Epigenome analysis of normal colon mucosa samples

To investigate whether lifestyle factors modulate the stability of gene promoter methylation in the normal aging colonic mucosa, we performed genome-scale DNA methylation profiling of 178 normal colon biopsies using the Illumina Infinium DNA methylation assay, which assesses the DNA methylation status of 27,578 CpG sites located at the promoter regions of 14,495 protein-coding genes. We identified Aspirin use and hormonal replacement therapy (HRT) suppress, whereas a high body mass index (BMI) and smoking promote age-related hyermethylation. Many of these loci modulated by lifestyle in the healthy colon mucosa coincide with loci hypermethylated in colorectal cancers and down-regulated in adenomas. The data show that lifestyle modulates the stability of DNA methylation in the aging colonic epithelium and thereby impacts the rate of evolution of cancer methylomes. Bisulphite converted DNA from the 178 samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip v1.2