1
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Cohen SM. Cell proliferation and carcinogenesis: an approach to screening for potential human carcinogens. Front Oncol 2024; 14:1394584. [PMID: 38868530 PMCID: PMC11168196 DOI: 10.3389/fonc.2024.1394584] [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: 03/01/2024] [Accepted: 04/22/2024] [Indexed: 06/14/2024] Open
Abstract
Cancer arises from multiple genetic errors occurring in a single stem cell (clonality). Every time DNA replicates, mistakes occur. Thus, agents can increase the risk of cancer either by directly damaging DNA (DNA-reactive carcinogens) or increasing the number of DNA replications (increased cell proliferation). Increased cell proliferation can be achieved either by direct mitogenesis or cytotoxicity with regenerative proliferation. Human carcinogens have a mode of action of DNA reactivity, immunomodulation (mostly immunosuppression), increased estrogenic activity (mitogenesis), or cytotoxicity and regeneration. By focusing on screening for these four effects utilizing in silico, in vitro, and short-term in vivo assays, a biologically based screening for human chemical carcinogens can be accomplished with greater predictivity than the traditional 2-year bioassay with considerably less cost, less time, and the use of fewer animals.
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Affiliation(s)
- Samuel M. Cohen
- Havlik-Wall Professor of Oncology, Department of Pathology, Microbiology, and Immunology and the Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, United States
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2
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Hilton GM, Adcock C, Akerman G, Baldassari J, Battalora M, Casey W, Clippinger AJ, Cope R, Goetz A, Hayes AW, Papineni S, Peffer RC, Ramsingh D, Williamson Riffle B, Sanches da Rocha M, Ryan N, Scollon E, Visconti N, Wolf DC, Yan Z, Lowit A. Rethinking chronic toxicity and carcinogenicity assessment for agrochemicals project (ReCAAP): A reporting framework to support a weight of evidence safety assessment without long-term rodent bioassays. Regul Toxicol Pharmacol 2022; 131:105160. [PMID: 35311659 DOI: 10.1016/j.yrtph.2022.105160] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 03/07/2022] [Accepted: 03/14/2022] [Indexed: 11/17/2022]
Abstract
Rodent cancer bioassays have been long-required studies for regulatory assessment of human cancer hazard and risk. These studies use hundreds of animals, are resource intensive, and certain aspects of these studies have limited human relevance. The past 10 years have seen an exponential growth of new technologies with the potential to effectively evaluate human cancer hazard and risk while reducing, refining, or replacing animal use. To streamline and facilitate uptake of new technologies, a workgroup comprised of scientists from government, academia, non-governmental organizations, and industry stakeholders developed a framework for waiver rationales of rodent cancer bioassays for consideration in agrochemical safety assessment. The workgroup used an iterative approach, incorporating regulatory agency feedback, and identifying critical information to be considered in a risk assessment-based weight of evidence determination of the need for rodent cancer bioassays. The reporting framework described herein was developed to support a chronic toxicity and carcinogenicity study waiver rationale, which includes information on use pattern(s), exposure scenario(s), pesticidal mode-of-action, physicochemical properties, metabolism, toxicokinetics, toxicological data including mechanistic data, and chemical read-across from similar registered pesticides. The framework could also be applied to endpoints other than chronic toxicity and carcinogenicity, and for chemicals other than agrochemicals.
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Affiliation(s)
- Gina M Hilton
- PETA Science Consortium International e.V., Stuttgart, Germany.
| | - Catherine Adcock
- Health Canada, Pest Management Regulatory Agency, Ottawa, Ontario, Canada
| | - Gregory Akerman
- United States Environmental Protection Agency, Office of Pesticide Programs, Washington DC, USA
| | | | | | - Warren Casey
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | | | - Rhian Cope
- Australian Pesticides and Veterinary Medicines Authority, Armidale, New South Wales, Australia
| | - Amber Goetz
- Syngenta Crop Protection, LLC, Greensboro, NC, USA
| | - A Wallace Hayes
- University of South Florida College of Public Health, Tampa, FL, USA
| | | | | | - Deborah Ramsingh
- Health Canada, Pest Management Regulatory Agency, Ottawa, Ontario, Canada
| | | | | | - Natalia Ryan
- Syngenta Crop Protection, LLC, Greensboro, NC, USA
| | | | | | | | | | - Anna Lowit
- United States Environmental Protection Agency, Office of Pesticide Programs, Washington DC, USA
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3
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Mistry P, McInnes EF, Beevers C, Wolf D, Currie RA, Salimraj R, Parsons P. An evaluation of carcinogenicity predictors from short-term and sub chronic repeat-dose studies of agrochemicals in rats: Opportunities to refine and reduce animal use. Toxicol Lett 2021; 351:18-27. [PMID: 34364947 DOI: 10.1016/j.toxlet.2021.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/15/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
The aim of this study was to examine whether short term, repeat dose, rat studies provide sufficient information about potential carcinogenicity to enable predictions about the carcinogenic potential of agrochemicals to be made earlier in compound development. This study aimed to identify any correlations between toxicity findings obtained for short term rat studies (28 day and 90 day) and neoplastic findings obtained from 24 month rat carcinogenicity studies for agrochemical compounds (18 compounds) tested in Han Wistar and Sprague Dawley rats. The macroscopic pathology, microscopic pathology, hematology, biochemistry, organ weights, estrogen receptor activation and genotoxicity results were examined. Seven out of 18 non genotoxic compounds developed tumors in treated rats in the carcinogenicity study and of these, two compounds showed no preneoplastic findings in the affected tissues (false positives). Of the remaining five true positives, correlations were noted between corneal opacity and keratitis (90 day study) as early indicators of squamous cell carcinoma and papilloma of the cornea of the eye (compound 1, a hydroxyphenylpyruvate dioxygenase inhibitor) and inflammation of the stomach and kidney (90 day study) and gastric squamous cell papilloma and squamous cell carcinoma and renal tubular adenoma and carcinoma, respectively (compound 12, a fungicide with multisite activity). Minor decreases in uterine weight and increases in estradiol hydroxylation activity at 28 days were associated with endometrial adenocarcinoma (compound 18, a mitochondrial complex II electron transport inhibitor). Early liver weight increases and hepatocellular centrilobular hypertrophy (28 day study) were associated with thyroid follicular adenomas (compound 11, a succinate dehydrogenase inhibitor) in female animals only. Hepatic centrilobular hypertrophy (28 day studies) correlated with thyroid adenomas in males in carcinogenicity studies (compound 2, a hydroxyphenylpyruvate dioxygenase inhibitor). In contrast, treatment related, nasopharynx tumors (compound 3, an elongase inhibitor) and uterine adenocarcinoma (compound 9, a succinate dehydrogenase inhibitor) could not be correlated with findings from the short term studies examined. Eleven compounds displayed preneoplastic findings with no tumors (false negatives) and there were no compounds with no preneoplastic findings and no tumors (true negatives). This work indicates the value of examining historical, short term studies for specific, nonneoplastic findings which correlate with tumors in carcinogenicity studies, which may obviate the need for further animal carcinogenicity studies.
