Breast cancer is the most frequently diagnosed cancer in women, and one of the leading causes of cancer-related deaths worldwide. Recent evidences indicate that dietary agents such as resveratrol may inhibit cancer progression through modulation of microRNAs (miRNAs). We demonstrate that resveratrol regulates apoptotic and cell cycle machinery in breast cancer cells by modulating key tumor-suppressive miRNAs including miR-125b-5p, miR-200c-3p, miR-409-3p, miR-122-5p and miR-542-3p. Resveratrol-mediated miRNA modulation regulates key anti-apoptotic and cell cycle proteins including Bcl-2, X-linked inhibitor of apoptosis protein and CDKs, which are critical for its activity. Modulating miRNAs with mimics or inhibitors further validated a key role for miR-542-3p in MCF-7 and miR-122-5p in MDA-MB-231 breast cancer cell death in response to resveratrol. In conclusion, this study reveals novel miRNAs modulated by resveratrol that have a key role in breast cancer cell death.

Background: Breast cancer is the second most common type of cancer in women, and the fifth most common cause of cancer related deaths in the world. Several drugs are being used for treatment, but it is seen that after prolonged use tumor cells develop resistance to these drugs rendering them ineffective. Identifying alternative and effective treatment options is crucial to improve the life expectancy of breast cancer patients. Resveratrol, a dietary agent found in grapes is being considered as a potential drug candidate due to its pro-apoptotic properties against cancer cells. Simultaneously, microRNAs (miRNAs) which are small non-coding single stranded RNA molecules are gaining ground as novel cancer therapeutics due to their capability to alter cell functions including apoptosis. Objective: The overall objective of this study is to elucidate that resveratrol-induced apoptosis in breast cancer cells occurs via tumor-suppressor miRNA. Experimental setup: Breast cancer cell lines MCF-7 (Estrogen Receptor positive) and MDA-MB-231 (Estrogen Receptor negative) were treated with different doses of resveratrol (0, 50, 100, 200 μM). Total RNA was isolated and miRNA analysis was performed using a breast cancer specific miRNA array to screen for miRNA known or predicted to have altered expression during breast cancer initiation or progression. A real-time PCR based on the SYBR Green technology was performed on these samples to study the expression profiles of 84 miRNAs using this method. Results: Analysis of cells after resveratrol treatment clearly showed an apoptotic effect on the cells in a dose dependent manner. Cell viability assay showed that the 50 μM dose had a protective effect with cells being more viable as compared to the control cells, but at consecutively higher doses resveratrol had a very distinct apoptotic effect. MiRNA data analysis revealed several miRNAs to be regulated in breast cancer cells. Hsa-miR-613 was found to be upregulated at both doses whereas hsa-miR-199b-5p was upregulated at 50 μM and downregulated at 200 μM in MCF-7. Similarly, for MDA-MB-231 cells hsa-miR -129-5p, hsa-miR-199b-3p and hsa-miR-199a-5p were upregulated at both doses whereas hsa-miR-214-3p was down regulated at 50 μM and upregulated at 200 μM. Interestingly, several members of the let-7 family were altered in both cell types. Several miRNAs associated with drug-resistance and ER dependence were also identified in both the cell types. Conclusion: Resveratrol induces apoptosis in breast cancer cells via the action of several miRNA. Therefore, treatment with resveratrol in conjunction with miRNAs that are altered by resveratrol has the potential to be a good therapeutic model to induce tumor suppression and ultimately destroy the tumors. Citation Format: Tanvi Muni, Anand Iyer, Neelam Azad. Resveratrol-induced apoptosis in breast cancer cells is mediated by tumor suppressor microRNA. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4164. doi:10.1158/1538-7445.AM2013-4164