Galectin-3 expression in medullary thyroid carcinoma in relation to tumor progression

BACKGROUND: Galectin-3, a lectin with specificity for beta galactosides, is believed to be implicated in multiple biological processes through interactions with complementary glycoconjugates. Alterations in galectin-3 expression are observed in a variety of human tumors. In thyroid, this lectin has been found to be highly expressed in malignancies of epithelial origin. We analyzed galectin-3 expression in medullary thyroid carcinoma (MTC). MATERIALS AND METHODS: An immunohistochemical study using monoclonal antibody was performed on paraffin sections of twenty cases of sporadic MTC comprising ten cases without and ten cases with lymph node metastases at the time of surgery. RESULTS: Positive cytoplasmic staining for galectin-3 was found in 16/20 cases, but varied in intensity and distribution from weak/focal (7/16) to moderate (7/16) or strong (2/16). Advanced stage of MTC (with lymph node metastases at the time of surgery) showed moderate to strong galectin-3 expression more frequently (8/10) than cases without lymph node metastases (1/10). CONCLUSION: These findings suggest that galectin-3 expression is associated with the advanced stage of disease and that this lection might play a role in the pathobiology of MTC.