Cytotoxic effects of escin on human castration-resistant prostate cancer cells through the induction of apoptosis and G2/M cell cycle arrest

Objective To evaluate the in vitro and in vivo effects of escin on human castration-resistant prostate cancer (CRPC) cells, PC-3 and DU-145. Materials and Methods The inhibition of cell proliferation and its mechanism were assessed through a cytotoxicity assay, flow cytometry, and Western blot. The in vivo efficacy of escin in CRPC cells was assessed using a xenograft tumor model subcutaneously established in BALB/c nude mice. Results The treatment with escin significantly reduced cell viability of CRPC cells in a dose- and time-dependent manner. Escin induced apoptosis in a time-dependent manner, which was accompanied by increases in pro-apoptotic (BCL-2 associated X protein, cleaved-caspase3, and cleaved-poly [adenosine diphosphate-ribose] polymerase) proteins and decreases in antiapoptotic (X-linked inhibitor of apoptosis protein, cellular inhibitor of apoptosis protein-1, cellular inhibitor of apoptosis protein-2B-cell leukemia/lymphoma-2, and B-cell lymphoma-extra large) proteins. Escin induced G2/M-phase cell cycle arrest and thus led to a significant decrease in the expression of cyclinB1 and its activating partner cyclin-dependent kinase 1, with the concomitant induction of p21. In addition, escin significantly inhibited the growth of CRPC cells in xenograft models. Conclusion The results show that escin induced cytotoxic effects on CRPC cells through the induction of apoptosis and G2/M cell cycle arrest, indicating it may be a novel therapeutic agent for CRPC.