Expression of the Cadherin-Catenin Complex in Well-Differentiated Human Thyroid Neoplastic Tissue

Abstract

E-cadherin is a member of the cadherin family that plays a major role in epithelial integrity and tumorogenesis. Catenins are a group of cytoplasmic proteins that regulate the intracellular anchorage of cadherin and are required for the linkage between cadherin and the actin cytoskeleton. Loss of E-cadherin contributes to the pathogenesis in tumor invasion and gives a poor prognosis. In order to investigate the adhesion property of intercellular junctions in thyroid tumors, expression of alfa- , beta-, and gamma-catenin should also bestudied. A correlation between these molecular markers andmalignancy would be useful as a preoperative diagnostic test for thyroid neoplasms. The expression of E- cadherin, alfa -, beta-, and gamma-catenin were studied in normal and neoplastic thyroid tissue by immunofluorescence microscopy and Western blot analysis. In the normal thyroid and in nodular goiter, and follicular adenoma, staining for E-cadherin, alfa-, beta-, and gamma-catenin was seen mainly at the lateral surface of epithelial cells in the follicle and the presence of these molecules was confirmed by Western blot analysis. Follicular carcinoma tissue stained positive for E-cadherin and alfa-catenin, but the results of beta- and gamma-catenin immunostaining were highly variable, with beta-catenin being absent in most follicular carcinomas (8/ 10) and gamma-catenin being absent in some follicular carcinomas (3/10). These results suggestthat E-cadherin expression was not reduced during the pathogenesis of differentiated thyroid malignancies.Impairment of the cadherin-catenin complex at the celljunction may contribute to the malignant progression of differentiated thyroid neoplastic tissue.