1
|
Kobets T, Hickey C, Johnson G, Duan JD, Etter S, Smith B, Williams GM. Assessment of no-observed-effect-levels for DNA adducts formation by genotoxic carcinogens in fetal turkey livers. Toxicology 2024; 501:153714. [PMID: 38141718 DOI: 10.1016/j.tox.2023.153714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/08/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023]
Abstract
For genotoxic carcinogens, covalent binding to DNA is a critical initiating event in tumorigenesis. The present research investigated dose-effect relationships of three genotoxic carcinogens representing different structural classes, 2-acetylaminofluorene (2-AAF), benzo[a]pyrene (B[a]P) and quinoline (QUI), to assess the existence of no-observed-effect-levels (NOELs) for the formation of DNA adducts. Carcinogens were administered into the air sac of fertilized turkey eggs over wide dose ranges in three daily injections on days 22 to 24 of incubation. DNA adducts were measured in the fetal turkey livers by the 32P-nucleotide postlabeling (NPL) assay. B[a]P and QUI produced DNA adducts in a dosage-related manner and exhibited NOELs at 0.65 and 0.35 mg/kg bw/day, respectively. In contrast, 2-AAF formed DNA adducts at all tested dosages down to 0.005 mg/kg bw/day. Benchmark dose (BMD) analysis identified the potencies of 2-AAF and QUI to be similar, while B[a]P was the least potent compound. Overall, findings in fetal turkey livers demonstrated that exposure levels to genotoxic compounds that do not result in DNA adducts can exist but are not evident with all carcinogens of this type. The use of mechanistic dose-effect studies for genotoxic endpoints can provide critical information for prioritization of concerns for risk assessment.
Collapse
Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA.
| | | | | | - Jian-Dong Duan
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
| | | | - Benjamin Smith
- Monell Chemical Senses Center, Philadelphia, PA 19104, USA
| | - Gary M Williams
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
| |
Collapse
|
2
|
Davidsen JM, Cohen SM, Eisenbrand G, Fukushima S, Gooderham NJ, Guengerich FP, Hecht SS, Rietjens IMCM, Rosol TJ, Harman CL, Taylor SV. FEMA GRAS assessment of derivatives of basil, nutmeg, parsley, tarragon and related allylalkoxybenzene-containing natural flavor complexes. Food Chem Toxicol 2023; 175:113646. [PMID: 36804339 DOI: 10.1016/j.fct.2023.113646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/18/2023]
Abstract
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients in food. In this publication, tenth in the series, NFCs containing a high percentage of at least one naturally occurring allylalkoxybenzene constituent with a suspected concern for genotoxicity and/or carcinogenicity are evaluated. In a related paper, ninth in the series, NFCs containing anethole and/or eugenol and relatively low percentages of these allylalkoxybenzenes are evaluated. The Panel applies the threshold of toxicological concern (TTC) concept and evaluates relevant toxicology data on the NFCs and their respective constituent congeneric groups. For NFCs containing allylalkoxybenzene constituent(s), the estimated intake of the constituent is compared to the TTC for compounds with structural alerts for genotoxicity and when exceeded, a margin of exposure (MOE) is calculated. BMDL10 values are derived from benchmark dose analyses using Bayesian model averaging for safrole, estragole and methyl eugenol using EPA's BMDS software version 3.2. BMDL10 values for myristicin, elemicin and parsley apiole were estimated by read-across using relative potency factors. Margins of safety for each constituent congeneric group and MOEs for each allylalkoxybenzene constituent for each NFC were determined that indicate no safety concern. The scope of the safety evaluation contained herein does not include added use in dietary supplements or any products other than food. Ten NFCs, derived from basil, estragon (tarragon), mace, nutmeg, parsley and Canadian snakeroot were determined or affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavor ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
Collapse
Affiliation(s)
- Jeanne M Davidsen
- Flavor and Extract Manufacturers Association, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA
| | - Samuel M Cohen
- Havlik-Wall Professor of Oncology, Dept. of Pathology and Microbiology, University of Nebraska Medical Center, 983135 Nebraska Medical Center, Omaha, NE, 68198-3135, USA
| | - Gerhard Eisenbrand
- University of Kaiserslautern, Germany (Retired), Kühler Grund 48/1, 69126, Heidelberg, Germany
| | - Shoji Fukushima
- Japan Bioassay Research Center, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan
| | - Nigel J Gooderham
- Dept. of Metabolism, Digestion, Reproduction, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, United Kingdom
| | - F Peter Guengerich
- Dept. of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA
| | - Stephen S Hecht
- Masonic Cancer Center and Dept. of Laboratory Medicine and Pathology, Cancer and Cardiovascular Research Building, 2231 6th St, S.E, Minneapolis, MN, 55455, USA
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 6708 WE, Wageningen, the Netherlands
| | - Thomas J Rosol
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, 1 Ohio University, Athens, OH, 45701, USA
| | - Christie L Harman
- Flavor and Extract Manufacturers Association, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA
| | - Sean V Taylor
- Scientific Secretary to the FEMA Expert Panel, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA.
