Binding Sites for Epidermal Growth Factor in Human Uterine Tissues and Leiomyomas

Abstract

There is no published data regarding whether human uterine tissues and leiomyomas contain binding sites for epidermal growth factor (EGF). The present study was undertaken with 33 myometria, 13 leiomyomas, and 4 endometria. All myometria (fundus) and leiomyomas and 3 of 4 endometria specifically bound ¹²⁵I-labeled mouse EGF (myometria: mean, 1.1; range, 0.1–3.9 fmol/mg protein; leiomyomas: mean, 1.1; range, 0.2–2.6 fmol/mg protein; endometria: mean, 1.0; range, 0.0–3.1 fmol/mg protein). [125I]EGF binding to myometrium was ligand specific in that only unlabeled EGF, but not unlabeled insulin, hCG, human PRL, prostaglandin E₁, or prostaglandin F_2α competed with [¹²⁵I]EGF for binding. The apparent dissociation constants and specific binding capacities for myometrium and leiomyoma were: 0.7 nM, 1.9 fmol/mg protein; and 0.1 and 3.7 nM, 0.1 and 4.4 fmol/mg protein, respectively. While smooth muscle content decreased from the fundus to the cervical end of uteri, [¹²⁵I]EGF binding did not correspondingly decrease (r =0.5; n = 4). The binding of [¹²⁵I]EGF to myometrium did not vary with the phase of the menstrual cycle or the patients’ diagnosis before hysterectomy (P < 0.1). In summary, these results demonstrate that human uteri and leiomyomas contain specific, high affinity binding sites for EGF, but the binding neither exhibited topographical changes nor varied with the phase of the menstrual cycle or benign pathological state of the tissue. (</ Clin Endocrinol Metab 58: 880, 1984)(</ Clin Endocrinol Metab 58: 880, 1984)