1, Alphα-internexin Insulin Malignant From Benign Tumors And Prognosis Of Two Transcription Factors MafA And PDX-1 Tumor Cells To Synthesize Insulin And Insulin Relationships

Purpose The aim of the study is to identify the expression of a-internexin in insulinomas and the regulatory mechanism; and to explore whether a-internexin can be used as a molecular marker for the identification of insulinomas in benign and malignant and to predict the prognosis.Methods Use immunohistochemical staining to test the expression of the a-internexin in165insulinomas,102of whom were followed up. The data were correlated with clinical-pathological characteristics, to find the relation between the expression of a-internexin and prognosis of insulinomas. Methylation of gene promoter in tumors was quantitatively measured by DHPLC.Results a-internexin was expressed in73.9%of165insulinomas, but none of109paired tissues (P=1.86×10-33). The expression of a-internexin was found in75.3%of145benign tumors, but7of20malignant tumors (P=2.32×10-5). The lower rate of a-internexin expression is significantly correlated with the metastatic tumors (78.8%vs.35.3%, P=3.94×10-4),and also with the worse prognosis(78.8%vs.35.3%, P=3.94×10-4). Moreover, the lower experession of a-internexin also is found in people much older or with tumors in the head of the pancreas(P=0.04,0.015), but no difference between male and female, bigger tumors and smaller tumors. Kaplan-Meier analysis showed that patients whose tumors did not express a-internexin had shorter overall survival time and disease-free survival time compared to those whose tumors expressed a-internexin (P=0.053,0.016).However, COX analysis showed that a-internexin was not a independent prognostic indicator of patients with insulinomas. The hypomethylation of a-internexin promoter(-149-+113) is remarkable correlated with the protein expression(P=0.008).Conclusion a-internexin may be a new biomarker to disguish the benign from the malignant in insulinomas, but not very useful to predict the prognosis. The methylation of a-internexin promoter is the molecular mechanism to regulate the expression of a-internexin in insulinomas. Purpose To test the expression of MafA and PDX-1in insulinomas, and to find the relationship between the two thranscription fators and insulin synthesis in insulinomas.Methods Use immunohistochemical staining to test the expression of insulin、 MafA and PDX-1in49insulinomas and30cases of paired peritumoral tissues, five normal pancreatic tissues. We take six non-insulinoma pancreatic endocrine tumors (gastrinoma, glucagon tumor, non-functional pancreatic endocrine tumors, two cases for each) as control, and detected the expression of insulin, MafA and PDX-1as well as their special hormones. Immunofluorescence double staining were used to co-localization the expression of insulin, MafA and PDX-1in cells and got the fluorescence intensity by confocal laser scanning and image analysis. The data were analyzed through Spearman’s rank correlation analysis to find the correlationship between the fluorescence intensity of MafA and insulin, also PDX-1and insulin in tumor cells. Nonparametric test were used to find the difference between the fluorescence intensity of tumor and the peritumoral islets cells. We think P≤0.05as significant different.Results Insulin was expressed in44of49insulinomas(90%), and was not expressed in5. The expression of MafA insulin-positive tumors was found in93%of44insulin-positive tumors, but not in the insulin-negative tumors(P=1.10×10-5). The expression of MafA insulin-positive tumors was found in86%of43insulin-positive tumors, but not in the insulin-negative tumors(P=1.47×10-4). So, there was38tumors with all expression of insulin, MafA, PDX-1, and5tumors with no expression of the three. Two cases of gastrinomas was positive staining for gastrin, and two cases of gluconomas was positive staining for glucagon. No expression of insulin was found in6no-insulinoma PETs, so MafA and PDX-1was, which was a indirect support for the thing that MafA and PDX-1were invovled in the insulin synthesis in insulinomas. MafA was found co-localize with insulin in most tumor cells, peritumoral islets β cells and normal islets β cells by double Immunofluorescence staining and confocal laser scanning. The date show that the fluorescence intensity of MafA and insulin is remarkably correlative (tumor cells:r=0.737, P=2.012×10-200; peritumoral islets β cells:r=0.565, P=8.0×10-49, normal islets β cells:r=0.717, P=1.01×10-42). Similar relationship was found in the fluorescence intensity of PDX-1and insulin, and they were colocalized in tumor cells too(r=0.701, P=9.89×10-45). Moreover, the fluorescence intensity of insulin in tumor cells was significantly lower than in peritumoral islets β cells, but no difference was found about the fluorescence intensity of MafA in two type cells.Conclusion MafA and PDX-1is widly expressed in insulinomas and is closely related to the synthesis of insulin in tumor cells.