| |
Collapse
|
3
|
Kobets T, Smith BPC, Williams GM. Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk. Foods 2022; 11:foods11182828. [PMID: 36140952 PMCID: PMC9497933 DOI: 10.3390/foods11182828] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.
Collapse
Affiliation(s)
- Tetyana Kobets
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
- Correspondence: ; Tel.: +1-914-594-3105; Fax: +1-914-594-4163
| | - Benjamin P. C. Smith
- Future Ready Food Safety Hub, Nanyang Technological University, Singapore 639798, Singapore
| | - Gary M. Williams
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA
| |
Collapse
|
4
|
Ara T, Nisa WU, Anjum M, Riaz L, Saleem AR, Hayat MT. Hexachlorocyclohexane toxicity in water bodies of Pakistan: challenges and possible reclamation technologies. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2021; 83:2345-2362. [PMID: 34032614 DOI: 10.2166/wst.2021.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pakistan is an agro-economy country where hexachlorocyclohexane (HCH) pesticides are being used to improve crop productivity, as a result the risk of contamination of soil and sediment has been increased. HCH exhibits all the characteristics of persistent organic pollutants (POP), and was therefore added to the list of 'new POPs' in 2009. This review report revealed that the major rivers of Pakistan such as the Indus Basin, River Ravi, River Chenab and their tributaries all are contaminated with HCH and the highest residual concentration (4,090 ng/g) was detected in a pesticide burial ground in Hyderabad city. Major sources of HCH contamination were identified as agricultural runoff, discharge of untreated industrial effluents and surface runoff. In order to manage HCH pollution, various ex-situ and in-situ remediation techniques along with their merits and demerits are thoroughly reviewed. Among these, microbial bioremediation is a low cost, environment friendly, effective in-situ remediation technique for remediation of HCH. Overall, the information provided in this manuscript will provide a future reference to the scientific community and bridge the knowledge gap between HCH release in the environment and their mitigation through proper treatment methods.
Collapse
Affiliation(s)
- Talat Ara
- Department of Environmental Science, International Islamic University Islamabad, Islamabad, Pakistan
| | - Waqar-Un Nisa
- Center for Interdisciplinary Research in Basic Sciences (SA-CIRBS), International Islamic University Islamabad, Islamabad, Pakistan
| | - Muzammil Anjum
- Department of Environmental Sciences, PMAS Arid Agriculture University, Rawalpindi 46300, Pakistan and School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou, China E-mail: ;
| | - Luqman Riaz
- College of Life Sciences, Henan Normal University, Xinxiang, China and Department of Environmental Sciences, University of Narowal, Narowal, Pakistan
| | - Aansa Rukya Saleem
- Department of Earth and Environmental Sciences, Bahria University, Islamabad, Pakistan
| | - Malik Tahir Hayat
- Department of Environmental Sciences, COMSATS Institute of Information and Technology, Abbotabad 22010, Pakistan
| |
Collapse
|
5
|
Hartwig A, Arand M, Epe B, Guth S, Jahnke G, Lampen A, Martus HJ, Monien B, Rietjens IMCM, Schmitz-Spanke S, Schriever-Schwemmer G, Steinberg P, Eisenbrand G. Mode of action-based risk assessment of genotoxic carcinogens. Arch Toxicol 2020; 94:1787-1877. [PMID: 32542409 PMCID: PMC7303094 DOI: 10.1007/s00204-020-02733-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B1, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
Collapse
Affiliation(s)
- Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany.
