Immunohistochemical localization of Galectin-3 in malignant and benign human thyroid tissue

Background: Galectin-3 is an endogenous beta-galactoside binding lectin with putative roles in development, immunomodulation, transformation and metastasis. The purpose of this study was to analyze galectin-3 expression in a series of human thyroid neoplastic lesions. Methods. A total of 76 cases, including 47 specimens of thyroid malignancies, 14 follicular adenomas and 15 specimens of normal thyroid tissue, were analyzed immunohistochemically using a monoclonal antibody to galectin-3 and avidin-biotin-peroxidase complex (ABC) method. Results: The immunohistochemical staining results showed galectin-3 expression in neoplastic cells of all 20 cases of papillary carcinoma, 11 out of 15 follicular carcinomas, both oxyphilic carcinomas, all 10 anaplastic carcinomas and 5 out of 14 follicular adenomas. Galectin-3 localization was mostly cytoplasmic, but also membraneous or nuclear in some cells. Follicular cells in normal thyroid tissue were negative. Conclusions. The results of this study indicate that galectin-3 gene is expressed at the protein level in most thyroid carcinomas and some adenomas. Galectin-3 expression was not clearlly correlated with histopathological aggressiveness, dedifferentiation state or determination of malignancy of the follicular tumour. The role of galectin-3 in thyroid tumour biology remains to be elucidated.