DNA甲基化和组蛋白修饰的关键酶在胃癌中存在相互作用

Interaction effects of DNA methylation and histone modification key enzymes in gastric cancer

目的研究胃癌细胞和组织中DNA甲基转移酶1（DNMTl）、果蝇zeste基因增强子人类同源基因2（EZH2）和组蛋白去乙酰化酶1（HDACl）的表达及三者的相互作用。方法实时定量PCR和Western印迹检测MKN28、SGc7901、BGC823、AGS4株胃癌细胞和正常胃上皮细胞GES-1以及10对新鲜胃癌组织和相应的正常胃组织中DNMTl、EZH2、HDACl的mRNA和蛋白表达水平；免疫共沉淀检测高分化（MKN28）、中分化（SGC7901）、低分化（BGC823）胃癌细胞和正常胃上皮细胞GES-1及中分化、中-低分化、低分化胃癌组织和正常胃组织中DNMTl、EZH2和HDACl是否形成复合物。结果与正常胃上皮细胞和胃组织相比，DNMTl、EZH2和HDACl在胃癌细胞株和胃癌组织中均高表达，免疫共沉淀检测发现DNMTl、EZH2和HDACl三者在高、中、低分化胃癌细胞株以及中、中-低、低分化胃癌组织中均形成复合物，但在正常胃上皮细胞和胃组织中不形成复合物。结论DNMTl、EZH2和HDACl在胃癌中高表达，并且三者存在相互作用，这可能是胃癌中DNA甲基化与组蛋白修饰存在相关性的重要机制。

Objective To study the expression and interactions of DNA methyltransferase 1 （DNMT1）, enhancer of zeste homolog 2 （EZH2） and histone deacetylase 1 （HDAC1） in gastric cancer cell lines and tissue specimens. Methods The expression of DNMT1, EZH2 and HDAC1 was detected at mRNA and protein level in gastric cancer lines MKN28, $GC7901, BGC823, AGS, normal gastric epithelium cell line GES-1 and 10 pairs of fresh gastric cancer tissues and corresponding normal gastric tissues by real-time polymerase chain reaction and Western blot. Whether DNMT1, EZH2 and HDAC1 forming complex or not was detected by co-immunoprecipitation （Co-IP） in well-differentiated gastric cancer cell line MKN28, medium-differentiated gastric cancer cell line SGC7901, low- differentiated gastric cancer cell line BCG823, normal gastric epithelium cell line GESq, medium- differentiated, medium to low-differentiated, low-differentiated gastric cancer tissues and corresponding normal gastric tissues. Results Compared with that of normal gastric epithelium cell and gastric tissue, the expression of DNMT1, EZH2 and HDAC1 in gastric cancer cell lines and gastric tissue was higher. The results of Co-IP indicated that DNMT1, EZH2 and HDAC1 formed complex in the high, medium, and poor differentiated gastric cancer cells and the medium, medium- low, poor differentiated gastric cancer tissues, but not in normal gastric epithelium cell and tissue.Conclusion DNMT1, EZH2 and HDAC1 highly expressed in gastric cancer and there was interaction effects among them, which might be an important mechanism in the correlation between DNA methylation and histone modifications in gastric cancer.