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zurich, Switzerland
| | - Bernd Epe
- Institute of Pharmacy and Biochemistry, University of Mainz, 55099, Mainz, Germany
| | - Sabine Guth
- Department of Toxicology, IfADo-Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund, Ardeystr. 67, 44139, Dortmund, Germany
| | - Gunnar Jahnke
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Alfonso Lampen
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Hans-Jörg Martus
- Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Bernhard Monien
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Henkestr. 9-11, 91054, Erlangen, Germany
| | - Gerlinde Schriever-Schwemmer
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany
| | - Gerhard Eisenbrand
- Retired Senior Professor for Food Chemistry and Toxicology, Kühler Grund 48/1, 69126, Heidelberg, Germany.
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Review of the evidence for thresholds for DNA-Reactive and epigenetic experimental chemical carcinogens. Chem Biol Interact 2019; 301:88-111. [DOI: 10.1016/j.cbi.2018.11.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/06/2018] [Accepted: 11/22/2018] [Indexed: 01/01/2023]
|
8
|
Braakhuis HM, Slob W, Olthof ED, Wolterink G, Zwart EP, Gremmer ER, Rorije E, van Benthem J, Woutersen R, van der Laan JW, Luijten M. Is current risk assessment of non-genotoxic carcinogens protective? Crit Rev Toxicol 2018; 48:500-511. [PMID: 29745287 DOI: 10.1080/10408444.2018.1458818] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Non-genotoxic carcinogens (NGTXCs) do not cause direct DNA damage but induce cancer via other mechanisms. In risk assessment of chemicals and pharmaceuticals, carcinogenic risks are determined using carcinogenicity studies in rodents. With the aim to reduce animal testing, REACH legislation states that carcinogenicity studies are only allowed when specific concerns are present; risk assessment of compounds that are potentially carcinogenic by a non-genotoxic mode of action is usually based on subchronic toxicity studies. Health-based guidance values (HBGVs) of NGTXCs may therefore be based on data from carcinogenicity or subchronic toxicity studies depending on the legal framework that applies. HBGVs are usually derived from No-Observed-Adverse-Effect-Levels (NOAELs). Here, we investigate whether current risk assessment of NGTXCs based on NOAELs is protective against cancer. To answer this question, we estimated Benchmark doses (BMDs) for carcinogenicity data of 44 known NGTXCs. These BMDs were compared to the NOAELs derived from the same carcinogenicity studies, as well as to the NOAELs derived from the associated subchronic studies. The results lead to two main conclusions. First, a NOAEL derived from a subchronic study is similar to a NOAEL based on cancer effects from a carcinogenicity study, supporting the current practice in REACH. Second, both the subchronic and cancer NOAELs are, on average, associated with a cancer risk of around 1% in rodents. This implies that for those chemicals that are potentially carcinogenic in humans, current risk assessment of NGTXCs may not be completely protective against cancer. Our results call for a broader discussion within the scientific community, followed by discussions among risk assessors, policy makers, and other stakeholders as to whether or not the potential cancer risk levels that appear to be associated with currently derived HBGVs of NGXTCs are acceptable.
