Latest Publications

@article{rihova_transcription_2022,

title = {Transcription factor c-Myb: novel prognostic factor in osteosarcoma.},

author = {Kamila Říhová and Monika Dúcka and Iva Staniczková Zambo and Ladislava Vymětalová and Martin Šrámek and Filip Trčka and Jan Verner and Stanislav Drápela and Radek Fedr and Tereza Suchánková and Barbora Pavlatovská and Eva Ondroušková and Irena Kubelková and Danica Zapletalová and Štěpán Tuček and Peter Múdry and Dagmar Adámková Krákorová and Lucia Knopfová and Jan Šmarda and Karel Souček and Lubor Borsig and Petr Beneš},

doi = {10.1007/s10585-021-10145-4},

issn = {1573-7276 0262-0898},

year  = {2022},

date = {2022-04-01},

journal = {Clinical & experimental metastasis},

volume = {39},

number = {2},

pages = {375–390},

abstract = {The transcription factor c-Myb is an oncoprotein promoting cell proliferation and survival when aberrantly activated/expressed, thus contributing to malignant transformation. Overexpression of c-Myb has been found in leukemias, breast, colon and adenoid cystic carcinoma. Recent studies revealed its expression also in osteosarcoma cell lines and suggested its functional importance during bone development. However, the relevance of c-Myb in control of osteosarcoma progression remains unknown. A retrospective clinical study was carried out to assess a relationship between c-Myb expression in archival osteosarcoma tissues and prognosis in a cohort of high-grade osteosarcoma patients. In addition, MYB was depleted in metastatic osteosarcoma cell lines SAOS-2 LM5 and 143B and their growth, chemosensitivity, migration and metastatic activity were determined. Immunohistochemical analysis revealed that high c-Myb expression was significantly associated with poor overall survival in the cohort and metastatic progression in young patients. Increased level of c-Myb was detected in metastatic osteosarcoma cell lines and its depletion suppressed their growth, colony-forming capacity, migration and chemoresistance in vitro in a cell line-dependent manner. MYB knock-out resulted in reduced metastatic activity of both SAOS-2 LM5 and 143B cell lines in immunodeficient mice. Transcriptomic analysis revealed the c-Myb-driven functional programs enriched for genes involved in the regulation of cell growth, stress response, cell adhesion and cell differentiation/morphogenesis. Wnt signaling pathway was identified as c-Myb target in osteosarcoma cells. Taken together, we identified c-Myb as a negative prognostic factor in osteosarcoma and showed its involvement in the regulation of osteosarcoma cell growth, chemosensitivity, migration and metastatic activity.},

note = {Place: Netherlands},

keywords = {*Bone Neoplasms/pathology, *Osteosarcoma/pathology, Animals, c-Myb, Cell Line, Cell Movement/genetics, Cell Proliferation, Chemoresistance, Gene Expression Regulation, Humans, Metastasis, Mice, Neoplastic, Osteosarcoma, Prognosis, proliferation, Retrospective Studies, Tumor, Wnt Signaling Pathway},

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{hyzdalova_prolonged_2021,

title = {A prolonged exposure of human lung carcinoma epithelial cells to benzo[a]pyrene induces p21-dependent epithelial-to-mesenchymal transition (EMT)-like phenotype.},

author = {Martina Hýžďalová and Jiřina Procházková and Simona Strapáčová and Lucie Svržková and Ondřej Vacek and Radek Fedr and Zdeněk Andrysík and Eva Hrubá and Helena Líbalová and Jiří Kléma and Jan Topinka and Josef Mašek and Karel Souček and Jan Vondráček and Miroslav Machala},

