Dioscin induces prostate cancer cell apoptosis through activation of estrogen receptor-β

Recent researches have shown that estrogen receptor-beta (ER beta) activator may be a potent anticancer agent for prostate cancer (PCa), and our previous study also indicated that dioscin can upregulate the expression of ER beta in MC3T3-E1 cell. In the present work, the activity and mechanism of dioscin, a natural product, against PCa were investigated. The results showed that dioscin markedly inhibited cell viability, colony formation, motility and induced apoptosis in PC3 cells. Moreover, dioscin disrupted the formation of PC3 cell-derived mammospheres and reduced aldehyde dehydrogenase (ALDH) level and the CD133(+)/CD44(+) cells, indicating that dioscin had a potent inhibitory activity on prostate cancer stem cells (PCSCs). In vivo results also showed that dioscin significantly suppressed the tumor growth of PC3 cell xenografts in nude mice. Furthermore, mechanism investigation showed that dioscin markedly upregulated ER beta expression level, subsequently increased prolyl hydroxylase 2 level, decreased the levels of hypoxia-inducible factor-1 alpha, vascular endothelial growth factor A and BMI-1, and thus induced cell apoptosis by regulating the expression levels of caspase-3 and Bcl-2 family proteins. In addition, transfection experiment of ER beta-siRNA further indicated that diosicn showed excellent activity against PCa in vitro and in vivo by increasing ER beta expression level. The co-immunoprecipitation (Co-IP) results further suggested that dioscin promoted the interaction of c-ABL and ER beta, but did not change c-ABL expression. Moreover, the molecular docking assay showed that dioscin processed powerful affinity toward to ER beta mainly through the strong hydrogen bonding and hydrophobic effects, and the actions of dioscin on ER beta activation and tumor cells inhibition were significantly weakened in the mutational (Phe-336, Phe-468) PC3 cells. Collectively, these findings proved that dioscin exerted efficient anti-PCa activity via activation of ER beta, which should be developed as an efficient candidate in clinical for treating this cancer in the future.