| Summary: | 碩士 === 國立成功大學 === 藥理學研究所 === 104 === Breast cancer ranks the top three cancers with high incidence rate among women. In addition, treating patients with estrogen receptor positive tamoxifen-resistant breast cancer and triple-negative breast cancer remains to be a therapeutic challenge in clinical situations. Resveratrol (3, 5, 4'- trans- trihydroxystilbene) is an anti-oxidant found in grapes and red wine. Interestingly, resveratrol has been shown to exhibit a wide spectrum of pharmacological properties with potential to be an anti-cancer agent. However, despite the anti-cancer effect of resveratrol has already been shown in a few studies, its molecular mechanism of actions are still incompletely known. Furthermore, it is still unclear on whether resveratrol can be used as a therapeutic agent for patients with different breast cancer subtypes.
In this study, we found that despite resveratrol exhibits similar cell viability inhibitory effects on the lumen A-like MCF7, MCF7-derivded tamoxifen-resistant MCF7-TamC3, HER2-like SK-BR-3, and basal-like triple-negative MDA-MB-231 breast cancer cells, it exhibits differential anti-proliferative effects and cytotoxicity towards different breast cancer cells in vitro. Results of the microscopic analysis, Brdu cell proliferation assay and LDH cytotoxicity assay showed that 2xIC50(MTT) (as determined by the MTT assay) resveratrol induced early cell proliferation inhibition (24 h post-treatment) and cell death (48 h post-treatment) in MCF7 and SK-BR-3 cells. Surprisingly, 2xIC50(MTT) resveratrol induced delayed cell proliferation inhibition and cell death in MDA-MB-231 cells. At the molecular level, Western blot analysis revealed that resveratrol increased the expression of gamma H2AX, which is a DNA damage marker, in MCF7 and SK-BR-3 as early as 24 h post-treatment. In contrast, increased expression of gamma H2AX was only observed in MDA-MB-231 cells 48 h post-treatment. Noticeably, re-determination of the IC50 values using the Brdu cell proliferation assay [IC50(Brdu)] instead of the originally used MTT cell viability assay showed that the IC50(Brdu) of resveratrol in MDA-MB-231 cells is at least 2-fold higher than that in MCF7 and SK-BR-3 cells. These results indicate that MDA-MB-231 cells are more resistant to resveratrol than MCF7 and SK-BR-3 cells in vitro. Mechanistic studies revealed that resveratrol decreased the expression of IAP-2, which is a member of the inhibitor-of-apoptosis proteins (IAPs) family, in MCF7, SK-BR-3 and MDA-MB-231 cells. Surprisingly, resveratrol only decreased the expression of survivin in MCF7 and SK-BR-3 cells but not in MDA-MB-231 cells. Indeed, resveratrol increased the expression of survivin and increased the stability of survivin protein in MDA-MB-231 cells. Moreover, resveratrol also up-regulated the expression of Bcl-2, which is a well-known inhibitor of apoptosis, in all of the tested breast cancer cell lines.
Taken together, our findings indicate that resveratrol induced differential cellular effects at least in part through differential regulation of survivin expression in different breast cancer subtypes. In addition, combination of Bcl-2 targeted therapy may provide a better therapeutic option against the odds of resveratrol in clinical application. Results of this study may provide important information for the use of resveratrol as a therapeutic agent for specific breast cancer subpopulations in the future.
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