doi = {10.1016/j.chemosphere.2020.128126},

issn = {1879-1298 0045-6535},

year  = {2021},

date = {2021-01-01},

journal = {Chemosphere},

volume = {263},

pages = {128126},

abstract = {Deciphering the role of the aryl hydrocarbon receptor (AhR) in lung cancer cells may help us to better understand the role of toxic AhR ligands in lung carcinogenesis, including cancer progression. We employed human lung carcinoma A549 cells to investigate their fate after continuous two-week exposure to model AhR agonists, genotoxic benzo[a]pyrene (BaP; 1 μM) and non-genotoxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 nM). While TCDD increased proliferative rate of A549 cells, exposure to BaP decreased cell proliferation and induced epithelial-to-mesenchymal transition (EMT)-like phenotype, which was associated with enhanced cell migration, invasion, and altered cell morphology. Although TCDD also suppressed expression of E-cadherin and activated some genes linked to EMT, it did not induce the EMT-like phenotype. The results of transcriptomic analysis, and the opposite effects of BaP and TCDD on cell proliferation, indicated that a delay in cell cycle progression, together with a slight increase of senescence (when coupled with AhR activation), favors the induction of EMT-like phenotype. The shift towards EMT-like phenotype observed after simultaneous treatment with TCDD and mitomycin C (an inhibitor of cell proliferation) confirmed the hypothesis. Since BaP decreased cell proliferative rate via induction of p21 expression, we generated the A549 cell model with reduced p21 expression and exposed it to BaP for two weeks. The p21 knockdown suppressed the BaP-mediated EMT-like phenotype in A549 cells, thus confirming that a delayed cell cycle progression, together with p21-dependent induction of senescence-related chemokine CCL2, may contribute to induction of EMT-like cell phenotype in lung cells exposed to genotoxic AhR ligands.},

note = {Place: England},

keywords = {*Carcinoma, *Lung Neoplasms/genetics, Aryl Hydrocarbon/genetics, BaP, Benzo(a)pyrene/toxicity, Cell Proliferation, EMT, Epithelial Cells, Humans, Lung, Lung carcinoma, Phenotype, Receptors, TCDD, Tumor progression},

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{svobodova_2378-tetrachlorodibenzo-p-dioxin_2019,

title = {2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Disrupts Control of Cell Proliferation and Apoptosis in a Human Model of Adult Liver Progenitors.},

author = {Jana Svobodová and Jiřina Procházková and Markéta Kabátková and Martin Krkoška and Lenka Šmerdová and Helena Líbalová and Jan Topinka and Jiří Kléma and Alois Kozubík and Miroslav Machala and Jan Vondráček},

doi = {10.1093/toxsci/kfz202},

issn = {1096-0929},

year  = {2019},

date = {2019-12-01},

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

volume = {172},

number = {2},

pages = {368–384},

abstract = {The aryl hydrocarbon receptor (AhR) activation has been shown to alter proliferation, apoptosis, or differentiation of adult rat liver progenitors. Here, we investigated the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated AhR activation on a human model of bipotent liver progenitors, undifferentiated HepaRG cells. We used both intact undifferentiated HepaRG cells, and the cells with silenced Hippo pathway effectors, yes-associated protein 1 (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), which play key role(s) in tissue-specific progenitor cell self-renewal and expansion, such as in liver, cardiac, or respiratory progenitors. TCDD induced cell proliferation in confluent undifferentiated HepaRG cells; however, following YAP, and, in particular, double YAP/TAZ knockdown, TCDD promoted induction of apoptosis. These results suggested that, unlike in mature hepatocytes, or hepatocyte-like cells, activation of the AhR may sensitize undifferentiated HepaRG cells to apoptotic stimuli. Induction of apoptosis in cells with silenced YAP/TAZ was associated with upregulation of death ligand TRAIL, and seemed to involve both extrinsic and mitochondrial apoptosis pathways. Global gene expression analysis further suggested that TCDD significantly altered expression of constituents and/or transcriptional targets of signaling pathways participating in control of expansion or differentiation of liver progenitors, including EGFR, Wnt/β-catenin, or tumor growth factor-β signaling pathways. TCDD significantly upregulated cytosolic proapoptotic protein BMF (Bcl-2 modifying factor) in HepaRG cells, which could be linked with an enhanced sensitivity of TCDD-treated cells to apoptosis. Our results suggest that, in addition to promotion of cell proliferation and alteration of signaling pathways controlling expansion of human adult liver progenitors, AhR ligands may also sensitize human liver progenitor cells to apoptosis.},

note = {Place: United States},

keywords = {*Models, Adaptor Proteins, Apoptosis, Apoptosis/*drug effects/genetics, Aryl hydrocarbon receptor, Aryl Hydrocarbon/metabolism, Biological, Cell Line, Cell Proliferation, Cell Proliferation/*drug effects/genetics, Gene Expression/drug effects, HepaRG cells, Hippo signaling, Humans, Liver/*drug effects/pathology, Polychlorinated Dibenzodioxins/*toxicity, Receptors, RNA, Signal Transducing/genetics, Signal Transduction, Small Interfering/genetics, Stem Cells/*drug effects/pathology, Trans-Activators/genetics, Transcription Factors/genetics, Transcriptional Coactivator with PDZ-Binding Motif Proteins, Transfection, YAP-Signaling Proteins},

