Expression Of P53 And Microsatellite Instability In Gastric Cancer And Its Correlation With Prognosis

Objective : To investigate the expression of P53 protein and microsatellite instability(MSI)in gastric carcinoma,and to explore the clinicopathological features and correlations of microsatellite instability(MSI)and P53 protein in gastric cancer,and to compare the clinicopathological and molecular factors on the impact of prognosis of gastric cancer,and to screen out the factors that really make sense for the prognosis of gastric cancer.Methods: A retrospective method was used to investigate the patients who underwent radical gastrectomy from January 2010 to December 2012.120 patients were screened according to the inclusion criteria and exclusion criteria.Eight of the factors were selected to to determine the independent prognostic factors of long-term survival for gastric cancer after curative resection(gender,age,tumor location,tumor size,histological differentiation,vascular invasion,TNM stage,CEA).Mismatch repair protein(MLH1,PMS2,MSH2,MSH6)and P53 protein expression in tumor tissues of patients with gastric cancer were detected by immunohistochemistry.The MSI-H and P53 expression deletion rate was obtained to evaluate the relationship between the clinical and pathological parameters of patients.Ten factors were identified.The postoperative survival rate was calculated by Kaplan-Meier method.Univariate analysis of prognosis were used by Log-rank method.Multivariable analysis of prognosis was used by Cox proportional hazard regression model.Then the prognostic factors for postoperative patients with gastric cancer were selected.Prognostic indexes(PI)values were calculated by the prognostic index(PI)formula(PI = B1X1 + B2X2 + B3X3...Bk Xk).The patients were divided into three groups: high risk,moderate risk and low risk.The survival rate of the three groups of patients was evaluated by the ROC curve.The prognosis index was used to predict the accuracy of the 5-year survival of gastric cancer patients.Results:1 There were 47 cases(39.2%)of MMRP lacking expression.The absent expression rates of MLH1,PMS2,MSH2 and MSH6 were 19.2%,6.7%,11.7% and 10.8%respectively.The absent expression rates of MLH1 and PSH2,MLH2 and MSH6,and all of proteins were 11.7%,6.7% and 1.6% respectively.Statistical analysis showed that the two were positively correlated.MLH1 was positively correlated with PMS2 expression(rs=0.446,P=0.001),while MSH2 was positively correlated with MSH6 expression(rs=0.373,P= 0.013).2 MLH1 expression was not significantly correlated with gender(P=0.08),age(P=0.69),tumor size(P=0.63),tumor location(P=0.7),tumor differentiation(P=0.8),and CEA(P=0.63)(P>0.05),but was statistically significant with TNM stage(P=0.03),vascular invasion(P=0.02).The earlier stage of TNM staging,MLH1 expression loss rate increased.PMS2 expression was only correlated with TNM(P=0.016),and was not significantly correlated with the factors,such as gender(P=0.794),age(P= 0.93),tumor size(P=0.358),tumor location(P=0.436),tumor differentiation(P=0.856),CEA(P=0.933).MSH2 expression was not significantly correlated with gender(P=0.79),age(P=0.3),tumor differentiation(P=0.514),tumor size(P=0.763),vascular invasion(P=0.592),CEA(P=0.665),but was statistically significant with Tumor location(P=0.036),TNM staging(P=0.016).MSH6 expression was not significantly correlated with age(P=0.689),tumor size(P=0.852),tumor location(P=0.279),tumor differentiation(P=0.787),vascular invasion(P=0.086),but was statistically significant with gender(P=0.044),TNM stage(P=0.011).The loss rate of MSH6 expression in female patients was significantly higher than that in male patients,and the deletion rate of MSH6 was significantly higher in patients with early gastric cancer than in advanced lesions.3 P53 expression P53 expression rate was 51.7%,and P53 overexpression was significantly correlated with histological differentiation(P=0.024),vascular invasion(P=0.01),TNM stage(P=0.02),and the difference was statistically significant meaning(P<0.05).The positive rate of P53 protein expression in poorly differentiated adenocarcinoma was significantly higher than that in well-differentiated adenocarcinoma.The positive rate of P53 protein expression in stage III tumor was significantly higher than that in stage I and stage II tumors.With the tumor invasion of the vessel,P53 expression rate was significantly higher.There was no significant difference in the expression of P53 protein between different sexes(P=0.95)and age(P=0.89)and CEA(P=0.16)(P> 0.05).4 High frequency MSI(MSI-H)expression According to the frequency of mismatch repair protein,120 patients with gastric cancerwere divided into three groups: none of the four mismatched repair proteins were identified as microsatellite stabilization(MSS),only one mismatch repair protein was MSL-L,at least two mismatch repair proteins were identified as MSI-H,27 cases of MSI-H group,20 cases of MSI-L group and 73 cases of MSS group.The positive rate of MSI was 39.2%(47/120),MSI was negatively correlated with P53(rs=0.36,P=0.001),and MSI-H positive rate was 22.5%(27/120).MSI-H was associated with tumor site(P=0.048),TNM staging(P=0.002),vascular invasion(P=0.019)(P <0.05).MSI-H expression in gastric antrum was significantly higher than that in gastric body and gastric cardia,and its expression was significantly correlated with that of TNM stage.The positive rate of MSI-H expression in stage III gastric cancer was significantly lower than that in stage I and stage II tumors.With the increase of local invasion of the vessel,the positive rate of MSI-H expression was gradually decreased.There was no significant difference in MSH-H between gender(P=0.567),age(P=0.861),histological differentiation(P=0.778),tumor size(P=0.523)and CEA(P = 0.38)(P> 0.05).5 Survival analysis.The