Distinct microbes, metabolites, and ecologies define the microbiome in deficient and proficient mismatch repair colorectal cancers.
Hale VL, Jeraldo P, Chen J, Mundy M, Yao J, Priya S, Keeney G, Lyke K, Ridlon J, White BA, French AJ, Thibodeau SN, Diener C, Resendis-Antonio O, Gransee J, Dutta T, Petterson XM, Sung J, Blekhman R, Boardman L, Larson D, Nelson H, Chia N
Genome Med. Oct 2018. doi: 10.1186/s13073-018-0586-6
COMMENT: Several studies have analyzed the differences in the microbial communities from colorectal cancers (CRC) and proved the importance of the microbiome in the CRC pathogenesis and prognosis. Up to date, the main factors found to have an influence on the microbial communities have been the location of the community: distal or proximal, on or off tumor; whether the tumor is microsatellite instable (MSI) or stable (MSS) and the tumor molecular subtypes.
In this article, the authors remark the relation of the status of the mismatch repair machinery (MMR), whether the tumor is mismatch repair deficient (dMMR) or proficient (pMMR), with the microbial communities found in the tumor. By means of 16S metagenomics analysis and metabolomics of samples taken from the tumor site and adjacent normal sites, the authors find that the MMR factor is the strongest predictor of the microbiome variance in the tumor.
Particularly they find a much higher hydrogen sulfide production in dMMR tumors and a strong repression of Bacteroides fragilis in pMMR.