5-Aza-CdR对肝癌细胞DAPK基因甲基化的影响

目的探讨去甲基化药物5-氮杂-2’-脱氧胞苷(5-Aza-CdR)对人肝癌细胞株SMMC-7721中死亡相关蛋白激酶(DAPK)基因启动子CpG岛甲基化的影响。方法不同浓度(0.5μmol/L、5.0μmol/L、50.0μmol/L)5-Aza-CdR处理人肝癌细胞株SMMC-772172小时后,用焦磷酸测序法检测处理前后DAPK基因启动子CpG岛甲基化水平。以未经处理的人肝癌细胞株SMMC-7721作为对照组。结果未经5-Aza-CdR处理的肝癌细胞SMMC-7721细胞株DAPK基因启动子高度甲基化,平均水平为76.71%。经3种不同浓度药物处理72小时后,各组间甲基化平均水平分别为78.29%、77.57%和66.00%,各组间甲基化水平差异均有统计学意义(F=39.71,P<0.01)。其中,50.0μmol/L处理组细胞甲基化水平最低,与其他各组差异均有统计学意义(P<0.01)。结论 SMMC-7721细胞株DAPK基因启动子区呈高度甲基化状态;5-Aza-CdR能够逆转人肝癌细胞SMMC-7721DAPK基因启动子区域的甲基化状态。

Effect of 5-Aza-CdR on methylation and expression of DAPK gene in hepatocellular carcinoma cell line

Objective To investigate the effect of DNA methylation inhibitor 5-Aza-2＇-deoxycytidine（5-Aza-CdR） on the level of promoter methylation in human hepatoma cell line SMMC-7721 cells.Methods Human hepatoma cell line SMMC-7721 cells were treated with different concentrations（0.5 μmol/L,5.0 μmol/L,50.0 μmol/L） of 5-Aza-CdR for 72 hours,with the untreated human hepatoma cell line SMMC-7721 cells as control group.The application of pyrosequencing was used to detect the average level of promoter methylation.Results DAPK gene promoter was highly methylated in human hepatoma cell line SMMC-7721 cells,with the average methylation level as 76.71%.When the cells were treated with different concentrations（0.5 μmol/L,5.0 μmol/L,50.0 μmol/L）of 5-Aza-CdR for 72 hours,the average methylation level of DAPK gene for each treatment group was 78.29%,77.57% and 66.00%,respectively,and statistically significant difference was found among different treatment groups（F = 39.71,P 〈0.01）.The average methylation level of DAPK gene in the 50.0 μmol/L treatment group was lowest,compared with other groups（P 〈0.01）.Conclusions 5-Aza-CdR can reverse the status of DAPK gene promoter methylation and induce the mRNA expresseion of DAPK in SMMC-7721 cells.