title: No major tumorigenic role for beta-catenin in serrated as opposed to conventional colorectal adenomas.
abstract: Intracellular redistribution of beta-catenin through mutation of the adenomatous polyposis coli (APC) gene has been proposed as an early tumorigenic event in most colorectal tumours. In serrated adenoma (SA), a newly recognised subtype of colorectal adenoma, APC mutations are uncommon, and the contribution of beta-catenin to tumorigenesis remains unclear. We compared intracellular localisation of beta-catenin and presence of mutations in exon 3 of beta-catenin between 45 SAs, with 71 conventional adenomas (CADs), and eight carcinomas invading the submucosa (SCAs). Widespread or focal nuclear beta-catenin expression was demonstrated in 7% of SAs (three out of 45), 61% of CADs (43 out of 71), and 88% of SCAs (seven out of eight). Cytoplasmic immunostaining for beta-catenin was demonstrated in 16% of SAs (seven out of 45), 77% of CADs (55 out of 71), and 88% of SCAs (seven out of eight). No mutation in exon 3 of beta-catenin was found in SAs or SCAs, while 7% of CADs (five out of 71) had beta-catenin mutations. No nuclear or cytoplasmic expression of beta-catenin was observed in the hyperplastic or conventionally adenomatous epithelium of mixed-type SAs. These findings suggest that beta-catenin mutation is unlikely to contribute to the tumorigenesis in SA, and that intracellular localisation of beta-catenin may not be associated with an early event of the tumour progression in most SAs.
authors.affiliation: Second Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Konishi
authors.forename: T
authors.initials: T
authors.lastname: Yamochi
authors.forename: R
authors.initials: R
authors.lastname: Makino
authors.forename: K
authors.initials: K
authors.lastname: Kaneko
authors.forename: T
authors.initials: T
authors.lastname: Shimamura
authors.forename: H
authors.initials: H
authors.lastname: Ota
authors.forename: K
authors.initials: K
authors.lastname: Mitamura
mesh_terms: D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015820:Cadherins; D002471:Cell Transformation, Neoplastic; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics* / Q000494:pharmacology*; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin