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Guth S, Baum M, Cartus AT, Diel P, Engel KH, Engeli B, Epe B, Grune T, Haller D, Heinz V, Hellwig M, Hengstler JG, Henle T, Humpf HU, Jäger H, Joost HG, Kulling SE, Lachenmeier DW, Lampen A, Leist M, Mally A, Marko D, Nöthlings U, Röhrdanz E, Roth A, Spranger J, Stadler R, Steinberg P, Vieths S, Wätjen W, Eisenbrand G. Evaluation of the genotoxic potential of acrylamide: Arguments for the derivation of a tolerable daily intake (TDI value). Food Chem Toxicol 2023; 173:113632. [PMID: 36708862 DOI: 10.1016/j.fct.2023.113632] [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: 12/21/2021] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023]
Abstract
This opinion of the Senate Commission on Food Safety (SKLM) of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) presents arguments for an updated risk assessment of diet-related exposure to acrylamide (AA), based on a critical review of scientific evidence relevant to low dose exposure. The SKLM arrives at the conclusion that as long as an appropriate exposure limit for AA is not exceeded, genotoxic effects resulting in carcinogenicity are unlikely to occur. Based on the totality of the evidence, the SKLM considers it scientifically justified to derive a tolerable daily intake (TDI) as a health-based guidance value.
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Affiliation(s)
- Sabine Guth
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139, Dortmund, Germany.
| | - Matthias Baum
- Solenis Germany Industries GmbH, Fütingsweg 20, 47805 Krefeld, Germany.
| | | | - Patrick Diel
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.
| | - Karl-Heinz Engel
- Technical University of Munich, Maximus-von-Imhof-Forum 2, 85354, Freising, Germany.
| | - Barbara Engeli
- Federal Food Safety and Veterinary Office (FSVO), Risk Assessment Division, Schwarzenburgstrasse 155, 3003, Bern, Switzerland.
| | - Bernd Epe
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, Staudinger Weg 5, 55128, Mainz, Germany.
| | - Tilman Grune
- Department of Molecular Toxicology, German Institute of Human Nutrition (DIfE), Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany.
| | - Dirk Haller
- ZIEL - Institute for Food & Health, Technical University of Munich, 85354, Freising, Germany; Technical University of Munich, Gregor-Mendel-Str. 2, 85354, Freising, Germany.
| | - Volker Heinz
- German Institute of Food Technologies (DIL), Prof.-von-Klitzing-Str. 7, 49610, Quakenbrück, Germany.
| | - Michael Hellwig
- Technische Universität Dresden, Bergstraße 66, 01062, Dresden, Germany.
| | - Jan G Hengstler
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139, Dortmund, Germany.
| | - Thomas Henle
- Department of Food Chemistry, TU Dresden, Bergstrasse 66, 01062, Dresden, Germany.
| | - Hans-Ulrich Humpf
- Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 45, 48149, Münster, Germany.
| | - Henry Jäger
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190, Vienna, Austria.
| | - Hans-Georg Joost
- Department of Experimental Diabetology, German Institute of Human Nutrition (DIfE), Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany.
| | - Sabine E Kulling
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany.
| | - Dirk W Lachenmeier
- Chemisches und Veterinäruntersuchungsamt Karlsruhe, Weißenburger Str. 3, 76187, Karlsruhe, Germany.
| | - Alfonso Lampen
- University of Veterinary Medicine Hannover, Institute for Food Quality and Food Safety, Bischofsholer Damm 15, 30173, Hannover, Germany.
| | - Marcel Leist
- In Vitro Toxicology and Biomedicine, Department Inaugurated By the Doerenkamp-Zbinden Foundation, University of Konstanz, Box 657, 78457, Konstanz, Germany.
| | - Angela Mally
- Department of Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
| | - Doris Marko
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Währinger Straße 38, 1090, Vienna, Austria.
| | - Ute Nöthlings
- Department of Nutrition and Food Sciences, Nutritional Epidemiology, Rheinische Friedrich-Wilhelms University Bonn, Friedrich-Hirzebruch-Allee 7, 53115, Bonn, Germany.
| | - Elke Röhrdanz
- Unit Reproductive and Genetic Toxicology, Federal Institute for Drugs and Medical Devices (BfArM), Kurt-Georg-Kiesinger Allee 3, 53175, Bonn, Germany.
| | - Angelika Roth
- Leibniz Research Centre for Working Environment and Human Factors (IfADo), Ardeystr. 67, 44139, Dortmund, Germany.
| | - Joachim Spranger
- Department of Endocrinology and Metabolic Medicine, Campus Benjamin Franklin, Charité University Medicine, Hindenburgdamm 30, 12200, Berlin, Germany.
| | - Richard Stadler
- Institute of Food Safety and Analytical Sciences, Nestlé Research Centre, Route du Jorat 57, 1000, Lausanne, 26, Switzerland.
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany.
| | - Stefan Vieths
- Paul-Ehrlich-Institut, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany.
| | - Wim Wätjen
- Institut für Agrar- und Ernährungswissenschaften, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 22, 06120, Halle (Saale), Germany.
