Relationgship Between Promoter Methylation Of The ERCC1 Gene And DNMT1 Expression In Gastric Cancer

Objectice:This study by detection of gene expression in gastric cancer and adjacent tissues,to investigate the status of methylation of ERCC1(human excision repair cross complementing gene 1)gene promoter region and DNMT1(DNA methyl transferase 1)gene protein expression in gastric cancer and to analyze their relationship with gastric carcinogenesis.Gastric cancer is one of the leading cause of death in the digestive system,most of the patients present with late stage cancer at diagnosis.The occurrence and development of gastric cancer is a complex process with multi genes and multi steps involved,including oncogene activation and tumor suppressor gene inactivation.,epigenetic mechanisms play an important role in carcinogenesis,and one of the most common is DNA methylation.Method:(1)Collect fresh tumor specimens of Municipal Hospital of Qingdao from January 2014 to October 2014 a total of 60 cases of resection in Department of general surgery,Specimens by the histologic diagnosis of primary gastric cancer,preoperative radiotherapy and chemotherapy were not accepted,gastric cancer tissue was taken from the central non necrotic region of the tumor,Take at least 5 cm away from the cancer tissue and regional organizations as the tissue adjacent to carcinoma.Separate specimens collected DNA in the organization,and then using sodium sulfite modification method to the DNA of decoration,with additional polymerase chain reaction technology has the DNA proliferation and for at least 5 cm away from the cancer tissue regional organizations as the tissue adjacent to carcinoma.Separate specimens collected DNA in the organization,and then using sodium sulfite modification method to the DNA of decoration,using polymerase increase chain reaction technology to expand the DNA proliferation.Explore the methylation status of ERCC1 gene promoter in gastric cancer tissues and adjacent tissues was by methylation specific PCR(MSP),and the expression status of DNMT1 gene.Analysis of the relationship between the two genes and the occurrence and development of gastric cancer.(2)Extraction of RNA from 60 cases of gastric cancer tissues and adjacent tissues,and reversely transcribed into cDNA,then modificate them by PCR.Used RT—PCR to detect the expression of ERCC1 and DNMT1.(3)Using immunohistochemical method to detect carcinoma tissues and adjacent tissue the protein expression level of ERCC1 and DNMT1,,to explore the relationship between them and gastric cancer.SPSS17.0 software was used to test the data parsing,using ?2 test method between count data comparison,the comparison between the group t test for processing;With P < 0.05 as evaluation standard,the difference has statistical significance..Reust:(1)The positive rates of promoter methylation of the ERCC1 in gastric cancer 69.3% by used MSP,higher than23.3% of normal tissue.There was a significant differenc between gastric cancer and in normal tissue(P<0.001).(2)The expression of DNMT1 in gastric carcinoma was higher than normal gastric tissues which the expression of ERCC1 was lower.The two were significantly different(P<0.05).(3)According to immunohistochemistry,The positive rate was 93.3% in the adjacent tissues of the expression of ERCC1 was higher than gastric cancer 56.7%.DNMT1 protein expression in gastric cancer 71.7%,was higher than adjacent tissues 16.7,the two were significantly different(P<0.001).(4)The relationship between the status of methylation of ERCC1 gene promoter region and expression of ERCC1 mRNA,in 41 cases of gastric cancer with negative expression of mRNA ERCC1,including 38 case which were detected methylation of the promoter region,in 19 cases of gastric cancer with positive expression of mRNA ERCC1,only 3 case were detected methylation of the promoter region,the difference was statistically significa(P<0.001).(5)To investigate the connection between expression of DNMT1 and ERCC1 protein in gastric carcinoma,the expression of ERCC1 and DNMT1 protein in gastric cancer tissue showed a negative correlation(P<0.001).Conclusion:(1)In gastric cancer,hypermethylation changes can be found in the promoter region of ERCC1 gene,and accompanied by the decreased expression of gene protein,there is a certain relationship with the occurrence of cancer of stomach.(2)Lower than that of the adjacent tissue ERCC1 gene mRNA expression in gastric carcinoma,the low expression of mRNA was related to the high methylation of CpG islands in the promoter region of ERCC1 gene.(3)The expression of ERCC1 and DNMT1 protein in gastric cancer tissue showed a negative correlation,DNMT1 mRNA and protein expression increased significantly in gastric cancer tissue,may be related to abnormal methylation in the promoter region of the ERCC1 gene promoter region,lead to reduce or missing the expression of tumor suppressor gene mRNA and protein.