Transforming growth factor beta 1 (TGF-beta 1) expression in proliferating thyroid disease.

In order to clarify some of the molecular mechanisms involved in the pathogenesis of thyroid proliferating diseases we have investigated the role of TGF-beta in thyroid carcinoma, adenoma and multinodular goiter. TGF-beta 1 expression studies were carried out in surgically removed thyroid tissue isolated from 15 patients affected by multinodular goiter, 4 patients affected by papillary carcinoma and 4 patients affected by follicular adenoma. TGF-beta 1 gene expression, evaluated by Northern analysis, dramatically increased in malignant proliferating thyroid disease and decreased drasticly in multinodular goiter patients with respect to normal thyroid. Immunocytochemical analysis demonstrated that TGF-beta 1 is produced by an autocrine mechanism in the carcinoma and in the benign thyroid disease (multinodular goiter), whereas TGF-beta seems to be produced in adenoma tissues in both an autocrine and a paracrine fashion. This feature further supports the hypothesis that TGF-beta may contribute to regulation of thyrocyte growth and differentiation.