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Revisiting the evidence for genotoxicity of acrylamide (AA), key to risk assessment of dietary AA exposure. Arch Toxicol 2020; 94:2939-2950. [PMID: 32494932 PMCID: PMC7415744 DOI: 10.1007/s00204-020-02794-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/20/2020] [Indexed: 12/16/2022]
Abstract
The weight of evidence pro/contra classifying the process-related food contaminant (PRC) acrylamide (AA) as a genotoxic carcinogen is reviewed. Current dietary AA exposure estimates reflect margins of exposure (MOEs) < 500. Several arguments support the view that AA may not act as a genotoxic carcinogen, especially not at consumer-relevant exposure levels: Biotransformation of AA into genotoxic glycidamide (GA) in primary rat hepatocytes is markedly slower than detoxifying coupling to glutathione (GS). Repeated feeding of rats with AA containing foods, bringing about uptake of 100 µg/kg/day of AA, resulted in dose x time-related buildup of AA-hemoglobin (Hb) adducts, whereas GA-Hb adducts remained within the background. Since hepatic oxidative biotransformation of AA into GA was proven by simultaneous urinary mercapturic acid monitoring it can be concluded that at this nutritional intake level any GA formed in the liver from AA is quantitatively coupled to GS to be excreted as mercapturic acid in urine. In an oral single dose–response study in rats, AA induced DNA N7-GA-Gua adducts dose-dependently in the high dose range (> 100 µg/kg b w). At variance, in the dose range below 100 µg/kg b.w. down to levels of average consumers exposure, DNA N7 -Gua lesions were found only sporadically, without dose dependence, and at levels close to the lower bound of similar human background DNA N7-Gua lesions. No DNA damage was detected by the comet assay within this low dose range. GA is a very weak mutagen, known to predominantly induce DNA N7-GA-Gua adducts, especially in the lower dose range. There is consensus that DNA N7-GA-Gua adducts exhibit rather low mutagenic potency. The low mutagenic potential of GA has further been evidenced by comparison to preactivated forms of other process-related contaminants, such as N-Nitroso compounds or polycyclic aromatic hydrocarbons, potent food borne mutagens/carcinogens. Toxicogenomic studies provide no evidence supporting a genotoxic mode of action (MOA), rather indicate effects on calcium signalling and cytoskeletal functions in rodent target organs. Rodent carcinogenicity studies show induction of strain- and species-specific neoplasms, with MOAs not considered likely predictive for human cancer risk. In summary, the overall evidence clearly argues for a nongenotoxic/nonmutagenic MOA underlying the neoplastic effects of AA in rodents. In consequence, a tolerable intake level (TDI) may be defined, guided by mechanistic elucidation of key adverse effects and supported by biomarker-based dosimetry in experimental systems and humans.
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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: 79] [Impact Index Per Article: 19.8] [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.
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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.
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Nakane Y, Kemmochi Y, Ogawa N, Sasase T, Ohta T, Higami Y, Fukai F. Hyperglycemia contributes to the development of Leydig cell hyperplasia in male Spontaneously Diabetic Torii rats. J Toxicol Pathol 2020; 33:121-129. [PMID: 32425345 PMCID: PMC7218238 DOI: 10.1293/tox.2019-0088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
Spontaneously Diabetic Torii (SDT) rats are a well-known animal model of non-obese type 2 diabetes mellitus. Although this animal model has been studied extensively over the last decade, the incidence rates of Leydig cell hyperplasia and tumors in this model have not been reported. In this study, pathophysiological analyses of the testes were performed on male SDT rats, to understand the effect of insulin treatment on the development of Leydig cell hyperplasia and tumors and the expression of integrins and extracellular matrix proteins. Testicular Leydig cell hyperplasia and tumors were observed in SDT rats at 64 weeks of age but were rarely identified in Sprague-Dawley (SD) rats of the same age. Insulin treatment decreased plasma glucose and HbA1c levels, and interestingly, decreased the number of hyperplastic Leydig cell foci and Leydig cell tumors in treated animals. A similar reduction in the expression of Ki67 in these Leydig cell foci was also observed. In addition, insulin treatment decreased the expression of integrin α5, integrin β1, integrin αvβ3, fibronectin, and vitronectin in hyperplastic Leydig cell foci. These results suggest that insulin might decrease the incidence of Leydig cell hyperplasia by reducing Leydig cell proliferation and the expression of integrins and extracellular matrix proteins through the reduction of serum glucose concentrations in these animals.
