The Analysis And Research On The Methylation Status Of The Gingival Cancer PTEN In Promoter Region And Squamous Cell Carcinoma As Well As Prognosis

Objectives To study phosphatase in cancer-the methylation status of PTEN in promoter region and protein expression level,analyze the relation between phosphatase and the gingival cancer cell differentiation degree,lymphatic metastasis and prognosis so as to provide theoretical basis for the targeted therapy of gingival cancer.Methods Take the paraffin specimen of gingival cancer patients admitted to Tangshan Union Hospital from September 2005 to September 2010 as research objects.The criterion to be the research objects: 1,Patients are diagnosed to have gingival cancer by Tangshan Union Hospital and the pathology department;2,Patients have been treated with gingival cancer primary resection by Tangshan Union Hospital and oral and maxillofacial surgery,at the same phase,treat the patient with neck lymph node dissection;3,Patients are with complete follow up data.Randomly pick up 10 cases with high,medium and low differentiation degree(together 30 cases).Select 10 cases with normal gingival tissues beside the gingival cancer from the 30 cases as the control group.Use immunohistochemical method to detect the different expression of PTEN protein in normal gingival and gingival cancer tissues and use methylation characteristics PCR method to detect the methylation status of the PTEN gene promoter region.Count the methylation status of PTEN gene promoter region of such cases and combine with case data and follow up information of the gingival cancer patients;Use Kaplan-Meier method to draw the survival curve and then analyze the correlation between PTEN methylation status and prognosis of gingival cancer.Results 1 Immunohistochemistry: the PTEN expression of the normal gingival group is strong positive expression,with positive rate of 100%;the PTEN expression of the high differentiation group is strong positive expression,with positive rate of 90%;the positive rate of PTEN expression of medium differentiation group is 60%;in the low differentiation group,there are only 2 cases of positive expression with positive expression rate of 20% and others are all negative expression.The statistics result shows statistic significance in difference between different groups.(P<0.05).2MSP: the methylation probability of PTEN gene in gingival cancer tissue is 56.67%,among which the methylation rate of the high differentiation group is 20%,the medium group of 50% and low differentiation group of 100%.The difference between groups has statistical significance(P<0.05).In 17 cases of gingival cancer tissues with PTEN gene methylation,there are 4 cases with PTEN protein positive expression;In 13 cases of non methylated gingival cancer tissues with PTEN genes,there are 13 cases PTEN protein positive expression.The methylation of PTEN gene promoter is relevant to PTEN protein expression(r=-0.765,P<0.05).3 Findings by referring to clinical medical records: there are 12 cases of patients with lymph node metastasis have methylation of PTEN gene promoter,methylation rate is 31.3%;The PTEN methylation rate of patients with lymph node metastasis is obviously higher than that of the patients without lymph node metastasis and the difference has statistical significance(P<0.05).The median tumor free survival time(DFS)and the general survival time(OS)of the PTEN gene promoter methylated patients respectively are 48 months and 56 months,and the DFS and OS time of the non methylated patients respectively are 83 months and 100 months;the difference between the two have statistical significance(P<0.05).Single factor analysis shows that the PTEN methylation,lymph metastasis and cell differentiation degree is relevant to the DFS and OS of thegingival cancer patients(P<0.05).COX prognosis multi-logistic regression analysis indicates that the PTEN methylation,lymph metastasis and cell differentiation degree is relevant to the DFS of gingival cancer patients(P<0.05);Lymph metastasis is relevant to the OS of gingival cancer patients while methylation is not obviously relevant to the OS of patients with gingival cancer(P=0.053).Conclusions 1 The expression level of PTEN protein in gingival cancer is lower that that in normal gingiva.The expression level of PTEN protein in low differentiated gingival cancer is lower that that in the highly differentiated gingival cancer.There is no methylation in normal gingiva while the PTEN methylation is very obvious in gingival cancer.Moreover,the methylation rate for the lowly differentiated gingival group is higher than that of the highly differentiated gingival cancer group.The PTEN gene methylation in the gingival cancer is negatively relevant to PTEN protein expression.2 The PTEN methylation is relevant to the cell differentiation degree and lymph metastasis,besides the PETN methylation rate of the lymph metastasis group is higher than that of the non lymph metastasis group.Single factor analyze that the PTEN methylation,lymph metastasis and cell differentiation degree is the risk factor of the reoccurrence of gingival cancer and survival time;Multi factor analyze that the PTEN methylation and cell differentiation degree is the risk factor for impacting the reoccurrence of gingival cancer and survival time;Lymph metastasis is the independent risk factor which impacts the OS of the patients with gingival cancer while the PTEN methylation is not the risk factor impacting the OS of the patients with gingival cancer.