Latest Publications

@article{karasova_inhibition_2022,

title = {Inhibition of Aryl Hydrocarbon Receptor (AhR) Expression Disrupts Cell Proliferation and Alters Energy Metabolism and Fatty Acid Synthesis in Colon Cancer Cells.},

author = {Martina Karasová and Jiřina Procházková and Zuzana Tylichová and Radek Fedr and Miroslav Ciganek and Miroslav Machala and Zdeněk Dvořák and Barbora Vyhlídalová and Iveta Zůvalová and Jiří Ehrmann and Jan Bouchal and Zdeněk Andrysík and Jan Vondráček},

doi = {10.3390/cancers14174245},

issn = {2072-6694},

year  = {2022},

date = {2022-08-01},

journal = {Cancers},

volume = {14},

number = {17},

abstract = {The aryl hydrocarbon receptor (AhR) plays a wide range of physiological roles in cellular processes such as proliferation, migration or control of immune responses. Several studies have also indicated that AhR might contribute to the regulation of energy balance or cellular metabolism. We observed that the AhR is upregulated in tumor epithelial cells derived from colon cancer patients. Using wild-type and the corresponding AhR knockout (AhR KO) variants of human colon cancer cell lines HCT116 and HT-29, we analyzed possible role(s) of the AhR in cell proliferation and metabolism, with a focus on regulation of the synthesis of fatty acids (FAs). We observed a decreased proliferation rate in the AhR KO cells, which was accompanied with altered cell cycle progression, as well as a decreased ATP production. We also found reduced mRNA levels of key enzymes of the FA biosynthetic pathway in AhR KO colon cancer cells, in particular of stearoyl-CoA desaturase 1 (SCD1). The loss of AhR was also associated with reduced expression and/or activity of components of the PI3K/Akt pathway, which controls lipid metabolism, and other lipogenic transcriptional regulators, such as sterol regulatory element binding transcription factor 1 (SREBP1). Together, our data indicate that disruption of AhR activity in colon tumor cells may, likely in a cell-specific manner, limit their proliferation, which could be linked with a suppressive effect on their endogenous FA metabolism. More attention should be paid to potential mechanistic links between overexpressed AhR and colon tumor cell metabolism.},

note = {Place: Switzerland},

keywords = {AhR, Akt pathway, colon cancer cells, fatty acid synthesis, metabolism, proliferation},

pubstate = {published},

tppubtype = {article}

}

@article{vazquez-gomez_aryl_2022,

title = {Aryl Hydrocarbon Receptor (AhR) Limits the Inflammatory Responses in Human Lung Adenocarcinoma A549 Cells via Interference with NF-κB Signaling.},

author = {Gerardo Vázquez-Gómez and Martina Karasová and Zuzana Tylichová and Markéta Kabátková and Aleš Hampl and Jason Matthews and Jiří Neča and Miroslav Ciganek and Miroslav Machala and Jan Vondráček},

doi = {10.3390/cells11040707},

issn = {2073-4409},

year  = {2022},

date = {2022-02-01},

journal = {Cells},

volume = {11},

number = {4},

abstract = {Apart from its role in the metabolism of carcinogens, the aryl hydrocarbon receptor (AhR) has been suggested to be involved in the control of inflammatory responses within the respiratory tract. However, the mechanisms responsible for this are only partially known. In this study, we used A549 cell line, as a human model of lung alveolar type II (ATII)-like cells, to study the functional role of the AhR in control of inflammatory responses. Using IL-1β as an inflammation inducer, we found that the induction of cyclooxygenase-2 and secretion of prostaglandins, as well as expression and release of pro-inflammatory cytokines, were significantly higher in the AhR-deficient A549 cells. This was linked with an increased nuclear factor-κB (NF-κB) activity, and significantly enhanced phosphorylation of its regulators, IKKα/β, and their target IκBα, in the AhR-deficient A549 cells. In line with this, when we mimicked the exposure to a complex mixture of airborne pollutants, using an organic extract of reference diesel exhaust particle mixture, an exacerbated inflammatory response was observed in the AhR-deficient cells, as compared with wild-type A549 cells. Together, the present results indicate that the AhR may act as a negative regulator of the inflammatory response in the A549 model, via a direct modulation of NF-κB signaling. Its role(s) in the control of inflammation within the lung alveoli exposed to airborne pollutants, especially those which simultaneously activate the AhR, thus deserve further attention.},

