Expression of transforming growth factor-beta 1 in thyroid tumors

Transforming growth factor-beta 1 (TGF beta 1) is a potent inhibitor of cel l proliferation in vitro, and recent studies demonstrated TGF beta 1 overex pression in several different tumors. The role of TGF beta 1 in hyperplasti c and neoplastic thyroid diseases, however, has not been fully explored. Th is 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 (h yperplastic and adenomatous) and malignant thyroid lesions, and at assessin g its clinicopathologic correlates. The results demonstrated significantly increased TGF beta 1 expression (p = 0.0009) in benign and malignant neopla sms, in comparison with nonneoplastic tissues; higher prevalence of TGF bet a 1 expression in thyroid carcinomas, as compared with adenomatous thyroids (p = 0.0008) was detected. Furthermore, TGF beta 1 immunoreactivity was co nsistently 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 malignanci es is attributable mainly to the actual synthesis by the neoplastic cells. We were unable, however, to document any correlation between TGF beta 1 exp ression and thyroid tumor progression, which makes unlikely an adverse effe ct of TGF beta 1 on the prognosis of thyroid carcinoma patients.