title: Differences between pulsatile or continuous exposure to melatonin on MCF-7 human breast cancer cell proliferation.
abstract: We studied the different in vitro antiproliferative actions of melatonin on MCF-7 cells, depending on whether the cells are exposed to hormone concentrations which remain constant in culture media (Group I, 10(-9) M; Group II, 10(-11) M melatonin) or varying at 12 h intervals, thus simulating a diurnal rhythm: Group III, 12 h in 10(-9) M melatonin/12 h without melatonin (10(-9) M/0 12/12 h); Group IV, 10(-11) M/0 12/12 h; Group V, 10(-9) M/10(-11) M 12/12 h. After 5 days of culture, cell proliferation appeared significantly inhibited in Groups I and III, but not in Groups II and IV. However, the highest antiproliferative effect was obtained by sequential exposure to 10(-9) M/10(-11) M melatonin (Group V), which mimics the physiological rhythm of serum melatonin concentration.
authors.affiliation: Department of Physiology and Pharmacology, School of Medicine, University of Cantabria, Santander, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Cos
authors.forename: E J
authors.initials: EJ
authors.lastname: Sánchez-Barceló
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002940:Circadian Rhythm; D004334:Drug Administration Schedule; D006801:Humans; D007700:Kinetics; D008550:Melatonin / Q000008:administration & dosage*; D011673:Pulsatile Flow; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D008550:Melatonin