Expression of fibroblast growth factor-2 and fibroblast growth factor receptor-1 in thyroid diseases: difference between neoplasms and hyperplastic lesions.

We studied the expression of both fibroblast growth factor-2 (FGF-2) and FGF receptor-1 (FGFR-1) in various histological types of human thyroid neoplastic and hyperplastic tissues to clarify the biological behavior of FGF-2. A total of 37 malignant tumors (24 papillary carcinomas, 10 follicular carcinomas, 3 anaplastic carcinomas), 8 follicular adenomas, and 12 adenomatous goiters were examined by immunohistochemical methods. With immunohistochemical staining, both FGF-2 and FGFR-1 were frequently detected in human thyroid carcinoma (79.2 to 100% and 80 to 100%, respectively). In thyroid hyperplastic lesions such as adenomatous goiter, the FGF-2 immunoreactivity in follicular cells was detected in 2 of 12 adenomatous goiters (16.7%). In contrast, FGFR-1 immunoreactivity was detected in 66.7% of cases of this disease. The endothelial cells of microvessels in the stroma adjacent to the neoplasms and hyperplastic lesions also showed cytoplasmic FGF-2 immunoreactivity. The difference between FGF-2 and FGFR-1 expression in adenomatous goiters was statistically significant (P<0.05). Furthermore, the difference in FGF-2 immunoreactivity between carcinoma and adenomatous goiter was statistically significant (P=0.0001). The present investigation demonstrated the possibility of an autocrine mechanism of action of FGF-2 in human thyroid carcinoma. Moreover, in thyroid hyperplastic lesions, FGF-2 derived from the stroma might be involved in the formation of nodular and/or diffuse goiters.