Casticin induces breast cancer cell apoptosis by inhibiting the expression of forkhead box protein M1.

Casticin is an active ingredient derived from Fructus Viticis, a traditional Chinese medicine. This study aimed to investigate the role of forkhead box O3 (FOXO3a) in breast cancer cells and examine the regulatory mechanisms of FOXO3a in response to casticin treatment of the cells by ELISA, flow cytometry, small interfering RNA (siRNA) transfection and western blot analysis. Casticin treatment induced apoptosis and reduced the expression of the transcription factor forkhead box protein M1 (FOXM1). In addition, FOXM1 repression induced by casticin treatment was associated with the activation of FOXO3a via increased dephosphorylation. Notably, silencing FOXO3a expression by siRNA-mediated gene knockdown attenuated casticin-mediated apoptosis. Collectively, these findings suggest that FOXO3a is a critical mediator of the inhibitory effects of casticin on apoptosis in breast cancer cells.