Latest Publications

@article{vyhlidalova_gut_2020,

title = {Gut Microbial Catabolites of Tryptophan Are Ligands and Agonists of the Aryl Hydrocarbon Receptor: A Detailed Characterization.},

author = {Barbora Vyhlídalová and Kristýna Krasulová and Petra Pečinková and Adéla Marcalíková and Radim Vrzal and Lenka Zemánková and Jan Vančo and Zdeněk Trávníček and Jan Vondráček and Martina Karasová and Sridhar Mani and Zdeněk Dvořák},

doi = {10.3390/ijms21072614},

issn = {1422-0067},

year  = {2020},

date = {2020-04-01},

journal = {International journal of molecular sciences},

volume = {21},

number = {7},

abstract = {We examined the effects of gut microbial catabolites of tryptophan on the aryl hydrocarbon receptor (AhR). Using a reporter gene assay, we show that all studied catabolites are low-potency agonists of human AhR. The efficacy of catabolites differed substantially, comprising agonists with no or low (i3-propionate, i3-acetate, i3-lactate, i3-aldehyde), medium (i3-ethanol, i3-acrylate, skatole, tryptamine), and high (indole, i3-acetamide, i3-pyruvate) efficacies. We displayed ligand-selective antagonist activities by i3-pyruvate, i3-aldehyde, indole, skatole, and tryptamine. Ligand binding assay identified low affinity (skatole, i3-pyruvate, and i3-acetamide) and very low affinity (i3-acrylate, i3-ethanol, indole) ligands of the murine AhR. Indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, and i3-acetamide induced CYP1A1 mRNA in intestinal LS180 and HT-29 cells, but not in the AhR-knockout HT-29 variant. We observed a similar CYP1A1 induction pattern in primary human hepatocytes. The most AhR-active catabolites (indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, i3-acetamide) elicited nuclear translocation of the AhR, followed by a formation of AhR-ARNT heterodimer and enhanced binding of the AhR to the CYP1A1 gene promoter. Collectively, we comprehensively characterized the interactions of gut microbial tryptophan catabolites with the AhR, which may expand the current understanding of their potential roles in intestinal health and disease.},

note = {Place: Switzerland},

keywords = {*Gastrointestinal Microbiome/drug effects, Animals, Aryl hydrocarbon receptor, Aryl Hydrocarbon/*agonists/*metabolism, Basic Helix-Loop-Helix Transcription Factors/*agonists/*metabolism, Cell Line, Cytochrome P-450 CYP1A1/genetics, Gene Expression, Genes, Genetic, Humans, Indoles, Ligands, Metabolic Networks and Pathways, Mice, Microbiome, Promoter Regions, Protein Binding, Protein Multimerization, Receptors, Reporter, tryptophan, Tryptophan/*metabolism, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{hyzdalova_aryl_2018,

title = {Aryl Hydrocarbon Receptor-Dependent Metabolism Plays a Significant Role in Estrogen-Like Effects of Polycyclic Aromatic Hydrocarbons on Cell Proliferation.},

author = {Martina Hýžd'alová and Jakub Pivnicka and Ondrej Zapletal and Gerardo Vázquez-Gómez and Jason Matthews and Jirí Neca and Katerina Pencíková and Miroslav Machala and Jan Vondrácek},

doi = {10.1093/toxsci/kfy153},

issn = {1096-0929 1096-6080},

year  = {2018},

date = {2018-10-01},

journal = {Toxicological sciences : an official journal of the Society of Toxicology},

volume = {165},

number = {2},

pages = {447–461},

abstract = {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.},

note = {Place: United States},

keywords = {Aryl Hydrocarbon/genetics/*metabolism, Cell Culture Techniques, Cell Cycle/drug effects/genetics, Cell Proliferation/*drug effects/genetics, Cytochrome P-450 CYP1A1/genetics/metabolism, Cytochrome P-450 CYP1B1/genetics/metabolism, Endocrine Disruptors/metabolism/*toxicity, Estrogen/genetics/metabolism, Gene Expression/drug effects, Gene Knockdown Techniques, Genes, Genetic Vectors, Humans, MCF-7 Cells, Plasmids, Polycyclic Aromatic Hydrocarbons/metabolism/*toxicity, Receptors, Reporter, Transfection},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_assessment_2017,