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Affiliation(s)
- Pratibha Mistry
- The Lenz, Hornbeam Park, Harrogate, North Yorkshire, HG2 8RE, United Kingdom
| | | | - Carol Beevers
- The Lenz, Hornbeam Park, Harrogate, North Yorkshire, HG2 8RE, United Kingdom
| | - Douglas Wolf
- Syngenta, Jealotts Hill, Bracknell, Berks, RG426EY, United Kingdom
| | - Richard A Currie
- Syngenta, Jealotts Hill, Bracknell, Berks, RG426EY, United Kingdom
| | - Rejin Salimraj
- Delphic HSE Solutions Ltd, Building B, Watchmoor Park, Camberley, Surrey, GU15 3YL, United Kingdom
| | - Paul Parsons
- The Lenz, Hornbeam Park, Harrogate, North Yorkshire, HG2 8RE, United Kingdom
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4
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Liang PI, Wang CC, Cheng HJ, Wang SS, Lin YC, Lin P, Tung CW. Curation of cancer hallmark-based genes and pathways for in silico characterization of chemical carcinogenesis. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2021; 2020:5857494. [PMID: 32539087 PMCID: PMC7294774 DOI: 10.1093/database/baaa045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 05/10/2020] [Accepted: 05/19/2020] [Indexed: 01/19/2023]
Abstract
Exposure to toxic substances in the environment is one of the most important causes of cancer. However, the time-consuming process for the identification and characterization of carcinogens is not applicable to a huge amount of testing chemicals. The data gaps make the carcinogenic risk uncontrollable. An efficient and effective way of prioritizing chemicals of carcinogenic concern with interpretable mechanism information is highly desirable. This study presents a curation work for genes and pathways associated with 11 hallmarks of cancer (HOCs) reported by the Halifax Project. To demonstrate the usefulness of the curated HOC data, the interacting HOC genes and affected HOC pathways of chemicals of the three carcinogen lists from IARC, NTP and EPA were analyzed using the in silico toxicogenomics ChemDIS system. Results showed that a higher number of affected HOCs were observed for known carcinogens than the other chemicals. The curated HOC data is expected to be useful for prioritizing chemicals of carcinogenic concern. Database URL: The HOC database is available at https://github.com/hocdb-KMU-TMU/hocdb and the website of Database journal as Supplementary Data.
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Affiliation(s)
- Peir-In Liang
- Phd Program in Toxicology, Kaohsiung Medical University, 100 Shiquan 1st Road, Kaohsiung 80706, Taiwan.,Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, 100 Ziyou 1st Road, Kaohsiung 80706, Taiwan
| | - Chia-Chi Wang
- Department and Graduate Institute of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, 1 Section 4 Roosevelt Rd, Taipei 10617, Taiwan
| | - Hsien-Jen Cheng
- National Institute of Environmental Health Sciences, National Health Research Institutes, 35 Keyan Road, Miaoli County 35053, Taiwan
| | - Shan-Shan Wang
- Graduate Institute of Data Science, College of Management, Taipei Medical University, 250 Wuxing Street, Taipei 10675, Taiwan
| | - Ying-Chi Lin
- Phd Program in Toxicology, Kaohsiung Medical University, 100 Shiquan 1st Road, Kaohsiung 80706, Taiwan.,School of Pharmacy, Kaohsiung Medical University, 100 Shiquan 1st Road, Kaohsiung 80706, Taiwan
| | - Pinpin Lin
- National Institute of Environmental Health Sciences, National Health Research Institutes, 35 Keyan Road, Miaoli County 35053, Taiwan
| | - Chun-Wei Tung
- National Institute of Environmental Health Sciences, National Health Research Institutes, 35 Keyan Road, Miaoli County 35053, Taiwan.,Graduate Institute of Data Science, College of Management, Taipei Medical University, 250 Wuxing Street, Taipei 10675, Taiwan
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5
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Heusinkveld H, Braakhuis H, Gommans R, Botham P, Corvaro M, van der Laan JW, Lewis D, Madia F, Manou I, Schorsch F, Wolterink G, Woutersen R, Corvi R, Mehta J, Luijten M. Towards a mechanism-based approach for the prediction of nongenotoxic carcinogenic potential of agrochemicals. Crit Rev Toxicol 2020; 50:725-739. [DOI: 10.1080/10408444.2020.1841732] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Harm Heusinkveld
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Hedwig Braakhuis
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Robin Gommans
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | | | | | | | | | - Federica Madia
- European Commission, Joint Research Centre (JRC), Ispra, Italy
| | - Irene Manou
- European Partnership for Alternative Approaches to Animal Testing (EPAA), Brussels, Belgium
| | | | - Gerrit Wolterink
- Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
| | - Ruud Woutersen
- TNO Quality of Life, Zeist, and Wageningen University & Research, Wageningen, the Netherlands
| | - Raffaella Corvi
- European Commission, Joint Research Centre (JRC), Ispra, Italy
| | | | - Mirjam Luijten
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
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Jacobs MN, Colacci A, Corvi R, Vaccari M, Aguila MC, Corvaro M, Delrue N, Desaulniers D, Ertych N, Jacobs A, Luijten M, Madia F, Nishikawa A, Ogawa K, Ohmori K, Paparella M, Sharma AK, Vasseur P. Chemical carcinogen safety testing: OECD expert group international consensus on the development of an integrated approach for the testing and assessment of chemical non-genotoxic carcinogens. Arch Toxicol 2020; 94:2899-2923. [PMID: 32594184 PMCID: PMC7395040 DOI: 10.1007/s00204-020-02784-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/07/2020] [Indexed: 12/26/2022]
Abstract
While regulatory requirements for carcinogenicity testing of chemicals vary according to product sector and regulatory jurisdiction, the standard approach starts with a battery of genotoxicity tests (which include mutagenicity assays). If any of the in vivo genotoxicity tests are positive, a lifetime rodent cancer bioassay may be requested, but under most chemical regulations (except plant protection, biocides, pharmaceuticals), this is rare. The decision to conduct further testing based on genotoxicity test outcomes creates a regulatory gap for the identification of non-genotoxic carcinogens (NGTxC). With the objective of addressing this gap, in 2016, the Organization of Economic Cooperation and Development (OECD) established an expert group to develop an integrated approach to the testing and assessment (IATA) of NGTxC. Through that work, a definition of NGTxC in a regulatory context was agreed. Using the adverse outcome pathway (AOP) concept, various cancer models were developed, and overarching mechanisms and modes of action were identified. After further refining and structuring with respect to the common hallmarks of cancer and knowing that NGTxC act through a large variety of specific mechanisms, with cell proliferation commonly being a unifying element, it became evident that a panel of tests covering multiple biological traits will be needed to populate the IATA. Consequently, in addition to literature and database investigation, the OECD opened a call for relevant assays in 2018 to receive suggestions. Here, we report on the definition of NGTxC, on the development of the overarching NGTxC IATA, and on the development of ranking parameters to evaluate the assays. Ultimately the intent is to select the best scoring assays for integration in an NGTxC IATA to better identify carcinogens and reduce public health hazards.
