Relationship With P27 Expression Of Insulin CIMP Tumors And Its Clinical Significance

Purpose Little is known about the molecular pathogenesis of sporadic insulinomas, and there is a lack of reliable biomarkers to differentiate benign from malignant tumors. Thus we analysed the CpG island methylator phenotype (CIMP) of multiple genes in sporadic insulinamas, as well as the expression of p27and the relationship between p27and CIMP.Materials and Methods Using Methylation Specific PCR, we examined the methylation status of p16、MLH1、RAR-β、O6-MGMT, THBS1in33insulinomas and20paired pancreatic tissues. The expression of p27was detected by immunohistochemistry staining. The experimental data were correlated with clinical-pathological characteristics, and were analysed by t-test, chi-square test and Fisher’s exact test.Results The incidence of CIMP-High was1/3in insulinomas, higher than its rate in the paired pancreatic tissues, but the difference was not significant (P=0.209). The methylation status of O6-MGMT and p16were ieversely correlated (P=0.003). Compared with the paired pancreaticl tissues, p27was down-regulated in tumours (85%vs.39%, P=0.008). Moreover, the down-regulation of p27was significantly related to the methylation of O6-MGMT (P=0.016). The down-regulation of p27might be related with higher rate of CIMP-High, but the the difference did not reach significance. The experimental data were not significantly associated with clinical-pathological characteristics in this study.Conclusion CIMP-High and p27down-regulation were observed in a subtype of insulinomas, and these molecular alterations may play a role in tumorigenesis of insulinoma.