title = {Assessment of the aryl hydrocarbon receptor-mediated activities of polycyclic aromatic hydrocarbons in a human cell-based reporter gene assay.},

author = {Jan Vondráček and Kateřina Pěnčíková and Jiří Neča and Miroslav Ciganek and Aneta Grycová and Zdeněk Dvořák and Miroslav Machala},

doi = {10.1016/j.envpol.2016.09.064},

issn = {1873-6424 0269-7491},

year  = {2017},

date = {2017-01-01},

journal = {Environmental pollution (Barking, Essex : 1987)},

volume = {220},

number = {Pt A},

pages = {307–316},

abstract = {Activation of the aryl hydrocarbon receptor (AhR)-mediated activity is one of key events in toxicity of polycyclic aromatic hydrocarbons (PAHs). Although various classes of AhR ligands may differentially activate human and rodent AhR, there is presently a lack of data on the human AhR-inducing relative potencies (REPs) of PAHs. Here, we focused on estimation of the AhR-mediated activities of a large set of environmental PAHs in human gene reporter AZ-AhR cell line, with an aim to develop the human AhR-based REP values with potential implications for risk assessment of PAHs. The previously identified weakly active PAHs mostly failed to activate the AhR in human cells. The order for REPs of individual PAHs in human cells largely corresponded with the available data from rodent-based experimental systems; nevertheless, we identified differences up to one order of magnitude in REP values of PAHs between human and rodent cells. Higher REP values were found in human cells for some important environmental contaminants or suspected carcinogens, such as indeno[1,2,3-cd]pyrene, benz[a]anthracene or benzo[b]fluoranthene, while lower REP values were determined for methyl-substituted PAHs. Our results also indicate that a different rate of metabolism for individual PAHs in human vs. rodent cells may affect estimation of REP values in human cell-based assay, and potentially alter toxicity of some compounds, such as benzofluoranthenes, in humans. We applied the AZ-AhR assay to evaluation of the AhR-mediated activity of complex mixtures of organic compounds associated with diesel exhaust particles, and we identified the polar compounds present in these mixtures as being particularly highly active in human cells, as compared with rodent cells. The present data suggest that differences may exist between the AhR-mediated potencies of PAHs in human and rodent cells, and that the AhR-mediated effects of polar PAH derivatives and metabolites in human cell models deserve further attention.},

note = {Place: England},

keywords = {AhR, AhR-mediated activity, Aryl Hydrocarbon/metabolism/*physiology, Basic Helix-Loop-Helix Transcription Factors/metabolism/*physiology, Biological Assay/methods, Carcinogens/toxicity, Cell Line, Environmental Pollutants/*toxicity, Genes, Humans, PAH mixtures, PAHs, Polycyclic Aromatic Hydrocarbons/*toxicity, Receptors, Relative effective potency, Reporter, Vehicle Emissions/toxicity},

pubstate = {published},

tppubtype = {article}

}

@article{kratochvilova_tumor_2015,

title = {Tumor suppressor candidate 3 (TUSC3) prevents the epithelial-to-mesenchymal transition and inhibits tumor growth by modulating the endoplasmic reticulum stress response in ovarian cancer cells.},

author = {Kateřina Kratochvílová and Peter Horak and Milan Ešner and Karel Souček and Dietmar Pils and Mariam Anees and Erwin Tomasich and František Dráfi and Veronika Jurtíková and Aleš Hampl and Michael Krainer and Petr Vaňhara},

doi = {10.1002/ijc.29502},

issn = {1097-0215 0020-7136},

year  = {2015},

date = {2015-09-01},

journal = {International journal of cancer},

volume = {137},

number = {6},

pages = {1330–1340},

abstract = {Ovarian cancer is one of the most common malignancies in women and contributes greatly to cancer-related deaths. Tumor suppressor candidate 3 (TUSC3) is a putative tumor suppressor gene located at chromosomal region 8p22, which is often lost in epithelial cancers. Epigenetic silencing of TUSC3 has been associated with poor prognosis, and hypermethylation of its promoter provides an independent biomarker of overall and disease-free survival in ovarian cancer patients. TUSC3 is localized to the endoplasmic reticulum in an oligosaccharyl tranferase complex responsible for the N-glycosylation of proteins. However, the precise molecular role of TUSC3 in ovarian cancer remains unclear. In this study, we establish TUSC3 as a novel ovarian cancer tumor suppressor using a xenograft mouse model and demonstrate that loss of TUSC3 alters the molecular response to endoplasmic reticulum stress and induces hallmarks of the epithelial-to-mesenchymal transition in ovarian cancer cells. In summary, we have confirmed the tumor-suppressive function of TUSC3 and identified the possible mechanism driving TUSC3-deficient ovarian cancer cells toward a malignant phenotype.},