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Affiliation(s)
- Yoshitomi Nakane
- Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan.,Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.,Laboratory of Molecular Pathophysiology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Yusuke Kemmochi
- Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan
| | - Naoto Ogawa
- Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan
| | - Tomohiko Sasase
- Japan Tobacco Inc., Central Pharmaceutical Research Institute, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan
| | - Takeshi Ohta
- Laboratory of Animal Physiology and Functional Anatomy, Graduate School of Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto-shi, Kyoto 606-8502, Japan
| | - Yoshikazu Higami
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Fumio Fukai
- Laboratory of Molecular Pathophysiology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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van den Brand AD, Rubinstein E, van den Berg M, van Duursen MBM. GH3 and RC-4BC cell lines are not suitable as in vitro models to study prolactin modulation and AHR responsiveness in rat pituitary. Mol Cell Endocrinol 2019; 496:110520. [PMID: 31352040 DOI: 10.1016/j.mce.2019.110520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/21/2019] [Accepted: 07/24/2019] [Indexed: 01/10/2023]
Abstract
Some environmental contaminants and pharmaceuticals increase the incidence of uterine tumors in toxicological studies with rats. These tumors can result from a hormonal imbalance due to rat-specific disrupted pituitary prolactin regulation, and are therefore of questionable relevance for humans. In this study we compared in vitro prolactin regulation in rat primary pituitary cells to that in pituitary cell lines, GH3 and RC-4BC. Moreover, we assessed the potential effects of aryl hydrocarbon receptor (AHR) activation on prolactin regulation by using two different AHR agonists, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and DELAQ, the N-deethylated minor metabolite of the pharmaceutical laquinimod. In rat primary pituitary cells, known prolactin stimulant thyrotropin-releasing hormone (TRH) marginally increased prolactin secretion (1.2-fold) and gene expression (1.3-fold). In contrast, synthetic dopamine receptor agonist quinpirole, a known inhibitor of prolactin release, significantly inhibited prolactin secretion (2.6-fold) and gene expression (3.6-fold). In GH3 cells, TRH strongly increased prolactin secretion (6.8-fold) and gene expression (30.8-fold), whereas quinpirole did not affect prolactin secretion nor gene expression. In RC-4BC cells, both TRH and quinpirole did not modulate prolactin secretion nor gene expression. Prolactin secretion and gene expression did not significantly change upon exposure to TCDD or DELAQ. However, DELAQ, but not TCDD, attenuated quinpirole-inhibited prolactin gene expression by 51% in primary pituitary cells. This study shows that pituitary prolactin regulation in rat primary pituitary cells in vitro is distinctly different from rat pituitary cell lines GH3 and RC-4BC. Therefore, effects on pituitary prolactin regulation in vitro should best be performed using rat primary pituitary cells. Additionally, AHR ligands may interact with rat pituitary prolactin regulation, but this appears to depend on the ligand and constitutive prolactin secretion. However, interpretation of the in vitro results with respect to occurrence of uterine tumors in rats should take the complex regulation of prolactin release in the pituitary into account as well as the in vivo hypothalamus-pituitary-gonadal (HPG) axis and its feedback loops.
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Affiliation(s)
- A D van den Brand
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 104, 3584 CM, the Netherlands.
| | - E Rubinstein
- TEVA Pharmaceutical Industries Ltd, Netanya, Israel
| | - M van den Berg
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 104, 3584 CM, the Netherlands
| | - M B M van Duursen
- Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 104, 3584 CM, the Netherlands; Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
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Van Cott A, Frericks M, Hastings C, Honarvar N, Flick B, Fabian E, van Ravenzwaay B. Uterine adenocarcinoma in the rat induced by afidopyropen. An analysis of the lesion's induction, progression and its relevance to humans. Regul Toxicol Pharmacol 2018; 95:29-51. [DOI: 10.1016/j.yrtph.2018.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/29/2018] [Accepted: 02/28/2018] [Indexed: 11/16/2022]
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Jean PA, Sloter ED, Plotzke KP. Effects of chronic exposure to octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane in the aging female Fischer 344 rat. Toxicol Lett 2017; 279 Suppl 1:54-74. [DOI: 10.1016/j.toxlet.2017.08.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 08/09/2017] [Accepted: 08/16/2017] [Indexed: 11/24/2022]
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Gong Y, Tian H, Dong Y, Zhang X, Wang W, Ru S. An in vivo assay performed using multiple biomarkers related to testosterone synthesis and conversion for assessing the androgenic potency of refuse leachate. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 135:82-89. [PMID: 27716536 DOI: 10.1016/j.ecoenv.2016.09.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 09/19/2016] [Accepted: 09/23/2016] [Indexed: 06/06/2023]
Abstract
Refuse leachate is likely an important source of androgens. However, common in vitro bioassays underestimate the potential androgenic activity of leachate, owing to non-receptor-mediated mechanisms that modify the balance of sex hormones and promote the accumulation of endogenous androgens. This study aimed to develop an in vivo assay by using multiple biomarkers related to testosterone synthesis and conversion for assessing the potential androgenic activity of refuse leachate sampled from a municipal solid waste treatment plant in Qingdao, China. The results indicated that exposure to leachate increased the levels of testosterone and luteinizing hormone, but decreased those of 17β-estradiol in both male and female goldfish (Carassius auratus), suggesting a potential androgenic activity. Further, Leydig cell hyperplasia and decreased gonadal P450 aromatase mRNA levels were observed; these alterations might promote the biosynthesis of testosterone and hinder the conversion of testosterone to 17β-estradiol, which in turn enhance testosterone accumulation. Exposure to leachate also resulted in reproductive impairments, including decreased gonadosomatic index and plasma vitellogenin levels of female goldfish, as well as decreased testicular enzyme activities in male goldfish. The integrated use of biochemical, molecular, and histological markers not only improved our understanding of the androgenic effects of leachate but also verified the reliability and validity of the results. Therefore, the in vivo bioassay described in this study might allow the investigation of the androgenic effects of other complex contaminant mixtures in the future.
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Affiliation(s)
- Yufeng Gong
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Hua Tian
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Yifei Dong
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Xiaona Zhang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
| | - Shaoguo Ru
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
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Sinkeldam EJ, Woutersen R, Hollanders V, Til H, Van Garderen-Hoetmer A, Bär A. Subchronic and Chronic Toxicity/Carcinogenicity Feeding Studies with Lactitol in Rats. ACTA ACUST UNITED AC 2016. [DOI: 10.3109/10915819209141497] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The toxicity and possible carcinogenicity of lactitol, a lactose-derived reduced calorie sugar substitute, were examined in Wistar Cpb:WU rats. In a first 13-week study, groups of 10 weanling rats of each sex were fed diets containing 0, 5, 10, or 20% lactitol, or 25% lactose. In a second 13-week study, groups of 20 rats of each sex received diets with 0, 10, or 20% lactitol, or 25% lactose starting from an age of 3 months. In a lifetime toxicity/cancerogenicity study with in utero exposure, groups of 50 rats of each sex consumed diets with 0, 2, 5, or 10% lactitol, or 20% lactose for 130 weeks. Satellite groups of 10 rats/group received the same diet but were sacrificed after 53 weeks. Subchronic and chronic ingestion of lactitol and lactose was generally well tolerated and an effect on mortality rate was not seen. Body weight gains were slightly decreased in a dose-related manner in all experiments. Dose-related cecal enlargement was observed consistently with lactitol and lactose. Examinations for hematological parameters and urine composition did not reveal any treatment-related abnormalities. The clinical chemistry examinations revealed increased plasma alkaline phosphatase (AP) levels in rats fed 5 or 10% lactitol, or 20% lactose. Slight (microscopic) cytoplasmic alterations in the staining pattern of hepatocytes were observed in the first but not the second 13-week study in a number of male rats of the 10 and 20% lactitol groups. In the chronic study, a statistically significant increase in bile duct hyperplasia was noted in female rats fed 5 or 10% lactitol, or 20% lactose. Measurement of femur calcium content in terminated female rats revealed a dose-related, yet statistically nonsignificant decrease in the lactitol groups and lowest levels in the 20% lactose group. The histopathological examination of rats treated with lactitol and lactose for their lifetime showed an increased incidence of (1) pelvic nephrocalcinosis (5% lactitol females, and 10% lactitol and 20% lactose males and females), (2) adrenomedullary proliferative changes (10% lactitol and 20% lactose males), and (3) hyperplastic and neoplastic changes of Leydig cells (10% lactitol and 20% lactose males). Results from other studies suggest that nephrocalcinosis and adrenal medullary proliferative disease represent sequelae of a chronic, treatment-related hyperabsorption of calcium which does not occur in man. The mechanism of the testicular effect is not yet identified. However, lactitol gave completely negative results in standard tests for mutagenicity and clastogenicity, and no testicular effects or other neoplastic response was observed in lactitol-fed mice. Since Leydig cell tumors occur in humans at an extremely low rate despite the ingestion of substantial amounts of lactose with ordinary meals, the observation made in rats lacks apparent relevance for man.
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Affiliation(s)
- E. J. Sinkeldam
- TNO Toxicology and Nutrition Institute, 3700 AJ Zeist, The Netherlands
| | - R.A. Woutersen
- TNO Toxicology and Nutrition Institute, 3700 AJ Zeist, The Netherlands
| | - V.M.H. Hollanders
- TNO Toxicology and Nutrition Institute, 3700 AJ Zeist, The Netherlands
| | - H.P. Til
- TNO Toxicology and Nutrition Institute, 3700 AJ Zeist, The Netherlands
| | | | - A. Bär
- Bioresco Ltd. Hauptstrasse 63 CH-4102 Binningen, Switzerland
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Davies TS, Monro A. Marketed Human Pharmaceuticals Reported to be Tumorigenic in Rodents. ACTA ACUST UNITED AC 2016. [DOI: 10.3109/10915819509008684] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The 1994 U.S. Physicians' Desk Reference reports the results of rodent carcinogenicity tests on 241 pharmaceutical agents. Positive results were reported for 101 agents, with a class label implying a carcinogenic hazard also attached to 9 estrogenic, 4 androgenic, and 3 progestogenic agents. Of the positive agents tested in both rats and mice, 39 of 72 were positive in both species, 22 were positive in rats only, and 11 were positive in mice only. There were few (19) unequivocally genotoxic agents, and only one of these was not reported to be tumorigenic to rodents. The liver was a common target organ in rats and mice. In rats, the other most common target organs for tumors were (in decreasing order) the thyroid, testis, mammary, adrenal, and pituitary. In mice, the only other common target organ was the lung.
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11
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Lynch BS, Bryant DW, Hook GJ, Nestmann ER, Munro IC. Carcinogenicity of Monochloro-1,2-Propanediol (α-Chlorohydrin, 3-MCPD). Int J Toxicol 2016. [DOI: 10.1080/109158198226756] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
3-Monochloro-1,2-propanediol (3-MCPD) is a by-product found in trace amounts, generally less than 1 mg/kg (<1 ppm), in hydrolyzed vegetable protein produced through acid hydrolysis. In a chronic study with F344 rats, high doses of 3-MCPD produced benign renal tumors in both sexes and Leydig-cell and mammary tumors in males. 3-MCPD is genotoxic in vitro, but there is no evidence of genotoxicity in vivo. There is some question about the mechanism responsible for the carcinogenicity of 3-MCPD in certain species. Here we present a critical review of the toxicological, metabolic, and mechanistic data on 3-MCPD. On the basis of this review, the tumors reported in F344 rats are concluded to have developed as a result of nongenotoxic mechanisms and are considered not to be relevant to humans exposed to trace amounts of 3-MCPD. This conclusion was based on the lack of carcinogenicity of 3-MCPD in mice or Sprague-Dawley rats; the benign nature of the tumors involved; the dependence of the Leydig-cell and mammary tumors on species-and strain-dependent mechanisms involving chronic changes in hormone balance; the association of the renal tumors with chronic nephropathy and nephrotoxicity; and differences between bacterial and mammalian systems in the metabolism of 3-MCPD that likely account for its genotoxic activity in certain in vitro test systems. At trace levels in foods, 3 MCPD is considered not to pose a carcinogenic risk to humans.
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Risks for human health related to the presence of 3‐ and 2‐monochloropropanediol (MCPD), and their fatty acid esters, and glycidyl fatty acid esters in food. EFSA J 2016. [DOI: 10.2903/j.efsa.2016.4426] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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13
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Collí-Dulá RC, Friedman MA, Hansen B, Denslow ND. Transcriptomics analysis and hormonal changes of male and female neonatal rats treated chronically with a low dose of acrylamide in their drinking water. Toxicol Rep 2016; 3:414-426. [PMID: 28959563 PMCID: PMC5615912 DOI: 10.1016/j.toxrep.2016.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/02/2016] [Accepted: 03/16/2016] [Indexed: 12/28/2022] Open
Abstract
Acrylamide is known to produce follicular cell tumors of the thyroid in rats. RccHan Wistar rats were exposed in utero to a carcinogenic dose of acrylamide (3 mg/Kg bw/day) from gestation day 6 to delivery and then through their drinking water to postnatal day 35. In order to identify potential mechanisms of carcinogenesis in the thyroid glands, we used a transcriptomics approach. Thyroid glands were collected from male pups at 10 PM and female pups at 10 AM or 10 PM in order to establish whether active exposure to acrylamide influenced gene expression patterns or pathways that could be related to carcinogenesis. While all animals exposed to acrylamide showed changes in expected target pathways related to carcinogenesis such as DNA repair, DNA replication, chromosome segregation, among others; animals that were sacrificed while actively drinking acrylamide-laced water during their active period at night showed increased changes in pathways related to oxidative stress, detoxification pathways, metabolism, and activation of checkpoint pathways, among others. In addition, thyroid hormones, triiodothyronine (T3) and thyroxine (T4), were increased in acrylamide-treated rats sampled at night, but not in quiescent animals when compared to controls. The data clearly indicate that time of day for sample collection is critical to identifying molecular pathways that are altered by the exposures. These results suggest that carcinogenesis in the thyroids of acrylamide treated rats may ensue from several different mechanisms such as hormonal changes and oxidative stress and not only from direct genotoxicity, as has been assumed to date.
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Key Words
- ADA, adenosine Deaminase
- ADRB2, adrenergic
- ASF1B, anti-Silencing Function 1B Histone Chaperone
- Acrylamide
- BRIP1, BRCA1 Interacting Protein C-Terminal Helicase 1
- BUB1B, BUB1 Mitotic Checkpoint Serine/Threonine Kinase B
- C1QTNF3, C1q and Tumor Necrosis Factor Related Protein 3
- C5, complement Component 5
- CALCR, calcitonin receptor
- CARD9, caspase recruitment domain family
- CCNA2, cyclin A2
- CCNG1, cyclin G1
- CD45, protein tyrosine phosphatase
- CD46, CD46 molecule
- CDC45, cell division cycle 45
- CDCA2, cell division cycle associated 2
- CDCA5, cell division cycle associated 5
- CENPT, centromere protein T
- CFB, complement factor B
- CGA, glycoprotein hormones
- CTLA4, cytotoxic T-lymphocyte-associated protein 4
- DAD1, defender against cell death 1
- DCTPP1, DCTP pyrophosphatase 1
- DNMT3A, DNA (cytosine-5-)-methyltransferase 3 alpha
- DUOX2, dual oxidase 2
- GCG, glucagon
- GCLC, glutamate-cysteine ligase
- GOLGA3, golgin A3
- GSTM1, glutathione S-transferase Mu 1
- GSTP1, glutathione S-transferase Pi 1
- HPSE, heparanase
- HSPA5, heat shock 70 kDa protein 5
- HSPB1, heat shock 27 KDa protein
- HSPB2, heat shock 27 kDa protein 2
- HSPH1, heat shock 105 kDa/110 kDa protein 1
- HTATIP2, HIV-1 tat interactive protein 2
- ID1, inhibitor of DNA binding 1
- IGF2, Insulin-like growth factor 2 (somatomedin A)
- IL1B, interleukin 1
- INHBA, inhibin
- IYD, iodotyrosine deiodinase
- KIF20B, kinesin family member 20B
- KIF22, kinesin family Member 22
- KLK1, kallikrein 1
- LAMA2, laminin, alpha 2
- MCM8, minichromosome maintenance complex component 8
- MIF, macrophage migration inhibitory factor
- MIS18A, MIS18 kinetochore protein A
- NDC80, NDC80 kinetochore complex component
- NPPC, natriuretic peptide precursor C
- NPY, neuropeptide
- NUBP1, nucleotide binding protein 1
- ORC1, origin recognition complex
- PDE3A, phosphodiesterase 3A
- PINK1, PTEN induced putative kinase 1
- PLCD1, phospholipase C
- PLK1, polo-like kinase 1
- POMC, proopiomelanocortin
- PRKAA2, protein kinase
- PRL, prolactin
- PRODH, proline dehydrogenase
- PTGIS, prostaglandin I2 (prostacyclin) synthase
- PTGS1, prostaglandin-endoperoxide synthase 1
- RAB5A, RAB5A
- RAN, ras-related nuclear protein
- RRM2, ribonucleotide reductase M2
- RccHan Wistar
- SCL5A5, solute carrier family 5 (sodium iodide symporter)
- SELP, selectin P (granule membrane protein 140 kDa
- SPAG8, sperm associated antigen 8
- TACC3, transforming
- TBCB, tubulin folding cofactor B
- TFRC, transferrin receptor
- TOP2A, topoisomerase (DNA) II alpha
- TPO, thyroid peroxidase
- TSHR, thyroid stimulating hormone receptor
- TSN, translin
- Thyroid
- Transcriptomics
- VWF, Von Willebrand Factor
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Affiliation(s)
- Reyna Cristina Collí-Dulá
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA
| | | | - Benjamin Hansen
- Laboratory of Pharmacology and Toxicology, D-211134, Hamburg, Germany
| | - Nancy D Denslow
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32611, USA
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Klaunig JE, Dekant W, Plotzke K, Scialli AR. Biological relevance of decamethylcyclopentasiloxane (D5) induced rat uterine endometrial adenocarcinoma tumorigenesis: Mode of action and relevance to humans. Regul Toxicol Pharmacol 2016; 74 Suppl:S44-56. [DOI: 10.1016/j.yrtph.2015.06.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/24/2015] [Accepted: 06/26/2015] [Indexed: 11/27/2022]
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15
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Reproductive senescence, fertility and reproductive tumour profile in ageing female Han Wistar rats. ACTA ACUST UNITED AC 2015; 68:143-7. [PMID: 26655996 DOI: 10.1016/j.etp.2015.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 11/04/2015] [Accepted: 11/24/2015] [Indexed: 11/24/2022]
Abstract
A study using vehicle administration in 104 female rats investigated reproductive aging in Han Wistar rats as a useful tool to interprete carcinogenicity studies where hormonal patterns are perturbated. From 16 weeks of age oestrous cycles were monitored every 6 weeks to investigate reproductive ageing. A subset of 20 females was used to assess fertility at 21 months of age. The animals were necropsied after 106-107 weeks on study and female reproductive organs, mammary glands and pituitary glands were examined for hyperplasias and/or tumours. The majority of rats had regular oestrous cycles up to 6 months of age. After this age, there was a rapid decline in the number of rats with regular oestrous cycles and an increase in irregular cycles and cycles in persistent di-oestrus with an occasional pro-oestrus. By the end of the study, the majority of animals were acyclic and the few remaining cyclic animals had irregular cycles. In the fertility assessment, 19/20 animals mated but only four animals became pregnant. These pregnant animals had normal numbers of corpora lutea of pregnancy but had high pre-implantation losses and could not sustain a viable pregnancy. 65 animals (62.5%) showed adenomas and/or pituitary hyperplasia in the pituitary gland at necropsy. The pituitary tumours were likely to be prolactin secreting that give rise to pseudopregnancy and mammary tumours, demonstrated by the fact that 43/65 (66%) of the affected animals had histopathological signs of these conditions. Multiple corpora lutea were found in 61% of all animals at time of termination. Only one uterine tumour was seen in this study probably due to lack of persistent oestrus seen in these animals.
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Tetrabromobisphenol A (TBBPA): Possible modes of action of toxicity and carcinogenicity in rodents. Food Chem Toxicol 2015; 80:206-214. [DOI: 10.1016/j.fct.2015.03.023] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 01/16/2023]
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17
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Scientific Opinion on the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs. EFSA J 2015. [DOI: 10.2903/j.efsa.2015.3978] [Citation(s) in RCA: 528] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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18
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Gouda ZA, Ahmed SM, Elghonaimy NM. Characterization of adult male albino rat mammary gland: a histological and serological study. ACTA ACUST UNITED AC 2015. [DOI: 10.7243/2055-091x-2-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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19
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Maronpot RR, Thoolen RJMM, Hansen B. Two-year carcinogenicity study of acrylamide in Wistar Han rats with in utero exposure. ACTA ACUST UNITED AC 2014; 67:189-95. [PMID: 25553597 DOI: 10.1016/j.etp.2014.11.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/30/2014] [Accepted: 11/19/2014] [Indexed: 11/19/2022]
Abstract
Acrylamide is an important chemical with widespread industrial and other uses in addition to generalized population exposure from certain cooked foods. Previous rat studies to assess the carcinogenic potential of acrylamide have been carried out exclusively in the Fischer 344 rat with identification of a number of tumors amongst which mesotheliomas of the tunica vaginalis is an important tumor endpoint in the classification of acrylamide as a 'probably human carcinogen. In a rat carcinogenicity study to determine the human relevance of mesotheliomas Wistar Han rats were exposed to 0, 0.5, 1.5, or 3.0mg acrylamide/kg body weight/day in drinking water starting at gestation day 6. At the end of two years, mammary gland fibroadenomas in females and thyroid follicular cell tumors in both sexes were the only tumors increased in acrylamide treated rats. These tumor endpoints have rat-specific modes of action suggesting less likelihood of human cancer risk than previously estimated. This study demonstrates that tunica vaginalis mesotheliomas are strain specific and not likely of genotoxic origin.
