Betulinic acid inhibits proliferation and triggers apoptosis in human breast cancer cells by modulating ER (α/β) and p53

Although betulinic acid (BA) has been shown to attenuate breast cancer cell lines, owing to its interaction with several signaling molecules; its potential interaction with estrogen receptors (ERs) and p53 is not fully understood. Hence, we aimed to investigate the anti-cancer effect of BA on breast cancer cells, focusing on its molecular mechanisms involving the ER and p53 signaling pathways. The cell cytotoxicity of ER-positive (MCF-7) and ER-positive (MDA-MB-231) breast cancer cells was studied using MTT assay. Apoptosis was investigated by flow cytometry and Western blot analysis. The expression levels of ERα/ERβ and wt-p53/mu-p53 were studied using Western blotting. Finally, a possible interaction between BA and its molecular targets was predicted using molecular docking. Upon BA treatment, both breast cancer cell lines underwent significant cell death and inhibition of cell proliferation. Flow cytometry and Western blot analysis showed that the MCF-7 cells underwent early and late apoptosis, while MDA-MB-231 underwent both apoptosis and necrosis within 48 h. The expression levels of ERα/ERβ and wt-p53/mu-p53 were significantly altered. This could be partly attributed to the activation of apoptosis and inhibition of proliferation through the p53 signaling pathway, as induced by the interaction of BA with its coupling molecules.