pubstate = {published},

tppubtype = {article}

}

@article{boudny_novel_2019,

title = {Novel CHK1 inhibitor MU380 exhibits significant single-agent activity in TP53-mutated chronic lymphocytic leukemia cells.},

author = {Miroslav Boudny and Jana Zemanova and Prashant Khirsariya and Marek Borsky and Jan Verner and Jana Cerna and Alexandra Oltova and Vaclav Seda and Marek Mraz and Josef Jaros and Zuzana Jaskova and Michaela Spunarova and Yvona Brychtova and Karel Soucek and Stanislav Drapela and Marie Kasparkova and Jiri Mayer and Kamil Paruch and Martin Trbusek},

doi = {10.3324/haematol.2018.203430},

issn = {1592-8721 0390-6078},

year  = {2019},

date = {2019-12-01},

journal = {Haematologica},

volume = {104},

number = {12},

pages = {2443–2455},

abstract = {Introduction of small-molecule inhibitors of B-cell receptor signaling and BCL2 protein significantly improves therapeutic options in chronic lymphocytic leukemia. However, some patients suffer from adverse effects mandating treatment discontinuation, and cases with TP53 defects more frequently experience early progression of the disease. Development of alternative therapeutic approaches is, therefore, of critical importance. Here we report details of the anti-chronic lymphocytic leukemia single-agent activity of MU380, our recently identified potent, selective, and metabolically robust inhibitor of checkpoint kinase 1. We also describe a newly developed enantioselective synthesis of MU380, which allows preparation of gram quantities of the substance. Checkpoint kinase 1 is a master regulator of replication operating primarily in intra-S and G(2)/M cell cycle checkpoints. Initially tested in leukemia and lymphoma cell lines, MU380 significantly potentiated efficacy of gemcitabine, a clinically used inducer of replication stress. Moreover, MU380 manifested substantial single-agent activity in both TP53-wild type and TP53-mutated leukemia and lymphoma cell lines. In chronic lymphocytic leukemia-derived cell lines MEC-1, MEC-2 (both TP53-mut), and OSU-CLL (TP53-wt) the inhibitor impaired cell cycle progression and induced apoptosis. In primary clinical samples, MU380 used as a single-agent noticeably reduced the viability of unstimulated chronic lymphocytic leukemia cells as well as those induced to proliferate by anti-CD40/IL-4 stimuli. In both cases, effects were comparable in samples harboring p53 pathway dysfunction (TP53 mutations or ATM mutations) and TP53-wt/ATM-wt cells. Lastly, MU380 also exhibited significant in vivo activity in a xenotransplant mouse model (immunodeficient strain NOD-scid IL2Rγ(null) ) where it efficiently suppressed growth of subcutaneous tumors generated from MEC-1 cells.},

note = {Place: Italy},

keywords = {*Drug Synergism, *Mutation, Animals, Antimetabolites, Antineoplastic/pharmacology, Apoptosis, B-Cell/*drug therapy/genetics/pathology, Biomarkers, Cell Cycle, Cell Proliferation, Checkpoint Kinase 1/*antagonists & inhibitors, Chronic, Cultured, Deoxycytidine/analogs & derivatives/pharmacology, Drug resistance, Female, gemcitabine, Gene Expression Regulation, Humans, Inbred NOD, Leukemia, Lymphocytic, Mice, Neoplasm/drug effects, Neoplastic/*drug effects, Piperidines/*pharmacology, Protein Kinase Inhibitors/pharmacology, Pyrazoles/*pharmacology, Pyrimidines/*pharmacology, SCID, Tumor Cells, Tumor Suppressor Protein p53/*genetics, Tumor/genetics, Xenograft Model Antitumor Assays},

pubstate = {published},

tppubtype = {article}

}

@article{kabatkova_inhibition_2015,

title = {Inhibition of β-catenin signalling promotes DNA damage elicited by benzo[a]pyrene in a model of human colon cancer cells via CYP1 deregulation.},

author = {Markéta Kabátková and Ondřej Zapletal and Zuzana Tylichová and Jiří Neča and Miroslav Machala and Alena Milcová and Jan Topinka and Alois Kozubík and Jan Vondráček},

