Reduced expression of p27 and the occurrence of CpG island methylator phenotype in insulinomas

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Introduction: The molecular pathogenesis of sporadic insulinoma is unclear, though some of the genes were found to be slienced by promoter methylation. CpG island methylator phenotype (CIMP) was found in a number of common tumors and correlated with loss of expression of p27, which may contribute to the tumorigenesis of the tumors.

Aim(s): To detect the occurrence of CpG island methylator phenotype (CIMP) and expression of p27 in sporadic insulinomas, and to analyze the relationship between p27 expression and CIMP.

Materials and methods: Using methylation specific PCR (MSP), we examined the methylation status of p16, MLH1, RAR-β, O6-MGMT, and THBS1 in 33 insulinomas and 20 paired pancreatic tissues. CIMP-high was defined as 4 or 5 of five genes shown with promoter methylation. The expression of p27 was detected by immunohistochemistry staining. The data were correlated with clinical-pathological characteristics such as tumor malignancy, size, and location. Student t-test and Fisher's exact test were used for statistical analysis.

Conference: 7th Annual ENETSConcerence (2010)

Presenting Author: Chen Y

Authors: Chen Y, Zhou Q, Xiao Y, Zhu Y, Liu T,

Keywords: insulinoma, p27 gene, promoter methylation, CpG island methylator phenotype ,