Collapse
Affiliation(s)
- Hedwig M Braakhuis
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Wout Slob
- b Centre for Nutrition, Prevention and Health services , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Evelyn D Olthof
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Gerrit Wolterink
- b Centre for Nutrition, Prevention and Health services , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Edwin P Zwart
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Eric R Gremmer
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Emiel Rorije
- c Centre for Safety of Substances and Products , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Jan van Benthem
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| | - Ruud Woutersen
- d Netherlands Organization for Applied Scientific Research (TNO) , Zeist , The Netherlands
| | | | - Mirjam Luijten
- a Centre for Health Protection , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands
| |
Collapse
|
9
|
Williams GM, Kobets T, Duan JD, Iatropoulos MJ. Assessment of DNA Binding and Oxidative DNA Damage by Acrylonitrile in Two Rat Target Tissues of Carcinogenicity: Implications for the Mechanism of Action. Chem Res Toxicol 2017; 30:1470-1480. [DOI: 10.1021/acs.chemrestox.7b00105] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gary M. Williams
- Chemical Safety Program,
Department of Pathology, New York Medical College, Valhalla, New York 10595, United States
| | - Tetyana Kobets
- Chemical Safety Program,
Department of Pathology, New York Medical College, Valhalla, New York 10595, United States
| | - Jian-Dong Duan
- Chemical Safety Program,
Department of Pathology, New York Medical College, Valhalla, New York 10595, United States
| | - Michael J. Iatropoulos
- Chemical Safety Program,
Department of Pathology, New York Medical College, Valhalla, New York 10595, United States
| |
Collapse
|
10
|
Carcinogenicity and mode of action evaluation for alpha-hexachlorocyclohexane: Implications for human health risk assessment. Regul Toxicol Pharmacol 2016; 76:152-73. [DOI: 10.1016/j.yrtph.2015.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 01/30/2023]
|
11
|
Luisier R, Unterberger EB, Goodman JI, Schwarz M, Moggs J, Terranova R, van Nimwegen E. Computational modeling identifies key gene regulatory interactions underlying phenobarbital-mediated tumor promotion. Nucleic Acids Res 2014; 42:4180-95. [PMID: 24464994 PMCID: PMC3985636 DOI: 10.1093/nar/gkt1415] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gene regulatory interactions underlying the early stages of non-genotoxic carcinogenesis are poorly understood. Here, we have identified key candidate regulators of phenobarbital (PB)-mediated mouse liver tumorigenesis, a well-characterized model of non-genotoxic carcinogenesis, by applying a new computational modeling approach to a comprehensive collection of in vivo gene expression studies. We have combined our previously developed motif activity response analysis (MARA), which models gene expression patterns in terms of computationally predicted transcription factor binding sites with singular value decomposition (SVD) of the inferred motif activities, to disentangle the roles that different transcriptional regulators play in specific biological pathways of tumor promotion. Furthermore, transgenic mouse models enabled us to identify which of these regulatory activities was downstream of constitutive androstane receptor and β-catenin signaling, both crucial components of PB-mediated liver tumorigenesis. We propose novel roles for E2F and ZFP161 in PB-mediated hepatocyte proliferation and suggest that PB-mediated suppression of ESR1 activity contributes to the development of a tumor-prone environment. Our study shows that combining MARA with SVD allows for automated identification of independent transcription regulatory programs within a complex in vivo tissue environment and provides novel mechanistic insights into PB-mediated hepatocarcinogenesis.
Collapse
Affiliation(s)
- Raphaëlle Luisier
- Discovery and Investigative Safety, Novartis Institutes for Biomedical Research, 4057 Basel, Switzerland, Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Tübingen, 72074 Tübingen, Germany, Department of Pharmacology and Toxicology, Michigan State University, MI 48824, USA and Biozentrum, University of Basel and Swiss Institute of Bioinformatics, 4056 Basel, Switzerland
| | | | | | | | | | | | | |
Collapse
|
12
|
Marone PA, Hall WC, Hayes AW. Reassessing the two-year rodent carcinogenicity bioassay: a review of the applicability to human risk and current perspectives. Regul Toxicol Pharmacol 2013; 68:108-18. [PMID: 24287155 DOI: 10.1016/j.yrtph.2013.11.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 11/15/2013] [Accepted: 11/17/2013] [Indexed: 12/16/2022]
Abstract
The 2-year rodent carcinogenicity test has been the regulatory standard for the prediction of human outcomes for exposure to industrial and agro-chemicals, food additives, pharmaceuticals and environmental pollutants for over 50 years. The extensive experience and data accumulated over that time has spurred a vigorous debate and assessment, particularly over the last 10 years, of the usefulness of this test in terms of cost and time for the information obtained. With renewed interest in the United States and globally, plus new regulations in the European Union, to reduce, refine and replace sentinel animals, this review offers the recommendation that reliance on information obtained from detailed shorter-term, 6 months rodent studies, combined with genotoxicity and chemical mode of action can realize effective prediction of human carcinogenicity instead of the classical two year rodent bioassay. The aim of carcinogenicity studies should not be on the length of time, and by obligation, number of animals expended but on the combined systemic pathophysiologic influence of a suspected chemical in determining disease. This perspective is in coordination with progressive regulatory standards and goals globally to utilize effectively resources of animal usage, time and cost for the goal of human disease predictability.
