Effect of arsenic trioxide on human hepatoma cell line BEL-7402 cultured in vitro

Abstract

Aim: To study the effect of a varying concentrations of arsenic trioxide on human hepatoma cell line BEL-7402 cultured in vitro and its mechanism of action. Methods: The BEL-7402 cells were treated with arsenic trioxide (at the concentrations of 0.5, 1, 2 μmol/L, respectively) for 4 successive days. The cell growth and proliferation were observed by cell counting and cell-growth curve. Morphologic changes were studied with electronmicroscopy. Flow cytometry was used to assay cell-DNA distribution and the protein expression of Bcl-2 and Bax detected by immunocytochemical method. Results: The cell growth was significantly inhibited by varying concentrations of arsenic trioxide as revealed by cell counting and cell-growth curve, which was dose- and time-dependent. Arsenic trioxide treatment at 0.5, 1 and 2 μmol/L resulted in a sub-G1 cell peak, the apoptosis rate of the control group was 9.31% and that of 0.5 μmol/L arsenic trioxide 15.53%, no significant difference was seen between the two. The apoptosis rates of 1, 2 μmol/L arsenic trioxide were 19.10% and 21.87% respectively, which were much higher (both P < 0.05). Decrease of G0/G1 phase cells and increase of S phase cells were observed by flow cytometry, suggesting the inhibition effect of 0.5, 1, 2 μmol/L arsenic trioxide on BEL-7402 cell lay in the G0/G1 phase. Morphologic changes such as intact cell membrane, nucleic condensation, apoptotic body formation were seen under transmission electronmicroscopy, whereas the 0.5 mol/L arsenic trioxide-treated BEL-7402 cells showed decrease of nucleocytoplasmic ratio, round nucleus, well-differentiated organelles in the cytoplasm. The processes and microvilli on the cell surface of the experimental groups under scanning electron microscopy were significantly decreased. High expressions of Bcl-2 and Bax were detected in 1 and 2 μmol/L arsenic trioxide-treated cells, these were 46%, 87.33% and 83.08%, 95.83% respectively, among which that of Bax was more significant. Arsenic trioxide treatment at 0.5 μmol/L resulted in a higher expression level of Bcl-2 and lower expression level of Bax, which were 8.81% and 3.83% respectively, as compared with that of the control group (15.33%) (P1 < 0.01, P2 < 0.01). Conclusion: Arsenic trioxide not only inhibited proliferation but also induced apoptosis of human hepatoma cell line BEL-7402. The induced-apoptosis effect of 1, 2 μmol/L arsenic trioxide was related to the expression level of Bcl-2 and Bax.