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Frequent activating GNAS mutations in villous adenoma of the colorectum
Author(s) -
Yamada Masayoshi,
Sekine Shigeki,
Ogawa Reiko,
Taniguchi Hirokazu,
Kushima Ryoji,
Tsuda Hitoshi,
Kanai Yae
Publication year - 2012
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.4012
Subject(s) - gnas complex locus , kras , villous adenoma , hyperplastic polyp , adenoma , mutation , tubular adenoma , pathology , cancer research , biology , medicine , colorectal cancer , colonoscopy , cancer , gene , genetics
To elucidate the role of GNAS mutations in colorectal tumourigenesis, we performed a mutation analysis in a total of 234 colorectal tumours, including adenomas, serrated lesions and adenocarcinomas. Activating GNAS mutations were found in 20 of the 24 villous adenomas (83%) but were absent in all the other tumours, except for one tubulovillous adenoma (3%) and two adenocarcinomas (3%). KRAS and BRAF mutations were always mutually exclusive. KRAS mutations were frequent in villous (67%) and tubulovillous (60%) adenomas but were rare or absent in tubular adenomas (6%) and serrated lesions, including hyperplastic polyps, sessile serrated polyps/sessile serrated lesions and traditional serrated adenomas (0‐9%). BRAF mutations were found in four villous adenomas (17%) and in the large majority of serrated lesions (81‐92%), but were absent in tubular and tubulovillous adenomas. Seventeen villous adenomas (71%) harboured GNAS mutations concomitantly with KRAS or BRAF mutations. Immunohistochemically, all the villous adenomas retained mismatch repair protein expression, suggesting that they are microsatellite‐stable. The current study showed that the presence of activating GNAS mutations, in association with KRAS or BRAF mutations, is a characteristic genetic feature of colorectal villous adenoma. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.