note = {Place: United States},

keywords = {Animals, Cell Line, Endoplasmic Reticulum Stress, Endoplasmic Reticulum Stress/*genetics, Epithelial-Mesenchymal Transition/*genetics, epithelial-to-mesenchymal transition, Female, Genes, Heterografts, Humans, Inbred NOD, Membrane Proteins/*genetics, Mice, N33, ovarian cancer, Ovarian Neoplasms/*genetics, SCID, Tumor, Tumor Suppressor, Tumor Suppressor Proteins/*genetics, Tumor Suppressor/physiology, TUSC3},

pubstate = {published},

tppubtype = {article}

}

@article{andrysik_activation_2011,

title = {Activation of the aryl hydrocarbon receptor is the major toxic mode of action of an organic extract of a reference urban dust particulate matter mixture: the role of polycyclic aromatic hydrocarbons.},

author = {Zdeněk Andrysík and Jan Vondráček and Soňa Marvanová and Miroslav Ciganek and Jiří Neča and Kateřina Pěnčíková and Brinda Mahadevan and Jan Topinka and William M. Baird and Alois Kozubík and Miroslav Machala},

doi = {10.1016/j.mrfmmm.2011.06.011},

issn = {0027-5107},

year  = {2011},

date = {2011-09-01},

journal = {Mutation research},

volume = {714},

number = {1-2},

pages = {53–62},

abstract = {Many of the toxic and carcinogenic effects of urban air pollution have been linked to polycyclic aromatic hydrocarbons (PAHs) adsorbed to airborne particulate matter (PM). The carcinogenic properties of PAHs in complex organic mixtures derived from PM have been chiefly attributed to their mutagenicity. Nevertheless, PAHs are also potent activators of the aryl hydrocarbon receptor (AhR), which may contribute to their nongenotoxic effects, including tumor promotion. As the genotoxicity of carcinogenic PAHs in complex mixtures derived from urban PM is often inhibited by other mixture constituents, the AhR-mediated activity of urban PM extracts might significantly contribute to the carcinogenic activity of such mixtures. In the present study, we used an organic extract of the urban dust standard reference material, SRM1649a, as a model mixture to study a range of toxic effects related to DNA damage and AhR activation. Both the organic extract and its neutral aromatic fraction formed a low number of DNA adducts per nucleotide in the liver epithelial WB-F344 cells model, without inducing DNA damage response, such as tumor suppressor p53 activation and apoptosis. In contrast, we found that this extract, as well as its neutral and polar fractions, were potent inducers of a range of AhR-mediated responses, including induction of the AhR-mediated transcription, such as cytochrome P450 1A1/1B1 expression, and the AhR-dependent cell proliferation. Importantly, these toxic events occurred at doses one order of magnitude lower than DNA damage. The AhR-mediated activity of the neutral fraction was linked to PAHs and their derivatives, as polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls were only minor contributors to the overall AhR-mediated activity. Taken together, our data suggest that more attention should be paid to the AhR-dependent nongenotoxic events elicited by urban PM constituents, especially PAHs and their derivatives.},

note = {Place: Netherlands},

keywords = {Animals, Apoptosis/drug effects, Aryl Hydrocarbon/*metabolism, Cell Line, Cell Proliferation/drug effects, Cytochrome P-450 CYP1A1/metabolism, DNA Adducts/drug effects, DNA Damage/*drug effects, Dose-Response Relationship, Drug, Genes, Liver/drug effects, Mutagens/*toxicity, Organic Chemicals/*toxicity, p53/drug effects, Particulate Matter/*toxicity, Polycyclic Aromatic Hydrocarbons/*toxicity, Rats, Receptors},

pubstate = {published},

tppubtype = {article}

}

@article{ondrouskova_alternative_2008,

title = {Alternative pathways of programmed cell death are activated in cells with defective caspase-dependent apoptosis.},

