Abstract 229: Omega-3 fatty acids strongly induce apoptosis in human breast cancer cells in vitro and in vivo via formation of reactive oxygen species and caspase 8 activation

Abstract

Abstract [Hypothesis] The present study sought to investigate the in vitro and in vivo anticancer effect of two representative omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), with a focus on assessing the role of fatty acid-induced oxidative stress and apoptosis as mechanisms for their anticancer actions. [Methods] We used in vitro cell culture of MCF-7 human breast cancer cells and in vivo athymic nude mice model to study the effect of omega-3 fatty acids on cancer cell proliferation and the mechanism of the cell death. [Results] In vitro studies showed that DHA and EPA each strongly reduced the viability and DNA synthesis of MCF-7 human breast cancer cells in culture, and they also promoted cell death via apoptosis. Mechanistically, accumulation of reactive oxygen species and activation of caspase 8 contributed critically to the induction of apoptotic cell death. Co-presence of antioxidants or a selective inhibition or knockdown of caspase 8 each effectively abrogated the cytotoxic effect of DHA. Using athymic nude mice as an in vivo model, we found that feeding animals with 5% fish oil-containing diet for 6 weeks significantly reduced the growth of MCF-7 human breast cancer cells through inhibition of cancer cell proliferation as well as promotion of cell death. Using 3-nitrotyrosine as a parameter, we confirmed that fish oil diet significantly increased oxidative stress in tumor cells in vivo. Analysis of fatty acid content in plasma and tissues showed that feeding animals a 5% fish oil diet significantly increased DHA and EPA levels in both normal and tumorous mammary tissues by 329 and 300%, respectively. [Conclusion] The results of this investigation clearly showed that omega-3 fatty acids strongly inhibited human breast cancer proliferation both in vitro and in vivo via formation of reactive oxygen species and induction of apoptosis by caspase 8 activation. This study calls for further studies in human subjects to assess the effectiveness of fish oil as a dietary supplement in the treatment of certain types of cancers. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 229.