Expression of transforming growth factor-beta 1 in thyroid tumor

Transforming growth factor-beta 1 (TGF beta 1) is a potent inhibitor of cell proliferation in vitro, and recent studies demonstrated TGF beta 1 overexpression in several different tumors. The role of TGF beta 1 in hyperplastic and neoplastic thyroid diseases, however, has not been fully explored. This study was aimed at evaluating the expression of TGF beta 1, both at the messenger RNA (mRNA) and protein levels, in normal thyroid and in benign (hyperplastic and adenomatous) and malignant thyroid lesions, and at assessing its clinicopathologic correlates. The results demonstrated significantly increased TGF beta 1 expression (p = 0.0009) in benign and malignant neoplasms, in comparison with nonneoplastic tissues; higher prevalence of TGF beta 1 expression in thyroid carcinomas, as compared with adenomatous thyroids (p = 0.0008) was detected. Furthermore, TGF beta 1 immunoreactivity was consistently correlated with a corresponding expression of mRNA in epithelial cells (p = 0.019). These data suggest that TGF beta 1 is actively involved in thyroid tumorigenesis and that its overexpression in thyroid malignancies is attributable mainly to the actual synthesis by the neoplastic cells. We were unable, however, to document any correlation between TGF beta 1 expression and thyroid tumor progression, which makes unlikely an adverse effect of TGF beta 1 on the prognosis of thyroid carcinoma patients.