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Affiliation(s)
- Miriam N Jacobs
- Centre for Radiation, Chemical and Environmental Hazards (CRCE), Public Health England, Chilton, UK.
| | - Annamaria Colacci
- Center for Environment, Prevention and Health, Regional Agency for Prevention, Environment and Energy Emilia Romagna Region (Arpae), Bologna, Italy
| | - Raffaella Corvi
- European Commission Joint Research Centre (EC JRC), Ispra, Italy
| | - Monica Vaccari
- Center for Environment, Prevention and Health, Regional Agency for Prevention, Environment and Energy Emilia Romagna Region (Arpae), Bologna, Italy
| | | | | | - Nathalie Delrue
- Organisation for Economic Cooperation and Development (OECD), Paris, France
| | | | - Norman Ertych
- German Centre for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277, Berlin, Germany
| | - Abigail Jacobs
- US Food and Drug Administration (FDA), Silver Spring, MD, USA
| | - Mirjam Luijten
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Federica Madia
- European Commission Joint Research Centre (EC JRC), Ispra, Italy
| | | | - Kumiko Ogawa
- National Institute of Health Sciences, Kawasaki, Japan
| | - Kiyomi Ohmori
- Kanagawa Prefectural Institute of Public Health, Chigasaki, Japan
| | - Martin Paparella
- Division of Medical Biochemistry, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
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7
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Cohen SM, Zhongyu Y, Bus JS. Relevance of mouse lung tumors to human risk assessment. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2020; 23:214-241. [PMID: 32452303 DOI: 10.1080/10937404.2020.1763879] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mouse lung is a common site for chemical tumorigenicity, but the relevance to human risk remains debated. Long-term bioassays need to be assessed for appropriateness of the dose, neither exceeding Maximum Tolerated Dose (MTD) nor Kinetically based Maximum Dose (KMD). An example of the KMD issue is 1,3-dichloropropene (1,3-D), which only produced an increased incidence of lung tumors at a dose exceeding the KMD. In addition, since mouse lung tumors are common (>1% incidence), the appropriate statistical significance is p < .01. Numerous differences exist for mouse lung and tumors compared to humans, including anatomy, respiratory rate, metabolism, tumor histogenesis, and metastatic frequency. The recent demonstration of the critical role of mouse lung specific Cyp2 F2 metabolism in mouse lung carcinogenicity including styrene or fluensulfone indicates that this tumor response is not qualitatively or quantitatively relevant to humans. For non-DNA reactive and non-mutagenic carcinogens, the mode of action involves direct mitogenicity such as for isoniazid, styrene, fluensulfone, permethrin or cytotoxicity with regeneration such as for naphthalene. However, the possibility of mixed mitogenic and cytotoxic modes of action cannot always be excluded. The numerous differences between mouse and human, combined with epidemiologic evidence of no increased cancer risk for several of these chemicals make the relevance of mouse lung tumors for human cancer risk dubious.
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Affiliation(s)
- Samuel M Cohen
- Havlik-Wall Professor of Oncology, University of Nebraska Medical Center , Omaha, NE, USA
- University of Nebraska Medical Center , Omaha, NE, USA
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8
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An FDA/CDER perspective on nonclinical testing strategies: Classical toxicology approaches and new approach methodologies (NAMs). Regul Toxicol Pharmacol 2020; 114:104662. [DOI: 10.1016/j.yrtph.2020.104662] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/03/2020] [Accepted: 04/15/2020] [Indexed: 02/08/2023]
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9
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Nicolaidou V, Koufaris C. Application of transcriptomic and microRNA profiling in the evaluation of potential liver carcinogens. Toxicol Ind Health 2020; 36:386-397. [PMID: 32419640 DOI: 10.1177/0748233720922710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hepatocarcinogens are agents that increase the incidence of liver cancer in exposed animals or humans. It is now established that carcinogenic exposures have a widespread impact on the transcriptome, inducing both adaptive and adverse changes in the activities of genes and pathways. Chemical hepatocarcinogens have also been shown to affect expression of microRNA (miRNA), the evolutionarily conserved noncoding RNA that regulates gene expression posttranscriptionally. Considerable effort has been invested into examining the involvement of mRNA in chemical hepatocarcinogenesis and their potential usage for the classification and prediction of new chemical entities. For miRNA, there has been an increasing number of studies reported over the past decade, although not to the same degree as for transcriptomic studies. Current data suggest that it is unlikely that any gene or miRNA signature associated with short-term carcinogen exposure can replace the rodent bioassay. In this review, we discuss the application of transcriptomic and miRNA profiles to increase mechanistic understanding of chemical carcinogens and to aid in their classification.
