Dioscin Decreases Breast Cancer Stem-like Cell Proliferation via Cell Cycle Arrest by Modulating p38 Mitogen-activated Protein Kinase and AKT/mTOR Signaling Pathways

Dioscin (DS), a steroidal saponin, has been shown to have anti-cancer activity by exerting antioxidant effects and inducing apoptosis. However, the anti-cancer activity of DS in breast cancer-derived stem cells is still controversial. The purpose of this study was to evaluate the effects of DS on migration, invasion, and colony formation in MDA-MB-231 and MCF-7 cell lines and the mechanism by which it inhibits proliferation of breast cancer stem-like cells after inducing differentiation into breast cancer stem cells. DS treatment significantly reduced cellular migration, invasion, and colony formation in MDA-MB-231 and MCF-7 cells. During the differentiation process that induced manifestation of breast cancer stem-like cells, DS significantly inhibited mammosphere formation in a dose-dependent manner and increased the expression of p53 and p21 in breast cancer stem-like cells, reducing the expression of cdc2 and cyclin B1 in MDA-MB-231 cells and cyclin D, cyclin E, CDK4, and CDK2 in MCF-7 cells. Interestingly, DS treatment induced G2/M and G0/G1 cell cycle arrest in the MDA-MB-231 and MCF-7 cells, respectively. DS also increased the phosphorylation of p38 and decreased the expression levels of p-AKT and p-mTOR. These results suggest that DS regulates the p38 mitogen-activated protein kinase and AKT/mTOR signaling pathways to reduce the proliferation of breast cancer stem-like cells through cell cycle arrest. Therefore, these findings suggest that DS may serve as a potential treatment candidate targeting breast cancer stem cells.