NEW YORK (Reuters Health) - DNA methylation patterns and extent may be indicative of whether certain colorectal hyperplastic polyps are likely to progress to malignancy, Australian researchers report in the April issue of Gut.
Dr. C. V. A. Wynter, of the Queensland Institute of Medical Research, Herston, and colleagues note that hyperplastic polyps have been traditionally regarded as being non-neoplastic.
However, recent data have implicated hyperplastic polyps characterized by extensive DNA methylation and microsatellite stability as being implicated in the pathogenesis of colorectal cancers.
To investigate features that might help identify such subtypes of hyperplastic polyps, the researchers studied 12 surgical colorectal specimens.
The lesions were broadly classified as clustering around a cancer of the distal colon or rectum or fulfilling the criteria for hyperplastic polyposis with or without coexisting colorectal cancer.
Those in the hyperplastic polyposis group showed significantly more methylation than did those in the clustering group at all but one locus. Furthermore, certain of these polyps showed morphological features, described as “sessile serrated adenomas,” which recently have been associated with adenocarcinomas.
“In summary, the findings lend support to the concept of a serrated pathway to colorectal cancer in which DNA methylation plays an important role. However, only a subset of serrated polyps is implicated.”
Similar lesions, lacking methylation, but showing a high frequency of K-ras mutation, they hypothesize, may also be precursors of certain colorectal cancers.
Source: Gut 2004;53:573-580. [ Google search on this article ]
MeSH Headings:Alkylation: Biological Sciences: Biology: Chemistry: Chemistry, Organic: Colonic Diseases: Digestive System Neoplasms: Gastrointestinal Neoplasms: Genetics: Genetics, Biochemical: Intestinal Neoplasms: Intestinal Polyps: Methylation: Molecular Biology: Neoplasms: Neoplasms by Site: Physical Sciences: Colorectal Neoplasms: DNA Methylation: Biological Sciences: Diseases: Physical SciencesCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.