DNA Methylation in the Rectal Mucosa Is Associated with Crypt Proliferation and Fecal Short-Chain Fatty Acids
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DNA methylation varies throughout the normal colorectal mucosa and DNA methylation in normal appearing mucosa is associated with serrated and adenomatous neoplasia elsewhere within the colorectum.
The purpose of this study was to measure luminal chemistry, rectal proliferation and mucosal DNA methylation and thus determine whether regional and pathological patterns of DNA methylation could be explained by luminal and epithelial factors.
Twenty healthy subjects had normal rectal mucosal biopsies and a 24-h fecal collection. Rectal biopsies were analyzed for epithelial proliferation (Ki67 immunohistochemistry) and DNA methylation at 17 different markers, including “type A” markers (ESR1, GATA5, HIC1, HPP1, SFRP1), “type C” markers (MGMT, MLH1, CDKN2A, MINT1, MINT2, MINT31, IGF2, CACNA1G, NEUROG1, SOCS1, RUNX3), and LINE-1. Fecal analysis included short-chain fatty acids (SCFA), pH and ammonia. Mean “type A” and CIMP panel methylation Z-scores were calculated.
Rectal proliferation was significantly correlated with methylation at ESR1 (ρ = 0.81, P = 0.003) and GATA5 (ρ = 0.78, P = 0.012). LINE-1 methylation was 71.7 vs. 74.1%, in patients with “low” and “high” fecal total SCFA concentration (defined by the median value), respectively (P = 0.0019). On multivariate linear regression “type A” methylation was independently associated with rectal proliferation (P = 0.001). LINE-1 methylation was directly associated with rectal proliferation (P = 0.038) and total fecal SCFA concentration (P = 0.002), and inversely associated with fecal NH3 concentrations (P = 0.003).
DNA methylation in normal rectal mucosa is associated with crypt proliferation and fecal SCFA concentration. These associations may help to explain regional differences in DNA methylation as well as providing a possible link between the colorectal lumen and carcinogenesis.
KeywordsDNA methylation Epigenetics Colorectal cancer Carcinogenesis
CpG island methylator phenotype
Percent of methylated reference
Thank you to the volunteers that took part in this study. This study was part funded by a National Health and Medical Research Council project grant (442965), National Starch Food Innovation support, a Gastroenterological Society of Australia post-graduate medical scholarship (D.L.W.), the Royal Australasian College of Physicians Cottrell Fellowship (D.L.W.), a Royal Brisbane and Women’s Hospital Foundation Research Grant (V.L.W, D.L.W, B.A.L) and a Queensland Smart State PhD award (D.L.W). This study was funded by a National Health and Medical Research Council project grant (442965), a Gastroenterological Society of Australia post-graduate medical scholarship (D.L.W), the Royal Australasian College of Physicians Cottrell Fellowship (D.L.W.), a Queensland Smart State PhD award (D.L.W), and the Royal Brisbane and Women’s Hospital Foundation.
Conflict of interest statement
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