| Objective: To investigate the expression of tumor suppression gene PTEN protein and the methylation of promotor region in human gastric cancer ,and compared with paraneoplastic normal gastric tissues, so we explore its biological relationship in gastric cancer.Method: Immunohistochemistry was applied to examine the expression of PTEN protein in 45 cases of human gastric cancer and its corresponding adjacent normal tissues.Methelation specific PCR(MSP) method was applied to examine the PTEN methylation of the promoter region in gastric cancer and its corresponding adjacent normal tissues. So we analysed its relationship with clinical pathological characteristics ,such as histologic type,clinical stage and lymphatic metastasis.Result: 1.Expression of PTEN protein:â‘ positive immunostaining with the antibody was bserved in the eytoplasmofeells.â‘¡The expression rate of PTEN protein in gastric cancer is 42.2 percent (19/45),and 66.7 percent (30/45) in adjacent normal group.The expression rate of PTEN protein in gastric cancer was significant lower than that of the adjacent normal tissues(P<0.05).â‘¢The relationship between the expression of PTEN protein and clinicopathological characteristics in gastric cancer:there was significant difference respectively between highly-moderately differentiated and poorly differentiated group, invasion of serous and no invasion of serous group, lymph node metastasis and no lymph node metastasis group, clinicopathological I+II stage and III+IV stage group(P<0.05).The development of clinicopathological stage,decrease of differentiated degree, increase of invasion and lymph node metastasis lead to the decrease of PTEN protein expression(P<0.05).In addition,there was no relationship between the expression of PTEN protein with patients'age, sex, tumor size and location(P>0.05).2.Methylation of PTEN gene:â‘ The methylation rate of PTEN gene was 40.0 persent in gastric cancer while 2.2 persent in adjacent normal tissues,there was significant difference between gastric cancer and adjacent normal tisssues(.P<0.05);â‘¡The relationship between PTEN gene methylation and its clinicopathological characteristics in gastric cancer: the methylation rate was 60.0 persent in poorly differentiated group while 15.0 persent in highly-moderately differentiatedv group,it was significantly higher than highly-moderately differentiatedv group(P<0.05);in 24 gastric cancer with lympha node metastasis,methylation had taken place in 16 patients,there was significant difference between lympha node metastasis and no lympha node metastasis group in gastric cancer(P<0.05).There was significant difference also between clinicopathological stage I+II and stage III+IV in PTEN methylation positive rate.(P<0.05).3.PTEN protein expression and PTEN gene methylation:4 cases were positive both in PTEN protein expression and gene methylation,and 12 cases were negative.The former was positive while later was negative in 15 cases,and former was negative later was positive in 14 cases.There was significant correlation between the positive rate of PTEN protein expression and gene methylation (Pr=0.331, P<0.05).Conclusion:There was significant relationship between PTEN protein expression and differentiated degree,invation degree,lympha node metastasis and clinicopathological stage;There was also significant relationship between PTEN gene promoter methylation and the incidence of gastric cancer,differentiated degree,lympha node metastasis; There was statistical correlation between them in development of gastric cancer.PTEN can be used as one of the objective indications which can evaluate the biological behavior of gastric cancer. |
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