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Affiliation(s)
- R R Maronpot
- Experimental Pathology Laboratories, Inc., Research Triangle Park, NC, United States.
| | | | - B Hansen
- LPT Laboratory of Pharmacology & Toxicology, Hamburg, Germany
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A peripherally restricted P2Y 12 receptor antagonist altered rat tumor incidences with no human relevance: Mode of action consistent with dopamine agonism. Toxicol Rep 2014; 1:1202-1212. [PMID: 28962330 PMCID: PMC5598522 DOI: 10.1016/j.toxrep.2014.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 11/10/2014] [Accepted: 11/11/2014] [Indexed: 12/26/2022] Open
Abstract
Background Ticagrelor is an orally available, direct acting and reversible P2Y12 receptor antagonist approved for treatment of acute coronary syndrome. The objectives of these studies were to (1) evaluate the Ticagrelor 2-year rat carcinogenicity bioassay data; (2) investigate potential mode of action (MOA) and (3) interpret human relevance. Methods The following studies were done (1) rat two-year carcinogenicity study in male and female rats, (2) in vitro and in vivo genotoxicity assays, (3) quantitative whole body autoradiography (QWBA; male and female rats), (4) in vitro pharmacological profiling for more than 300 assays, and (5) in vivo ovariectomized rat assay. Results The carcinogenicity study indicated Ticagrelor increased uterine tumor incidence while decreasing mammary and pituitary tumors/hyperplasia incidences in only high dose female rats. However, this altered tumor incidences were not P2Y12 target related since marketed non-reversible P2Y12 receptor antagonists were not associated with alter tumor incidences. MOA studies determined Ticagrelor exposure in the anterior pituitary and Ticagrelor was (1) non-genotoxic, (2) peripherally-restricted, (3) a dopamine transport (DAT) inhibitor with an IC50 lower than systemic free exposure in the rat carcinogenic study and more than a log higher than the free systemic exposure seen in clinical trials and (4) an inhibitor of estradiol-induced prolactin secretion. Discussion Similar to Ticagrelor, centrally active dopamine agonists induce the same altered tumor incidence patterns that according to literature do not translate into the clinical setting, with a MOA involving decreased prolactin secretion. The Ticagrelor MOA data and literature suggest that altered dopamine levels in the hypophyseal part of the hypothalamus–hypophyseal axis (by Ticagrelor) will result in similar altered tumor incidences in rat that do not translate into the clinical setting, based on qualitative species differences. In conclusion Ticagrelor increased uterine tumors in the rat carcinogenesis study by a MOA consistent with reduced dopamine inhibition of prolactin, which is not a patient safety risk.
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Key Words
- ADP, adenosine-5′-diphosphate
- AUC, area under the curve
- CHO, Chinese hamster ovary
- Carcinogenicity
- Cmax, maximal concentration, DAT, dopamine transport
- Dopamine transport inhibitor
- E2, estradiol
- GLP, good laboratory practice
- H&E, hematoxylin and eosin
- IC50, inhibitory concentration fifty percent
- Ki, inhibition concentration
- LC-MS/MS, liquid chromatography-mass spectrometric
- LLOQ, lower limits of quantification
- MOA, mode of action
- MTD, maximum tolerated dose
- NH, Hill coefficient
- Prolactin
- QWBA, quantitative whole body autoradiography
- TK, toxicokinetics
- Translational
- Uterine tumor
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21
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Toxicology and pathology of female reproductive tract. Cell Biol Toxicol 2013; 29:131-41. [DOI: 10.1007/s10565-013-9244-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/04/2013] [Indexed: 10/26/2022]
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Harleman JH, Hargreaves A, Andersson H, Kirk S. A Review of the Incidence and Coincidence of Uterine and Mammary Tumors in Wistar and Sprague-Dawley Rats Based on the RITA Database and the Role of Prolactin. Toxicol Pathol 2012; 40:926-30. [DOI: 10.1177/0192623312444621] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Wistar rats are frequently selected for use in carcinogenicity studies because of their advantageous survival rate, which is more favorable than other strains such as the Sprague-Dawley (SD) strain. Uterine and mammary tumors are relatively common spontaneous neoplasms of both strains. We examined the incidence and coincidence of uterine tumors and mammary tumors in control animals of both strains within the RITA database. There was a strong inverse relationship between these tumor types in Wistar rats ( p < .001). A less strong relationship was present in SD rats ( p = .057). This association is likely to be related to prolactin. A short review of the role of prolactin in rats is given. These results are also discussed in the background of nonspecific toxicity at high dose levels in carcinogenicity studies above MTD levels resulting in reduction in body weights of >10%.
