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Decreased expression and promoter methylation of the menin tumor suppressor in pancreatic ductal adenocarcinoma
Author(s) -
Cavallari Ilaria,
SilicBenussi Micol,
Rende Francesca,
Martines Annalisa,
Fogar Paola,
Basso Daniela,
Vella Manuela Della,
Pedrazzoli Sergio,
Herman James G.,
ChiecoBianchi Luigi,
Esposito Giovanni,
Ciminale Vincenzo,
D'Agostino Donna M.
Publication year - 2009
Publication title -
genes, chromosomes and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.754
H-Index - 119
eISSN - 1098-2264
pISSN - 1045-2257
DOI - 10.1002/gcc.20650
Subject(s) - men1 , loss of heterozygosity , cancer research , tumor suppressor gene , biology , dna methylation , ectopic expression , pancreas , methylation , gene silencing , multiple endocrine neoplasia , bisulfite sequencing , carcinogenesis , endocrinology , gene expression , gene , genetics , allele
Loss of menin, a tumor suppressor coded by the MEN1 gene, is a key factor in the pathogenesis of multiple endocrine neoplasia type I and in a percentage of sporadic endocrine tumors of the pancreas and parathyroid glands. This study investigated expression of the menin protein in the normal exocrine pancreas and in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic tumor. Immunofluorescence (IF) analyses showed that menin is expressed at high levels in normal acinar and duct cells. Examination of 24 clinical samples of PDAC revealed a pronounced decrease in menin expression in all tumors examined. To identify alterations underlying this defect, we searched for disruption and epigenetic silencing of the MEN1 gene. Analysis of nine laser‐microdissected tumors revealed loss of heterozygosity of intragenic (one tumor) or adjacent (three tumors) MEN1 microsatellite markers. Methylation of CpG sites in the MEN1 promoter was documented in five of 24 tumors. IF analyses also revealed low to undetectable menin expression in the PDAC cell lines MiaPaCa‐2 and Panc‐1. Ectopic expression of menin in these cells resulted in a marked alteration of the cell cycle, with an increase in the G1/S+G2 ratio. These findings represent the first evidence that the MEN1 gene is a target of mutation and methylation in PDAC and that menin influences the cell cycle profile of duct cells. © 2009 Wiley‐Liss,Inc.