Expression of fibroblast growth factors in thyroid cancer.

We have examined immunoreactive fibroblast growth factor-1 (FGF-1) and FGF-2 in thyroid sections from normal tissue, follicular adenoma, differentiated follicular and papillary carcinoma, and anaplastic carcinoma. Polyclonal primary antibodies (Dr. A. Baird, Whittier Institute, La Jolla, CA) to FGF-1 and FGF-2 and fluorescein-conjugated secondary antibodies were used with confocal microscopy to allow quantitation and subcellular localization of the antigens. Staining for FGF-1 and FGF-2 was intense in the differentiated malignant tumor specimens, whereas staining in the normal thyroid tissue controls was not detectable above background fluorescence. Staining for FGF-1 and FGF-2 was intracellular and was not found in the nucleus. Staining using either antibody was enhanced in follicular adenomas, but was less intense than that in the malignant tumors. Sections from anaplastic carcinomas also stained positively. In primary cultures of thyroid cells derived from a papillary carcinoma, staining for FGF-2 was 10-fold greater than that from normal thyroid cells from the same patient. The data suggest a possible role for FGFs in the etiology of thyroid carcinoma.