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Affiliation(s)
- Vicky Nicolaidou
- Department of Life and Health Sciences, University of Nicosia, Nicosia, Cyprus
| | - Costas Koufaris
- Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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10
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Gooderham NJ, Cohen SM, Eisenbrand G, Fukushima S, Guengerich FP, Hecht SS, Rietjens IMCM, Rosol TJ, Bastaki M, Linman MJ, Taylor SV. The safety evaluation of food flavoring substances: the role of genotoxicity studies. Crit Rev Toxicol 2020; 50:1-27. [PMID: 32162576 DOI: 10.1080/10408444.2020.1712589] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Flavor and Extract Manufacturers Association (FEMA) Expert Panel relies on the weight of evidence from all available data in the safety evaluation of flavoring substances. This process includes data from genotoxicity studies designed to assess the potential of a chemical agent to react with DNA or otherwise cause changes to DNA, either in vitro or in vivo. The Panel has reviewed a large number of in vitro and in vivo genotoxicity studies during the course of its ongoing safety evaluations of flavorings. The adherence of genotoxicity studies to standardized protocols and guidelines, the biological relevance of the results from those studies, and the human relevance of these studies are all important considerations in assessing whether the results raise specific concerns for genotoxic potential. The Panel evaluates genotoxicity studies not only for evidence of genotoxicity hazard, but also for the probability of risk to the consumer in the context of exposure from their use as flavoring substances. The majority of flavoring substances have given no indication of genotoxic potential in studies evaluated by the FEMA Expert Panel. Examples illustrating the assessment of genotoxicity data for flavoring substances and the consideration of the factors noted above are provided. The weight of evidence approach adopted by the FEMA Expert Panel leads to a rational assessment of risk associated with consumer intake of flavoring substances under the conditions of use.
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Affiliation(s)
| | - Samuel M Cohen
- Havlik-Wall Professor of Oncology, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Gerhard Eisenbrand
- Food Chemistry & Toxicology, University of Kaiserslautern (retired), Heidelberg, Germany
| | | | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Stephen S Hecht
- Masonic Cancer Center and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | | | - Thomas J Rosol
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Maria Bastaki
- Flavor and Extract Manufacturers Association, Washington, DC, USA
| | - Matthew J Linman
- Flavor and Extract Manufacturers Association, Washington, DC, USA
| | - Sean V Taylor
- Flavor and Extract Manufacturers Association, Washington, DC, USA
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Shao K, Chen Q, Wang Z. Quantifying association between liver tumor incidence and early-stage liver weight increase - An NTP data analysis. Toxicol Rep 2019; 6:674-682. [PMID: 31360640 PMCID: PMC6639686 DOI: 10.1016/j.toxrep.2019.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/28/2019] [Accepted: 07/06/2019] [Indexed: 11/06/2022] Open
Abstract
Two-year toxicology and carcinogenesis rodent studies conducted at the National Toxicology Program (NTP) are used to identify potential adverse health effects in humans due to chemical exposure, including cancer. Liver tumor, the most frequently diagnosed tumor type of chemically induced neoplastic effects documented in NTP's carcinogenicity studies, is usually difficult to be detected at early stage due to the inconspicuous symptoms. However, the abnormal growth of liver cells can lead to liver weight increase, so it is hypothesized that liver tumor incidence is associated with early stage liver weight increase. In this study, the association between liver weight increase and liver tumor incidence are quantified by (1) calculating the correlation coefficient of and (2) building quantitative linear relationship between benchmark dose estimates derived from these two types of data collected from NTP studies. Together with 151 chemical/species/sex combinations of liver tumor data showing positive evidence collected from 76 NTP long-term studies, short-term liver weight data reported in the same NTP report were extracted to be paired with the liver tumor data for the analyses. Results show that the estimated correlation coefficients (as high as 0.78) along with the adequately fitted linear models suggest that the association between relative liver weight increase and aggregated liver tumor incidence are relatively strong. Additional analyses focused on some more specific situations (e.g., specific tumor type or specific strain/sex combination) further confirmed the strong association. Given the design of this study, the interpretation of the findings is not that liver weight increase can be used to predict liver tumor incidence, instead, evident increase in liver weight might be used as a reason to prioritize the test article for a two-year toxicology and carcinogenesis study.
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Affiliation(s)
- Kan Shao
- Department of Environmental and Occupational Health, School of Public Health, Indiana University, Bloomington, IN, 47405, USA
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12
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Doe JE, Boobis AR, Dellarco V, Fenner-Crisp PA, Moretto A, Pastoor TP, Schoeny RS, Seed JG, Wolf DC. Chemical carcinogenicity revisited 2: Current knowledge of carcinogenesis shows that categorization as a carcinogen or non-carcinogen is not scientifically credible. Regul Toxicol Pharmacol 2019; 103:124-129. [DOI: 10.1016/j.yrtph.2019.01.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/09/2019] [Accepted: 01/16/2019] [Indexed: 11/28/2022]
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13
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Cohen SM, Boobis AR, Dellarco VL, Doe JE, Fenner-Crisp PA, Moretto A, Pastoor TP, Schoeny RS, Seed JG, Wolf DC. Chemical carcinogenicity revisited 3: Risk assessment of carcinogenic potential based on the current state of knowledge of carcinogenesis in humans. Regul Toxicol Pharmacol 2019; 103:100-105. [DOI: 10.1016/j.yrtph.2019.01.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/04/2019] [Accepted: 01/07/2019] [Indexed: 01/27/2023]
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14
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FEMA GRAS assessment of natural flavor complexes: Citrus-derived flavoring ingredients. Food Chem Toxicol 2018; 124:192-218. [PMID: 30481573 DOI: 10.1016/j.fct.2018.11.052] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 11/19/2018] [Accepted: 11/23/2018] [Indexed: 01/06/2023]
Abstract
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients. This publication is the first in a series and summarizes the evaluation of 54 Citrus-derived NFCs using the procedure outlined in Smith et al. (2005) and updated in Cohen et al. (2018) to evaluate the safety of naturally-occurring mixtures for their intended use as flavoring ingredients. The procedure relies on a complete chemical characterization of each NFC intended for commerce and organization of each NFC's chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of members of the congeneric groups and the NFC under evaluation. As a result of the application of the procedure, 54 natural flavor complexes derived from botanicals of the Citrus genus were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavoring ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
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15
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Hard GC. Critical review of renal tubule karyomegaly in non-clinical safety evaluation studies and its significance for human risk assessment. Crit Rev Toxicol 2018; 48:575-595. [DOI: 10.1080/10408444.2018.1503641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Primate-specific Long Non-coding RNAs and MicroRNAs. GENOMICS PROTEOMICS & BIOINFORMATICS 2017; 15:187-195. [PMID: 28602844 PMCID: PMC5487532 DOI: 10.1016/j.gpb.2017.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 03/25/2017] [Accepted: 04/05/2017] [Indexed: 12/21/2022]
Abstract
Non-coding RNAs (ncRNAs) are critical regulators of gene expression in essentially all life forms. Long ncRNAs (lncRNAs) and microRNAs (miRNAs) are two important RNA classes possessing regulatory functions. Up to date, many primate-specific ncRNAs have been identified and investigated. Their expression specificity to primate lineage suggests primate-specific roles. It is thus critical to elucidate the biological significance of primate or even human-specific ncRNAs, and to develop potential ncRNA-based therapeutics. Here, we have summarized the studies regarding regulatory roles of some key primate-specific lncRNAs and miRNAs.
