The Effect Of SAM On C-myc Abnormal Expression Induced By As₂O₃ In Normal Human Liver Cells

The effect of S-adenosyl-L-methionine(SAM) on the c-myc expression induced by AS₂O₃ was studied using normal human liver cells(HL-7702) in vitro, and the potential inhibitory effect of SAM on arsenic carcinogenesis was discussed. Experiment was divided into three groups;c-myc expression of each group was examined by RT-PCR.First,HL-7702 cells were exposed to As₂O₃ at different concentrations(0.0,1.0,5.0,10.0,20.0μM) for 24 h;the c-myc expression raised to approximately 1.5 folds of control when As₂O₃≥1.0μM(p＜0.05) and the dose of 1.0μM reached peak.Then,HL-7702 cells were exposed to SAM at different concentrations(0.0,0.2,1.0,5.0,25.0μM) with 1μM As₂O₃ for 24 h;the dose of 0.2μM could significantly inhibited the c-myc overexpression induced by As₂O₃(p＜0.05),but with the increase of SAM concentration,the inhibitory effect of SAM decreased and c-myc expression started to increase gradually again.Finally, HL-7702 cells were exposed to 1.0μM As₂O₃ and 0.2μM SAM for different time (18,24,30,36 h),SAM exhibited prominent inhibitory effect on c-myc overexpression at 24 h and 30 h(p＜0.05).Taken together,these results indicate that SAM could inhibit c-myc overexpression which could be induced by As₂O₃. These findings are of significance to the exploration of SAM efficacy in preventing arsenic carcinogenesis.