Expression status of E-cadherin and alpha-, beta-, and gamma-catenins in thymoma.

A loss or dysfunction of E-cadherin or catenins, which maintain tissue integrity, is associated with an invasive phenotype of various solid tumors. Therefore, we analyzed the expression of E-cadherin and alpha-catenin, beta-catenin, and gamma-catenin in thymoma tissue specimens to investigate its clinical significance. The expressions of E-cadherin and alpha-catenin, beta-catenin, and gamma-catenin in thymoma tissues were evaluated in 21 patients, including 9 epithelial predominant type, 5 lymphocytic predominant type, and 7 mixed type patients based on an immunohistochemical analysis using monoclonal antibodies, and the relationship between the expression status and clinicopathologic features was investigated. Reduced expressions were observed in 11 patients (52%) for E-cadherin, 10 (45%) for alpha-catenin, 6 (27%) for beta-catenin, and 10 (45%) for gamma-catenin. Such an expression status (reduced or preserved) of the molecules closely correlated with each other. The expression of E-cadherin was well preserved in 5 of 5 patients with lymphocyte predominant type whereas E-cadherin was reduced in 11 of 17 patients with other histologic subtypes. All of the 9 cortex type thymomas (B1 to 3) showed preserved expression of beta-catenin. There was no significant relationship among the expressions of the molecules and the Masaoka stage classification (I versus others). The status of expressions for these molecules may affect the degree of lymphoid infiltration while not affecting the degree of invasiveness in thymoma.