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Woutersen RA, Soffers AE, Kroese ED, Krul CA, van der Laan JW, van Benthem J, Luijten M. Prediction of carcinogenic potential of chemicals using repeated-dose (13-week) toxicity data. Regul Toxicol Pharmacol 2016; 81:242-249. [DOI: 10.1016/j.yrtph.2016.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 08/30/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022]
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van der Laan JW, Buitenhuis WHW, Wagenaar L, Soffers AEMF, van Someren EP, Krul CAM, Woutersen RA. Prediction of the Carcinogenic Potential of Human Pharmaceuticals Using Repeated Dose Toxicity Data and Their Pharmacological Properties. Front Med (Lausanne) 2016; 3:45. [PMID: 27790617 PMCID: PMC5063850 DOI: 10.3389/fmed.2016.00045] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/20/2016] [Indexed: 01/06/2023] Open
Abstract
In an exercise designed to reduce animal use, we analyzed the results of rat subchronic toxicity studies from 289 pharmaceutical compounds with the aim to predict the tumor outcome of carcinogenicity studies in this species. The results were obtained from the assessment reports available at the Medicines Evaluation Board of the Netherlands for 289 pharmaceutical compounds that had been shown to be non-genotoxic. One hundred forty-three of the 239 compounds not inducing putative preneoplastic lesions in the subchronic study did not induce tumors in the carcinogenicity study [true negatives (TNs)], whereas 96 compounds were categorized as false negatives (FNs) because tumors were observed in the carcinogenicity study. Of the remaining 50 compounds, 31 showed preneoplastic lesions in the subchronic study and tumors in the carcinogenicity study [true positives (TPs)], and 19 only showed preneoplastic lesions in subchronic studies but no tumors in the carcinogenicity study [false positives (FPs)]. In addition, we then re-assessed the prediction of the tumor outcome by integrating the pharmacological properties of these compounds. These pharmacological properties were evaluated with respect to the presence or absence of a direct or indirect proliferative action. We found support for the absence of cellular proliferation for 204 compounds (TN). For 67 compounds, the presence of cellular hyperplasia as evidence for proliferative action could be found (TP). Therefore, this approach resulted in an ability to predict non-carcinogens at a success rate of 92% and the ability to detect carcinogens at 98%. The combined evaluation of pharmacological and histopathological endpoints eventually led to only 18 unknown outcomes (17 categorized as FN and 1 as FP), thereby enhancing both the negative and positive predictivity of an evaluation based upon histopathological evaluation only. The data show the added value of a consideration of the pharmacological properties of compounds in relation to potential class effects, both in the negative and positive direction. A high negative and a high positive predictivity will both result in waiving the need for conducting 2-year rat carcinogenicity studies, if this is accepted by Regulatory Authorities, which will save large numbers of animals and reduce drug development costs and time.
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Affiliation(s)
- Jan Willem van der Laan
- Medicines Evaluation Board, Utrecht, Netherlands
- Division of Toxicology, Leiden Academic Center for Drug Research, Leiden, Netherlands
| | | | | | - Ans E. M. F. Soffers
- Division of Toxicology, Wageningen University and Research Centre, Wageningen, Netherlands
| | | | | | - Ruud A. Woutersen
- Division of Toxicology, Wageningen University and Research Centre, Wageningen, Netherlands
- TNO Innovation for Life, Zeist, Netherlands
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Hill T, Nelms MD, Edwards SW, Martin M, Judson R, Corton JC, Wood CE. Editor’s Highlight: Negative Predictors of Carcinogenicity for Environmental Chemicals. Toxicol Sci 2016; 155:157-169. [DOI: 10.1093/toxsci/kfw195] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Strupp C, Bomann W, Cohen SM, Weber K. Relationship of Metabolism and Cell Proliferation to the Mode of Action of Fluensulfone-Induced Mouse Lung Tumors. II: Additional Mechanistic Studies. Toxicol Sci 2016; 154:296-308. [DOI: 10.1093/toxsci/kfw168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Luijten M, Olthof ED, Hakkert BC, Rorije E, van der Laan JW, Woutersen RA, van Benthem J. An integrative test strategy for cancer hazard identification. Crit Rev Toxicol 2016; 46:615-39. [PMID: 27142259 DOI: 10.3109/10408444.2016.1171294] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Assessment of genotoxic and carcinogenic potential is considered one of the basic requirements when evaluating possible human health risks associated with exposure to chemicals. Test strategies currently in place focus primarily on identifying genotoxic potential due to the strong association between the accumulation of genetic damage and cancer. Using genotoxicity assays to predict carcinogenic potential has the significant drawback that risks from non-genotoxic carcinogens remain largely undetected unless carcinogenicity studies are performed. Furthermore, test systems already developed to reduce animal use are not easily accepted and implemented by either industries or regulators. This manuscript reviews the test methods for cancer hazard identification that have been adopted by the regulatory authorities, and discusses the most promising alternative methods that have been developed to date. Based on these findings, a generally applicable tiered test strategy is proposed that can be considered capable of detecting both genotoxic as well as non-genotoxic carcinogens and will improve understanding of the underlying mode of action. Finally, strengths and weaknesses of this new integrative test strategy for cancer hazard identification are presented.