doi = {10.1093/mutage/gev019},

issn = {1464-3804 0267-8357},

year  = {2015},

date = {2015-07-01},

journal = {Mutagenesis},

volume = {30},

number = {4},

pages = {565–576},

abstract = {Deregulation of Wnt/β-catenin signalling plays an important role in the pathogenesis of colorectal cancer. Interestingly, this pathway has been recently implicated in transcriptional control of cytochrome P450 (CYP) family 1 enzymes, which are responsible for bioactivation of a number of dietary carcinogens. In the present study, we investigated the impact of inhibition of Wnt/β-catenin pathway on metabolism and genotoxicity of benzo[a]pyrene (BaP), a highly mutagenic polycyclic aromatic hydrocarbon and an efficient ligand of the aryl hydrocarbon receptor, which is known as a primary regulator of CYP1 expression, in cellular models derived from colorectal tumours. We observed that a synthetic inhibitor of β-catenin, JW74, significantly increased formation of BaP-induced DNA adducts in both colorectal adenoma and carcinoma-derived cell lines. Using the short interfering RNA (siRNA) targeting β-catenin, we then found that β-catenin knockdown in HCT116 colon carcinoma cells significantly enhanced formation of covalent DNA adducts by BaP and histone H2AX phosphorylation, as detected by (32)P-postlabelling technique and immunocytochemistry, respectively, and it also induced expression of DNA damage response genes, such as CDKN1A or DDB2. The increased formation of DNA adducts formed by BaP upon β-catenin knockdown corresponded with enhanced production of major BaP metabolites, as well as with an increased expression/activity of CYP1 enzymes. Finally, using siRNA-mediated knockdown of CYP1A1, we confirmed that this enzyme plays a major role in formation of BaP-induced DNA adducts in HCT116 cells. Taken together, the present results indicated that the siRNA-mediated inhibition of β-catenin signalling, which is aberrantly activated in a majority of colorectal cancers, modulated genotoxicity of dietary carcinogen BaP in colon cell model in vitro, via a mechanism involving up-regulation of CYP1 expression and activity.},

note = {Place: England},

keywords = {*DNA Damage, Apoptosis, Aryl Hydrocarbon/genetics/metabolism, Benzo(a)pyrene/*adverse effects, beta Catenin/*antagonists & inhibitors/genetics/metabolism, Blotting, Carcinogens, Cell Proliferation, Colonic Neoplasms/drug therapy/*etiology/*pathology, Cultured, Cytochrome P-450 CYP1A1/antagonists & inhibitors/genetics/*metabolism, DNA Adducts/*adverse effects, Environmental/adverse effects, Enzymologic/*drug effects, Gene Expression Regulation, Humans, Immunoenzyme Techniques, Messenger/genetics, Neoplastic/*drug effects, Real-Time Polymerase Chain Reaction, Receptors, Reverse Transcriptase Polymerase Chain Reaction, RNA, Small Interfering/genetics, Tumor Cells, Western},

pubstate = {published},

tppubtype = {article}

}

@article{palkova_aryl_2015,

title = {The aryl hydrocarbon receptor-mediated and genotoxic effects of fractionated extract of standard reference diesel exhaust particle material in pulmonary, liver and prostate cells.},

author = {Lenka Pálková and Jan Vondráček and Lenka Trilecová and Miroslav Ciganek and Kateřina Pěnčíková and Jiří Neča and Alena Milcová and Jan Topinka and Miroslav Machala},

doi = {10.1016/j.tiv.2014.12.002},

issn = {1879-3177 0887-2333},

year  = {2015},

date = {2015-04-01},

journal = {Toxicology in vitro : an international journal published in association with BIBRA},

volume = {29},

number = {3},

pages = {438–448},

abstract = {Diesel exhaust particles (DEP) and the associated complex mixtures of organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), or their derivatives, have been suggested to exert deleterious effects on human health. We used a set of defined cellular models representing liver, lung and prostate tissues, in order to compare non-genotoxic and genotoxic effects of crude and fractionated extract of a standard reference DEP material - SRM 1650b. We focused on the aryl hydrocarbon receptor (AhR)-mediated activity, modulation of cell proliferation, formation of DNA adducts, oxidative DNA damage, and induction of DNA damage responses, including evaluation of apoptosis, and phosphorylation of p53 tumor suppressor and checkpoint kinases (Chk). Both PAHs and the polar aromatic compounds contributed to the AhR-mediated activity of DEP-associated organic pollutants. The principal identified AhR agonists included benzo[k]fluoranthene, indeno[1,2,3-c,d]pyrene, chrysene and several non-priority PAHs, including benzochrysenes and methylated PAHs. In contrast to PAHs, polar compounds contributed more significantly to overall formation of DNA adducts associated with phosphorylation of p53, Chk1 or Chk2, and partly with apoptosis. Therefore, more attention should be paid to identification of DEP-associated polar organic compounds, contributing to the AhR activation and cytotoxic/genotoxic effects of complex airborne mixtures of organic contaminants produced by diesel engines.},

note = {Place: England},

keywords = {Air Pollutants/*toxicity, Air pollution, Animals, Apoptosis, Apoptosis/drug effects, Aryl Hydrocarbon/*drug effects, Cell Cycle/drug effects, Cell Death/drug effects, Cell Proliferation, DNA adducts, DNA Damage, DNA damage response, Liver/*pathology, Lung/*pathology, Male, Mutagens/*toxicity, PAHs, Particulate Matter/*toxicity, Prostate/*pathology, Rats, Receptors, SRM 1650b, Vehicle Emissions/*toxicity},

pubstate = {published},

tppubtype = {article}

}

@article{kabatkova_interactive_2015,

title = {Interactive effects of inflammatory cytokine and abundant low-molecular-weight PAHs on inhibition of gap junctional intercellular communication, disruption of cell proliferation control, and the AhR-dependent transcription.},

author = {Markéta Kabátková and Jana Svobodová and Kateřina Pěnčíková and Dilshad Shaik Mohatad and Lenka Šmerdová and Alois Kozubík and Miroslav Machala and Jan Vondráček},

doi = {10.1016/j.toxlet.2014.09.023},

issn = {1879-3169 0378-4274},

year  = {2015},

date = {2015-01-01},

journal = {Toxicology letters},

volume = {232},

number = {1},

pages = {113–121},

abstract = {Polycyclic aromatic hydrocarbons (PAHs) with lower molecular weight exhibit lesser genotoxicity and carcinogenicity than highly carcinogenic PAHs with a higher number of benzene rings. Nevertheless, they elicit specific effects linked with tumor promotion, such as acute inhibition of gap junctional intercellular communication (GJIC). Although inflammatory reaction may alter bioactivation and toxicity of carcinogenic PAHs, little is known about the impact of pro-inflammatory cytokines on toxic effects of the low-molecular-weight PAHs. Here, we investigated the impact of a pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α), on the effects associated with tumor promotion and with induction of the aryl hydrocarbon receptor (AhR)-dependent gene expression in rat liver epithelial cells. We found that a prolonged incubation with TNF-α induced a down-regulation of GJIC, associated with reduced expression of connexin 43 (Cx43), a major connexin isoform found in liver epithelial cells. The Cx43 down-regulation was partly mediated by the activity of the mitogen-activated protein (MAP) p38 kinase. Independently of GJIC modulation, or p38 activation, TNF-α potentiated the AhR-dependent proliferative effect of a model low-molecular-weight PAH, fluoranthene, on contact-inhibited cells. In contrast, this pro-inflammatory cytokine repressed the fluoranthene-induced expression of a majority of model AhR gene targets, such as Cyp1a1, Ahrr or Tiparp. The results of the present study indicate that inflammatory reaction may differentially modulate various toxic effects of low-molecular-weight PAHs; the exposure to pro-inflammatory cytokines may both strengthen (inhibition of GJIC, disruption of contact inhibition) and repress (expression of a majority of AhR-dependent genes) their impact on toxic endpoints associated with carcinogenesis.},

note = {Place: Netherlands},

keywords = {Animals, Aryl hydrocarbon receptor, Aryl Hydrocarbon/*agonists/genetics/metabolism, Basic Helix-Loop-Helix Transcription Factors/*agonists/genetics/metabolism, Cell Communication/*drug effects, Cell Line, Cell Proliferation, Cell Proliferation/*drug effects, Cell Transformation, Connexin 43/genetics/metabolism, Dose-Response Relationship, Drug, Enzyme Activation, Epithelial Cells/*drug effects/metabolism/pathology, Fluorenes/*toxicity, Gap junctions, Gap Junctions/*drug effects/metabolism/pathology, Gene Expression Regulation/drug effects, Genetic/*drug effects, Inflammation, Inflammation/chemically induced/genetics/metabolism/pathology, Liver Neoplasms/chemically induced/metabolism/pathology, Liver/*drug effects/metabolism/pathology, Molecular Weight, Neoplastic/chemically induced/metabolism/pathology, p38 Mitogen-Activated Protein Kinases/metabolism, PAHs, Rats, Receptors, Signal Transduction/drug effects, Time Factors, Transcription, Tumor Necrosis Factor-alpha/*toxicity},

