Abstract

DNA hypomethylation was previously implicated in cancer progression and metastasis. The purpose of this study was to examine whether stilbenoids, resveratrol and pterostilbene thought to exert anticancer effects, target genes with oncogenic function for de novo methylation and silencing, leading to inactivation of related signaling pathways. Following Illumina 450K, genome-wide DNA methylation analysis reveals that stilbenoids alter DNA methylation patterns in breast cancer cells. On average, 75% of differentially methylated genes have increased methylation, and these genes are enriched for oncogenic functions, including NOTCH signaling pathway. MAML2, a coactivator of NOTCH targets, is methylated at the enhancer region and transcriptionally silenced in response to stilbenoids, possibly explaining the downregulation of NOTCH target genes. The increased DNA methylation at MAML2 enhancer coincides with increased occupancy of repressive histone marks and decrease in activating marks. This condensed chromatin structure is associated with binding of DNMT3B and decreased occupancy of OCT1 transcription factor at MAML2 enhancer, suggesting a role of DNMT3B in increasing methylation of MAML2 after stilbenoid treatment. Our results deliver a novel insight into epigeneticregulation of oncogenic signals in cancer and provide support for epigenetic-targeting strategies as an effective anticancer approach.

PMID: 27207652