INCREASED EXPRESSION OF INSULIN-LIKE GROWTH-FACTOR-1 (IGF-1) IN MULTINODULAR NON TOXIC GOITER

Thyroid cell growth and function both in vivo and in vitro, are mainly regulated by TSH. Recent studies have shown that growth factors inclu ding insulin-like growth factors (IGF-1) have an important role in the control of thyrocyte proliferation and differentiation. The aim of th is study was to evaluate the expression of the IGF-1 gene by Northern analysis and the IGF-1 tissue protein by radioimmunoassay in multinodu lar euthyroid goiters. The study population consisted of 20 patients w ith multinodular goiter (14 females and 6 males) living in a non endem ic geographic area. All patients were euthyroid at the time of surgery and submitted to total or subtotal thyroidectomy. Samples of normal t hyroid tissue were obtained from three patients who were operated due to laryngeal carcinomas. The IGF-1 protein content was increased in no n toxic multinodular goiter, 22 ng/g vs. 14 in controls (p<0.03), as w as IGF-1 gene expression (p<0.05). The increase in the steady state mR NA content correlated with the increase in the protein content (r=0.66 5; p<0.005). These results suggest that IGF-1 may play a role in proli feration events involved in benign hyperplastic thyroid diseases.