pubstate = {published},

tppubtype = {article}

}

@article{prochazkova_aryl_2013,

title = {Aryl hydrocarbon receptor negatively regulates expression of the plakoglobin gene (jup).},

author = {Jiřina Procházková and Markéta Kabátková and Lenka Šmerdová and Jiří Pacherník and Dominika Sykorová and Jiří Kohoutek and Pavlína Šimečková and Eva Hrubá and Alois Kozubík and Miroslav Machala and Jan Vondráček},

doi = {10.1093/toxsci/kft110},

issn = {1096-0929},

year  = {2013},

date = {2013-08-01},

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

volume = {134},

number = {2},

pages = {258–270},

abstract = {Plakoglobin is an important component of intercellular junctions, including both desmosomes and adherens junctions, which is known as a tumor suppressor. Although mutations in the plakoglobin gene (Jup) and/or changes in its protein levels have been observed in various disease states, including cancer progression or cardiovascular defects, the information about endogenous or exogenous stimuli orchestrating Jup expression is limited. Here we show that the aryl hydrocarbon receptor (AhR) may regulate Jup expression in a cell-specific manner. We observed a significant suppressive effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a model toxic exogenous activator of the AhR signaling, on Jup expression in a variety of experimental models derived from rodent tissues, including contact-inhibited rat liver progenitor cells (where TCDD induces cell proliferation), rat and mouse hepatoma cell models (where TCDD inhibits cell cycle progression), cardiac cells derived from the mouse embryonic stem cells, or cardiomyocytes isolated from neonatal rat hearts. The small interfering RNA (siRNA)-mediated knockdown of AhR confirmed its role in both basal and TCDD-deregulated Jup expression. The analysis of genomic DNA located textasciitilde2.5kb upstream of rat Jup gene revealed a presence of evolutionarily conserved AhR binding motifs, which were confirmed upon their cloning into luciferase reporter construct. The siRNA-mediated knockdown of Jup expression affected both proliferation and attachment of liver progenitor cells. The present data indicate that the AhR may contribute to negative regulation of Jup gene expression in rodent cellular models, which may affect cell adherence and proliferation.},

note = {Place: United States},

keywords = {Animals, Aryl hydrocarbon receptor, Aryl Hydrocarbon/*physiology, Base Sequence, cardiomyocytes., Cell Adhesion, Cell Line, Cell Proliferation, Cloning, desmosomes, dioxin, DNA Primers, Down-Regulation, gamma Catenin/*genetics, Gene Expression Regulation/*physiology, Genetic, Inbred F344, liver progenitor cells, Molecular, plakoglobin, Polychlorinated Dibenzodioxins/pharmacology, Promoter Regions, Rats, Real-Time Polymerase Chain Reaction, Receptors},

pubstate = {published},

tppubtype = {article}

}

@article{andrysik_aryl_2013,

title = {Aryl hydrocarbon receptor-mediated disruption of contact inhibition is associated with connexin43 downregulation and inhibition of gap junctional intercellular communication.},

author = {Zdeněk Andrysík and Jiřina Procházková and Markéta Kabátková and Lenka Umannová and Pavlína Simečková and Jiří Kohoutek and Alois Kozubík and Miroslav Machala and Jan Vondráček},

