Abstract 4217: The anti-malarial compound artesunate induces reactive oxygen species-dependent killing of breast cancer cells

Abstract

Abstract Introduction: Artesunate is a semi-synthetic derivative of artemisinin, a natural compound from the herb Artemisia annua L. Artemisinin has been used in traditional Chinese medicine while artesunate has recently been used as an anti-malarial drug. Artesunate is also cytotoxic to human cancer cells. Since the use of artesunate as an anti-malarial agent is associated with few adverse effects, artesunate may represent a less toxic alternative to conventional chemotherapy. This study investigates the cytotoxic effect of artesunate on breast cancer cell lines and the mechanism(s) underlying its activity. Methods and Results: Artesunate exhibited a time- and dose-dependent cytotoxic effect on all breast carcinoma cell lines examined (MCF-7, T47D, SK-BR-3, MDA-MB-231, MDA-MB-468). Further examination of MDA-MB-468 cells using Oregon Green-488 and Annexin-V-FLUOS/propidium iodide staining indicated that artesunate had an anti-proliferative effect that was associated with apoptosis induction. Cell cycle arrest occurred in the G2 phase, and was evident as early as 24h after artesunate treatment. Artesunate-induced apoptosis was low in normal fibroblasts at concentrations cytotoxic to breast cancer cells, although fibroblast proliferation was inhibited. DiOC6 staining revealed dose-dependent destabilization of the mitochondrial membrane in artesunate-treated MDA-MB-468 cells. Artesunate-treated MDA-MB-468 cells also displayed cytosolic cytochrome c and PARP cleavage, as demonstrated by Western blotting, which was consistent with apoptosis induction. Pretreatment with reduced glutathione rescued MDA-MB-468 cells from artesunate-induced apoptosis, indicating that reactive oxygen species (ROS) mediate artesunate-induced cytotoxicity. In addition, MDA-MB-468 cells that were pretreated with holotransferrin showed increased killing by artesunate, suggesting that iron promotes artesunate-mediated apoptosis. Induction of the endoplasmic reticulum stress pathway in artesunate-treated cells was demonstrated by Western blotting, suggesting involvement of this apoptosis-inducing pathway in artesunate-mediated cytotoxicity. Conclusions: These data show that artesunate causes reactive oxygen species-dependent induction of apoptosis in breast cancer cells and therefore warrants further investigation as a possible treatment for breast cancer. Supported by NSERC and the Canadian Breast Cancer Foundation-Atlantic Region Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4217. doi:10.1158/1538-7445.AM2011-4217