Patterns of β-Catenin Expression in Gastric Carcinoma: Clinicopathological Relevance and Mutation Analysis

Abstract
Studies on the expression of β-catenin (β-ct) in gastric carcinoma have provided conflicting results, and the role played by β-ct mutations in gastric carcinogenesis remains unclear. In an attempt to clarify the aforementioned issues we undertook the retrospective study of 157 gastric carcinomas by using immunohistochemistry and molecular genetics. Reduced/absent membranous β-ct expression was significantly associated with isolated-cell/diffuse histotype both in “pure” diffuse gastric carcinomas and in the isolated-cell/diffuse component of mixed carcinomas. Cytoplasmic and/or nuclear β-ct expression was particularly prevalent in mixed carcinomas and was significantly associated with lymphatic vessel invasion and lymph node metastases. β-ct mutations were not detected in any case. We conclude that the pattern of β-ct expression is closely related to gastric carcinoma histotype. The activation of Wnt/β-ct pathway is associated with mixed gastric carcinoma and with features of clinical aggressiveness; the mechanism(s) underlying this pathway in gastric carcinoma are not due to β-ct mutations and remain to be elucidated.