2015
Kabátková, Markéta; Svobodová, Jana; Pěnčíková, Kateřina; Mohatad, Dilshad Shaik; Šmerdová, Lenka; Kozubík, Alois; Machala, Miroslav; Vondráček, Jan
In: Toxicology letters, vol. 232, no. 1, pp. 113–121, 2015, ISSN: 1879-3169 0378-4274, (Place: Netherlands).
Abstract | Links | BibTeX | Tags: 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
@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}
}
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.
2013
Andrysík, Zdeněk; Procházková, Jiřina; Kabátková, Markéta; Umannová, Lenka; Simečková, Pavlína; Kohoutek, Jiří; Kozubík, Alois; Machala, Miroslav; Vondráček, Jan
In: Archives of toxicology, vol. 87, no. 3, pp. 491–503, 2013, ISSN: 1432-0738 0340-5761, (Place: Germany).
Abstract | Links | BibTeX | Tags: 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
@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}
}
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.