Effect of berberine on the proliferation and apoptosis of a human skin squamous cell carcinoma cell line A431

Objective To estimate the effect of berberine on the proliferation of and expressions of apoptosis-related factors Bax and Bcl-2 in a human skin squamous cell carcinoma cell line A431. Methods A431 cells were cultured in vitro, and classified into various groups to be treated with berberine at different concentrations (12.5, 25, 5, 100 mg/L) or cisplatin at 250 mg/L (positive control group) for different durations (12, 24, 48 and 72 hours). The A431 cells remaining untreated served as the negative control group. Subsequently, methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate cell growth, and inverted microscopy to observe cell morphology. Real time quantitative reverse transcription-PCR and an immunofluorescence assay were conducted to measure the mRNA and protein expressions of Bax and Bcl-2 respectively. Statistical analysis was done by multi-way analysis of variance (ANOVA) using the software SPSS 13.0. Results MTT assay showed that berberine inhibited the growth of A431 cells, and the inhibitory effect increased with the increase in concentration (F=1118.312, P<0.001) and treatment duration (F=510. 927, P<0.001) of berberine. Moreover, there was a significant interaction between the concentration and treatment duration of berberine (F=70.239, P<0.001). Inverted microscopy revealed that when the concentration of berberine increased, cell density was reduced, and cell morphology changed from polygonal to round with cell body shrinkage. The ratio of bax to Bcl-2 mRNA was elevated with the increase in treatment duration and concentration of berberine, and there were significant differences in the mRNA ratio among cells treated with berberine for different time durations at same concentrations (F=226.231, 1300.636, 4325.139 for berberine at 25, 50 and 100 mg/L respectively, all P<0.001). Immunofluorescence staining indicated that the fluorescence intensity of Bax was enhanced, while that of Bcl-2 was weakened after berberine treatment. Conclusions Berberine inhibits the growth of A431 cells in a dose- and time-dependent manner, and may induce the apoptosis of A431 cells via regulating the expressions of Bax and Bcl-2. Key words: Berberine; Carcinoma, squamous cell; Proto-oncogene proteins c-bcl-2; bcl-2-Associated X protein; Apoptosis; Cell proliferation; A431 cell