2008
Umannová, Lenka; Machala, Miroslav; Topinka, Jan; Nováková, Zuzana; Milcová, Alena; Kozubík, Alois; Vondrácek, Jan
In: Mutation research, vol. 640, no. 1-2, pp. 162–169, 2008, ISSN: 0027-5107, (Place: Netherlands).
Abstract | Links | BibTeX | Tags: Animals, Aryl Hydrocarbon Hydroxylases/*metabolism, Benzo(a)pyrene/*toxicity, Cell Line, Cytochrome P-450 CYP1B1, Drug Synergism, Epithelial Cells/drug effects/enzymology, Liver/*drug effects/*enzymology, Male, Rats, Tumor Necrosis Factor-alpha/*pharmacology, Up-Regulation
@article{umannova_tumor_2008,
title = {Tumor necrosis factor-alpha potentiates genotoxic effects of benzo[a]pyrene in rat liver epithelial cells through upregulation of cytochrome P450 1B1 expression.},
author = {Lenka Umannová and Miroslav Machala and Jan Topinka and Zuzana Nováková and Alena Milcová and Alois Kozubík and Jan Vondrácek},
doi = {10.1016/j.mrfmmm.2008.02.001},
issn = {0027-5107},
year = {2008},
date = {2008-04-01},
journal = {Mutation research},
volume = {640},
number = {1-2},
pages = {162–169},
abstract = {Benzo[a]pyrene (BaP) is a ubiquitous environmental pollutant, which may contribute to the development of human cancer. The ultimate carcinogenic BaP metabolite produced by cytochrome P450 enzymes (CYP), such as CYP1A1 and CYP1B1, anti-BaP-7,8-diol-9,10-epoxide, binds covalently to DNA and causes mutations. The levels of various CYP isoforms can be significantly modulated under inflammatory conditions. As the chronic inflammation is known to contribute to carcinogenesis, we investigated interactions of a major proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), and BaP in regulation of the expression of CYP1A1/1B1 and induction of DNA damage in rat liver epithelial WB-F344 cells. TNF-alpha enhanced induction of CYP1B1, while it simultaneously suppressed the BaP-induced CYP1A1 expression. The observed deregulation of CYP1 induction was found to be associated with a significantly enhanced formation of DNA adducts. The elevated DNA damage corresponded with increased phosphorylation of p53 tumor suppressor at Ser-15 residue, enhanced accumulation of cells in the S-phase of cell cycle and potentiation of BaP-induced apoptosis. Inhibition of CYP1B1 by fluoranthene significantly decreased both the formation of DNA adducts and the induction of apoptosis in WB-F344 cells treated with BaP and TNF-alpha, thus suggesting that this isoform might be responsible for genotoxic effects of BaP in nonparenchymal liver cells. Our results seem to indicate that inflammatory conditions might enhance genotoxic effects of carcinogenic polycyclic aromatic hydrocarbons through upregulation of CYP1B1 expression.},
note = {Place: Netherlands},
keywords = {Animals, Aryl Hydrocarbon Hydroxylases/*metabolism, Benzo(a)pyrene/*toxicity, Cell Line, Cytochrome P-450 CYP1B1, Drug Synergism, Epithelial Cells/drug effects/enzymology, Liver/*drug effects/*enzymology, Male, Rats, Tumor Necrosis Factor-alpha/*pharmacology, Up-Regulation},
pubstate = {published},
tppubtype = {article}
}
Benzo[a]pyrene (BaP) is a ubiquitous environmental pollutant, which may contribute to the development of human cancer. The ultimate carcinogenic BaP metabolite produced by cytochrome P450 enzymes (CYP), such as CYP1A1 and CYP1B1, anti-BaP-7,8-diol-9,10-epoxide, binds covalently to DNA and causes mutations. The levels of various CYP isoforms can be significantly modulated under inflammatory conditions. As the chronic inflammation is known to contribute to carcinogenesis, we investigated interactions of a major proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), and BaP in regulation of the expression of CYP1A1/1B1 and induction of DNA damage in rat liver epithelial WB-F344 cells. TNF-alpha enhanced induction of CYP1B1, while it simultaneously suppressed the BaP-induced CYP1A1 expression. The observed deregulation of CYP1 induction was found to be associated with a significantly enhanced formation of DNA adducts. The elevated DNA damage corresponded with increased phosphorylation of p53 tumor suppressor at Ser-15 residue, enhanced accumulation of cells in the S-phase of cell cycle and potentiation of BaP-induced apoptosis. Inhibition of CYP1B1 by fluoranthene significantly decreased both the formation of DNA adducts and the induction of apoptosis in WB-F344 cells treated with BaP and TNF-alpha, thus suggesting that this isoform might be responsible for genotoxic effects of BaP in nonparenchymal liver cells. Our results seem to indicate that inflammatory conditions might enhance genotoxic effects of carcinogenic polycyclic aromatic hydrocarbons through upregulation of CYP1B1 expression.
