Anti-proliferative effect of digoxin on breast cancer cells via inducing apoptosis.

OBJECTIVE: Digoxin is a kind of plant-derived cardiac glycoside that is mainly used to treat heart diseases, especially in congestive heart failure or arrhythmia. However, its potentiality presented in anti-tumor remains unexplored. The purpose of this study was designed to investigate the beneficial pharmacological activity of digoxin on breast cancer cell line (MDA-MB-231, MM231). MATERIALS AND METHODS: The methyl thiazolyl tetrazolium (MTT) assay was utilized to detect the proliferation of the breast cancer MM231. The apoptotic cell numbers were determined by the flow cytometry analysis. The expressions of Bcl-2 (B-cell lymphoma-2) and Bax (Bcl2-associated X protein) were detected by Western blot analysis. RESULTS: Digoxin dose-dependently blocked the cell growth of the breast cancer MM231 through MTT assay, whereas the apoptotic numbers were significantly elevated as reflected in acridine orange staining and flow cytometry analysis. In addition, findings from Western blotting method indicated that digoxin intervention showed reduced Bcl-2 expression and elevated Bax level in MM231 cells, characterized by increased Bax/Bcl-2 ratio. CONCLUSIONS: Digoxin plays a potential anti-tumor role in breast cancer in vitro, possibly by inducing mitochondria-dependent apoptosis.