Mutational analysis of the beta-catenin gene in gastric carcinomas.

Previous studies reported that mutation of the adenomatous polyposis coli (APC) gene was not observed in the majority of gastric cancers. To evaluate the role of the APC/beta-catenin/Tcf pathway, we analyzed mutations in the beta-catenin gene and the accumulation of beta-catenin protein in gastric carcinomas. An interstitial deletion spanning exon 3 of the beta-catenin gene was observed in 1 of 13 gastric cancer cell lines. No missense mutation was found in these 13 cell lines. Nuclear and/or cytoplasmic localization of beta-catenin was observed in 16 of 70 primary gastric carcinomas by immunohistochemistry, while we found no mutations in exon 3 in 35 carcinoma tissues available for PCR amplification. Our findings suggest that somatic mutations of the beta-catenin gene are rare in human gastric carcinomas and that accumulation of normal beta-catenin protein in a subset of gastric cancers may be due to other mechanisms of its activation.