title: Epidermal growth factor-binding sites, present in normal human and rat pituitaries, are absent in human pituitary adenomas.
abstract: To investigate the involvement of epidermal growth factor (EGF) and its receptor in the pathogenesis of human pituitary adenomas, we examined the presence of EGF-binding sites in normal rat and human pituitaries and in human PRL- and GH-secreting and nonsecreting pituitary adenomas. Using crude membrane preparations, specific binding for [125I] EGF was found in normal rat and human pituitaries. Equilibrium was reached at 25 C in 40 min. There was no change in the Kd values between male rats [Kd, 0.65 +/- 0.35 nM (mean +/- SD)] and female rats (Kd, 0.51 +/- 0.15 nM), while the maximum capacity was significantly higher (P less than 0.05) in male rats (21 +/- 8 fmol/mg protein) than in female rats (10 +/- 2 fmol/mg protein). Scatchard analysis of the data suggested the presence of a single class of binding sites. In the three normal human pituitaries tested, specific [125I]EGF binding was also demonstrated. However, both the Kd and the maximum capacity varied widely. Twenty-two human pituitary adenomas were tested, but no specific binding was detected in any of them. In addition to the binding experiments, a radioreceptor assay using rat liver membranes was developed to detect EGF or EGF-like material in extracts of six human pituitary adenomas (two of each type). No EGF activity was detected in any of the extracts. From these results, we conclude that EGF-binding sites are present in normal pituitary tissue, suggesting a physiological role for EGF in this tissue. Consequently, the reason(s) for the lack of EGF binding in pituitary adenoma membranes is not known.
mesh_terms: D000236:Adenoma / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D066246:ErbB Receptors