Somatic beta-catenin mutation in gastric carcinoma - an infrequent event that is not specific for microsatellite instability

We screened 90 cases of gastric carcinoma (GCA) samples for beta -catenin e xon 3 mutation and assessed its possible relationship with microsatellite i nstability (MSI). Three mutations were detected in two samples, including a single mutation in an intestinal type and double mutations in a diffuse ty pe GCA. One of the mutations found in the diffuse type GCA sample was a non -sense mutation at codon 68 (CAG --> TAG). This novel mutation was predicte d to disrupt the binding of beta -catenin to alpha -catenin and may be rela ted to the diffuse type morphology. The other two mutations were missense m utations involved or related to the GSK-3 beta phosphorylation site, which have been reported previously. No MSI can be demonstrated in the two cases with beta -catenin mutation. Our results suggested that beta -catenin mutat ion was infrequent in GCA and appeared not specific for MSI. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.