喉癌细胞系中抑癌基因MGMT表达与DNA甲基化及组蛋白H3-K9甲基化的关系

Correlation between histone H3-K9 methylation,DNA methylation and expression of gene MGMT in Hep-2 cell line

目的:探讨喉癌Hep-2细胞中组蛋白H3-K9甲基化与DNA甲基化及抑癌基因MGMT表达的关系。方法:应用去甲基化制剂5-氮杂-2′-脱氧胞苷(5-Aza-dC)处理体外培养的Hep-2细胞。应用染色质免疫沉淀技术、甲基化特异性聚合酶链反应和实时定量逆转录聚合酶链反应分析药物作用前后MGMT基因启动子区组蛋白H3-K9甲基化、DNA甲基化和MGMT表达情况。结果:①在Hep-2细胞未经药物干预前,MGMT表现为DNA甲基化,组蛋白H3-K9高甲基化,MGMT低表达。②在5-Aza-dC的作用下,Hep-2细胞中MGMT的组蛋白H3-K9甲基化状态被降低;MGMT的DNA甲基化状态得到了逆转;原来低表达的MGMT表达上调。结论:喉癌细胞系中MGMT启动子区甲基化可能是导致其基因失活的主要原因。DNA甲基化可能导致组蛋白H3-K9高甲基化。应用5-Aza-dC能够通过逆转MGMT的DNA甲基化水平从而降低MGMT组蛋白H3-K9甲基化水平来使抑癌基因表达上调,从而抑制肿瘤的发生和发展。

To explore the correlation between histone H3-K9 methylation, DNA methylation and expression of carcinoma suppressor gene MGMT in laryngeal carcinoma Hep-2 cell line. Method： 5-Aza-dC was used to deal with Hep-2 cell cultured in vitro. CHIP, MSP and Realtime- PCR were used to deteet H3-K9 methylation, DNA methylation, of MGMT gene promoter region and MGMT gene expression before and after treatment with drugs. Result：①In Hep-2 cell line,gene MGMT was characterized by DNA methylation and histone H3-K9 hypermethylation. ②5-Aza-dC was able to reduce H3-K9 methylation of MGMT gene histone in Hep-2 cell line,5Aza dC was able to reverse DNA methylation of MGMT gene histone in Hep-2 cell line,5-Aza-dC was able to up- regulate the down-regulated gene expression of tumor suppressor genes MGMT, Conclusion：Promoter methylation of cancer suppressor gene MGMT may induce the gene inactivity. DNA methylation may increase H3-K9 methylation. 5-Aza-dC can reduce H3-K9 methylation of tumor suppressor gene MGMT histone by reversing DNA methylation of tumor suppressor gene MGMT, and then the expression of tumor suppressor genes is increased and tumor development is inhibited.