title: Low frequency of promoter methylation of O6-methylguanine DNA methyltransferase and hMLH1 in ulcerative colitis-associated tumors: comparison with sporadic colonic tumors.
abstract: To cast light on the contribution of methylation to genesis of ulcerative colitis (UC)-associated tumors, promoter methylation and expression of O6-methylguanine DNA methyltransferase (MGMT), hMLH1, p16INK4, and E-cadherin were examined in 14 low-grade dysplasias (LGDs), 15 high-grade dysplasias (HGDs), and 14 adenocarcinomas associated with UC and, for comparison, in 30 sporadic adenomas with LGD, 30 adenomas with HGD, and 60 adenocarcinomas, using methylation-specific polymerase chain reaction and immunohistochemical analysis. The frequency of MGMT and hMLH1 methylation in UC-associated tumors was low, with a significant difference between HGD and sporadic adenomas with HGD of the left hemicolon. The methylation frequency of p16INK4 in UC-associated tumors was also relatively low compared with sporadic colonic tumors. For E-cadherin, methylation was limited in both types of tumor. Decrease of expression of MGMT, hMLH1, and p16INK4 was significantly correlated with methylation. Thus, compared with the sporadic type, contribution of methylation to UC-associated tumorigenesis seems to be low.
authors.affiliation: Department of Pathology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Tetuo
authors.initials: T
authors.lastname: Mikami
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Yoshida
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Numata
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shiraishi
authors.forename: Kayo
authors.initials: K
authors.lastname: Araki
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Guiot
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Jass
authors.forename: Isao
authors.initials: I
authors.lastname: Okayasu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003093:Colitis, Ulcerative / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D005787:Gene Frequency; D006801:Humans; D007150:Immunohistochemistry; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015820:Cadherins; D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D019853:O(6)-Methylguanine-DNA Methyltransferase; D000070957:MutL Protein Homolog 1