overall survival rates were 91.7%,70.0% and 56.5% in 120 patients with gastric cancer.The median survival time was 60 months,the median survival time was46.2 months,95% confidence interval(42.816,49.534).Univariate analysis revealed that tumor differentiation(P=0.038),CEA(P=0.048),TNM stage(P= 0.001),P53(P =0.012)and MSI-H(P=0.003)were significantly correlated with the prognosis of gastric cancer.But the factors,such as age(P=0.405),gender(P=0.491),tumor location(P=0.821),Tumor maximal diameter(P=0.622),vascular invasion(P=0.157)had no correlation with survival rates(all P>0.05).Multiva Iiate analysis showed that TNM stage(B=0.826,P=0.018,95% confidence interval 1.152,4.532),P53 protein(B=0.671,P=0.032,95%confidence interval 1.059,3.614)and MSI-H(B=1.007,P=0.028,95% confidence interval 1.121,7.691)were independent prognostic factors of gastric cancer(P <0.05),but not histological differentiation(P=0.064)and CEA(P=0.264).The 1-,3-,5-year survival rates of patients with TNM I / II were 100%,81.6% and 75.4%,respectively.The 1-,3-,5-year survival rates of patients with stage III were 85.9%,59.2% And 43.5%,the difference was statistically significant(X2 =12.107,P = 0.001).The median survival time of patients with stage I / II and stage III was 53.1 months,95% confidence interval was(49.304,56.766),and 41.5 months,95% confidence interval was(36.695,46.199),respectively.The survival rates of 1-,3-and 5-year patients with negative P53-negative gastric cancer were 98.3%,79.3% and 67.2% respectively.The survival rates of 1-,3-and 5-year patients with P53 positive gastric cancer were 85.5%,58.1% and 46.5%,the difference was statistically significant(X2=6.388,P=0.012).The median survival time of patients with P53 negative and P53 positive patients were 51.1 months,95% confidence interval(47.282,54.849),and 41.6 months,95% confidence interval(36.397,49.534),respectively.The 1-,3-,5-year survival rates of MSI-H patients were 98.3%,79.3% and67.2%,respectively.The survival rates of MSI-L/MSS patients with gastric cancer were85.5%,58.1% and 46.5%,respectively,the difference was statistically significant(X2=6.388,P=0.012).The overall survival time of MSI-H and MSI-L/MSS gastric cancer patients was 56.2 months,95% confidence interval was(52.783,59.587),and 43.3months,95% confidence interval(39.234,47.294),respectively.6 Prognostic index(PI)and ROC curve analysis The three prognostic factors(TNM,P53,MSI-H)was assigned to use of its corresponding B value according to the different variables.The prognostic index PI was in the range of 0-2.574.120 patients were divided into 3 groups,low risk group(PI?0.635)a total of 12 cases,the middle risk group(0.635<PI <1.9305)a total 71 cases,high risk group(PI? 1.9305)a total of 37 cases.The median survival time was 46.175months(standard error:1.714,95%confidence interval:42.816,49.534).When it is used as the reference point,the PI sensitivity is 91.7% and the specificity is 40.7%.Univariate analysis revealed the 1-,3-,and 5-year survival rates of PI1 Low risk group were100%,100%,90.9%,the 1-,3-,and 5-year survival rates of PI2 middle risk group were98.6%,78.9%,67.5%,the 1-,3-,and 5-year survival rates of PI3 high risk group were76.3%,39.5%,25.8%.The difference of the three groups were statistically significant by Logrank test(X2 =32.332,P=0.000).The median survival time of PI1 low risk group,PI2 risk group and PI3 high risk group was 58.5 months,95% confidence interval was(55.827,61.264),51.2 months,95% confidence interval was(47.875,54.566),33.2months,95% confidence interval(26.396,39.949),respectively.The cumulative survival rate decreased with the increase of PI value,and the prognostic index(PI)value could reflect the prognosis of the patients.As the prognosis index(PI)value increases,the prognosis becomes worse.The PI sensitivity was 90.9% and the specificity was 40.4%when the mean survival time was 46.75 months.The 5-year survival rate of gastric cancer was analyzed by ROC curve analysis.The area under PI curve was 0.695,the standard error was 0.061,and the 95% confidence interval was(0.576-0.814),P=0.027;The area under the TNM curve is 0.659,the standard error is 0.049,the 95% confidence interval is(0.563-0.775),P=0.003;The area under the MSI-H curve is 0.684,the standard error is0.051,the 95% confidence interval is(0.584-0.784),P=0.004;The area under the P53 curve is 0.627,the standard error is 0.051,the 95% confidence interval is(0.528-0.727),P=0.016.These results indicated that these four indicators were the factors that affected the prognosis of gastric cancer(P <0.05).Conclusion:1 The four mismatched repair proteins are mainly associated with TNM,but have their own characteristics.MLH1 and PMS2,MSH2 and MSH6 are often synergistically expressed or deleted.2 Compared with MSI-L or MSS type,gastric cancer with MSI-H has unique clinical pathologic behavior,which was related with Tumor site,TNM stages,and vascular invasion.P53 overexpression in gastric cancer was significantly correlated with histological differentiation,vascular invasion,TNM staging.MSI and P53 expression were negatively correlated,suggesting that the two involved in the development of different process.MSI-H and P53 were closely related to clinicopathological features,which were useful for predicting the risk and malignant degree of gastric cancer and could be used as a reference index to evaluate the malignant biological behavior and prognosis of gastric cancer.3 TNM stage,MSI-H and P53 were independent prognostic factors for gastric cancer.The prognostic index(PI)can effectively predict the prognosis of patients with gastric cancer.The cumulative 5-year survival rate of patients with gastric cancer decreased with the increase of PI value.To understand the factors that affected the prognosis of gastric cancer contributed to the clinical treatment of patients.