Abstract 2881: Benzyl isothiocyanate-mediated growth inhibition of MDA-MB-231 human breast cancer xenograft is associated with reduced cell proliferation, inhibition of angiogenesis, and induction of autophagy

Benzyl isothiocyanate (BITC), a constituent of many edible cruciferous vegetables, inhibits growth of cultured human breast cancer cells by causing apoptosis. The present study was undertaken to determine in vivo efficacy of BITC using triple negative MDA-MB-231 human breast cancer xenograft as a model. BITC administration retarded growth of MDA-MB-231 cells subcutaneously as well as orthotopically implanted in female nude mice without causing weight loss or any other side effects. BITC-mediated suppression of MDA-MB-231 xenograft growth correlated with reduced cell proliferation as revealed by immunohistochemical analyses of Ki-67 and proliferating cell nuclear antigen expression. Analysis of vasculature in tumors from the BITC-treated mice revealed smaller vessel area compared with control tumors based on immunohistochemistry for angiogenesis marker CD31. BITC-mediated inhibition of angiogenesis in vivo correlated with down-regulation of VEGF-receptor 2 protein level in the tumor. Consistent with these results, BITC treatment suppressed VEGF secretion and VEGF-receptor 2 protein level in cultured MDA-MB-231 cells. Moreover, the BITC-treated MDA-MB-231 cells exhibited reduced capacity for migration compared with vehicle-treated control cells. In contrast to cellular data, BITC administration failed to elicit apoptotic response as judged by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. Instead, the tumors from BITC-treated mice exhibited increased cleavage of microtubule-associated protein 1 light chain 3 (LC3), which is a marker of autophagic cell death. In agreement with these results, BITC treatment resulted in several features characteristic of autophagy in cultured MDA-MB-231 cells including formation of membrane vacuoles and acidic vesicular organelles (judged by microscopy after staining with lysosomotropic agent acridine orange), and cleavage of LC3. In conclusion, the present study indicates that BITC administration inhibits growth of MDA-MB-231 xenografts in association with reduced cell proliferation, inhibition of angiogenesis, and induction of autophagy. These preclinical observations underscore in vitro and in vivo differences in mechanisms for anticancer effect of BITC. This investigation was supported by the National Cancer Institute grant 1 RO1 CA129347-03. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010