note = {Place: Switzerland},

keywords = {*Environmental Pollutants/toxicity, *Inflammation/pathology, *NF-kappa B/metabolism, *Receptors, A549 Cells, AhR, alveolar epithelial type II cells, Aryl Hydrocarbon/metabolism, cytokines, Humans, Inflammation, NF-κB, prostaglandins},

pubstate = {published},

tppubtype = {article}

}

@article{krkoska_role_2022,

title = {Role of miR-653 and miR-29c in downregulation of CYP1A2 expression in hepatocellular carcinoma.},

author = {Martin Krkoška and Jana Nekvindová and Kateřina Nevědělová and Veronika Zubáňová and Lenka Radová and Jan Vondráček and Jarmila Herůdková and Ondřej Slabý and Igor Kiss and Lucia Bohovicová and Pavel Fabian and Zuzana Tylichová and Zdeněk Kala and Petr Kysela and Lenka Ostřížková and Vladimír Palička and Alena Hyršlová Vaculová},

doi = {10.1007/s43440-021-00338-9},

issn = {2299-5684 1734-1140},

year  = {2022},

date = {2022-02-01},

journal = {Pharmacological reports : PR},

volume = {74},

number = {1},

pages = {148–158},

abstract = {BACKGROUND: Hepatocellular carcinoma (HCC) is a major contributor to the worldwide cancer burden. Recent studies on HCC have demonstrated dramatic alterations in expression of several cytochrome P450 (CYP) family members that play a crucial role in biotransformation of many drugs and other xenobiotics; however, the mechanisms responsible for their deregulation remain unclear. METHODS: We investigated a potential involvement of miRNAs in downregulation of expression of CYPs observed in HCC tumors. We compared miRNA expression profiles (TaqMan Array Human MicroRNA v3.0 TLDA qPCR) between HCC human patient tumors with strong (CYP-) and weak/no (CYP+) downregulation of drug-metabolizing CYPs. The role of significantly deregulated miRNAs in modulation of expression of the CYPs and associated xenobiotic receptors was then investigated in human liver HepaRG cells transfected with relevant miRNA mimics or inhibitors. RESULTS: We identified five differentially expressed miRNAs in CYP- versus CYP+ tumors, namely miR-29c, miR-125b1, miR-505, miR-653 and miR-675. The two most-upregulated miRNAs found in CYP- tumor samples, miR-29c and miR-653, were found to act as efficient suppressors of CYP1A2 or AHR expression. CONCLUSIONS: Our results revealed a novel role of miR-653 and miR-29c in regulation of expresion of CYPs involved in crucial biotransformation processes in liver, which are often deregulated during liver cancer progression.},

note = {Place: Switzerland},

keywords = {*Carcinoma, *Liver Neoplasms/genetics/metabolism, AhR, Biotransformation, Cell Line, CYP1A2, Cytochrome P-450 CYP1A2/*metabolism, Down-Regulation, Gene Expression Regulation, Hepatocellular carcinoma, Hepatocellular/genetics/metabolism, Hepatocytes/metabolism, Humans, MicroRNA, MicroRNAs/*metabolism, Neoplastic, Tumor, Xenobiotics/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{krkoska_deregulation_2021,

title = {Deregulation of signaling pathways controlling cell survival and proliferation in cancer cells alters induction of cytochrome P450 family 1 enzymes.},

author = {Martin Krkoška and Jana Svobodová and Markéta Kabátková and Ondřej Zapletal and Alena Hyršlová Vaculová and Jana Nekvindová and Jan Vondráček},