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Affiliation(s)
- Mirjam Luijten
- a Centre for Health Protection, 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
| | - Betty C Hakkert
- b Centre for Safety of Substances and Products, National Institute for Public Health and the Environment (RIVM) , Bilthoven , the Netherlands
| | - Emiel Rorije
- b Centre for Safety of Substances and Products, National Institute for Public Health and the Environment (RIVM) , Bilthoven , the Netherlands
| | | | - Ruud A Woutersen
- d Netherlands Organization for Applied Scientific Research (TNO) , Zeist , the Netherlands
| | - Jan van Benthem
- a Centre for Health Protection, National Institute for Public Health and the Environment (RIVM) , Bilthoven , the Netherlands
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Kuwata K, Inoue K, Ichimura R, Takahashi M, Kodama Y, Shibutani M, Yoshida M. Involvement of Mouse Constitutive Androstane Receptor in Acifluorfen-Induced Liver Injury and Subsequent Tumor Development. Toxicol Sci 2016; 151:271-85. [DOI: 10.1093/toxsci/kfw040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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23
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Kuwata K, Inoue K, Ichimura R, Takahashi M, Kodama Y, Yoshida M. Constitutive active/androstane receptor, peroxisome proliferator-activated receptor α, and cytotoxicity are involved in oxadiazon-induced liver tumor development in mice. Food Chem Toxicol 2016; 88:75-86. [DOI: 10.1016/j.fct.2015.12.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 12/14/2015] [Accepted: 12/15/2015] [Indexed: 10/22/2022]
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24
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Koufaris C. Human and primate-specific microRNAs in cancer: Evolution, and significance in comparison with more distantly-related research models. Bioessays 2016; 38:286-94. [DOI: 10.1002/bies.201500135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Costas Koufaris
- Department of Cytogenetics and Genomics; Cyprus institute of Neurology and Genetics; Nicosia Cyprus
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Ring M, Eskofier BM. Data mining in the U.S. National Toxicology Program (NTP) database reveals a potential bias regarding liver tumors in rodents irrespective of the test agent. PLoS One 2015; 10:e0116488. [PMID: 25658102 PMCID: PMC4319901 DOI: 10.1371/journal.pone.0116488] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/08/2014] [Indexed: 11/19/2022] Open
Abstract
Long-term studies in rodents are the benchmark method to assess carcinogenicity of single substances, mixtures, and multi-compounds. In such a study, mice and rats are exposed to a test agent at different dose levels for a period of two years and the incidence of neoplastic lesions is observed. However, this two-year study is also expensive, time-consuming, and burdensome to the experimental animals. Consequently, various alternatives have been proposed in the literature to assess carcinogenicity on basis of short-term studies. In this paper, we investigated if effects on the rodents' liver weight in short-term studies can be exploited to predict the incidence of liver tumors in long-term studies. A set of 138 paired short- and long-term studies was compiled from the database of the U.S. National Toxicology Program (NTP), more precisely, from (long-term) two-year carcinogenicity studies and their preceding (short-term) dose finding studies. In this set, data mining methods revealed patterns that can predict the incidence of liver tumors with accuracies of over 80%. However, the results simultaneously indicated a potential bias regarding liver tumors in two-year NTP studies. The incidence of liver tumors does not only depend on the test agent but also on other confounding factors in the study design, e.g., species, sex, type of substance. We recommend considering this bias if the hazard or risk of a test agent is assessed on basis of a NTP carcinogenicity study.
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Affiliation(s)
- Matthias Ring
- Digital Sports Group, Pattern Recognition Lab, Friedrich-Alexander-Universität, Erlangen-Nürnberg (FAU), Germany
- * E-mail:
| | - Bjoern M. Eskofier
- Digital Sports Group, Pattern Recognition Lab, Friedrich-Alexander-Universität, Erlangen-Nürnberg (FAU), Germany
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Gooderham N, Koufaris C. Using microRNA profiles to predict and evaluate hepatic carcinogenic potential. Toxicol Lett 2014; 228:127-32. [DOI: 10.1016/j.toxlet.2014.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/17/2014] [Accepted: 04/20/2014] [Indexed: 01/17/2023]
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27
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Wood CE, Jokinen MP, Johnson CL, Olson GR, Hester S, George M, Chorley BN, Carswell G, Carter JH, Wood CR, Bhat VS, Corton JC, DeAngelo AB. Comparative time course profiles of phthalate stereoisomers in mice. Toxicol Sci 2014; 139:21-34. [PMID: 24496636 DOI: 10.1093/toxsci/kfu025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
More efficient models are needed to assess potential carcinogenicity hazard of environmental chemicals based on early events in tumorigenesis. Here, we investigated time course profiles for key events in an established cancer mode of action. Using a case study approach, we evaluated two reference phthalates, di(2-ethylhexyl) phthalate (DEHP) and its stereoisomer di-n-octyl phthalate (DNOP), across the span of a two-year carcinogenicity bioassay. Male B6C3F1 mice received diets with no phthalate added (control), DEHP at 0.12, 0.60, or 1.20%, or DNOP at 0.10, 0.50, or 1.00% (n = 80-83/group) for up to 104 weeks with six interim evaluations starting at week 4. Mean phthalate doses were 139, 845, and 3147 mg/kg/day for DEHP and 113, 755, and 1281 mg/kg/day for DNOP groups, respectively. Incidence and number of hepatocellular tumors (adenoma and/or carcinoma) were greater at ≥ 60 weeks for all DEHP groups with time and dose trends, whereas DNOP had no significant effects. Key events supported a peroxisome proliferator-activated receptor alpha (PPARα) mode of action for DEHP, with secondary cytotoxicity at the high dose, whereas DNOP induced modest increases in PPARα activity without proliferative or cytotoxic effects. Threshold estimates for later tumorigenic effects were identified at week 4 for relative liver weight (+24%) and PPARα activity (+79%) relative to the control group. Benchmark doses (BMDs) for these measures at week 4 clearly distinguished DEHP and DNOP and showed strong concordance with values at later time points and tumorigenic BMDs. Other target sites included testis and kidney, which showed degenerative changes at higher doses of DEHP but not DNOP. Our results highlight marked differences in the chronic toxicity profiles of structurally similar phthalates and demonstrate quantitative relationships between early bioindicators and later tumor outcomes.
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Affiliation(s)
- Charles E Wood
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709
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Elcombe CR, Peffer RC, Wolf DC, Bailey J, Bars R, Bell D, Cattley RC, Ferguson SS, Geter D, Goetz A, Goodman JI, Hester S, Jacobs A, Omiecinski CJ, Schoeny R, Xie W, Lake BG. Mode of action and human relevance analysis for nuclear receptor-mediated liver toxicity: A case study with phenobarbital as a model constitutive androstane receptor (CAR) activator. Crit Rev Toxicol 2013; 44:64-82. [PMID: 24180433 DOI: 10.3109/10408444.2013.835786] [Citation(s) in RCA: 188] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are important nuclear receptors involved in the regulation of cellular responses from exposure to many xenobiotics and various physiological processes. Phenobarbital (PB) is a non-genotoxic indirect CAR activator, which induces cytochrome P450 (CYP) and other xenobiotic metabolizing enzymes and is known to produce liver foci/tumors in mice and rats. From literature data, a mode of action (MOA) for PB-induced rodent liver tumor formation was developed. A MOA for PXR activators was not established owing to a lack of suitable data. The key events in the PB-induced liver tumor MOA comprise activation of CAR followed by altered gene expression specific to CAR activation, increased cell proliferation, formation of altered hepatic foci and ultimately the development of liver tumors. Associative events in the MOA include altered epigenetic changes, induction of hepatic CYP2B enzymes, liver hypertrophy and decreased apoptosis; with inhibition of gap junctional intercellular communication being an associative event or modulating factor. The MOA was evaluated using the modified Bradford Hill criteria for causality and other possible MOAs were excluded. While PB produces liver tumors in rodents, important species differences were identified including a lack of cell proliferation in cultured human hepatocytes. The MOA for PB-induced rodent liver tumor formation was considered to be qualitatively not plausible for humans. This conclusion is supported by data from a number of epidemiological studies conducted in human populations chronically exposed to PB in which there is no clear evidence for increased liver tumor risk.
