EPIDERMAL GROWTH-FACTOR RECEPTOR STATUS IN HYPERPARATHYROIDISM - IMMUNOCYTOCHEMICAL AND IN-SITU HYBRIDIZATION STUDY

The epidermal growth factor receptor (EGFr) family has been increasing ly recognized as an important component in the control of normal cell proliferation and the pathogenesis of cancer. We have studied EGFr exp ression in 104 cases of hyperparathyroidism by immunocytochemistry (IC C) and by in situ hybridization (ISH). Using two different monoclonal antibodies, ICC for EGFr was performed on 66 cryostat sections and 38 wax-embedded parathyroid glands. ISH was performed on 49 of these glan ds using a cocktail of three anti-sense probes to EGFr mRNA and a nons pecific control probe to human HPV-18 virus. Breast and prostate tumor s were employed as positive controls for both ICC and ISH. Controls de monstrated positive EGFr staining. None of the 104 parathyroid glands showed any ICC positivity. ISH displayed positive staining for EGFr mR NA in five of six carcinomas and eight of nine nonrenal hyperplastic g lands. Only 3 of 15 adenomas and 3 of 19 renal hyperplastic glands sho wed positive staining. This difference was statistically significant b etween adenoma and carcinoma (p < 0.05) and between adenoma and nonren al hyperplasia (p < 0.01) (Tukey's multiple comparison test). This stu dy demonstrates that EGFr mRNA is present in parathyroid tumors. Expre ssion in carcinoma and nonrenal hyperplasia is significantly different from adenoma and renal hyperplastic glands. In contrast, ICC failed t o demonstrate EGFr protein expression. These findings suggest that eit her receptor numbers are too low to detect by ICC or there is a failur e of mRNA translation. More studies are needed to establish whether th e EGFr plays a role in the development of parathyroid cancer or hyperp lasia.