Latest Publications

@article{simeckova_vitro_2022,

title = {In vitro profiling of toxic effects of environmental polycyclic aromatic hydrocarbons on nuclear receptor signaling, disruption of endogenous metabolism and induction of cellular stress.},

author = {Pavlína Šimečková and Kateřina Pěnčíková and Ondrej Kováč and Josef Slavík and Martina Pařenicová and Jan Vondráček and Miroslav Machala},

doi = {10.1016/j.scitotenv.2021.151967},

issn = {1879-1026 0048-9697},

year  = {2022},

date = {2022-04-01},

journal = {The Science of the total environment},

volume = {815},

pages = {151967},

abstract = {Polycyclic aromatic hydrocarbons (PAHs) may interact with multiple intracellular receptors and related signaling pathways. We comprehensively evaluated the toxicity profiles of six environmentally relevant PAHs differing in structure, genotoxicity and their ability to activate the aryl hydrocarbon receptor (AhR). We focused particularly on their impact on intracellular hormone-, xenobiotic- and lipid-sensing receptors, as well as on cellular stress markers, combining a battery of human reporter gene assays and qRT-PCR evaluation of endogenous gene expression in human hepatocyte-like HepaRG cells, with LC/MS-MS analysis of cellular sphingolipids. The effects of PAHs included: activation of estrogen receptor α (in case of fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), benzo[a]pyrene (BaP)), suppression of androgen receptor activity (Fla, BaA, BaP and benzo[k]fluoranthene (BkF)), enhancement of dexamethasone-induced glucocorticoid receptor activity (chrysene (Chry), BaA, and BaP), and potentiation of triiodothyronine-induced thyroid receptor α activity (all tested PAHs). PAHs also induced transcription of endogenous gene targets of constitutive androstane receptor (Fla, Pyr), or repression of target genes of pregnane X receptor and peroxisome proliferator-activated receptor α (in case of the AhR-activating PAHs - Chry, BaA, BaP, and BkF) in HepaRG cells. In the same cell model, the AhR agonists reduced the expression of glucose metabolism genes (PCK1, G6PC and PDK4), and they up-regulated levels of glucosylceramides, together with a concomitant induction of expression of UGCG, glucosylceramide synthesis enzyme. Finally, both BaP and BkF were found to induce expression of early stress and genotoxicity markers: ATF3, EGR1, GDF15, CDKN1A/p21, and GADD45A mRNAs, while BaP alone increased levels of IL-6 mRNA. Overall, whereas low-molecular-weight PAHs exerted significant effects on nuclear receptors (with CYP2B6 induction observed already at nanomolar concentrations), the AhR activation by 4-ring and 5-ring PAHs appeared to be a key mechanism underlying their impact on nuclear receptor signaling, endogenous metabolism and induction of early stress and genotoxicity markers.},

note = {Place: Netherlands},

keywords = {*Polycyclic Aromatic Hydrocarbons/toxicity, Aryl Hydrocarbon/genetics/metabolism, Benzo(a)pyrene, Cellular stress response, Cytoplasmic and Nuclear/genetics, Energy Metabolism, Humans, Nuclear receptors, Polycyclic aromatic hydrocarbons, Receptors, Signal Transduction, Sphingolipids, Xenobiotics},

pubstate = {published},

tppubtype = {article}

}

@article{zapletal_butyrate_2019,

title = {Butyrate interacts with benzo[a]pyrene to alter expression and activities of xenobiotic metabolizing enzymes involved in metabolism of carcinogens within colon epithelial cell models.},

author = {Ondřej Zapletal and Jiřina Procházková and Vít Dubec and Jiřina Hofmanová and Alois Kozubík and Jan Vondráček},

