Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants that interact in a complex manner with both the aryl hydrocarbon receptor (AhR) and estrogen receptors (ER). Their potential endocrine-disrupting activities may depend on both inhibitory AhR-ER cross-talk and on AhR-dependent metabolic production of estrogenic PAH metabolites. Here, we analyzed the impact of AhR on estrogen-like effects of PAHs, such as benzo[a]pyrene (BaP), in particular, on control of cell cycle progression/cell proliferation. Using AhR knockout variant of estrogen-sensitive human breast cancer MCF-7 cells (MCF-7 AhRKO cells), we observed that the AhR-dependent control of cytochrome P450 family 1 (CYP1) expression played a major role in formation of estrogenic BaP metabolites, most notably 3-OH-BaP, which contributed to the ER-dependent induction of cell cycle progression/cell proliferation. Both BaP metabolism and the BaP-induced S-phase transition/cell proliferation were inhibited in MCF-7 AhRKO cells, whereas these cells remained sensitive towards both endogenous estrogen 17β-estradiol or hydroxylated BaP metabolites. BaP was found to increase the activity of ER-dependent luciferase reporter gene in wild-type MCF-7 cells; however, unlike its hydroxylated metabolite, BaP failed to stimulate luciferase activity in MCF-7 AhRKO cells. Similarly, estrogen-like effects of other known estrogenic PAHs, such as benz[a]anthracene or 3-methylcholanthrene, were diminished in MCF-7 AhRKO cells. Ectopic expression of human CYP1A1 and CYP1B1 enzymes partly restored both BaP metabolism and its effects on cell proliferation. Taken together, our data suggest that the AhR-dependent metabolism of PAHs contributes significantly to the impact of PAHs on cell proliferation in estrogen-sensitive cells.

• MeSH
• Cell Culture Techniques MeSH
• Cell Cycle drug effects   genetics   MeSH
• Cytochrome P-450 CYP1A1 genetics   metabolism   MeSH
• Cytochrome P-450 CYP1B1 genetics   metabolism   MeSH
• Endocrine Disruptors metabolism   toxicity   MeSH
• Gene Expression drug effects   MeSH
• Genetic Vectors MeSH
• Gene Knockdown Techniques MeSH
• Humans MeSH
• MCF-7 Cells MeSH
• Plasmids MeSH
• Polycyclic Aromatic Hydrocarbons metabolism   toxicity   MeSH
• Cell Proliferation drug effects   genetics   MeSH
• Receptors, Aryl Hydrocarbon genetics   metabolism   MeSH
• Receptors, Estrogen genetics   metabolism   MeSH
• Genes, Reporter MeSH
• Transfection MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• CYP1A1 protein, human MeSH Browser
• CYP1B1 protein, human MeSH Browser
• Cytochrome P-450 CYP1A1 MeSH
• Cytochrome P-450 CYP1B1 MeSH
• Endocrine Disruptors MeSH
• Polycyclic Aromatic Hydrocarbons MeSH
• Receptors, Aryl Hydrocarbon MeSH
• Receptors, Estrogen MeSH

Many studies about endocrine pollution in the aquatic environment reveal changes in the reproduction system of biota. We analysed endocrine activities in two rivers in Southern Germany using three approaches: (1) chemical analyses, (2) in vitro bioassays, and (3) in vivo investigations in fish and snails. Chemical analyses were based on gas chromatography coupled with mass spectrometry. For in vitro analyses of endocrine potentials in water, sediment, and waste water samples, we used the E-screen assay (human breast cancer cells MCF-7) and reporter gene assays (human cell line HeLa-9903 and MDA-kb2). In addition, we performed reproduction tests with the freshwater mudsnail Potamopyrgus antipodarum to analyse water and sediment samples. We exposed juvenile brown trout (Salmo trutta f. fario) to water downstream of a wastewater outfall (Schussen River) or to water from a reference site (Argen River) to investigate the vitellogenin production. Furthermore, two feral fish species, chub (Leuciscus cephalus) and spirlin (Alburnoides bipunctatus), were caught in both rivers to determine their gonadal maturity and the gonadosomatic index. Chemical analyses provided only little information about endocrine active substances, whereas the in vitro assays revealed endocrine potentials in most of the samples. In addition to endocrine potentials, we also observed toxic potentials (E-screen/reproduction test) in waste water samples, which could interfere with and camouflage endocrine effects. The results of our in vivo tests were mostly in line with the results of the in vitro assays and revealed a consistent reproduction-disrupting (reproduction tests) and an occasional endocrine action (vitellogenin levels) in both investigated rivers, with more pronounced effects for the Schussen river (e.g. a lower gonadosomatic index). We were able to show that biological in vitro assays for endocrine potentials in natural stream water reasonably reflect reproduction and endocrine disruption observed in snails and field-exposed fish, respectively.

