Epigenetic differences in normal colon mucosa of cancer patients suggest altered dietary metabolic pathways.

We have compared DNA methylation in normal colon mucosa between patients with colon cancer and patients without cancer. We identified significant differences in methylation between the two groups at 114 to 874 genes. The majority of the differences are in pathways involved in the metabolism of carbohydrates, lipids, and amino acids. We also compared transcript levels of genes in the insulin signaling pathway. We found that the mucosa of patients with cancer had significantly higher transcript levels of several hormones regulating glucose metabolism and significantly lower transcript levels of a glycolytic enzyme and a key regulator of glucose and lipid homeostasis. These differences suggest that the normal colon mucosa of patients with cancer metabolizes dietary components differently than the colon mucosa of controls. Because the differences identified are present in morphologically normal tissue, they may be diagnostic of colon cancer and/or prognostic of colon cancer susceptibility.