title: Evaluation of methylation of MGMT (O⁶-methylguanine-DNA methyltransferase) gene promoter in sporadic colorectal cancer.
abstract: The DNA repair gene O⁶-methylguanine-DNA methyltransferase (MGMT) is frequently methylated in colorectal cancer (CRC). The aim of this study was to demonstrate that MGMT methylation may be one of the candidate mediators of field cancerization in the colon mucosa. Therefore, quantitative methylation-specific polymerase chain reaction was performed on tumor itself and additional samples of 5 and 10 cm away from the tumor in 40 CRC patients. Moreover, colon mucosa was examined from 30 cases with no evidence of cancer as a control. MGMT promoter methylation was present in 27.5% of colorectal tumor specimens. Tumors that showed MGMT promoter methylation had substantial MGMT promoter methylation in their normal adjacent mucosa. The methylation was also observed in 36.36% (4/11) of normal samples with MGMT promoter methylation in the adjacent tumors, in 20.79% (6/29) of samples without MGMT methylation in the adjacent tumors, and in 6.66% (2/30) of control samples (p<0.006 and p<0.001 respectively). Finally, the mean of MGMT methylation levels was significantly higher in the cancerous group than in the control group (6.25±1.702 vs. 0.086±0.036, p<0.001). Some CRCs arise from a field defect defined by epigenetic inactivation of MGMT. Detection of such abnormality may ultimately be useful in risk assessment for CRCs.
authors.affiliation: Department of Internal Medicine, Ghaem Hospital, School of Medicine, Mashhad University of Medical Sciences, Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Farzanehfar
authors.forename: Hasan
authors.initials: H
authors.lastname: Vossoughinia
authors.forename: Raheleh
authors.initials: R
authors.lastname: Jabini
authors.forename: Alireza
authors.initials: A
authors.lastname: Tavassoli
authors.forename: Hasan
authors.initials: H
authors.lastname: Saadatnia
authors.forename: Ahmad Khosravi
authors.initials: AK
authors.lastname: Khorashad
authors.forename: Mitra
authors.initials: M
authors.lastname: Ahadi
authors.forename: Monavvar
authors.initials: M
authors.lastname: Afzalaghaee
authors.forename: Ehsan
authors.initials: E
authors.lastname: Ghayoor Karimiani
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Mirzaei
authors.forename: Hossein
authors.initials: H
authors.lastname: Ayatollahi
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000235:genetics*; D004247:DNA / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*
chemical_list: D004247:DNA; D019853:O(6)-Methylguanine-DNA Methyltransferase