• MeSH
• Cell Line MeSH
• Water Pollutants, Chemical analysis   MeSH
• Ecotoxicology methods   MeSH
• Endocrine Disruptors analysis   chemistry   MeSH
• Snails MeSH
• Humans MeSH
• Environmental Monitoring methods   MeSH
• Rivers chemistry   MeSH
• Fishes MeSH
• In Vitro Techniques MeSH
• Vitellogenins chemistry   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Germany MeSH
• Names of Substances
• Water Pollutants, Chemical MeSH
• Endocrine Disruptors MeSH
• Vitellogenins MeSH

Changes in pollutant loads in relatively dynamic river sediments, which contain very complex mixtures of compounds, can play a crucial role in the fate and effects of pollutants in fluvial ecosystems. The contamination of sediments by bioactive substances can be sensitively assessed by in vitro bioassays. This is the first study that characterizes detailed short- and long-term changes in concentrations of contaminants with several modes of action in river sediments. One-year long monthly study described seasonal and spatial variability of contamination of sediments in a representative industrialized area by dioxin-like and endocrine disruptive chemicals. There were significant seasonal changes in both antiandrogenic and androgenic as well as dioxin-like potential of river sediments, while there were no general seasonal trends in estrogenicity. Aryl hydrocarbon receptor-dependent potency (dioxin-like potency) expressed as biological TCDD-equivalents (BIOTEQ) was in the range of 0.5-17.7 ng/g, dry mass (dm). The greatest BIOTEQ levels in sediments were observed during winter, particularly at locations downstream of the industrial area. Estrogenicity expressed as estradiol equivalents (EEQ) was in the range of 0.02-3.8 ng/g, dm. Antiandrogenicity was detected in all samples, while androgenic potency in the range of 0.7-16.8 ng/g, dm dihydrotestosterone equivalents (DHT-EQ) was found in only 30 % of samples, most often during autumn, when antiandrogenicity was the least. PAHs were predominant contaminants among analyzed pollutants, responsible, on average, for 13-21 % of BIOTEQ. Longer-term changes in concentrations of BIOTEQ corresponded to seasonal fluctuations, whereas for EEQ, the inter-annual changes at some locations were greater than seasonal variability during 1 year. The inter- as well as intra-annual variability in concentrations of both BIOTEQ and EEQ at individual sites was greater in spring than in autumn which was related to hydrological conditions in the river. This study stresses the importance of river hydrology and its seasonal variations in the design of effective sampling campaigns, as well as in the interpretation of any monitoring results.

• MeSH
• Biological Assay MeSH
• Water Pollutants, Chemical analysis   MeSH
• Water Pollution, Chemical statistics & numerical data   MeSH
• Dioxins analysis   MeSH
• Endocrine Disruptors analysis   MeSH
• Geologic Sediments chemistry   MeSH
• Environmental Monitoring * MeSH
• Polychlorinated Dibenzodioxins analysis   MeSH
• Polycyclic Aromatic Hydrocarbons analysis   MeSH
• Receptors, Aryl Hydrocarbon MeSH
• Rivers chemistry   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Water Pollutants, Chemical MeSH
• Dioxins MeSH
• Endocrine Disruptors MeSH
• Polychlorinated Dibenzodioxins MeSH
• Polycyclic Aromatic Hydrocarbons MeSH
• Receptors, Aryl Hydrocarbon MeSH