Activated BRAF Targets Proximal Colon Tumors with Mismatch Repair Deficiency and MLH1 Inactivation

Enric Domingo, Eloi Espín, Manel Armengol, Carla Oliveira, Mafalda Pinto, Alex Duval, Caroline Brennetot, Raquel Seruca, Richard Hamelin, Hiroyuki Yamamoto, Simó Schwartz*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

89 Citations (Scopus)


BRAF, a serine/threonine kinase of the RAF family, is a downstream transducer of the RAS-regulated MAPK pathway and signals upstream of MEK1/2 kinases. Recently, activating mutations within BRAF have been reported in a high percentage of melanomas and colorectal carcinomas and shown to have oncogenic capabilities. Further, their association to mismatch-repair-deficient tumors has suggested the involvement of the RAS/RAF pathway in the tumorigenesis of microsatellite-unstable colon cancers, and that RAS and RAF mutations are alternative genetic events. We determined whether colorectal mismatch-repair-deficient tumors with BRAF mutations show a specific genotype when compared with tumors with wild-type BRAF, and whether they can be associated with a particular clinicopathological feature. Here, we report a striking association of BRAF, but not of APC, KRAS2, AXIN2, and TP53 mutations, with proximal mismatch-repair-deficient colon tumors and MLH1 hypermethylation. Our results support the hypothesis that proximal and distal colorectal tumors with mismatch repair deficiency harbor different genetic alterations, and we suggest that the involvement of the RAS/RAF pathway in colorectal tumorigenesis is differentially modulated according to tumor location and MLH1 inactivation.

Original languageEnglish
Pages (from-to)138-142
Number of pages5
JournalGenes Chromosomes and Cancer
Issue number2
Publication statusPublished - Feb 2004


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