2007
Umannová, Lenka; Zatloukalová, Jirina; Machala, Miroslav; Krcmár, Pavel; Májková, Zuzana; Hennig, Bernhard; Kozubík, Alois; Vondrácek, Jan
In: Toxicological sciences : an official journal of the Society of Toxicology, vol. 99, no. 1, pp. 79–89, 2007, ISSN: 1096-6080 1096-0929, (Place: United States).
Abstract | Links | BibTeX | Tags: Animals, Aryl Hydrocarbon Hydroxylases/genetics/*metabolism, Aryl Hydrocarbon/*drug effects/metabolism, Carcinogens/metabolism/toxicity, Cell Proliferation/drug effects, Cells, Cultured, Cytochrome P-450 CYP1A1/genetics/metabolism, Cytochrome P-450 CYP1B1, Dose-Response Relationship, Drug, Drug Combinations, Drug Interactions, Enzymologic/*drug effects, Epithelial Cells/drug effects/enzymology, Gene Expression Regulation, Inbred F344, Ligands, Liver/cytology, Polychlorinated Biphenyls/metabolism/*toxicity, Polychlorinated Dibenzodioxins/metabolism/*toxicity, Rats, Receptors, Stem Cells/*drug effects/enzymology, Tumor Necrosis Factor-alpha/*pharmacology
@article{umannova_tumor_2007,
title = {Tumor necrosis factor-alpha modulates effects of aryl hydrocarbon receptor ligands on cell proliferation and expression of cytochrome P450 enzymes in rat liver "stem-like" cells.},
author = {Lenka Umannová and Jirina Zatloukalová and Miroslav Machala and Pavel Krcmár and Zuzana Májková and Bernhard Hennig and Alois Kozubík and Jan Vondrácek},
doi = {10.1093/toxsci/kfm149},
issn = {1096-6080 1096-0929},
year = {2007},
date = {2007-09-01},
journal = {Toxicological sciences : an official journal of the Society of Toxicology},
volume = {99},
number = {1},
pages = {79–89},
abstract = {Various liver diseases lead to an extensive inflammatory response and release of a number of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha). This cytokine is known to play a major role in liver regeneration as well as in carcinogenesis. We investigated possible interactions of TNF-alpha with ligands of the aryl hydrocarbon receptor (AhR) and known liver carcinogens, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and coplanar 3,3',4,4',5-pentachlorobiphenyl (PCB 126). These compounds have been previously found to disrupt cell cycle control in contact-inhibited rat liver WB-F344 cells, an in vitro model of adult liver progenitor cells. TNF-alpha itself had no significant effect on the proliferation/apoptosis ratio in the WB-F344 cell line. However, it significantly potentiated proliferative effects of low picomolar range doses of both TCDD and PCB 126, leading to an increase in cell numbers, as well as an increased percentage of cells entering the S-phase of the cell cycle. The combination of TNF-alpha with low concentrations of AhR ligands increased both messenger RNA (mRNA) and protein levels of cyclin A, a principle cyclin involved in disruption of contact inhibition. TNF-alpha temporarily inhibited AhR-dependent induction of cytochrome P450 1A1 (CYP1A1). In contrast, TNF-alpha significantly enhanced induction of CYP1B1 at both mRNA and protein levels, by a mechanism, which was independent of nuclear factor-kappaB activation. These results suggest that TNF-alpha can significantly amplify effects of AhR ligands on deregulation of cell proliferation control, as well as on expression of CYP1B1, which is involved in metabolic activation of a number of mutagenic compounds.},
note = {Place: United States},
keywords = {Animals, Aryl Hydrocarbon Hydroxylases/genetics/*metabolism, Aryl Hydrocarbon/*drug effects/metabolism, Carcinogens/metabolism/toxicity, Cell Proliferation/drug effects, Cells, Cultured, Cytochrome P-450 CYP1A1/genetics/metabolism, Cytochrome P-450 CYP1B1, Dose-Response Relationship, Drug, Drug Combinations, Drug Interactions, Enzymologic/*drug effects, Epithelial Cells/drug effects/enzymology, Gene Expression Regulation, Inbred F344, Ligands, Liver/cytology, Polychlorinated Biphenyls/metabolism/*toxicity, Polychlorinated Dibenzodioxins/metabolism/*toxicity, Rats, Receptors, Stem Cells/*drug effects/enzymology, Tumor Necrosis Factor-alpha/*pharmacology},
