Assessment of CTNNB1 gene mutations and beta-catenin immunoexpression in salivary gland pleomorphic adenomas and adenoid cystic carcinomas.

beta-Catenin exerts multiple functions in several neoplasms, playing a major role in cell signaling and tumor progression. This study analyzed possible CTNNB1 mutations in salivary gland pleomorphic adenomas (PAs) and adenoid cystic carcinomas (ACCs), and determined possible differences in beta-catenin immunoexpression in relation to these mutations, as well as histopathological aspects of these tumors. Twenty-four PAs (15 cell-rich and 9 cell-poor tumors) and 24 ACCs (10 tubular, 8 cribriform, and 6 solid tumors) were selected for the analysis of beta-catenin distribution and cellular localization. Furthermore, beta-catenin expression was evaluated using the H-score scoring system. Mutations in CTNNB1 exon 3 were investigated by the single-strand conformational polymorphism test. Diffuse beta-catenin expression was more frequently observed in ACCs compared to PAs (P = 0.008). No significant difference in beta-catenin cellular localization was observed between these tumors (P = 0.098). Comparisons between PA and ACC cases revealed a higher median H-score in the latter (P = 0.036). Cell-rich PAs exhibited a trend for higher H-score than cell-poor tumors (P = 0.060), whereas lower H-scores were observed in cribriform ACCs when compared to tubular and solid ACCs (P = 0.042). Mutations in CTNNB1 were observed in 6 PAs and 7 ACCs, with no significant difference in H-scores for beta-catenin according to mutation status (P = 0.135). beta-Catenin is important in the pathogenesis of salivary gland PAs and ACCs. In addition, CTNNB1 exon 3 mutations do not seem to significantly influence beta-catenin cytoplasmic/membranous expression or nuclear translocation in these tumors.