doi = {10.1016/j.tox.2018.11.001},

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

year  = {2019},

date = {2019-01-01},

journal = {Toxicology},

volume = {412},

pages = {1–11},

abstract = {Butyrate helps to maintain colon homeostasis and exhibits chemopreventive effects in colon epithelium. We examined the interactive effects of butyrate and benzo[a]pyrene (BaP), dietary carcinogen, in regulation of expression of a panel of phase I and II xenobiotic metabolizing enzymes (XMEs) in human colon cells. In human colon carcinoma HCT-116 and HT-29 cell lines, butyrate alone increased mRNA levels of some enzymes, such as N-acetyltransferases (in particular NAT2). In combination with BaP, butyrate potentiated induction of cytochrome P450 family 1 enzymes (CYP1A1), aldo-keto reductases (AKR1C1) or UDP-glucuronosyltransferases (UGT1A1). There were some notable differences between cell lines, as butyrate potentiated induction of NAD(P)H:quinone oxidoreductase 1 (NQO1) and UGT1A4 only in HCT-116 cells, and it even repressed AKR1C3 induction in HT-29 cells. Butyrate also promoted induction of CYP1, NQO1, NAT2, UGT1A1 or UGT1A4 in human colon Caco-2 cells, in a differentiation-dependent manner. Differentiated Caco-2 cells exhibited a higher inducibility of selected XME genes than undifferentiated cells. Butyrate increased induction of enzymatic activities of NATs, NQO1 and UGTs by BaP in HCT-116 and HT29 cells, whereas in differentiated Caco-2 cells it helped to increase only enzymatic activity of NQO1 and UGTs. Together, the present data suggest that butyrate may modulate expression/activities of several enzymes involved in metabolism of carcinogens in colon. In some cases (NAT2, UGT1 A1), this was linked to inhibition of histone deacetylases (HDAC), as confirmed by using HDAC inhibitor trichostatin A. These results may have implications for our understanding of the role of butyrate in regulation of XMEs and carcinogen metabolism in colon.},

note = {Place: Ireland},

keywords = {Benzo(a)pyrene/*toxicity, Butyrate, Butyrates/*pharmacology, Carcinogens/*toxicity, Cell Line, Colon epithelium, Colon/cytology, Epithelial Cells/drug effects/metabolism, Humans, N-acetyltransferases, NAD(P)H:quinone oxidoreductase 1, Oxidoreductases/genetics/*metabolism, Polycyclic aromatic hydrocarbons, Transferases/genetics/*metabolism, UDP-glucuronosyltransferases, Xenobiotics/metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{zapletal_butyrate_2017,

title = {Butyrate alters expression of cytochrome P450 1A1 and metabolism of benzo[a]pyrene via its histone deacetylase activity in colon epithelial cell models.},

author = {Ondřej Zapletal and Zuzana Tylichová and Jiří Neča and Jiří Kohoutek and Miroslav Machala and Alena Milcová and Michaela Pokorná and Jan Topinka and Mary Pat Moyer and Jiřina Hofmanová and Alois Kozubík and Jan Vondráček},

doi = {10.1007/s00204-016-1887-4},

issn = {1432-0738 0340-5761},

year  = {2017},

date = {2017-05-01},

journal = {Archives of toxicology},

volume = {91},

number = {5},

pages = {2135–2150},

abstract = {Butyrate, a short-chain fatty acid produced by fermentation of dietary fiber, is an important regulator of colonic epithelium homeostasis. In this study, we investigated the impact of this histone deacetylase (HDAC) inhibitor on expression/activity of cytochrome P450 family 1 (CYP1) and on metabolism of carcinogenic polycyclic aromatic hydrocarbon, benzo[a]pyrene (BaP), in colon epithelial cells. Sodium butyrate (NaBt) strongly potentiated the BaP-induced expression of CYP1A1 in human colon carcinoma HCT116 cells. It also co-stimulated the 7-ethoxyresorufin-O-deethylase (EROD) activity induced by the 2,3,7,8-tetrachlorodibenzo-p-dioxin, a prototypical ligand of the aryl hydrocarbon receptor. Up-regulation of CYP1A1 expression/activity corresponded with an enhanced metabolism of BaP and formation of covalent DNA adducts. NaBt significantly potentiated CYP1A1 induction and/or metabolic activation of BaP also in other human colon cell models, colon adenoma AA/C1 cells, colon carcinoma HT-29 cells, or in NCM460D cell line derived from normal colon mucosa. Our results suggest that the effects of NaBt were due to its impact on histone acetylation, because additional HDAC inhibitors (trichostatin A and suberanilohydroxamic acid) likewise increased both the induction of EROD activity and formation of covalent DNA adducts. NaBt-induced acetylation of histone H3 (at Lys14) and histone H4 (at Lys16), two histone modifications modulated during activation of CYP1A1 transcription, and it reduced binding of HDAC1 to the enhancer region of CYP1A1 gene. This in vitro study suggests that butyrate, through modulation of histone acetylation, may potentiate induction of CYP1A1 expression, which might in turn alter the metabolism of BaP within colon epithelial cells.},