pubstate = {published},
tppubtype = {article}
}
Various liver diseases lead to an extensive inflammatory response and release of a number of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha). This cytokine is known to play a major role in liver regeneration as well as in carcinogenesis. We investigated possible interactions of TNF-alpha with ligands of the aryl hydrocarbon receptor (AhR) and known liver carcinogens, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and coplanar 3,3',4,4',5-pentachlorobiphenyl (PCB 126). These compounds have been previously found to disrupt cell cycle control in contact-inhibited rat liver WB-F344 cells, an in vitro model of adult liver progenitor cells. TNF-alpha itself had no significant effect on the proliferation/apoptosis ratio in the WB-F344 cell line. However, it significantly potentiated proliferative effects of low picomolar range doses of both TCDD and PCB 126, leading to an increase in cell numbers, as well as an increased percentage of cells entering the S-phase of the cell cycle. The combination of TNF-alpha with low concentrations of AhR ligands increased both messenger RNA (mRNA) and protein levels of cyclin A, a principle cyclin involved in disruption of contact inhibition. TNF-alpha temporarily inhibited AhR-dependent induction of cytochrome P450 1A1 (CYP1A1). In contrast, TNF-alpha significantly enhanced induction of CYP1B1 at both mRNA and protein levels, by a mechanism, which was independent of nuclear factor-kappaB activation. These results suggest that TNF-alpha can significantly amplify effects of AhR ligands on deregulation of cell proliferation control, as well as on expression of CYP1B1, which is involved in metabolic activation of a number of mutagenic compounds.
2003
Machala, Miroslav; Bláha, Ludek; Vondrácek, Jan; Trosko, James E.; Scott, Jacob; Upham, Brad L.
In: Toxicological sciences : an official journal of the Society of Toxicology, vol. 76, no. 1, pp. 102–111, 2003, ISSN: 1096-6080 1096-0929, (Place: United States).
Abstract | Links | BibTeX | Tags: Animals, Blotting, Cell Line, Epidermal Growth Factor/toxicity, Epithelial Cells/drug effects/enzymology, Gap Junctions/*drug effects/enzymology, Liver/cytology, Mitogen-Activated Protein Kinases/metabolism, Polychlorinated Biphenyls/*toxicity, Rats, Signal Transduction/*drug effects, Sphingomyelin Phosphodiesterase/metabolism, src-Family Kinases/metabolism, Tetradecanoylphorbol Acetate/toxicity, Western
@article{machala_inhibition_2003,
title = {Inhibition of gap junctional intercellular communication by noncoplanar polychlorinated biphenyls: inhibitory potencies and screening for potential mode(s) of action.},
author = {Miroslav Machala and Ludek Bláha and Jan Vondrácek and James E. Trosko and Jacob Scott and Brad L. Upham},
doi = {10.1093/toxsci/kfg209},
issn = {1096-6080 1096-0929},
year = {2003},
date = {2003-11-01},
journal = {Toxicological sciences : an official journal of the Society of Toxicology},
volume = {76},
number = {1},
pages = {102–111},
abstract = {Polychlorinated biphenyls (PCBs), a structurally diverse group of environmental pollutants, are effective promoters in two-stage cancer models, which implies that epigenetic mechanisms are involved. Inhibition of gap junctional intercellular communication (GJIC) belongs among critical epigenetic events of tumor promotion. We determined the relative potencies of a series of environmentally relevant PCB congeners to inhibit GJIC in vitro in a rat liver epithelial cell line with pluripotent oval cell characteristics. The nonplanar PCBs were potent inhibitors of GJIC, whereas the coplanar