Collapse
Affiliation(s)
| | - William C Hall
- Hall Consulting, Inc., 110 Shady Brook Circle #300, St. Simons Island, GA 31522, USA.
| | - A Wallace Hayes
- Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA.
| |
Collapse
|
13
|
Enzmann H, Brunnemann K, Iatropoulos M, Shpyleva S, Lukyanova N, Todor I, Moore M, Spicher K, Chekhun V, Tsuda H, Williams G. Inter-laboratory comparison of turkey in ovo carcinogenicity assessment (IOCA) of hepatocarcinogens. ACTA ACUST UNITED AC 2013; 65:729-35. [DOI: 10.1016/j.etp.2012.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 08/03/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
|
14
|
Bomhard EM, Gelbke HP, Schenk H, Williams GM, Cohen SM. Evaluation of the carcinogenicity of gallium arsenide. Crit Rev Toxicol 2013; 43:436-66. [DOI: 10.3109/10408444.2013.792329] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
15
|
Thompson CM, Proctor DM, Suh M, Haws LC, Kirman CR, Harris MA. Assessment of the mode of action underlying development of rodent small intestinal tumors following oral exposure to hexavalent chromium and relevance to humans. Crit Rev Toxicol 2013; 43:244-74. [PMID: 23445218 PMCID: PMC3604738 DOI: 10.3109/10408444.2013.768596] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/16/2013] [Accepted: 01/17/2013] [Indexed: 12/13/2022]
Abstract
Abstract Chronic exposure to high concentrations of hexavalent chromium (Cr(VI)) in drinking water causes intestinal adenomas and carcinomas in mice, but not in rats. Cr(VI) causes damage to intestinal villi and crypt hyperplasia in mice after only one week of exposure. After two years of exposure, intestinal damage and crypt hyperplasia are evident in mice (but not rats), as are intestinal tumors. Although Cr(VI) has genotoxic properties, these findings suggest that intestinal tumors in mice arise as a result of chronic mucosal injury. To better understand the mode of action (MOA) of Cr(VI) in the intestine, a 90-day drinking water study was conducted to collect histological, biochemical, toxicogenomic and pharmacokinetic data in intestinal tissues. Using MOA analyses and human relevance frameworks proposed by national and international regulatory agencies, the weight of evidence supports a cytotoxic MOA with the following key events: (a) absorption of Cr(VI) from the intestinal lumen, (b) toxicity to intestinal villi, (c) crypt regenerative hyperplasia and (d) clonal expansion of mutations within the crypt stem cells, resulting in late onset tumorigenesis. This article summarizes the data supporting each key event in the MOA, as well as data that argue against a mutagenic MOA for Cr(VI)-induced intestinal tumors.
