Anti-proliferative and pro-apoptotic effects of cinobufagin on human breast cancer MCF-7 cells and its molecular mechanism

<p>Cinobufagin (CBF) is an active ingredient isolated from Venenum Bufonis extracted and dried from the secretory glands of <i>Bufo gargarizans Cantor</i>. The purpose of the study was to investigate the effects and underlying mechanisms of CBF on human breast cancer MCF-7 cells <i>in vitro</i>. Our results showed that CBF exhibited obvious cytotoxicity on MCF-7 cells in a dose- and time-dependent manner, as indicated by CCK-8 assays. Also, Hoechst 33258 staining and flow cytometry assays showed that CBF strongly induced MCF-7 cell apoptosis and G1 phase arrest. In addition, further molecular mechanistic investigation demonstrated that cinobufagin significantly increased Bax expression, decreased Bcl-2 expression level and up-regulated the ratio of the pro-apoptosis/anti-apoptosis protein Bax/Bcl-2, which were demonstrated by RT-qPCR and western blot assays. Taken together, our data confirm that CBF inhibits growth and triggers apoptosis of MCF-7 cells by affecting the expression of Bax and Bcl-2 <i>in vitro</i>.</p