Galectin-3: A promising marker of thyroid malignancy

Background: Galectin-3 is an endogenous beta-galactoside binding lectin implicated in neoplastic transformation and tumor progression. High levels of this lectin have recently been found in malignant thyroid tumors, but not in normal or benign thyroid tissue, suggesting galectin-3 as a promising presurgical marker of thyroid malignancy. Methods: We analyzed immunohistochemically galectin-3 expression in thyroid tissue using a monoclonal antibody. The total of 108 tissue specimens included 55 cases of thyroid carcinoma (30 papillary, 15 follicular, and 10 anaplastic type), 15 samples of follicular adenoma, 15 samples of normal thyroid tissue, and 23 thyroid tissue specimens from human fetuses (16 to 37 weeks of intrauterine life). Results: The results showed galectin-3 expression in 20/30 papillary carcinomas, 11/15 follicular carcinomas, 10/10 anaplastic carcinomas, and 4/15 follicular adenomas. Thyroid follicular cells in normal adult and fetal tissue were negative. Conclusions: These results further confirm that galectin-3 expression is a feature of malignant thyroid cells, and that immunohistochemical detection of galectin-3 could be useful in thyroid carcinoma diagnostics. The absence of galectin-3 in thyroid cells during fetal development suggests that galectin-3 is expressed de novo during malignant transformation of thyroid epithelium, thus it should not be considered an oncofetal antigen.