Cell cycle arrest-mediated cell death by morin in MDA-MB-231 triple-negative breast cancer cells

Background Morin, a flavonoid extracted from Moraceace family and exhibits several pharmacological activities including anti-cancer activity. Although the anticancer activity of morin in breast cancer was estimated in some investigations, the pharmaceutical mechanism has not been fully elucidated. Therefore, we investigated to unveil the detail signaling pathway in morin-treated in MDA-MB-231 triple-negative breast cancer cells. Methods The cytotoxicity of morin in MDA-MB-231 cells was confirmed by sulforhodamine B (SRB) assay and colony formation assay. Flow cytometry was performed to examine the cell cycle and cell death patterns and the protein expression and phosphorylation were detected by western blotting. Results Our results showed that morin inhibited MDA-MB-231 cells proliferation in time and concentration-dependent manner. Morphological changes were observed when treated with various concentration of morin in MDA-MB-231 cells. In regard to protein expression, morin induced the phosphorylation of ERK and p-H2A.X and decreased the level of DNA repair markers, RAD51 and survivin. In addition, flow cytometry showed S and G2/M arrest by morin that was associated with the decrease in the protein expression of cyclin A2 and cyclin B1 and upregulation of p21. Interestingly, annexin V/PI staining result clearly showed that morin induced cell death without apoptosis. Furthermore, attenuated FoxM1 by morin was co-related with cell cycle regulators including p21, cyclin A2 and cyclin B1. Conclusion Taken together, our study indicates that morin-induced cell death of MDA-MB-231 is caused by sustained cell cycle arrest via the induction of p21 expression by activation of ERK and repression of FOXM1 signaling pathways.