title: Transient inhibition of synergistically insulin-like growth factor-1- and bisphenol A-induced poliferation of estrogen receptor alpha (ERalpha)-positive human breast cancer MCF-7 cells by melatonin.
abstract: There are many subclones of human breast cancer MCF-7 cells that respond to different levels of estrogen and that have been used for evaluating the estrogenic potential of environmental chemicals such as bisphenol A. In this study, I examined the effects of melatonin, an endogenous growth-inhibitory hormone, on the bisphenol A-induced proliferation of an MCF-7 subclone, designated as MCF-7-EMF cells. MCF-7-EMF cell growth was extremely slow in the presence of either estrogen at 10(-7) M or bisphenol A at 10(-7) M in a phenol-red-free medium and 10% charcoal-stripped fetal bovine serum. It was difficult to detect the increment of BrdU incorporation in MCF-7-EMF cells (2x10(4) cells) upon exposure to 10(-7) M bisphenol A alone for up to 50 h. The same result was obtained with cells exposed to 10 ng/ml insulin-like growth factor-1 (IGF-1) alone for up to 50 h. However, in the presence of 10 ng/ml IGF-1, bisphenol A markedly increased cell proliferation. The synergistic response was transiently inhibited by 10(-10) M melatonin (p<0.05). Thus, melatonin caused a transient inhibition of cell growth of estrogen receptor alpha (ERalpha)-positive MCF-7-EMF cells induced synergistically by both IGF-1 and bisphenol A.
authors.affiliation: Endocrine Disruptors and Dioxin Research Projects, National Institute for Environmental Studies, Tsukuba 305-8506, Japan. ishidou@nies.go.jp
authors.forename: Masami
authors.initials: M
authors.lastname: Ishido
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001559:Benzhydryl Compounds; D001943:Breast Neoplasms / Q000473:pathology*; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D047628:Estrogen Receptor alpha / Q000502:physiology*; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008550:Melatonin / Q000494:pharmacology*; D010636:Phenols / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D000098826:Bisphenol A Compounds
chemical_list: D000975:Antioxidants; D001559:Benzhydryl Compounds; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal; D007334:Insulin-Like Growth Factor I; D008550:Melatonin; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds