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

AIM To study the effect of a varyingconcentrations of arsenic trioxide on humanhepatoma cell line BEL-?402 cultured in vitro andits mechanism of action.METHODS The BEL-7402 cells were treatedwith arsenic trioxide（at the concentrations of0.5,1,2 μmol/L,respectively）for 4 successivedays.The cell growth and proliferation wereobserved by cell counting and cell-growth curve.Morphologic changes were studied withelectronmicroscopy.Flow cytometry was usedto assay celI-DNA distribution and the proteinexpression of Bcl-2 and Bax detected byimmunocytochemical method.RESULTS The cell growth was significantlyinhibited by varying concentrations of arsenictrioxide as revealed by cell counting and cell-growth curve,which was dose- and time-dependent.Arsenic trioxide treatment at 0.5,1and 2 μmol/L resulted in a sub-G1 cell peak,theapoptosis 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 thetwo.The apoptosis rates of 1,2 μmol/L arsenictrioxide were 19.10% and 21.87% respectively,which were much higher（both P【0.05）.Decrease of G0/G1 phase cells and increase of Sphase 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 asintact cell membrane,nucleic condensation,apoptotic body formation were seen undertransmission electronmicrescopy,whereas the0.5 mol/L arsenic trioxide-treated BEL-7402cells showed decrease of nucleocytoplasmicratio,round nucleus,well-differentiatedorganelles in the cytoplasm.The processes andmicrovilli on the cell surface of the experimentalgroups under scanning electron microscopy weresignificantly decreased.High expressions ofBcl-2 and Bax were detected in 1 and 2 μmol/Larsenic 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/Lresulted in a higher expression level of Bcl-2 andlower expression level of Bax,which were8.81% and 3.83% respectively,as comparedwith that of the control group（15.33%）（P1【0.01,P2【0.01）.CONCLUSION Arsenic trioxide not onlyinhibited proliferation but also induced apoptosisof human hepatoma cell line BEL-7402.Theinduced-apoptosis effect of 1,2 μmol/L arsenictrioxide was related to the expression level ofBcl-2 and Bax.

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&mgr;mol/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&mgr;mol/L resulted in a sub-G1 cell peak, the apoptosis rate of the control group was 9.31% and that of 0.5&mgr;mol/L arsenic trioxide 15.53%, no significant difference was seen between the two.The apoptosis rates of 1,2&mgr;mol/L arsenic trioxide were 19.10% and 21.87% respectively, which were much higher (both P < 0.05). Decrease of G(0)/G(1) phase cells and increase of S phase cells were observed by flow cytometry, suggesting the inhibition effect of 0.5, 1, 2&mgr;mol/L arsenic trioxide on BEL-7402 cell lay in the G(0)/G(1) phase. Morphologic changes such as intact cell membrane, nucleic condensation, apoptotic body formation were seen under transmission electronmicrescopy, whereas the 0.5mol/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&mgr;mol/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&mgr;mol/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%) (P(1)<0.01, P(2)<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&mgr;mol/L arsenic trioxide was related to the expression level of Bcl-2 and Bax.