Hydroxylated polychlorinated biphenyl metabolites are anti-estrogenic in a stably transfected human breast adenocarcinoma (MCF7) cell line.
Hydroxylated metabolites of polychlorinated biphenyls (OHCBs) have been identified in blood of marine mammals, fish-eating birds, and humans at concentrations in some cases exceeding those of the unmetabolized polychlorinated biphenyls (PCBs). OHCBs have been associated with inhibition of vitamin A and thyroxin transport, estrogenicity in a mouse uterotrophic assay, and feminization of male turtle sexual development. OHCBs, representing both environmentally derived and laboratory exposure-derived metabolites, were tested in an in vitro bioassay utilizing an estrogen-responsive human breast adenocarcinoma cell line (MCF7-LUC) stably transfected with a luciferase reporter gene linked to estrogen responsive elements. OHCB activity was tested at three different media concentrations of 17beta-estradiol (E2), comparing the concentration-response curves using charcoal-stripped medium (0.0009 nM E2), and two physiologically relevant E2 concentrations (0.1 and 1.0 nM E2). Eleven of 13 OHCBs tested were anti-estrogenic. Evidence for an estrogen receptor mediated mechanism of action was apparent for only two OHCBs-4-OH-2',3,3',4',5,5'-Cl6-biphenyl and 4,4'-(OH)2-3,3',5,5'-Cl4-biphenyl. These two have not been identified in environmental samples. The remaining OHCBs exhibited "anti-estrogenicity" that was related to their effect on cell viability and, therefore, cannot be described as exhibiting "hormone disruption" solely by an estrogen receptor mediated mechanism. OHCB anti-estrogenic activity was eliminated in the presence of E2 concentrations normally found in humans, except for 4,4'(OH)2-3,3',5,5'-Cl4-biphenyl. 4-OH-2',3',4',5'-Cl4-biphenyl and 4-OH-2',4',6'-Cl3-biphenyl were partial estrogen agonists, exhibiting weak estrogenicity in the presence of 0.0009 nM E2 and weak anti-estrogenicity in the presence of 0.1 and 1 nM E2. Human metabolites of PCBs were not estrogenic in MCF7 cells.
Kramer
V J
VJ
Pesticide Research Center and Department of Fisheries and Wildlife, Institute of Environmental Toxicology, Michigan State University, East Lansing 48824-1222, USA. rahvjk@rohmhaas.com
Helferich
W G
WG
Bergman
A
A
Klasson-Wehler
E
E
Giesy
J P
JP
D000230:Adenocarcinoma / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001943:Breast Neoplasms / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000633:toxicity*; D005260:Female; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis / Q000187:drug effects; D008297:Male; D051379:Mice; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D011960:Receptors, Estrogen / Q000378:metabolism; D018570:Risk Assessment; D013329:Structure-Activity Relationship; D014162:Transfection; D014407:Tumor Cells, Cultured
D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D004958:Estradiol; D011078:Polychlorinated Biphenyls; D008156:Luciferases