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Sex differences in blood genotoxic and cytotoxic effects as a consequence of vanadium inhalation: micronucleus assay evaluation. J Appl Toxicol 2013; 34:258-64. [DOI: 10.1002/jat.2873] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/11/2013] [Accepted: 02/11/2013] [Indexed: 02/04/2023]
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30
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Monticello T, Bussiere J. Nonclinical Safety Evaluation of Drugs. Toxicol Pathol 2013. [DOI: 10.1201/b13783-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Koufaris C, Wright J, Currie RA, Gooderham NJ. Hepatic microRNA profiles offer predictive and mechanistic insights after exposure to genotoxic and epigenetic hepatocarcinogens. Toxicol Sci 2012; 128:532-43. [PMID: 22584684 DOI: 10.1093/toxsci/kfs170] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In recent years, accumulating evidence supports the importance of microRNAs in liver physiology and disease; however, few studies have examined the involvement of these noncoding genes in chemical hepatocarcinogenesis. Here, we examined the liver microRNA profile of male Fischer rats exposed through their diet to genotoxic (2-acetylaminofluorene) and epigenetic (phenobarbital, diethylhexylphthalate, methapyrilene HCL, monuron, and chlorendic acid) chemical hepatocarcinogens, as well as to non-hepatocarcinogenic treatments (benzophenone, and diethylthiourea) for 3 months. The effects of these treatments on liver pathology, plasma clinical parameters, and liver mRNAs were also determined. All hepatocarcinogens affected the expression of liver mRNAs, while the hepatic microRNA profiles were associated with the mode of action of the chemical treatments and corresponded to chemical carcinogenicity. The three nuclear receptor-activating chemicals (phenobarbital, benzophenone, and diethylhexylphthalate) were characterized by the highly correlated induction of the miR-200a/200b/429, which is involved in protecting the epithelial status of cells and of the miR-96/182 clusters. The four non-nuclear receptor-activating hepatocarcinogens were characterized by the early, persistent induction of miR-34, which was associated with DNA damage and oxidative stress in vivo and in vitro. Repression of this microRNA in a hepatoma cell line led to increased cell growth; thus, miR-34a could act to block abnormal cell proliferation in cells exposed to DNA damage or oxidative stress. This study supports the proposal that hepatic microRNA profiles could assist in the earlier evaluation and identification of hepatocarcinogens, especially those acting by epigenetic mechanisms.
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Affiliation(s)
- Costas Koufaris
- Biomolecular Medicine, Imperial College London, London SW72AZ, UK
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Strupp C, Banas DA, Cohen SM, Gordon EB, Jaeger M, Weber K. Relationship of metabolism and cell proliferation to the mode of action of fluensulfone-induced mouse lung tumors: analysis of their human relevance using the IPCS framework. Toxicol Sci 2012; 128:284-94. [PMID: 22491425 PMCID: PMC3391030 DOI: 10.1093/toxsci/kfs127] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Species-specific lung tumors in the mouse are induced by a number of chemicals. The underlying cause appears to be a high metabolic activity of mouse lung, due to relatively high abundance of Clara cells in mice compared with humans and the mouse-specific cytochrome P450 isoform 2f2 in the Clara cells. The chemicals are activated to reactive intermediates, leading to local cytotoxicity or mitogenicity resulting in increased cell proliferation and tumors. Rats have lower metabolic activity than mice (already below the threshold needed to cause lung tumors upon lifetime exposure) and activity in humans is lower than in rats. The carcinogenic risk for human lung is low for this mode of action (MOA). Fluensulfone has shown an increased incidence of lung adenomas in mice, but not in rats, at high doses. Fluensulfone is not genotoxic. MOA studies were conducted investigating key events of the postulated MOA. Fluensulfone is extensively metabolized by mouse lung microsomes, whereas no metabolic activity is seen with human lung microsomes. Cyp 2f2 is a major contributor in fluensulfone’s metabolism and Cyp 2e1 is not involved. Furthermore, administration of fluensulfone to mice led to an early increase in Clara cell proliferation. The International Programme on Chemical Safety (IPCS) MOA and human relevance framework was used to evaluate the collective data on fluensulfone. We concluded that fluensulfone leads to species-specific mouse lung tumors and that these tumors are likely not relevant to human hazard or risk.
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Affiliation(s)
- Christian Strupp
- Makhteshim Agan Holding B.V., Schaffhausen Branch, 8200 Schaffhausen, Switzerland.
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Doktorova TY, Pauwels M, Vinken M, Vanhaecke T, Rogiers V. Opportunities for an alternative integrating testing strategy for carcinogen hazard assessment? Crit Rev Toxicol 2011; 42:91-106. [DOI: 10.3109/10408444.2011.623151] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Travlos GS, Hard GC, Betz LJ, Kissling GE. Chronic progressive nephropathy in male F344 rats in 90-day toxicity studies: its occurrence and association with renal tubule tumors in subsequent 2-year bioassays. Toxicol Pathol 2011; 39:381-9. [PMID: 21422264 DOI: 10.1177/0192623310388432] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The occurrence and severity of spontaneous chronic progressive nephropathy (CPN) in control male F344 rats as well as the frequency of treatment-related CPN exacerbation were histopathologically reevaluated. A series of 43 National Toxicology Program (NTP) 90-day toxicity studies comparing the influence of NIH-07 or NTP-2000 diets was examined. Relationships between the histopathologic findings at 90 days and renal tubule proliferative lesions recorded in subsequent 2-year bioassays for 24 chemicals were statistically analyzed. CPN lesions were observed in 100% of the control male rats regardless of diet, but CPN was more severe in control rats fed NIH-07. Approximately one-third of the 90-day studies demonstrated a treatment-related exacerbation of CPN severity, which was independent of diet. For chemicals that proceeded to 2-year bioassays, all studies with a statistically significant increase in renal tubule tumors (RTT) at 2 years had treatment-related exacerbation of CPN in the 90-day and 2-year studies. These findings indicate that CPN occurs ubiquitously in young male F344 rats and that treatment-related exacerbation of CPN in 90-day studies is a relatively common occurrence, having the potential to be predictive of an increased incidence of RTT in subsequent 2-year bioassays.
