POLD1基因突变及蛋白表达在胃癌组织中的临床意义

Clinical significance of POLD1 gene mutation and protein expression in gastric carcinoma

目的:观察DNA聚合酶δ(polymerase data, Polδ)的催化亚基p125与胃癌细胞恶性增殖的关系,并探讨p125的编码基因POLD1与胃癌发生、发展的关系。方法:采用免疫组化法检测胃癌组织及癌旁组织中p125的表达;沉默胃癌细胞中POLD1基因,用MTT实验检测POLD1基因沉默前后胃癌细胞的增殖速率。采用Sanger测序法对胃癌细胞株MGC-803中POLD1基因cDNA进行测序。结果:免疫组化结果显示,胃癌组织中p125表达明显高于癌旁组织。MTT实验结果显示,POLD1基因沉默的胃癌细胞生长速率明显低于对照组细胞。Sanger测序结果显示,胃癌细胞中POLD1基因cDNA的碱基序列发生了4处点突变,1个碱基插入,1个碱基缺失。结论:p125高表达与胃癌细胞恶性增殖相关;胃癌细胞中POLD1基因cDNA碱基序列发生点突变、碱基插入从而引起其氨基酸序列改变,这有可能是导致胃癌细胞中p125高表达并引起癌细胞恶性增殖的分子机制之一。

Objective:To investigate the relationship between the catalytic subunit p125 of DNA polymerase data(Pol δ) and the malignant proliferation of gastric cancer cells, and to explore the relationship between POLD1 gene and the occurrence and development of gastric carcinoma.Methods:The expression of p125 in gastric carcinoma and its peritumoral tissues was detected by immunohistochemical method.POLD1 gene was silenced in gastric carcinoma cells, and the proliferation rate of gastric cancinoma cells before and after POLD1 gene silencing was measured by MTT Assay.The cDNA of POLD1 gene in gastric cancinoma cells was sequenced by sanger method.Results:Immunohistochemical staining results showed that the positive rate of p125 expression in gastric carcinoma was significantly higher than that in peritumoral tissue.The results of MTT assay showed that the proliferation rate of POLD1 gene silenced gastric carcinoma cells was significantly lower than that of control cells.Sanger’s sequence analysis showed that there were 4 point mutations, 1 base insertion and 1 base deletion in the cDNA of POLD1 gene in gastric carcinoma cells.Conclusion:Over-expression of p125 is associated with malignant proliferation of gastric carcinoma.The point mutation and base insertion of POLD1 gene in gastric carcinoma cells result in the alteration of its amino acid sequence, which may be one of the molecular mechanisms leading to the overexpression of p125 and the malignant proliferation of gastric carcinoma cells.