Background: 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.
Methods: 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.
Results: 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).
Conclusions: The status of expressions for these molecules may affect the degree of lymphoid infiltration while not affecting the degree of invasiveness in thymoma.