Collapse
|
16
|
Paini A, Punt A, Scholz G, Gremaud E, Spenkelink B, Alink G, Schilter B, van Bladeren PJ, Rietjens IM. In vivo validation of DNA adduct formation by estragole in rats predicted by physiologically based biodynamic modelling. Mutagenesis 2012; 27:653-63. [DOI: 10.1093/mutage/ges031] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
17
|
Paini A, Scholz G, Marin-Kuan M, Schilter B, O'Brien J, van Bladeren PJ, Rietjens IMCM. Quantitative comparison between in vivo DNA adduct formation from exposure to selected DNA-reactive carcinogens, natural background levels of DNA adduct formation and tumour incidence in rodent bioassays. Mutagenesis 2011; 26:605-18. [PMID: 21642616 DOI: 10.1093/mutage/ger022] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This study aimed at quantitatively comparing the occurrence/formation of DNA adducts with the carcinogenicity induced by a selection of DNA-reactive genotoxic carcinogens. Contrary to previous efforts, we used a very uniform set of data, limited to in vivo rat liver studies in order to investigate whether a correlation can be obtained, using a benchmark dose (BMD) approach. Dose-response data on both carcinogenicity and in vivo DNA adduct formation were available for six compounds, i.e. 2-acetylaminofluorene, aflatoxin B1, methyleugenol, safrole, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline and tamoxifen. BMD(10) values for liver carcinogenicity were calculated using the US Environmental Protection Agency BMD software. DNA adduct levels at this dose were extrapolated assuming linearity of the DNA adduct dose response. In addition, the levels of DNA adducts at the BMD(10) were compared to available data on endogenous background DNA damage in the target organ. Although for an individual carcinogen the tumour response increases when adduct levels increase, our results demonstrate that when comparing different carcinogens, no quantitative correlation exists between the level of DNA adduct formation and carcinogenicity. These data confirm that the quantity of DNA adducts formed by a DNA-reactive compound is not a carcinogenicity predictor but that other factors such as type of adduct and mutagenic potential may be equally relevant. Moreover, comparison to background DNA damage supports the notion that the mere occurrence of DNA adducts above or below the level of endogenous DNA damage is neither correlated to development of cancer. These data strongly emphasise the need to apply the mode of action framework to understand the contribution of other biological effect markers playing a role in carcinogenicity.
Collapse
Affiliation(s)
- Alicia Paini
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
18
|
A review of mammalian carcinogenicity study design and potential effects of alternate test procedures on the safety evaluation of food ingredients. Regul Toxicol Pharmacol 2011; 60:S1-34. [DOI: 10.1016/j.yrtph.2010.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 10/04/2010] [Indexed: 11/22/2022]
|
19
|
Carmichael N, Bausen M, Boobis AR, Cohen SM, Embry M, Fruijtier-Pölloth C, Greim H, Lewis R, Bette Meek ME, Mellor H, Vickers C, Doe J. Using mode of action information to improve regulatory decision-making: an ECETOC/ILSI RF/HESI workshop overview. Crit Rev Toxicol 2011; 41:175-86. [PMID: 21401325 DOI: 10.3109/10408444.2010.541225] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), the International Life Sciences Institute (ILSI) Research Foundation (RF), and the ILSI Health and Environmental Sciences Institute (HESI) hosted a workshop in November 2009 to review current practice in the application of mode of action (MOA) considerations in chemical risk assessment. The aim was to provide a rationale for a more general, but flexible approach and to propose steps to facilitate broader uptake and use of the MOA concept. There was consensus amongst the workshop participants that it will require substantial effort and cooperation from the multiple disciplines involved to embrace a common, consistent, and transparent approach. Setting up a repository of accepted MOAs and associated guidance concerning appropriate data to support specific MOAs for critical effects would facilitate categorization of chemicals and allow predictions of toxicity outcomes by read-across. This should in future contribute to the reduction of toxicity testing in animals. The workshop participants also acknowledged the value and importance of human data and the importance of integrating information from biological pathway analyses into current MOA/human relevance frameworks.
