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Kobets T, Duan JD, Vock E, Deschl U, Williams GM. Evaluation of Pharmaceuticals for DNA Damage in the Chicken Egg Genotoxicity Assay (CEGA). Int J Toxicol 2022; 41:297-311. [PMID: 35658642 DOI: 10.1177/10915818221093583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
DNA damage is an established initiating event in the mutagenicity and carcinogenicity of genotoxic chemicals. Accordingly, assessment of this endpoint is critical for chemicals which are being developed for use in humans. To assess the ability of the Chicken Egg Genotoxicity Assay (CEGA) to detect genotoxic pharmaceuticals, a set of 23 compounds with different pharmacological and reported genotoxic effects was tested for the potential to produce nuclear DNA adducts and strand breaks in the embryo-fetal livers using the 32P-nucleotide postlabeling (NPL) and comet assays, respectively. Due to high toxicity, two aneugens, colchicine and vinblastine, and an autophagy inhibitor, hydroxychloroquine, could not be evaluated. Out of the 20 remaining pharmaceuticals, 10 including estrogen modulators, diethylstilbestrol and tamoxifen, antineoplastics cyclophosphamide, etoposide, and mitomycin C, antifungal griseofulvin, local anesthetics lidocaine and prilocaine, and antihistamines diphenhydramine and doxylamine, yielded clear positive outcomes in at least one of the assays. The antihypertensive vasodilator hydralazine and antineoplastics streptozotocin and teniposide, produced only DNA strand breaks, which were not dose-dependent, and thus, the results with these 3 pharmaceuticals were considered equivocal. No DNA damage was detected for 7 compounds, including the purine antagonist 6-thioguanine, antipyretic analgesics acetaminophen and phenacetin, antibiotic ciprofloxacin, antilipidemic clofibrate, anti-inflammatory ibuprofen, and sedative phenobarbital. However, low solubility of these compounds limited dosages tested in CEGA. Overall, results in CEGA were largely in concordance with the outcomes in other systems in vitro and in vivo, indicating that CEGA provides reliable detection of DNA damaging activity of genotoxic compounds. Further evaluations with a broader set of compounds would support this conclusion.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Immunology and Microbiology, 8137New York Medical College, Valhalla, NY, USA
| | - Jian-Dong Duan
- Department of Pathology, Immunology and Microbiology, 8137New York Medical College, Valhalla, NY, USA
| | - Esther Vock
- Boehringer Ingelheim Pharma GmbH&Co. KG, Biberach an der Riss, Germany
| | - Ulrich Deschl
- Boehringer Ingelheim Pharma GmbH&Co. KG, Biberach an der Riss, Germany
| | - Gary M Williams
- Department of Pathology, Immunology and Microbiology, 8137New York Medical College, Valhalla, NY, USA
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Alhamdow A, Essig YJ, Krais AM, Gustavsson P, Tinnerberg H, Lindh CH, Hagberg J, Graff P, Albin M, Broberg K. Fluorene exposure among PAH-exposed workers is associated with epigenetic markers related to lung cancer. Occup Environ Med 2020; 77:488-495. [PMID: 32385190 PMCID: PMC7306866 DOI: 10.1136/oemed-2020-106413] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/02/2020] [Accepted: 04/05/2020] [Indexed: 01/03/2023]
Abstract
Objectives Exposure to high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) may cause cancer in chimney sweeps and creosote-exposed workers, however, knowledge about exposure to low-molecular-weight PAHs in relation to cancer risk is limited. In this study, we aimed to investigate occupational exposure to the low-molecular-weight PAHs phenanthrene and fluorene in relation to different cancer biomarkers. Methods We recruited 151 chimney sweeps, 19 creosote-exposed workers and 152 unexposed workers (controls), all men. We measured monohydroxylated metabolites of phenanthrene and fluorene in urine using liquid chromatography coupled to tandem mass spectrometry. We measured, in peripheral blood, the cancer biomarkers telomere length and mitochondrial DNA copy number using quantitative PCR; and DNA methylation of F2RL3 and AHRR using pyrosequencing. Results Median PAH metabolite concentrations were higher among chimney sweeps (up to 3 times) and creosote-exposed workers (up to 353 times), compared with controls (p<0.001; adjusted for age and smoking). ∑OH-fluorene (sum of 2-hydroxyfluorene and 3-hydroxyfluorene) showed inverse associations with percentage DNA methylation of F2RL3 and AHRR in chimney sweeps (B (95% CI)=–2.7 (–3.9 to –1.5) for F2RL3_cg03636183, and –7.1 (–9.6 to –4.7) for AHRR_cg05575921: adjusted for age and smoking), but not in creosote-exposed workers. In addition, ∑OH-fluorene showed a 42% mediation effect on the inverse association between being a chimney sweep and DNA methylation of AHRR CpG2. Conclusions Chimney sweeps and creosote-exposed workers were occupationally exposed to low-molecular-weight PAHs. Increasing fluorene exposure, among chimney sweeps, was associated with lower DNA methylation of F2RL3 and AHRR, markers for increased lung cancer risk. These findings warrant further investigation of fluorene exposure and toxicity.
