甲基化修饰对人胃癌细胞系中多种基因的调控

Regulation of DNA Methylation on Expression of Genes in Human Gastric Cancer Cell Lines

甲基化紊乱与胃癌的发生有关,近年来甲基化已成为肿瘤研究的热点。目的:探讨在DNA甲基转移酶抑制剂5-氮脱氧胞苷(5-aza-2'-deoxycytidine,5-aza-dC)的化学干预下,不同分化胃癌细胞系的抑癌基因、癌基因和与凋亡相关的基因与甲基化调控的关系,并辅以流式细胞仪检测细胞周期的变化。方法:培养高分化、中分化和未分化胃癌细胞系MKN-45、MKN-28和:HGC-27,分别以不同浓度的5-aza-dC干预细胞。提取细胞的RNA,用逆转录聚合酶链反应(RT-PCR)方法检测p16INK4A、p21WAF1、p73、c-myc、c-Ha-ras、survivin和死亡相关蛋白激酶(DAP-ki-nase)等多种基因的表达情况;同时以流式细胞仪分析细胞周期的变化。结果:抑癌基因中,MKN-45和HGC-27细胞中有p16INK4A表达,用5-aza-dC干预后其表达增强,MKN-45细胞的p16INK4A在5-aza-dC 10μmcl/L 24 h、2 μmol/L72 h和5μmol/L 72 h组表达增强,HGC-27细胞的p16INK4A在5 μmol/L 24 h和10 μmol/L 24 h组表达也有明显增强;p21WAF1、p73无明显变化。癌基因中c-myc、c-Ha-ras变化不明显。与凋亡相关的基因中,MKN-45细胞的survivin在5-aza-dC处理后表达增强,但HGC-27细胞的DAP-kinase无明显变化。结论:在不同分化的人胃癌细胞系中,甲基化修饰对抑癌基因。

The aberrant methylation is associated with the development of gastric cancer. In recent years the methylation has been a hot spot in cancer research. Aims: To investigate the effects of DMA methylation on tumor suppressor genes, oncogenes and apoptosis-associated genes in different human gastric cancer cell lines by DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC) intervention, and to detect the changes of cell cycle by using flow cytometry. Methods: Three gastric cancer cell lines (MKN-45, MKN-28 and HGC-27) were treated with 5-aza-dC in different concentrations. The expression of p16INK4A, p21WAF1, p73, c-myc, c-Ha-ras, survivin and death-associated protein ki-nase (DAP-kinase) genes were assayed by reverse transcriptase polymerase chain reaction (RT-PCR). Cell cycle was analyzed by flow cytometry. Results: Tumor suppressor gene pl6INK4A expression was detected in MKN-45 and HGC-27 cells. The expression of pl6INK4A was obviously up-regulated at either 10 μmol/L of 5-aza-dC for 24 hours or other concentrations for 72 hours, and 5 μ.mol/L or 10 μmol/L for 24 hours, in MKN-45 and HGC-27 cells, respectively. However, p21WAF1 and p73 gene's transcription levels were not changed, so did the oncogenes c-myc and c-Ha-ras. survivin, an apoptosis-associated gene's expression was increased at MKN-45 cell, but DAP-kinase gene had no significant change at HGC-27 cell. Conclusions: The effects of DNA methylation on tumor suppressor genes, oncogenes and apoptosis-associated genes in different human cancer cell lines are quite distinct. The expression of pl6'NK4A and survivin genes can be regulated by DNA methylation in MKN-45 and HGC-27 cells, and MKN-45 cell respectively, but not MKN-28.