| Objective:This study by detecting the status of the methylation of MGMT gene and the gene expression in gastric cancer and adjacent tissues,to investigate the role of the promoter methylation of the MGMT gene in gastric cancer.We detected the DNMT1(DNA methyl transferase 1)gene protein expression in gastric cancer,in order to analyze its relationship with gastric carcinogenesis.Furthermore,The the relationship between the methylation of the MGMT gene and DNMT1 expression in gastric cancer was also analysed.Methods:1.Collect the gastric cancer tissue and the tissue adjacent to carcinoma from the stomach of 60 gastric cancer patients.The fresh tumor specimens were taken by surgery that performed by the department of general surgery of Qingdao Municipal Hospital from January 2015 to July 2016.Gastric cancer tissue was taken from the central non necrotic region of the tumor.The tissue adjacent to carcinoma was taken at least 5 cm away from the cancer tissue.Preoperative radiotherapy,chemotherapy and targeted therapy were not accepted.Separate specimens collected DNA in the tissue,and explore the methylation status of MGMT gene promoter in gastric cancer tissues and adjacent tissues by methylation specific PCR.Analyze the relationship between the promoter methylation of the MGMT gene and gastric cancer gastric cancer.2.Extract the RNA from the gastric cancer tissues and adjacent tissues,then use RT-PCR to detect the expression of MGMT and DNMT1 mRNA.3.Imunohistochemistry was used to detect the the protein expression of MGMT and DNMT1 in gastric cancer tissue and adjacent tissue,in order to explore their relationship with gastric cancer.Results:1.The positive rate of promoter methylation of the MGMT in gastric cancer detected by MSP was 45.00%,while The positive rate of promoter methylation was 13.33%.The rate was significantly significantly higher than that in adjacent tissue,with ?2=14.56 and P<0.001.2.The positive rate of MGMT mRNA in gastric cancer was significantly lower than that in normal tissue(41.67%vs93.33%,?2=36.51,P<0.001),While the positive rate of DNMT1 mRNA in gastric cancer was higher than that in normal tissue(76.67%vs18.33%, ?2=40.94,P<0.001).3.The positive rate of promoter methylation of the MGMT in gastric cancer tissue that do not express MGMT mRNA was higher than that in gastric cancer tissue that express MGMT mRNA(57.14%vs28.00%),with ?2=11.96 and P<0.05.4.The positive rate of the expression of MGMT was 40.00%(24/60)in gastric cancer,while the rate was the 93.33%(56/60)in adjacent tissues,the rate in gastric cancer was significantly lower than that in adjacent tissues(?2=38.4,P<0.001).However,the positive rate of DNMT1 protein in gastric cancer(76.67%,46/60)was significantly higher than that in adjacent tissues(6.67%,4/60),with ?2= 60.48 and P<0.001.5.It showed a negative correlation between MGMT protein expression with DNMT1 protein expression in gastric cancer tissue(r=-0.795,P<0.01).Conclusions:1.There may be a relationship between the hypermethylation in the promoter region of MGMT gene and the occurrence of gastric cancer.2.The low expression of MGMT and the high expression of DNMT1 may have a relationship with the occurrence of gastric cancer.3.The hypermethylation of MGMT gene may lead to the low expression of MGMT in gastric cancer.4.DNMT1 may involve in promoter methylation of the MGMT gene in gastric cancer.Significance:Gastric cancer is a kind of malignant tumor with a high mortality.It is in the terminal stage of cancer when the most gastric cancer patients are diagnosed,so the early diagnosis is extremely important.The occurrence and development of gastric cancer is a very complex process,it is caused by many aspects,including The environment factors and genetic factors.DNA methylation takes an important role in the occurrence and development of gastric cancer.This experiment offer a new idea in the diagnosis and treatment of gastric cancer,by exploring the relationship between promoter methylation of the MGMT gene and DNMT1 expression in gastric cancer. |
PDF Full Text Request