PCBs did not inhibit GJIC. We then compared the effects of the coplanar PCB 126 (3,3',4,4',5-pentachlorobiphenyl) and the noncoplanar PCB 153 (2,2',4,4',5,5'-hexachlorobiphenyl) with effects of two model GJIC inhibitors, a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and epidermal growth factor (EGF). In contrast to TPA or EGF, PCB 153 elicited a long-term downregulation of GJIC (up to 48 h). Using Western blot analysis with phospho-specific antibodies, it was found that PCB 153, and not PCB 126, activated mitogen-activated protein kinases ERK1/2; however in contrast to TPA and EGF, this activation was observed at the time points subsequent to GJIC inhibition. Moreover, blocking of ERK1/2 activation did not prevent the GJIC inhibition induced by PCB 153. Therefore, additional intracellular signaling pathways potentially involved in the downregulation of GJIC by PCBs were screened by using specific chemical probes inhibiting serine/threonine kinases, tyrosine kinases, and phospholipases. The inhibition of diacylglycerol lipase partially blocked and the selective inhibition of Src kinases and phosphatidylcholine-specific phospholipase C (PC-PLC) completely blocked the inhibitory effects of the noncoplanar PCB on GJIC, indicating that PC-PLC or sphingomyelinase and Src might be upstream regulators of noncoplanar PCB-induced inhibition of GJIC.},
note = {Place: United States},
keywords = {Animals, Blotting, Cell Line, Epidermal Growth Factor/toxicity, Epithelial Cells/drug effects/enzymology, Gap Junctions/*drug effects/enzymology, Liver/cytology, Mitogen-Activated Protein Kinases/metabolism, Polychlorinated Biphenyls/*toxicity, Rats, Signal Transduction/*drug effects, Sphingomyelin Phosphodiesterase/metabolism, src-Family Kinases/metabolism, Tetradecanoylphorbol Acetate/toxicity, Western},
pubstate = {published},
tppubtype = {article}
}
Polychlorinated biphenyls (PCBs), a structurally diverse group of environmental pollutants, are effective promoters in two-stage cancer models, which implies that epigenetic mechanisms are involved. Inhibition of gap junctional intercellular communication (GJIC) belongs among critical epigenetic events of tumor promotion. We determined the relative potencies of a series of environmentally relevant PCB congeners to inhibit GJIC in vitro in a rat liver epithelial cell line with pluripotent oval cell characteristics. The nonplanar PCBs were potent inhibitors of GJIC, whereas the coplanar PCBs did not inhibit GJIC. We then compared the effects of the coplanar PCB 126 (3,3',4,4',5-pentachlorobiphenyl) and the noncoplanar PCB 153 (2,2',4,4',5,5'-hexachlorobiphenyl) with effects of two model GJIC inhibitors, a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and epidermal growth factor (EGF). In contrast to TPA or EGF, PCB 153 elicited a long-term downregulation of GJIC (up to 48 h). Using Western blot analysis with phospho-specific antibodies, it was found that PCB 153, and not PCB 126, activated mitogen-activated protein kinases ERK1/2; however in contrast to TPA and EGF, this activation was observed at the time points subsequent to GJIC inhibition. Moreover, blocking of ERK1/2 activation did not prevent the GJIC inhibition induced by PCB 153. Therefore, additional intracellular signaling pathways potentially involved in the downregulation of GJIC by PCBs were screened by using specific chemical probes inhibiting serine/threonine kinases, tyrosine kinases, and phospholipases. The inhibition of diacylglycerol lipase partially blocked and the selective inhibition of Src kinases and phosphatidylcholine-specific phospholipase C (PC-PLC) completely blocked the inhibitory effects of the noncoplanar PCB on GJIC, indicating that PC-PLC or sphingomyelinase and Src might be upstream regulators of noncoplanar PCB-induced inhibition of GJIC.