As if one kind of colorectal cancer (CRC) isn’t bad enough, new research has uncovered four DNA methylation-based versions of the insidious disease.
Our So-Cal neighbors, Toshinori Hinoue and Daniel Weisenberger and team over at the USC Epigenome Center cranked out genome-scale DNA methylation profiles for 125 colorectal tumor and 29 normal tissue samples. The profiles were subjected to some serious data crunching which revealed four distinct CRC subtypes:
- The CpG island methylator phenotype-high (CIMP-H) group shows hypermethylation at a large number of cancer related genes.
- CIMP-low (CIMP-L) tumors are hypermethylated at a smaller set of the same cancer genes.
- Group 3 was non-CIMP related, had a high frequency of TP53 mutations and occurs often in the distal colon.
- The fourth set was also non-CIMP, but didn’t show much DNA hypermethylation or mutations of cancer genes and was often found in rectal tumors.
Finding out that there are different types of the same cancer might seem a little like staring blankly at all the different shades of “white” paint at Home Depot, but the new understanding of the CRC epigenetic landscape may eventually lead to better diagnosis and treatment of colorectal tumors.
See the rest of CRC’s aberrant DNA methylation profile at Genome Research, June 2011.