The relationships between the expression of MGMT and prognosis in the advanced patients with gastric carcinoma

Objective O6-methylguanine-DNA-methyltransferase(MGMT)is the key enzyme to repair the DNA damage caused by alkylating agents damage DNA.It is also one of the reasons of resistence for alkylating agent drugs.p53 protein is the product of p53 gene.p53 gene mutation is related to the development and progression of tumors.Our experiment is to study the expression of MGMT in advanced gastric carcinoma tissues and to investigate the relationship between MGMT protein expression and the clinicopathological features of advanced gastric carcinoma.The study also aimed to explore the correlation of the expressions of MGMT protein and p53 protein,the relationship between their expressions and prognosis in advance gastric carcinoma.Methods We investigated the expression of MGMT in 158 advanced gastric cancer specimens by immunohistochemical assay.The relationship among clinicopathologic features,prognosis and expressions of MGMT protein and p53 protein were studied.Results The positive rates of MGMT protein expression in advanced gastric carcinoma was 76.58 %(121/158).MGMT expressions were not related to histologic classification,infiltrating depth,lymph nodes metastasis,TNM stages,nerve encroachment,cancer embolus of vessel.Spearman analysis indicated that the expressions of MGMT and P53 in the advanced gastric carcinoma were negative related each other(r=-0.2534,P=0.0023).COX multivariate regression analysis revealed that MGMT and p53 protein expression did not impact on OS(hazard ratio:1.339,P=0.1363;hazard ratio:1.174,P=0.4082,respectively).The survival curve showed that the loss and decrease of MGMT protein were correlated with a poor prognosis.Combined evaluation of MGMT and p53 revealed that the survival of patients with positive status for MGMT and negative status for p53 were more beneficial.The survival of p53(+),low MGM expression group were higher than that of p53(+),high MGMT expression group.Conclusion The loss and decrease of MGMT protein expression and the enhancement of p53 protein may be related to the progression of tumors.Combined evaluation of the expression of MGMT and p53 protein may be valuable in evaluating the prognosis of advance gastric carcinoma patients.The survival is longer in MGMT expression group than that in MGMT high expression group,while there may be other reasons that influent the prognosis of patients.