Overexpression of c-Ras in hyperplasia and adenomas of the feline thyroid gland: An immunohistochemical analysis of 34 cases

Formalin-fixed, paraffin-embedded thyroid glands from 18 cats diagnosed wit h hyperthyroidism were evaluated immunohistochemically for overexpression o f the products of oncogenes c-ras and bc12 and the tumor suppressor gene p5 3. Fourteen thyroid glands from euthyroid cats without histologically detec table thyroid lesions were examined similarly as controls. Results from the se investigations showed that all cases of nodular follicular hyperplasia/a denomas stained positively for overexpression of c-Ras protein using a mous e monoclonal anti-human pan-Ras antibody. The most intensely positively sta ining regions were in luminal cells surrounding abortive follicles. Subjace nt thyroid and parathyroid glands from euthyroid cats did not stain immunoh istochemically for pan-Pas. There was no detectable staining for either Bcl 2 or p53 in any of the cats. These results indicated that overexpression of c-ras was highly associated with areas of nodular follicular hyperplasia/a denomas of feline thyroid glands, and mutations in this oncogene may play a role in the etiopathogenesis of hyperthyroidism in cats.