Galectin-3 expression in various thyroid neoplasms and its possible role in metastasis formation

Galectin-3 is a member of the beta-galactoside-binding protein family that plays an important role in cell-cell adhesion and in cell-matrix interactio n. We have examined the expression of galectin-3 in normal, adenomatous, an d malignant thyroid tissues and also in metastatic lesions. Galectin-3 was rarely expressed in normal thyroid tissue but was abundant in the cytoplasm of the neoplastic lesions. Among neoplastic lesions, galectin-3 was expres sed to a greater extent in follicular carcinomas than in follicular adenoma s and was present in greater amounts: in papillary carcinomas than in folli cular adenomas or carcinomas. Primary lesions of papillary carcinoma with m etastasis contained significantly higher concentrations of galectin-3 than tumors of this type without metastases. However, the expression of galectin -3 was significantly decreased in metastatic lesions in the lymph nodes com pared with their primary lesions. From these results, we assumed that galec tin-3 works in different ways at different stages of thyroid neoplasm proli feration. Among primary tumors, galectin-3 expression is significantly diff erent in 3 histological types. However, the continuity of progression among these tumors is not yet proven. In later stages, decreased expression of g alectin-3 may aid the release of cancer cells from the primary lesions for invasion and metastasis. HUM PATHOL 31:428-433, 2000. Copyright (C) 2000 by W.B. Saunders Company.