Collapse
Affiliation(s)
- Neil Carmichael
- European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), Brussels, Belgium.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Rietjens IMCM, Louisse J, Punt A. Tutorial on physiologically based kinetic modeling in molecular nutrition and food research. Mol Nutr Food Res 2011; 55:941-56. [DOI: 10.1002/mnfr.201000655] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 11/11/2022]
|
21
|
Mally A, Graff C, Schmal O, Moro S, Hamberger C, Schauer UM, Brück J, Özden S, Sieber M, Steger U, Schrenk D, Hard GC, Chipman JK, Dekant W. Functional and proliferative effects of repeated low-dose oral administration of furan in rat liver. Mol Nutr Food Res 2010; 54:1556-67. [DOI: 10.1002/mnfr.201000064] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
22
|
Thompson CM, Haws LC, Harris MA, Gatto NM, Proctor DM. Application of the U.S. EPA mode of action Framework for purposes of guiding future research: a case study involving the oral carcinogenicity of hexavalent chromium. Toxicol Sci 2010; 119:20-40. [PMID: 20947717 PMCID: PMC3003834 DOI: 10.1093/toxsci/kfq320] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mode of action (MOA) analysis provides a systematic description of key events leading to adverse health effects in animal bioassays for the purpose of informing human health risk assessment. Uncertainties and data gaps identified in the MOA analysis may also be used to guide future research to improve understanding of the MOAs underlying a specific toxic response and foster development of toxicokinetic and toxicodynamic models. An MOA analysis, consistent with approaches outlined in the MOA Framework as described in the Guidelines for Carcinogen Risk Assessment, was conducted to evaluate small intestinal tumors observed in mice chronically exposed to relatively high concentrations of hexavalent chromium (Cr(VI)) in drinking water. Based on review of the literature, key events in the MOA are hypothesized to include saturation of the reductive capacity of the upper gastrointestinal tract, absorption of Cr(VI) into the intestinal epithelium, oxidative stress and inflammation, cell proliferation, direct and/or indirect DNA modification, and mutagenesis. Although available data generally support the plausibility of these key events, several unresolved questions and data gaps were identified, highlighting the need for obtaining critical toxicokinetic and toxicodynamic data in the target tissue and in the low-dose range. Experimental assays that can address these data gaps are discussed along with strategies for comparisons between responsive and nonresponsive tissues and species. This analysis provides a practical application of MOA Framework guidance and is instructive for the design of studies to improve upon the information available for quantitative risk assessment.
Collapse
|
23
|
Rietjens IMCM, Al Huseiny W, Boersma MG. Flavonoids and alkenylbenzenes: New concepts in bioactivation studies. Chem Biol Interact 2010; 192:87-95. [PMID: 20863818 DOI: 10.1016/j.cbi.2010.09.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 09/08/2010] [Accepted: 09/14/2010] [Indexed: 11/30/2022]
Abstract
The present paper focuses on the biological reactive intermediates formed from two categories of botanical ingredients: flavonoids and alkenylbenzenes. The paper especially presents an overview of three concepts in bioactivation studies on flavonoids and alkenylbenzenes elucidated by our recent studies. These new concepts include (i) the fact that reactive electrophilic quinone/quinone methide type metabolites of flavonoids may be the intermediates required for the induction of the beneficial gene expression through electrophile responsive element (EpRE)-mediated pathways, pointing at a possible beneficial effect of a reactive intermediate, (ii) the development of physiologically based kinetic (PBK) and physiologically based dynamic (PBD) models providing a new way to obtain insight in levels of formation of biologically reactive and unstable intermediates in vivo at high but also more realistic low dose levels, and (iii) the concept of the matrix effect that should be taken into account when studying the bioactivation of food-borne genotoxic carcinogens including the alkenylbenzenes, the bioactivation of which was shown to be inhibited by flavonoids. Together the results presented reveal that by studying the mode of action (MOA) new concepts in bioactivation studies of importance for future risk assessment and/or risk-benefit assessment of the flavonoids and alkenylbenzenes are obtained.
Collapse
Affiliation(s)
- Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE, Wageningen, The Netherlands.
| | | | | |
Collapse
|
24
|
Risk assessment of carcinogens in food. Toxicol Appl Pharmacol 2010; 243:180-90. [DOI: 10.1016/j.taap.2009.11.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 10/31/2009] [Accepted: 11/04/2009] [Indexed: 11/18/2022]
|