doi = {10.1016/j.tox.2021.152897},

issn = {1879-3185 0300-483X},

year  = {2021},

date = {2021-09-01},

journal = {Toxicology},

volume = {461},

pages = {152897},

abstract = {Cytochrome P450 family 1 (CYP1) enzymes contribute both to metabolism of xenobiotics and to the control of endogenous levels of ligands of the aryl hydrocarbon receptor (AhR). Their activities, similar to other CYPs, can be altered in tumor tissues. Here, we examined a possible role of proliferative/survival pathways signaling, which is often deregulated in tumor cells, and possible links with p300 histone acetyltransferase (a transcriptional co-activator) in the control of CYP1 expression, focusing particularly on CYP1A1. Using cell models derived from human liver, we observed that the induction of CYP1A1 expression, as well as other CYP1 enzymes, was reduced in exponentially growing cells, as compared with their non-dividing counterparts. The siRNA-mediated inhibition of proliferation/pro-survival signaling pathway effectors (such as β-catenin and/or Hippo pathway effectors YAP/TAZ) increased the AhR ligand-induced CYP1A1 mRNA levels in liver HepaRG cells, and/or in colon carcinoma HCT-116 cells. The activation of proliferative Wnt/β-catenin signaling in HCT-116 cells reduced both the induction of CYP1 enzymes and the binding of p300 to the promoter of CYP1A1 or CYP1B1 genes. These results seem to indicate that aberrant proliferative signaling in tumor cells could suppress induction of CYP1A1 (or other CYP1 enzymes) via competition for p300 binding. This mechanism could be involved in modulation of the metabolism of both endogenous and exogenous substrates of CYP1A1 (and other CYP1 enzymes), with possible further consequences for alterations of the AhR signaling in tumor cells, or additional functional roles of CYP1 enzymes.},

note = {Place: Ireland},

keywords = {AhR, Cancer cells, Cell Line, Cell Proliferation, Cell Proliferation/*physiology, Cell Survival/physiology, Colonic Neoplasms/genetics/*pathology, CYP1 enzymes, Cytochrome P-450 CYP1A1/biosynthesis/*genetics, E1A-Associated p300 Protein/metabolism, Enzyme Induction/physiology, Gene Expression Regulation, HCT116 Cells, Hippo Signaling Pathway/physiology, Humans, Liver/*pathology, Neoplastic, p300, Signal Transduction/physiology, Tumor, Wnt Signaling Pathway/physiology, β-Catenin signaling},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_role_2021,

title = {The Role of Metabolism in Toxicity of Polycyclic Aromatic Hydrocarbons and their Non-genotoxic Modes of Action.},

author = {Jan Vondráček and Miroslav Machala},

doi = {10.2174/1389200221999201125205725},

issn = {1875-5453 1389-2002},

year  = {2021},

date = {2021-01-01},

journal = {Current drug metabolism},

volume = {22},

number = {8},

pages = {584–595},

abstract = {Polycyclic aromatic hydrocarbons (PAHs) represent a class of widely distributed environmental pollutants that have been primarily studied as genotoxic compounds. Their mutagenicity/genotoxicity largely depends on their oxidative metabolism leading to the production of dihydrodiol epoxide metabolites, as well as additional metabolites contributing to oxidative DNA damage, such as PAH quinones. However, both parental PAHs and their metabolites, including PAH quinones or hydroxylated PAHs, have been shown to produce various types of non-genotoxic effects. These include e.g., activation of the aryl hydrocarbon receptor and/or additional nuclear receptors, activation of membrane receptors, including tyrosine kinases and G-protein coupled receptors, or activation of intracellular signaling pathways, such as mitogen-activated protein kinases, Akt kinase and Ca(2+)-dependent signaling. These pathways may, together with the cellular DNA damage responses, modulate cell proliferation, cell survival or cell-to-cell communication, thus contributing to the known carcinogenic effects of PAHs. In the present review, we summarize some of the known non-genotoxic effects of PAHs, focusing primarily on those that have also been shown to be modulated by PAH metabolites. Despite the limitations of the available data, it seems evident that more attention should be paid to the discrimination between the potential non-genotoxic effects of parental PAHs and those of their metabolites. This may provide further insight into the mechanisms of toxicity of this large and diverse group of environmental pollutants.},

note = {Place: Netherlands},

keywords = {Activation, AhR, Animals, Benzo[a]pyrene, Cell Proliferation, Cell Survival, cell-to-cell communication, DNA Damage, Environmental Pollutants/*pharmacokinetics/*toxicity, Humans, Metabolic, Mutagens/*pharmacokinetics/*toxicity, oxidative stress, PAH metabolism., Polycyclic Aromatic Hydrocarbons/*pharmacokinetics/*toxicity},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_environmental_2020,

title = {Environmental six-ring polycyclic aromatic hydrocarbons are potent inducers of the AhR-dependent signaling in human cells.},

