3‐O‐Acetyloleanolic Acid Induces Apoptosis in Human Colon Carcinoma Hct‐116 Cells

The cytotoxic effect of 3‐O‐acetyloleanolic acid, an oleanolic acid derivative isolated from the seeds of Vigna sinensis K., was investigated in human colon carcinoma HCT‐116 cells. 3‐O‐acetyloleanolic acid dose‐dependently inhibited the viability of HCT‐116 cells. Apoptosis was characterized by detection of cell surface annexin V and sub‐G1 apoptotic cell populations. The number of immunostained cells with annexin V‐FITC was increased after treatment with 3‐O‐acetyloleanolic acid. The sub‐G1 cell population was also increased. Expression of TRAIL‐mediated apoptosis signaling‐related death receptor DR5 was increased in 3‐O‐acetyloleanolic acid‐treated HCT‐116 cells. Activation of caspase‐8 and caspase‐3, critical mediators of extrinsic apoptosis signaling, was also increased by 3‐O‐acetyloleanolic acid. The results indicate that 3‐O‐acetyloleanolic acid induces apoptosis in HCT‐116 cells mediated by an extrinsic apoptosis signaling cascade via up‐regulation of DR5. Copyright © 2012 John Wiley & Sons, Ltd.