Galectin-3 and CD44v6 isoforms in the preoperative evaluation of thyroid nodules

Thyroid cancer is the most frequently occurring endocrine malignancy; however, preoperative diagnosis of some lesions, in particular those with follicular histology, is difficult, and a consistent number of not otherwise-specified "follicular nodules" are surgically resected more for diagnosis than therapeutic purposes. In this study, we investigated whether the lectin-related molecules CD44v6 and galectin-3, the expression of which is altered during deregulated cell growth and malignant transformation, could be potential markers for improving the diagnostic accuracy of conventional cytology.

A comparative immuno-chemical and molecular analysis was performed on 157 thyroid specimens representative of normal, benign, and malignant tissues, and on 36 cytologic samples obtained preoperatively by fine-needle aspiration biopsy from nonselected patients with palpable thyroid nodules.

Normal thyrocytes did not express galectin-3 nor CD44v6. Although the expression of CD44v6 isnegligible in thyroiditis, these molecules are variably detected in benign and malignant proliferative lesions. Interestingly, galectin-3 is never expressed in benign lesions, but it is invariably detected in cancers. A comparative evaluation of CD44v6 and galectin-3 expression in thyroid malignancies demonstrated that these molecules are coexpressed at the messenger RNA and protein level in almost all lesions.

Our findings suggest that CD44v6 and galectin-3 could be potential markers to preoperatively identify malignant transformed thyrocytes. Immunodetection of these molecules on cytologic specimens obtained by fine-needle aspiration biopsy is an accurate and improved method for selecting, on a molecular basis, those nodular lesions of the thyroid gland that need to be surgically resected.