Withaferin A inhibits cell proliferation of U266B1 and IM-9 human myeloma cells by inducing intrinsic apoptosis

Abstract

Withaferin A, a withanolide obtained from Withania somnifera exhibits remarkable pharmacological properties. Withaferin A has been reported to exert cytotoxic effects against human multiple myeloma cells. Nevertheless, the in-depth understanding of the withaferin A induced antiproliferative effects against human myeloma cells is still unclear. The results showed that withaferin A inhibited the viability of six different myeloma cells with a lowest IC50 of 9 μM against the U266B1 and IM-9 cell lines. Withaferin A inhibited the viability and colony formation of the U266B1 and IM-9 cells in a dose and time-dependent manner. The DAPI and annexin V/PI staining assays revealed that withaferin A exerts anticancer effects against the human myeloma cells via induction of apoptosis. The induction of apoptosis in U266B1 and IM-9 cells was associated with upregulation of Bax and cytochrome c, downregulation of Bcl-2 and activation of PARP, caspase-3 and capase-9 cleavage. Additionally, withaferin A triggered the production of ROS in human myeloma cells indicative of ROS mediated apoptosis in human myeloma cells. The treatment of the U266B1 and IM-9 with ascorbic acid (antioxidant) could prevent the withaferin A mediated ROS production and the withaferin A induced antiproliferative effects. Collectively, the results show that withaferin A inhibits human myeloma cell proliferation via ROS mediated intrinsic apoptosis.