author = {Eva Ondrousková and Karel Soucek and Viktor Horváth and Jan Smarda},

doi = {10.1016/j.leukres.2007.05.012},

issn = {0145-2126},

year  = {2008},

date = {2008-04-01},

journal = {Leukemia research},

volume = {32},

number = {4},

pages = {599–609},

abstract = {Loss of programmed cell death pathways is one of the features of malignancy that complicate the response of cancer cells to a therapy. Activation of alternative cell death pathways offers a promising approach to enhance efficiency of cancer chemotherapy. We analysed programmed cell death pathways of v-myb-transformed BM2 monoblasts induced by arsenic trioxide, cycloheximide and camptothecin with U937 promonocytes as a reference cell line. We show that induced death of BM2 cells is not executed by caspases but rather by alternative cell death pathways. Camptothecin induces the lysosome-dependent cell death, arsenic trioxide induces autophagy, and most of cycloheximide-treated BM2 cells die by necrosis. The fact that alternative cell death pathways can be switched in cells with defects in activation and/or function of caspases suggests that understanding and targeting of these pathways could improve therapy of cancer cells suffering from defective apoptosis.},

note = {Place: England},

keywords = {Animals, Antineoplastic Agents/*pharmacology, Apoptosis/*drug effects, Arsenic Trioxide, Arsenicals/pharmacology, Autophagy/*drug effects, Blotting, Camptothecin/pharmacology, Caspases/*metabolism, Cell Line, Cell Transformation, Chickens, Cycloheximide/pharmacology, Fluorescence, Genes, Humans, Microscopy, myb/physiology, Necrosis, Neoplastic/*pathology, Oxides/pharmacology, Signal Transduction/*drug effects, Transformed, U937 Cells/drug effects, Western},

pubstate = {published},

tppubtype = {article}

}

@article{marvanova_toxic_2008,

title = {Toxic effects of methylated benz[a]anthracenes in liver cells.},

author = {Sona Marvanová and Jan Vondrácek and Katerrina Penccíková and Lenka Trilecová and Pavel Krcmárr and Jan Topinka and Zuzana Nováková and Alena Milcová and Miroslav Machala},

doi = {10.1021/tx700305x},

issn = {0893-228X},

year  = {2008},

date = {2008-02-01},

journal = {Chemical research in toxicology},

volume = {21},

number = {2},

pages = {503–512},

abstract = {Monomethylated benz[ a]anthracenes (MeBaAs) are an important group of methylated derivatives of polycyclic aromatic hydrocarbons (PAHs). Although the methyl substitution reportedly affects their mutagenicity and tumor-initiating activity, little is known about the impact of methylation on the effects associated with activation of the aryl hydrocarbon receptor (AhR)-dependent gene expression and/or toxic events associated with tumor promotion. In the present study, we studied the effects of a series of MeBaAs on the above-mentioned end points in rat liver cell lines and compared them with the effects of benz[ a]anthracene (BaA) and the potent carcinogen 7,12-dimethylbenz[ a]anthracene (DMBA). Methyl substitution enhanced the AhR-mediated activity of BaA derivatives determined in a reporter gene assay, as the induction equivalency factors (IEFs) of all MeBaAs were higher than that of BaA. IEFs of 6-MeBaA and 9-MeBaA, two of the most potent MeBaAs, were more than two orders of magnitude higher than the IEF of BaA. Correspondingly, all MeBaAs induced higher levels of cytochrome P450 1A1 mRNA. Both BaA and MeBaAs had similar effects on the expression of cytochrome P450 1B1 or aldo-keto reductase 1C9 in rat liver epithelial WB-F344 cells. In contrast to genotoxic DMBA, MeBaAs induced low DNA adduct formation. Only 10-MeBaA induced apoptosis and accumulation of phosphorylated p53, which could be associated with the induction of oxidative stress, similar to DMBA. With the exception of 10-MeBaA, all MeBaAs induced cell proliferation in contact-inhibited WB-F344 cells, which corresponded with their ability to activate AhR. 1-, 2-, 8-, 10-, 11-, and 12-MeBaA inhibited gap junctional intercellular communication (GJIC) in WB-F344 cells. This mode of action, like disruption of cell proliferation control, might contribute to tumor promotion. Taken together, these data showed that the methyl substitution significantly influences those effects of MeBaAs associated with AhR activation or GJIC inhibition.},

