Epidermal Growth Factor-Binding Sites, Present in Normal Human and Rat Pituitaries, Are Absent in Human Pituitary Adenomas*

To investigate the involvement of epidermal growth factor (EGF) and its receptor in the pathogenesis of human pituitary adenomas, we examined the presence of EGFbinding 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 < 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 speci...