author = {Jan Vondráček and Kateřina Pěnčíková and Miroslav Ciganek and Jakub Pivnička and Martina Karasová and Martina Hýžďalová and Simona Strapáčová and Lenka Pálková and Jiří Neča and Jason Matthews and Michal Vojtíšek Lom and Jan Topinka and Alena Milcová and Miroslav Machala},

doi = {10.1016/j.envpol.2020.115125},

issn = {1873-6424 0269-7491},

year  = {2020},

date = {2020-11-01},

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

volume = {266},

number = {Pt 2},

pages = {115125},

abstract = {The toxicities of many environmental polycyclic aromatic hydrocarbons (PAHs), in particular those of high-molecular-weight PAHs (with MW higher than 300), remain poorly characterized. The objective of this study was to evaluate the ability of selected environmentally relevant PAHs with MW 302 (MW302 PAHs) to activate the aryl hydrocarbon receptor (AhR), since this represents a major toxic mode of action of PAHs. A large number of the evaluated compounds exhibited strong AhR-mediated activities, in particular in human models. The studied MW302 PAHs also significantly contributed to the overall calculated AhR activities of complex environmental mixtures, including both defined standard reference materials and collected diesel exhaust particles. The high AhR-mediated activities of representative MW302 PAHs, e.g. naphtho[1,2-k]fluoranthene, corresponded with the modulation of expression of relevant AhR target genes in a human lung cell model, or with the AhR-dependent suppression of cell cycle progression/proliferation in estrogen-sensitive cells. This was in a marked contrast with the limited genotoxicity of the same compound(s). Given the substantial levels of the AhR-activating MW302 PAHs in combustion particles, it seems important to continue to investigate the toxic modes of action of this large group of PAHs associated with airborne particulate matter.},

note = {Place: England},

keywords = {*Polycyclic Aromatic Hydrocarbons, *Receptors, AhR, Anti-estrogenicity, Aryl Hydrocarbon, Carcinogenic PAHs, Genotoxicity, Humans, Lung cell toxicity, Particulate Matter, Signal Transduction, Vehicle Emissions},

pubstate = {published},

tppubtype = {article}

}

@article{strapacova_relative_2018,

title = {Relative effective potencies of dioxin-like compounds in rodent and human lung cell models.},

author = {Simona Strapáčová and Petra Brenerová and Pavel Krčmář and Patrik Andersson and Karin I. Ede and Majorie B. M. Duursen and Martin Berg and Jan Vondráček and Miroslav Machala},

doi = {10.1016/j.tox.2018.05.004},

issn = {1879-3185 0300-483X},

year  = {2018},

date = {2018-07-01},

journal = {Toxicology},

volume = {404-405},

pages = {33–41},

abstract = {Toxicity of dioxin-like compounds (DLCs), such as polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls, is largely mediated via aryl hydrocarbon receptor (AhR) activation. AhR-mediated gene expression can be tissue-specific; however, the inducibility of AhR in the lungs, a major target of DLCs, remains poorly characterized. In this study, we developed relative effective potencies (REPs) for a series of DLCs in both rodent (MLE-12, RLE-6TN) and human (A549, BEAS-2B) lung and bronchial epithelial cell models, using expression of both canonical (CYP1A1, CYP1B1) and less well characterized (TIPARP, AHRR, ALDH3A1) AhR target genes. The use of rat, murine and human cell lines allowed us to determine both species-specific differences in sensitivity of responses to DLCs in lung cellular models and deviations from established WHO toxic equivalency factor values (TEF) values. Finally, expression of selected AhR target genes was determined in vivo, using lung tissues of female rats exposed to a single oral dose of DLCs and compared with the obtained in vitro data. All cell models were highly sensitive to DLCs, with murine MLE-12 cells being the most sensitive and human A549 cells being the least sensitive. Interestingly, we observed that four AhR target genes were more sensitive than CYP1A1 in lung cell models (CYP1B1, AHRR, TIPARP and/or ALDH3A1). We found some deviations, with strikingly low REPs for polychlorinated biphenyls PCBs 105, 167, 169 and 189 in rat RLE-6TN cells-derived REPs for a series of 20 DLCs evaluated in this study, as compared with WHO TEF values. For other DLCs, including PCBs 126, 118 and 156, REPs were generally in good accordance with WHO TEF values. This conclusion was supported by in vivo data obtained in rat lung tissue. However, we found that human lung REPs for 2,3,4,7,8-pentachlorodibenzofuran and PCB 126 were much lower than the respective rat lung REPs. Furthermore, PCBs 118 and 156 were almost inactive in these human cells. Our observations may have consequences for risk assessment. Given the differences observed between rat and human data sets, development of human-specific REP/TEFs, and the use of CYP1B1, AHRR, TIPARP and/or ALDH3A1 mRNA inducibility as sensitive endpoints, are recommended for assessment of relative effective potencies of DLCs.},