doi = {10.1007/s00204-012-0963-7},

issn = {1432-0738 0340-5761},

year  = {2013},

date = {2013-03-01},

journal = {Archives of toxicology},

volume = {87},

number = {3},

pages = {491–503},

abstract = {The aryl hydrocarbon receptor (AhR) contributes to the control of cell-to-cell communication, cell adhesion, migration or proliferation. In the present study, we investigated the regulation of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) during the AhR-dependent disruption of contact inhibition in non-tumorigenic liver epithelial cells. The contact inhibition of cell proliferation is a process restricting the cell division of confluent non-transformed cells, which is frequently abolished in cancer cells; however, the mechanisms contributing to its disruption are still only partially understood. Disruption of contact inhibition, which was induced by toxic AhR ligands 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or polycyclic aromatic hydrocarbons in epithelial WB-F344 cells, reduced Cx43 protein levels, possibly via enhanced proteasomal degradation, significantly decreased the amount of gap junction plaques and downregulated GJIC, in an AhR-dependent manner. Although both intracellular and membrane Cx43 pools were markedly reduced in cells released from contact inhibition by TCDD, siRNA-mediated Cx43 knock-down was not sufficient to stimulate proliferation in contact-inhibited cells. Our data suggest that downregulation of Cx43/GJIC in non-transformed epithelial cells is an inherent part of disruption of contact inhibition, which occurs at the post-transcriptional level. This process runs in parallel with alterations of other forms of cell-to-cell communication, thus suggesting that toxic AhR agonists may simultaneously abrogate contact inhibition and reduce GJIC, two essential mechanisms linked to deregulation of cell-to-cell communication during tumor promotion and progression.},

note = {Place: Germany},

keywords = {Animals, Aryl Hydrocarbon/*agonists/genetics/metabolism, Benz(a)Anthracenes/toxicity, Carcinogens/*toxicity, Cell Communication/*drug effects, Cell Line, Cell Proliferation, Cell Transformation, Connexin 43/genetics/*metabolism, Contact Inhibition/*drug effects, Dose-Response Relationship, Down-Regulation, Drug, Epithelial Cells/*drug effects/metabolism/pathology, Fluorenes/toxicity, Gap Junctions/*drug effects/metabolism/pathology, Gene Knockdown Techniques, Indoles/pharmacology, Ligands, Liver Neoplasms/chemically induced/metabolism/pathology, Liver/*drug effects/metabolism/pathology, Neoplastic/chemically induced/metabolism/pathology, Phloroglucinol/analogs & derivatives/pharmacology, Phosphorylation, Polychlorinated Dibenzodioxins/toxicity, Proteasome Endopeptidase Complex/metabolism, Rats, Receptors, RNA Interference, Signal Transduction/*drug effects, Time Factors, Transfection},

pubstate = {published},

tppubtype = {article}

}

@article{starsichova_tgf-beta1_2010,

title = {TGF-beta1 suppresses IL-6-induced STAT3 activation through regulation of Jak2 expression in prostate epithelial cells.},

author = {Andrea Starsíchová and Eva Lincová and Zuzana Pernicová and Alois Kozubík and Karel Soucek},

doi = {10.1016/j.cellsig.2010.06.014},

issn = {1873-3913 0898-6568},

year  = {2010},

date = {2010-11-01},

journal = {Cellular signalling},

volume = {22},

number = {11},

pages = {1734–1744},

abstract = {Chronic inflammation plays an important role in the initiation and progression of various human diseases including benign prostatic hyperplasia or prostate cancer. Here we show that the proinflammatory cytokine interleukin-6 (IL-6) has prosurvival effects and chronically activates the Jak2/STAT3 signalling pathway in a model of benign prostatic hyperplasia (BPH-1). We demonstrate that the antiinflammatory cytokine transforming growth factor-beta1 (TGF-beta1), which also permanently activates its canonical signalling pathway through SMAD proteins in BPH-1 cells, modifies the effects of IL-6 on cell proliferation. Importantly, TGF-beta1 inhibits IL-6 signal transduction by decreasing the phosphorylation levels of STAT3. This effect is associated with decreased expression of Jak2 at both mRNA and protein levels. Moreover, we showed that TGF-beta1 inhibits IL-6-induced expression of the cancer-associated gene MUC1. These observations demonstrated a novel interaction between TGF-beta1 and IL-6 signalling and suggested another mechanism of how defects in TGF-beta signalling, frequently associated with prostate pathologies, can contribute to the disruption of tissue homeostasis.},

note = {Place: England},

keywords = {Cell Line, Cell Proliferation, Epithelial Cells/*metabolism, Humans, Interleukin-6/*antagonists & inhibitors/pharmacology, Janus Kinase 2/genetics/*metabolism, Male, Mucin-1/metabolism, Phosphorylation, Prostate/cytology/enzymology/*metabolism, Prostatic Hyperplasia/enzymology/*metabolism, RNA, RNA Interference, Signal Transduction, Smad Proteins/metabolism, Small Interfering/metabolism, STAT3 Transcription Factor/*metabolism, Transforming Growth Factor beta1/*pharmacology},

pubstate = {published},

tppubtype = {article}

}