note = {Place: United States},

keywords = {10-Dimethyl-1, 2-benzanthracene/chemistry/metabolism/toxicity, 9, Animals, Apoptosis/drug effects, Benz(a)Anthracenes/chemistry/metabolism/*toxicity, Carcinoma, Cell Line, Cell Proliferation/drug effects, Cytochrome P-450 Enzyme System/genetics/metabolism, DNA Adducts/analysis/metabolism, DNA/drug effects/metabolism, Dose-Response Relationship, Drug, Enzyme Induction, Enzymologic/drug effects, Gap Junctions/drug effects, Gene Expression Regulation, Genes, Hepatocellular, Hepatocytes/*drug effects/metabolism/pathology, Inbred F344, Liver Neoplasms, Messenger/metabolism, Methylation, Rats, Reporter/drug effects, RNA, Stem Cells/*drug effects/metabolism/pathology, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{davis_effect_2006,

title = {Effect of apple extracts on NF-kappaB activation in human umbilical vein endothelial cells.},

author = {Paul A. Davis and John A. Polagruto and Giuseppe Valacchi and Anh Phung and Karel Soucek and Carl L. Keen and M. Eric Gershwin},

doi = {10.1177/153537020623100514},

issn = {1535-3702 1535-3699},

year  = {2006},

date = {2006-05-01},

journal = {Experimental biology and medicine (Maywood, N.J.)},

volume = {231},

number = {5},

pages = {594–598},

abstract = {The mechanisms by which foods, such as fruit, are able to reduce the risk of chronic disease are still unclear. Several fruit products, including apples and apple juice, that are flavonoid-rich are reported to increase antioxidant levels in human subjects. This is supported by the finding from our previous studies that the chronic consumption of apple juice by human subjects reduced ex vivo low-density lipoprotein (LDL) oxidation; we hypothesized that this was due to the flavonoid in the apple juice, which, as we reported earlier, reduced in vitro LDL oxidation. To further explore whether the mixture of flavonoids and other phytochemicals in apples are biologically relevant antioxidants, we tested the effects of this flavonoid-rich apple extract (AE) on oxidant-related pathways in a model of the endothelium: human umbilical vascular endothelial cells (HU-VECs). The effects of AE on oxidant-responsive (i.e., tumor necrosis factor [TNF]-alpha-induced) nuclear factor (NF)- kappaB signaling in cell culture were assessed in transfected HUVECs by using a construct that expressed luciferase under the control of NF-kappaB. Incubation of HUVEC for 24 hrs with up to 10 mM (as gallic acid equivalents) of AE demonstrated no cytotoxicity, as determined by lactate dehydrogenase release, caspase 3 activation, and apoptosis marker-based FACS analysis. AE after a 24-hr incubation period at either 200 or 2000 nM showed a complex pattern of decreased basal and TNF-alpha-stimulated NF-kappaB signaling (63% maximal decrease) as assessed by luciferase activity in the transfected HUVECs, as well as by reduced levels of IkappaBalpha protein phosphorylation detected by Western blot analysis. We suggest that AE downregulates NF-kappaB signaling and that this is indicative of an antioxidant effect of the flavonoids present in AE.},

note = {Place: Switzerland},

keywords = {Cell Line, Endothelial Cells/cytology/*metabolism, Flavonoids/*metabolism, Genes, Humans, I-kappa B Proteins/metabolism, Malus/*chemistry, NF-kappa B/*metabolism, NF-KappaB Inhibitor alpha, Plant Extracts/*metabolism, Reporter, Umbilical Veins/*cytology},

pubstate = {published},

tppubtype = {article}

}

@article{nemajerova_trichostatin_2003,

title = {Trichostatin A suppresses transformation by the v-myb oncogene in BM2 cells.},

author = {Alice Nemajerová and Jan Smarda and Pierre Jurdic and Lukás Kubala and Karel Soucek and Jana Smardová},

