Age-related methylation in normal colon mucosa differs between the proximal and distal colon in patients who underwent colonoscopy

Objectives: To examine the difference in the methylation status ill normal colon mucosa between the proximal and distal colon. in relation to the correlation between the methylation status of normal mucosa and characteristics of neoplasia. Design and methods: Paired biopsy specimens of normal mucosa from the proximal and distal colon of 82 patients who underwent colonoscopy were obtained. The methylation status of the promoter region of estrogen receptor 1 (ESR1) and myogenic differentiation 1 (MYOD1) was examined. Results: Normal mucosa was more highly methylated ill the distal than in the proximal colon in both ESR1 and MYOD1 loci (p<0.0001 and p = 0.0009, respectively). Advanced characteristics of polyps in the distal colon were frequently observed in patients with lower methylation of ESR1 in the distal colon normal mucosa. Conclusions: Methylation levels in normal mucosa differ between the proximal and distal colon, and lower methylation of ESR1 in the distal colon normal mucosa may correlate with advanced features of neoplasia in the distal colon. (c) 2008 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.