To examine the anti-cancer effects of berberine on multiple cancer cell lines, and to clarify the underlying molecular mechanisms.The IC50 values for the action of berberine on Tca8113 (oral squamous cell carcinoma), CNE2 (nasopharyngeal carcinoma cell), MCF-7 (breast cancer), Hela (cervical carcinoma), and HT29 (colon cancer) cells were determined by MTT cell viability assay. Early apoptosis and cell cycle arrest were examined by flow cytometry with annexin V and propidium iodide (PI) staining, respectively. For expression of BAX and BCL-2 genes and proteins were detected by real-time PCR and western blotting, respectively.Berberine displayed a cytotoxic effect on all the cell lines tested. The IC50 values were determined (Tca8113, 218.52 ±18.71; CNE2, 249.18 ±18.14; MCF-7, 272.15 ±11.06; Hela, 245.18 ±17.33; and HT29, 52.37 ±3.45). PI staining revealed that berberine treatment resulted in cell cycle arrest at G2/M. The treatment also induced early apoptosis as shown by annexin V staining. In addition, berberine significant elevated gene and protein expression of BAX, which was accompanied by substantial decreases in BCL-2 gene and protein levels. The effects of berberine on BAX and BCL-2 were time-dependent.Berberine exhibited cytotoxic effects on multiple cancer cell lines by inducing apoptosis and cell cycle arrest. The BCL-2/BAX signaling pathway may be the common pathway underlying the anti-tumor effect of berberine. The findings support the notion that berberine is a dietary compound that can be further developed into a drug candidate for cancer treatment.Copyright: © 2021 Termedia & Banach.