Distinct expression patterns of E-cadherin and beta-catenin in signet ring cell carcinoma components of primary pulmonary adenocarcinoma

E-Cadherin and beta-catenin complexes have been suggested to have critical roles in cancer development and progression. Primary signet ring cell carcinoma (SRCC) of the lung is a rare variant of pulmonary adenocarcinoma, and E-cadherin and beta-catenin expressions of this tumor have not been documented, to our knowledge. To characterize the E-cadherin and beta-catenin expressions in SRCC of the lung. An immunohistochemical evaluation of E-cadherin and beta-catenin expressions in 10 cases of SRCC of the lung, 10 cases of conventional pulmonary adenocarcinoma, 10 cases of gastric SRCC, and 10 cases of colorectal SRCC was performed. Membranous E-cadherin and beta-catenin expressions were frequently reduced or absent in all types of tumors tested. Aberrant E-cadherin localization and nuclear beta-catenin accumulation were frequently found in gastric (6/10 and 5/10, respectively) and colorectal (7/10 and 9/ 10, respectively) SRCCs, whereas SRCC of the lung rarely showed aberrant E-cadherin localization (1/10) or nuclear beta-catenin accumulation (0/10). Signet ring cell carcinoma of the lung rarely showed aberrant E-cadherin localization or beta-catenin nuclear accumulation, which are frequent events in gastric and colorectal SRCCs. These results suggest that the biologic roles of E-cadherin and beta-catenin complexes in SRCC of the lung differ from their roles in gastric or colorectal SRCCs.