title: K-ras mutations and p53 alterations in neoplastic and nonneoplastic lesions associated with longstanding ulcerative colitis.
abstract: We have analyzed K-ras mutations and p53 alterations in 39 tumor and nontumor samples taken from nine patients with longstanding ulcerative colitis and colorectal carcinoma. Two of nine invasive carcinomas contained a K-ras mutation. By a combination of immunohistochemistry and single-strand conformation polymorphism analysis, p53 alterations were found in three of nine carcinomas. Five of 13 dysplastic lesions harbored a mutated K-ras gene, even in the absence of detectable changes in associated invasive tumors. One single focus of dysplastic mucosa harbored concomitant K-ras and p53 gene alterations. In two patients, a K-ras mutation was detected in epithelial lesions considered to be devoid of malignant potential (villous regeneration, active colitis). Our results indicate that: 1) the prevalence of K-ras and p53 genetic alterations found in ulcerative colitis-associated colonic carcinomas appears to be lower than in sporadic carcinomas; 2) K-ras mutations can be detected in dysplasia, villous regeneration, and active colitis and affect a subpopulation of the cells composing the lesions; 3) diverse genetic alterations can be detected in the same patient and the dysplastic lesions can exhibit a different genotype than the carcinomas; and 4) at least part of active colitis and villous regeneration lesions should be considered as preneoplastic in ulcerative colitis.
authors.affiliation: Institut Universitaire de Pathologie, Lausanne, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Chaubert
authors.forename: J
authors.initials: J
authors.lastname: Benhattar
authors.forename: E
authors.initials: E
authors.lastname: Saraga
authors.forename: J
authors.initials: J
authors.lastname: Costa
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D002277:Carcinoma / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D003093:Colitis, Ulcerative / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D015689:Oncogene Protein p21(ras)