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Affiliation(s)
- Ayman Alhamdow
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Yona J Essig
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
| | - Annette M Krais
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
| | - Per Gustavsson
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.,Region Stockholm, Centre for Occupational and Environmental Medicine, Stockholm, Sweden
| | - Håkan Tinnerberg
- School of Public Health and Community Medicine, Section of Occupational and Environmental Medicine, University of Gothenburg Sahlgrenska Academy, Göteborg, Sweden
| | - Christian H Lindh
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
| | - Jessika Hagberg
- MTM Research Centre, Örebro universitet Akademin för Naturvetenskap och Teknik, Orebro, Sweden.,Department of Occupational and Environmental Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
| | - Pål Graff
- Department of Chemical and Biological Work Environment, STAMI, Oslo, Norway
| | - Maria Albin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.,Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden.,Region Stockholm, Centre for Occupational and Environmental Medicine, Stockholm, Sweden
| | - Karin Broberg
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden .,Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
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Kobets T, Iatropoulos MJ, Duan JD, Brunnemann KD, Iacobas DA, Iacobas S, Vock E, Deschl U, Williams GM. Expression of Genes Encoding for Xenobiotic Metabolism After Exposure to Dialkylnitrosamines in the Chicken Egg Genotoxicity Alternative Model. Toxicol Sci 2019; 166:82-96. [PMID: 30102407 DOI: 10.1093/toxsci/kfy197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The Chicken Egg Genotoxicity Assay (CEGA) demonstrated responsiveness to various DNA-reactive chemicals requiring metabolic activation, which implies broad bioactivation capability. To assess potential metabolic competence, expression profiles of metabolic genes in the embryo-chicken fetal liver were determined using microarray technology. Fertilized chicken eggs were injected under the CEGA protocol with vehicle (deionized water [DW]), the activation-dependent carcinogens, diethylnitrosamine (DEN), and N-nitrosodiethanolamine (NDELA) at doses producing no effect on survival. Previously in CEGA, DEN produced DNA damage, whereas NDELA did not. Expressions of 463 genes known to encode for phase I and II of endo- and xenobiotic metabolism were detected on the array. DW did not affect the expression of the selected genes, deregulating less than 1% of them. In contrast, DEN at 2 mg/egg and NDELA at 4 mg/egg produced significant transcriptomic alterations, up-regulating up to 41% and down-regulating over 31% of studied genes. Both nitrosamines modulated the majority of the genes in a similar manner, sharing 64 up-regulated and 93 down-regulated genes with respect to control group, indicating similarity in the regulation of their metabolism by avian liver. Differences in gene expression between DEN and NDELA were documented for several phase I CYP 450 genes that are responsible for nitrosamine biotransformation, as well as for phase II genes that regulate detoxication reactions. These findings could underlie the difference in genotoxicity of DEN and NDELA in CEGA. In conclusion, the analysis of gene expression profiles in embryo-chicken fetal liver dosed with dialkylnitrosamines demonstrated that avian species possess a complex array of inducible genes coding for biotransformation.