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Affiliation(s)
- Greg S Travlos
- National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, USA.
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Adler S, Basketter D, Creton S, Pelkonen O, van Benthem J, Zuang V, Andersen KE, Angers-Loustau A, Aptula A, Bal-Price A, Benfenati E, Bernauer U, Bessems J, Bois FY, Boobis A, Brandon E, Bremer S, Broschard T, Casati S, Coecke S, Corvi R, Cronin M, Daston G, Dekant W, Felter S, Grignard E, Gundert-Remy U, Heinonen T, Kimber I, Kleinjans J, Komulainen H, Kreiling R, Kreysa J, Leite SB, Loizou G, Maxwell G, Mazzatorta P, Munn S, Pfuhler S, Phrakonkham P, Piersma A, Poth A, Prieto P, Repetto G, Rogiers V, Schoeters G, Schwarz M, Serafimova R, Tähti H, Testai E, van Delft J, van Loveren H, Vinken M, Worth A, Zaldivar JM. Alternative (non-animal) methods for cosmetics testing: current status and future prospects-2010. Arch Toxicol 2011; 85:367-485. [PMID: 21533817 DOI: 10.1007/s00204-011-0693-2] [Citation(s) in RCA: 358] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/03/2011] [Indexed: 01/09/2023]
Abstract
The 7th amendment to the EU Cosmetics Directive prohibits to put animal-tested cosmetics on the market in Europe after 2013. In that context, the European Commission invited stakeholder bodies (industry, non-governmental organisations, EU Member States, and the Commission's Scientific Committee on Consumer Safety) to identify scientific experts in five toxicological areas, i.e. toxicokinetics, repeated dose toxicity, carcinogenicity, skin sensitisation, and reproductive toxicity for which the Directive foresees that the 2013 deadline could be further extended in case alternative and validated methods would not be available in time. The selected experts were asked to analyse the status and prospects of alternative methods and to provide a scientifically sound estimate of the time necessary to achieve full replacement of animal testing. In summary, the experts confirmed that it will take at least another 7-9 years for the replacement of the current in vivo animal tests used for the safety assessment of cosmetic ingredients for skin sensitisation. However, the experts were also of the opinion that alternative methods may be able to give hazard information, i.e. to differentiate between sensitisers and non-sensitisers, ahead of 2017. This would, however, not provide the complete picture of what is a safe exposure because the relative potency of a sensitiser would not be known. For toxicokinetics, the timeframe was 5-7 years to develop the models still lacking to predict lung absorption and renal/biliary excretion, and even longer to integrate the methods to fully replace the animal toxicokinetic models. For the systemic toxicological endpoints of repeated dose toxicity, carcinogenicity and reproductive toxicity, the time horizon for full replacement could not be estimated.
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Affiliation(s)
- Sarah Adler
- Centre for Documentation and Evaluation of Alternatives to Animal Experiments (ZEBET), Federal Institute for Risk Assessment (BfR), Berlin, Germany
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Bonnefoi MS, Belanger SE, Devlin DJ, Doerrer NG, Embry MR, Fukushima S, Harpur ES, Hines RN, Holsapple MP, Kim JH, MacDonald JS, O’Lone R, Pettit SD, Stevens JL, Takei AS, Tinkle SS, van der Laan JW. Human and environmental health challenges for the next decade (2010–2020). Crit Rev Toxicol 2010; 40:893-911. [DOI: 10.3109/10408444.2010.506640] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Downes N. Revisiting alternative approaches to the assessment of carcinogenic risk. Toxicol Pathol 2010; 38:324-7. [PMID: 20124498 DOI: 10.1177/0192623309360214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The rodent bioassay has been a mainstay of carcinogenic risk assessment for close to half a century; not that it has been without criticism in that time. As early as the 1990s, there were clearly established shortcomings with regard to relevance and extrapolation, but despite these concerns, this test continues relatively unchanged. As our understanding of the mechanisms of carcinogenesis and the availability of investigative techniques improve, there seems less reason than ever to persist with this exercise that provides little meaningful scientific data at great cost in terms of animal usage and pathologist time. This article highlights possible ways to gather and present data pertinent to carcinogenesis in man and suggests that it is the toxicological pathology community that should take the lead here in persuading regulators that there is great room for improvement in this particular aspect of regulatory pathology.
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Boobis AR. Mode of action considerations in the quantitative assessment of tumour responses in the liver. Basic Clin Pharmacol Toxicol 2009; 106:173-9. [PMID: 20030633 DOI: 10.1111/j.1742-7843.2009.00505.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chemical carcinogenesis is a complex, multi-stage process and the relationship between dose and tumour formation is an important consideration in the risk assessment of chemicals. Extrapolation from empirical dose-response relationships obtained in experimental studies has been criticized, as it fails to take into account information on mode of action. Strategies for incorporating mode of action information into the risk assessment of chemical carcinogens are described, with a focus on hepatic cancer. Either toxicokinetic or toxicodynamic processes can be addressed. Whilst the former have been the focus of more attention to date, for example by using physiologically based modelling, there is increasing interest in the development of mode of action-based toxicodynamic models. These have the advantage that they do not require extreme assumptions, and may be amenable to paramaterization using human data. This is rarely if ever possible when using conventional dose-tumour response relationships. The approaches discussed are illustrated using chloroform as a case study. This compound is converted to a cytotoxic metabolite, phosgene, by CYP2E1 in liver and/or kidney. Cytotoxicity results in proliferative regeneration, with increased probability of tumour formation. Both physiologically based toxicokinetic and toxicodynamic models have been developed, and it is possible to use probabilistic approaches incorporating, for example, data on the distribution of hepatic CYP2E1 levels. Mode of action can provide an invaluable link between observable, experimental data, on both toxicokinetics and toxicodynamics, and chemical-specific risk assessment, based on physiological approaches.
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Affiliation(s)
- Alan R Boobis
- Department of Experimental Medicine and Toxicology, Division of Investigative Science, Imperial College London, UK.
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