苯代谢物氢醌对人体肝细胞内DNA甲基转移酶基因和蛋白表达的影响

Effects of Hydroquinone on the Expression of DNA Methyltransferase mRNA and Protein in L02 cells

苯是一种具有致癌效应的环境污染物,氢醌(Hydroquinone,HQ)作为重要的苯代谢物,其介导的毒性可能是苯致癌的原因之一.越来越多的证据表明,DNA甲基化异常是致癌物质发挥毒作用的一种主要途径,HQ可以诱导人体肝细胞DNA甲基化水平改变,但其作用机制尚不清楚.为探索HQ诱导DNA甲基化改变的主要因素,本文应用RT-PCR和Western blotting技术,研究不同浓度HQ(0、5、10、25和50μM)染毒暴露对L02肝细胞内DNA甲基化转移酶(DNMT1,DNMT 3a和DNMT 3b)基因和蛋白表达的影响.实验结果表明,HQ可诱导三种酶的基因表达不同程度升高,高剂量组(≥10μM)与对照组相比差异具有统计学意义(P<0.05);0~50μM范围内HQ可诱导DNMT 1和DNMT 3b的蛋白表达呈浓度依赖性增高,25和50μM实验组与对照组相比差异显著(P<0.05).这些结果表明HQ的暴露可引起L02细胞内DNA甲基化转移酶的基因和蛋白表达升高,这可能导致一些目的基因DNA甲基化发生异常,本实验从表观遗传学角度暗示了HQ影响人体早期健康的机制.

Abstract ： As a major metabolite of environmental carcinogen benzene, hydroquinone （HQ） may play an impor- tant role in toxicity of benzene, but its mechanisms are not fully understood. More and more data indicate that aberrant DNA methylation is the important mechanism of carcinogenesis, and HQ has been reported to induce ab- normal DNA methylation in human cells. To understand the potential mechanism of DNA methylation alteration, the effects of HQ （0, 5, 10, 25, and 50 p,M） on the genes and protein expression of DNA methylation enzymes （DNMTs）, which mostly includes DNMT 1, DNMT 3a, and DNMT 3b, are investigated in L02 cells by RT-PCR and Western Blotting methods. Results show that 10, 25, and 50 t^M HQ significantly up -regulate the gene expression of DNMTs （ P 〈 0. 05 ） in L02 cells; in addition, 25, and 50 ~M HQ significantly up - regulate the protein expression of DNMT 1, and DNMT 3b （P 〈0. 05）. These data suggest that the up- regulated gene and protein expression of DNMTs induced by HQ may lead to DNA methylation levels increasing in the promoter area of some genes, rather than the global DNA hypomethylation levels induced by HQ. This study provides the new insights into the epigenetics carcinogenesis of HQ.