note = {Place: Germany},

keywords = {Benzo(a)pyrene/metabolism/*pharmacokinetics, beta Catenin/metabolism, Butyrate, Butyric Acid/*pharmacology, Colon epithelial cells, Colon/*drug effects/metabolism, CYP1A1, Cytochrome P-450 CYP1A1/genetics/*metabolism, DNA adducts, DNA Adducts/drug effects/metabolism, Enhancer Elements, Genetic/drug effects, HCT116 Cells, Histone Deacetylase 1/antagonists & inhibitors/metabolism, Histone Deacetylase Inhibitors/pharmacology, Histone deacetylases, Histones/metabolism, HT29 Cells, Humans, Inactivation, Metabolic, Polycyclic aromatic hydrocarbons},

pubstate = {published},

tppubtype = {article}

}

@article{smerdova_inflammatory_2013,

title = {Inflammatory mediators accelerate metabolism of benzo[a]pyrene in rat alveolar type II cells: the role of enhanced cytochrome P450 1B1 expression.},

author = {Lenka Smerdová and Jiří Neča and Jana Svobodová and Jan Topinka and Jana Schmuczerová and Alois Kozubík and Miroslav Machala and Jan Vondráček},

doi = {10.1016/j.tox.2013.09.001},

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

year  = {2013},

date = {2013-12-01},

journal = {Toxicology},

volume = {314},

number = {1},

pages = {30–38},

abstract = {Long-term deregulated inflammation represents one of the key factors contributing to lung cancer etiology. Previously, we have observed that tumor necrosis factor-α (TNF-α), a major pro-inflammatory cytokine, enhances genotoxicity of benzo[a]pyrene (B[a]P), a highly carcinogenic polycyclic aromatic hydrocarbon, in rat lung epithelial RLE-6TN cells, a model of alveolar type II cells. Therefore, we analyzed B[a]P metabolism in RLE-6TN cells under inflammatory conditions, simulated using either recombinant TNF-α, or a mixture of inflammatory mediators derived from activated alveolar macrophage cell line. Inflammatory conditions significantly accelerated BaP metabolism, as evidenced by decreased levels of both parent B[a]P and its metabolites. TNF-α altered production of the metabolites associated with dihydrodiol-epoxide and radical cation pathways of B[a]P metabolism, especially B[a]P-dihydrodiols, and B[a]P-diones. We then evaluated the role of cytochrome P450 1B1 (CYP1B1), which is strongly up-regulated in cells treated with B[a]P under inflammatory conditions, in the observed effects. The siRNA-mediated CYP1B1 knock-down increased levels of B[a]P and reduced formation of stable DNA adducts, thus confirming the essential role of CYP1B1 in B[a]P metabolism under inflammatory conditions. TNF-α also reduced expression of aldo-keto reductase 1C14, which may compete with CYP1B1 for B[a]P-7,8-dihydrodiol and divert it from the formation of ultimate B[a]P dihydrodiol epoxide. Together, the present data suggests that the CYP1B1-catalyzed metabolism of polycyclic aromatic hydrocarbons might contribute to their enhanced bioactivation and genotoxic effects under inflammatory conditions.},

note = {Place: Ireland},

keywords = {Animals, Aryl Hydrocarbon Hydroxylases/*biosynthesis/genetics, ATP Binding Cassette Transporter, Benzo(a)pyrene/*metabolism, Blotting, Cell Line, Conditioned, Culture Media, CYP1B1, Cytochrome P-450 CYP1B1, Cytokines/metabolism, DNA adducts, Inflammation, Inflammation Mediators/*pharmacology, metabolism, Oxidoreductases Acting on Aldehyde or Oxo Group Donors/biosynthesis/genetics, Polycyclic aromatic hydrocarbons, Pulmonary Alveoli/cytology/drug effects/*metabolism, Rats, Real-Time Polymerase Chain Reaction, RNA, Small Interfering, Subfamily B/biosynthesis/genetics, Tandem Mass Spectrometry, Transfection, Western},

pubstate = {published},

tppubtype = {article}

}