Expression of galectin‐1 in normal human thyroid gland and in differentiated and poorly differentiated thyroid tumors

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Abstract
We previously reported that galectin‐l gene expression increases up to 100‐fold in oncogene‐transformed rat thyroid cells compared with their normal counterparts and that the relative mRNA levels correlate with the degree of malignancy. In the present study we investigated whether galectin‐l is differentially expressed in human thyroid neoplasms, which range from well‐differentiated tumors to undifferentiated ana‐plastic carcinomas. We analyzed 74 human thyroid specimens of neoplastic, hyperproliferative and normal tissues and several tumor cell lines. Galectin‐l mRNA and protein levels were higher in 6 thyroid carcinoma‐derived cell lines than in normal thyroid primary cultures and adenoma cells. Galectin‐l mRNA levels increased in 28/40 papillary carcinomas and in 6/7 anaplastic carcinomas compared with normal or hyperplastic thyroid. Conversely, galectin‐l expression was unaffected in follicular carcinomas and benign adenomas. Immunohistochemi‐cal analysis of normal thyroid and papillary carcinoma sections revealed a higher content of galectin‐l protein in neoplastic follicular cells than in normal cells.