note = {Place: Ireland},

keywords = {A549 Cells, Acute/methods, AhR, Animals, Dioxin-like compounds, Dioxins/*toxicity, Dose-Response Relationship, Drug, Endogenous target genes, Female, Humans, Lung epithelial cells, Lung/*drug effects/metabolism/*pathology, Mice, Rats, Relative effective potencies, Rodentia, Species Specificity, Sprague-Dawley, Toxicity Tests},

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{svobodova_aryl_2015,

title = {The aryl hydrocarbon receptor-dependent disruption of contact inhibition in rat liver WB-F344 epithelial cells is linked with induction of survivin, but not with inhibition of apoptosis.},

author = {Jana Svobodová and Markéta Kabátková and Lenka Šmerdová and Petra Brenerová and Zdeněk Dvořák and Miroslav Machala and Jan Vondráček},

doi = {10.1016/j.tox.2015.04.001},

issn = {1879-3185 0300-483X},

year  = {2015},

date = {2015-07-01},

journal = {Toxicology},

volume = {333},

pages = {37–44},

abstract = {Inhibition of apoptosis by the ligands of the aryl hydrocarbon receptor (AhR) has been proposed to play a role in their tumor promoting effects on liver parenchymal cells. However, little is presently known about the impact of toxic AhR ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on apoptosis in other liver cell types, such as in liver epithelial/progenitor cells. In the present study, we focused on the effects of TCDD on apoptosis regulation in a model of liver progenitor cells, rat WB-F344 cell line, during the TCDD-elicited release from contact inhibition. The stimulation of cell proliferation in this cell line was associated with deregulated expression of a number of genes known to be under transcriptional control of the Hippo signaling pathway, a principal regulatory pathway involved in contact inhibition of cell proliferation. Interestingly, we found that mRNA and protein levels of survivin, a known Hippo target, which plays a role both in cell division and inhibition of apoptosis, were significantly up-regulated in rat liver epithelial cell model, as well as in undifferentiated human liver HepaRG cells. Using the short interfering RNA-mediated knockdown, we confirmed that survivin plays a central role in cell division of WB-F344 cells. When evaluating the effects of TCDD on apoptosis induction by camptothecin, a genotoxic topoisomerase I inhibitor, we observed that the pre-treatment of WB-F344 cells with TCDD increased number of cells with apoptotic nuclear morphology, and it potentiated cleavage of both caspase-3 and poly(ADP-ribose) polymerase I. This indicated that despite the observed up-regulation of survivin, apoptosis induced by the genotoxin was potentiated in the model of rat liver progenitor cells. The present results indicate that, unlike in hepatocytes, AhR agonists may not prevent induction of apoptosis elicited by DNA-damaging agents in a model of rat liver progenitor cells.},

note = {Place: Ireland},

keywords = {AhR, Animals, Apoptosis, Apoptosis/*drug effects, Aryl Hydrocarbon/*agonists/metabolism, Basic Helix-Loop-Helix Transcription Factors/*agonists/metabolism, BIRC5/survivin, Camptothecin/*toxicity, Caspase 3/metabolism, Cell Line, Contact inhibition, Contact Inhibition/*drug effects, Epithelial Cells/*drug effects/metabolism/pathology, Genetic/drug effects, Hippo signaling, Humans, Inbred F344, Inhibitor of Apoptosis Proteins/genetics/metabolism, Liver/*drug effects/metabolism/pathology, Microtubule-Associated Proteins/genetics/*metabolism, Poly (ADP-Ribose) Polymerase-1, Poly(ADP-ribose) Polymerases/metabolism, Polychlorinated Dibenzodioxins/*toxicity, Rats, Receptors, RNA Interference, Signal Transduction/drug effects, Survivin, TCDD, Time Factors, Topoisomerase I Inhibitors/*toxicity, Transcription, Transfection, Up-Regulation},

pubstate = {published},

tppubtype = {article}

}