title: Effects of the environmental contaminants DEHP and TCDD on estradiol synthesis and aryl hydrocarbon receptor and peroxisome proliferator-activated receptor signalling in the human granulosa cell line KGN.
abstract: Environmental contaminants binding to transcription factors, such as the aryl hydrocarbon receptor (AhR) and the alpha and gamma peroxisome proliferator-activated receptors (PPARs), contribute to adverse effects on the reproductive system. Expressing both the AhR and PPARs, the human granulosa cell line KGN offers the opportunity to investigate the regulatory mechanisms involved in receptor crosstalk, independent of overriding hormonal control. The aim of the present study was to investigate the impact of two environmental contaminants, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an AhR ligand) and di-(2-ethylhexyl) phthalate (DEHP, a PPAR ligand), on gonadotrophin sensitivity and estrogen synthesis in KGN cells. Accumulation of the DEHP metabolite mono-(2-ethylhexyl) phthalate (MEHP) in DEHP-exposed cells was measured by high-performance liquid chromatography mass spectrometry, thereby demonstrating DEHP metabolism to MEHP by KGN cells. By employing TCDD ( an AhR agonist), rosiglitazone (a PPARgamma agonist) or bezafibrate (a PPARalpha agonist), the presence of a functional AhR and PPAR cascade was confirmed in KGN cells. Cytotoxicity testing revealed no effect on KGN cell proliferation for the concentrations of TCDD and DEHP used in the current study. FSH-stimulated cells were exposed to TCDD, DEHP or a mix of both and estradiol synthesis was measured by enzyme-linked immunosorbent assay and gene expression by quantitative RT-PCR. Exposure decreased estradiol synthesis (TCDD, DEHP, mix) and reduced the mRNA expression of CYP19 aromatase (DEHP, mix) and FSHR (DEHP). DEHP induced the expression of the alpha and gamma PPARs and AhR, an effect which was inhibited by selective PPAR antagonists. Studies in the human granulosa cell line KGN show that the action of endocrine-disrupting chemicals may be due to a direct activation of AhR, for example by TCDD, and by a transactivation via PPARs, for example by DEHP, inducing subsequent transcriptional changes with a broad range of effects on granulosa cell function.
authors.affiliation: Department of Anatomy and Cell Biology, Martin Luther University Faculty of Medicine, Grosse Steinstrasse 52, Halle(Saale) D-06097, Germany jana.ernst@medizin.uni-halle.de.
authors.forename: Jana
authors.initials: J
authors.lastname: Ernst
authors.affiliation: Department of Anatomy and Cell Biology, Martin Luther University Faculty of Medicine, Grosse Steinstrasse 52, Halle(Saale) D-06097, Germany.
authors.forename: Johann-Christoph
authors.initials: JC
authors.lastname: Jann
authors.affiliation: Department of Clinical Chemistry and Pathobiochemistry, Otto-von-Guericke-University, Leipziger Strasse 44, Magdeburg D-39120, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Biemann
authors.affiliation: Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University Bochum (IPA), Bürkle-de-la-Camp-Platz 1, Bochum D-44789, Germany.
authors.forename: Holger M
authors.initials: HM
authors.lastname: Koch
authors.affiliation: Department of Anatomy and Cell Biology, Martin Luther University Faculty of Medicine, Grosse Steinstrasse 52, Halle(Saale) D-06097, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Fischer
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D001629:Bezafibrate / Q000494:pharmacology; D001711:Biotransformation; D049109:Cell Proliferation / Q000187:drug effects; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D052244:Endocrine Disruptors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004785:Environmental Pollutants / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D047493:PPAR alpha / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D047495:PPAR gamma / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020025:Peroxisome Proliferators / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D010968:Plasticizers / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000494:pharmacology*; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000077154:Rosiglitazone; D015398:Signal Transduction / Q000187:drug effects*; D045162:Thiazolidinediones / Q000494:pharmacology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D001629:Bezafibrate; D004051:Diethylhexyl Phthalate; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D008024:Ligands; D047493:PPAR alpha; D047495:PPAR gamma; D020025:Peroxisome Proliferators; D010968:Plasticizers; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D000077154:Rosiglitazone; D045162:Thiazolidinediones; C111235:AHR protein, human; C016599:mono-(2-ethylhexyl)phthalate
keywords: KGN granulosa cells; aryl hydrocarbon receptor; estradiol; peroxisome proliferator-activated receptor; phthalate diesters