title: In vitro modulation of prolactin binding to human mammary carcinoma cells by steroid hormones and prolactin.
abstract: This study demonstrates the specific binding of human (h) PRL to mammary carcinoma cells of the newly established line EFM-19. Under saturating conditions, [125I]hPRL bound to these cells with high affinity (Ka = 4.3 X 10(10) M-1) and low capacity (4080 binding sites/cell). In serum-free medium, stimulation of cell proliferation by PRL was found, suggesting a biological role in the growth of human breast cancer. hPRL was more effective in binding to and promoting the growth of EFM-19 cells than ovine PRL or other lactogenic hormones. Up- and down-regulation of [125I]hPRL binding occurred after pretreatment of EFM-19 cell cultures with subphysiological or higher hPRL concentrations, respectively. Physiological concentrations of 17 beta-estradiol or dihydrotestosterone increased the cellular capacity of hPRL binding. Pharmacological concentrations of dihydrotestosterone or physiological concentrations of progesterone reduced the binding of [125I]hPRL. The results provide evidence for complex regulatory mechanisms of PRL binding by human mammary carcinoma cells involving steroid hormones.
authors.forename: W E
authors.initials: WE
authors.lastname: Simon
authors.forename: V G
authors.initials: VG
authors.lastname: Pahnke
authors.forename: F
authors.initials: F
authors.lastname: Hölzel
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D013196:Dihydrotestosterone; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006801:Humans; D007700:Kinetics; D008938:Mitosis / Q000187:drug effects; D011388:Prolactin / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects*; D011981:Receptors, Prolactin
chemical_list: D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D013196:Dihydrotestosterone; D004958:Estradiol; D011388:Prolactin