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Affiliation(s)
- Tetyana Kobets
- Department of Pthology, New York Medical College, Valhalla, New York 10595
| | | | - Jiandong D Duan
- Department of Pthology, New York Medical College, Valhalla, New York 10595
| | - Klaus D Brunnemann
- Department of Pthology, New York Medical College, Valhalla, New York 10595
| | - Dumitru A Iacobas
- Center for Computational Systems Biology, Prairie View A&M University, Prairie View, Texas 77446
| | - Sanda Iacobas
- Department of Pthology, New York Medical College, Valhalla, New York 10595
| | - Esther Vock
- Boehringer Ingelheim Pharma GmbH&Co. KG, Biberach an der Riss, Germany 88397
| | - Ulrich Deschl
- Boehringer Ingelheim Pharma GmbH&Co. KG, Biberach an der Riss, Germany 88397
| | - Gary M Williams
- Department of Pthology, New York Medical College, Valhalla, New York 10595
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Kobets T, Duan JD, Brunnemann KD, Vock E, Deschl U, Williams GM. DNA-damaging activities of twenty-four structurally diverse unsubstituted and substituted cyclic compounds in embryo-fetal chicken livers. Mutat Res 2019; 844:10-24. [PMID: 31326031 DOI: 10.1016/j.mrgentox.2019.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/28/2019] [Accepted: 06/13/2019] [Indexed: 01/28/2023]
Abstract
DNA-damaging activities of twenty-four structurally diverse unsubstituted and substituted cyclic compounds were assessed in embryo-fetal chicken livers. Formation of DNA adducts and strand breaks were measured using the nucleotide 32P-postlabelling (NPL) and comet assays, respectively. Unsubstituted monocyclic benzene, polycyclic fused ring compound naphthalene, covalently connected polycyclic ring compound biphenyl, and heterocyclic ring compound fluorene did not produce DNA damage. Amino-substituted monocyclic compounds, aniline and p-phenylenediamine, as well as polycyclic 1-naphthylamine were also negative. In contrast, carcinogenic monocyclic methyl-substituted anilines: o-toluidine, 2,6-xylidine, 3,4-dimethylaniline, 4-chloro-o-toluidine; 2 methoxy-substituted methylaniline: p-cresidine; 2,4 and 2,6 diamino- or dinitro- substituted toluenes all produced DNA damage. Genotoxic polycyclic amino-substituted 2-naphthylamine, 4-aminobiphenyl, benzidine, methyl-substituted 3,2'-dimethyl-4-aminobiphenyl and 4-dimethylaminoazobenzene as well as amino- and nitro- fluorenes substituted at the 1 or 2 positions also were positive in at least one of the assays. Overall, the DNA damaging activity of cyclic compounds in embryo-fetal chicken livers reflected the type and position of the substitution on the aromatic ring. Additionally, substituted polycyclic compounds exhibited higher DNA-damaging potency compared to monocyclic chemicals. These results are congruent with in vivo findings in other species, establishing chicken eggs as a reliable system for structure-activity assessment of members of groups of related chemicals.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Jian-Dong Duan
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Klaus D Brunnemann
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
| | - Esther Vock
- Boehringer Ingelheim Pharma GmbH & Co, Biberach an der Riss, Germany.
| | - Ulrich Deschl
- Boehringer Ingelheim Pharma GmbH & Co, Biberach an der Riss, Germany.
| | - Gary M Williams
- Department of Pathology, New York Medical College, Valhalla, NY, 10595, USA.
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Kobets T, Iatropoulos MJ, Williams GM. Mechanisms of DNA-reactive and epigenetic chemical carcinogens: applications to carcinogenicity testing and risk assessment. Toxicol Res (Camb) 2019; 8:123-145. [PMID: 30997017 PMCID: PMC6417487 DOI: 10.1039/c8tx00250a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 12/18/2018] [Indexed: 01/03/2023] Open
Abstract
Chemicals with carcinogenic activity in either animals or humans produce increases in neoplasia through diverse mechanisms. One mechanism is reaction with nuclear DNA. Other mechanisms consist of epigenetic effects involving either modifications of regulatory macromolecules or perturbation of cellular regulatory processes. The basis for distinguishing between carcinogens that have either DNA reactivity or an epigenetic activity as their primary mechanism of action is detailed in this review. In addition, important applications of information on these mechanisms of action to carcinogenicity testing and human risk assessment are discussed.
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Affiliation(s)
- Tetyana Kobets
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
| | - Michael J Iatropoulos
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
| | - Gary M Williams
- Department of Pathology , New York Medical College , Valhalla , NY 10595 , USA . ; ; Tel: +1 914-594-3105
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