doi = {10.1089/152581603321628368},

issn = {1525-8165},

year  = {2003},

date = {2003-04-01},

journal = {Journal of hematotherapy & stem cell research},

volume = {12},

number = {2},

pages = {225–235},

abstract = {BM2 cells are chicken monoblasts transformed by the v-myb oncogene of avian myeloblastosis virus. The constitutively high v-myb expression interferes with the terminal differentiation of BM2 cells, but these cells can be induced to differentiate into macrophage-like cells by phorbol esters. Histone acetylation plays an important role in regulation of transcription and is particularly relevant to the regulation and pathology of hematopoiesis. In the present study, we examined the contribution of elevated histone acetylation to the differentiation of BM2 cells. Inhibition of the activity of endogenous histone deacetylases by trichostatin A (TSA) resulted in histone hyperacetylation causing cell cycle arrest and differentiation of BM2 cells into macrophage polykaryons. TSA did not affect the level of v-Myb protein in BM2 cells, but it downregulated its transcription activation capability. This suggests that chromatin remodeling can be significantly engaged in regulation of proliferation and differentiation of leukemic cells.},

note = {Place: United States},

keywords = {Acetylation, Animals, Cell Cycle, Cell Differentiation, Cell Line, Cell Transformation, Chickens, Chromatin Assembly and Disassembly/physiology, Genes, Histone Deacetylases/drug effects, Histones/metabolism/physiology, Hydroxamic Acids/*pharmacology, Macrophages/cytology, myb/drug effects/*physiology, Transformed, Viral/*drug effects},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_modulation_2002,

title = {Modulation of estrogen receptor-dependent reporter construct activation and G0/G1-S-phase transition by polycyclic aromatic hydrocarbons in human breast carcinoma MCF-7 cells.},

author = {Jan Vondrácek and Alois Kozubík and Miroslav Machala},

doi = {10.1093/toxsci/70.2.193},

issn = {1096-6080 1096-0929},

year  = {2002},

date = {2002-12-01},

journal = {Toxicological sciences : an official journal of the Society of Toxicology},

volume = {70},

number = {2},

pages = {193–201},

abstract = {It has been suggested that the estrogenicity of PAHs could contribute to their carcinogenic effects via increased tissue-specific cell proliferation. Both benzo[a]pyrene (BaP) and benz[a]anthracene (BaA) are known to weakly activate estrogen receptor (ER)-dependent reporter constructs. In this study, several other PAHs, including fluorene, fluoranthene, pyrene, chrysene, phenanthrene and anthracene, were found to act as very weak inducers of ER-mediated activity in the MCF-7 cell line stably transfected with a luciferase reporter gene. The effects of PAHs were time-dependent and they were not completely inhibited by antiestrogen ICI 182,780. In addition, BaP and BaA, as well as weakly estrogenic fluoranthene, significantly potentiated the maximum ER-mediated activity of 17beta-estradiol. Therefore, the effects of inhibitors of several types of protein kinases known to activate ERalpha in a ligand-independent manner were investigated. However, neither inhibitors nor inducers of extracellular signal-regulated kinases 1 and 2 (ERK1/2), phosphatidylinositol-3 kinase, protein kinase C, c-Src, or protein kinase A modified ER-mediated activity in this model. Neither estradiol nor BaA activated ERK1/2, two kinases suggested to play significant roles in ER signaling, suggesting that another kinase is involved in the observed phosphorylation of ERalpha. Similar to 17beta-estradiol, BaA stimulated G(0)/G(1)-S-phase transition in MCF-7 cells, which was fully suppressed by ICI 182,780. In conclusion, some PAHs can potentiate 17beta-estradiol-induced ER activation and stimulate cell cycle entry in vitro. However, their exact mode(s) of action and whether this phenomenon is of in vivo relevance remains to be elucidated.},

note = {Place: United States},

keywords = {Breast Neoplasms/*metabolism, Cell Cycle/*drug effects/genetics, Cell Cycle/drug effects/genetics, Cultured, Estrogen Receptor alpha, Estrogen Receptor Modulators/pharmacology, Estrogen/genetics/*metabolism, G1 Phase/drug effects/genetics, Genes, Genetic/drug effects, Humans, Phosphorylation/drug effects, Polycyclic Aromatic Hydrocarbons/metabolism/*toxicity, Receptors, Reporter/*genetics, Resting Phase, S Phase/drug effects/genetics, Transcription, Tumor Cells},

pubstate = {published},

tppubtype = {article}

}