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Affiliation(s)
| | - Adam Hargreaves
- Astra Zeneca, Safety Assessment, Mereside Alderley Park, Macclesfield, UK
| | | | - Sarah Kirk
- Astra Zeneca, Safety Assessment, Mereside Alderley Park, Macclesfield, UK
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Harvey PW. Hypothesis: prolactin is tumorigenic to human breast: dispelling the myth that prolactin-induced mammary tumors are rodent-specific. J Appl Toxicol 2011; 32:1-9. [PMID: 22095846 DOI: 10.1002/jat.1772] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 10/14/2011] [Accepted: 10/14/2011] [Indexed: 11/09/2022]
Abstract
The commonly held assumption that rodent mammary tumors resulting from elevated prolactin are species-specific, or not biologically relevant to humans, is incorrect. Substantial epidemiological, clinical, and biological evidence now exists confirming the role of prolactin in human breast cancer. This evidence is evaluated and the argument presented that the tumorigenic risk from prolactin is therefore not species-specific to rodents but directly applies to humans. Further, as the mechanisms of prolactin-induced mammary tumor promotion and development appear analogous between rodents and humans, mammary tumorigenic findings in rodent carcinogenicity bioassays are both predictive and biologically relevant to the human response. Toxicologists and regulators need to consider this in carcinogenicity risk assessments.
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Affiliation(s)
- Philip W Harvey
- Covance Laboratories, Otley Road, Harrogate, North Yorkshire, HG3 1PY, UK.
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Sistare FD, Morton D, Alden C, Christensen J, Keller D, Jonghe SD, Storer RD, Reddy MV, Kraynak A, Trela B, Bienvenu JG, Bjurström S, Bosmans V, Brewster D, Colman K, Dominick M, Evans J, Hailey JR, Kinter L, Liu M, Mahrt C, Marien D, Myer J, Perry R, Potenta D, Roth A, Sherratt P, Singer T, Slim R, Soper K, Fransson-Steen R, Stoltz J, Turner O, Turnquist S, van Heerden M, Woicke J, DeGeorge JJ. An analysis of pharmaceutical experience with decades of rat carcinogenicity testing: support for a proposal to modify current regulatory guidelines. Toxicol Pathol 2011; 39:716-44. [PMID: 21666103 DOI: 10.1177/0192623311406935] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Data collected from 182 marketed and nonmarketed pharmaceuticals demonstrate that there is little value gained in conducting a rat two-year carcinogenicity study for compounds that lack: (1) histopathologic risk factors for rat neoplasia in chronic toxicology studies, (2) evidence of hormonal perturbation, and (3) positive genetic toxicology results. Using a single positive result among these three criteria as a test for outcome in the two-year study, fifty-two of sixty-six rat tumorigens were correctly identified, yielding 79% test sensitivity. When all three criteria were negative, sixty-two of seventy-six pharmaceuticals (82%) were correctly predicted to be rat noncarcinogens. The fourteen rat false negatives had two-year study findings of questionable human relevance. Applying these criteria to eighty-six additional chemicals identified by the International Agency for Research on Cancer as likely human carcinogens and to drugs withdrawn from the market for carcinogenicity concerns confirmed their sensitivity for predicting rat carcinogenicity outcome. These analyses support a proposal to refine regulatory criteria for conducting a two-year rat study to be based on assessment of histopathologic findings from a rat six-month study, evidence of hormonal perturbation, genetic toxicology results, and the findings of a six-month transgenic mouse carcinogenicity study. This proposed decision paradigm has the potential to eliminate over 40% of rat two-year testing on new pharmaceuticals without compromise to patient safety.
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Affiliation(s)
- Frank D Sistare
- Merck and Co., Inc., West Point, Pennsylvania 19486-0004, USA.
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Hargreaves A, Harleman J. Preclinical risk assessment of drug-induced hypo- and hyperprolactinemia. J Appl Toxicol 2011; 31:599-607. [DOI: 10.1002/jat.1723] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 11/08/2022]
Affiliation(s)
- Adam Hargreaves
- Pathology Department; Safety Assessment, Astrazeneca Pharmaceuticals; Alderley Park; Cheshire; SK10 4TG; UK
| | - Johannes Harleman
- Pathology Department; Safety Assessment, Astrazeneca Pharmaceuticals; Alderley Park; Cheshire; SK10 4TG; UK
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Nagaraja AK, Agno JE, Kumar TR, Matzuk MM. Luteinizing hormone promotes gonadal tumorigenesis in inhibin-deficient mice. Mol Cell Endocrinol 2008; 294:19-28. [PMID: 18657590 PMCID: PMC2743404 DOI: 10.1016/j.mce.2008.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 05/25/2008] [Accepted: 06/28/2008] [Indexed: 11/23/2022]
Abstract
The inhibins are secreted alpha:beta heterodimers of the TGF-beta superfamily that are mainly synthesized in Sertoli cells and granulosa cells, and are critical regulators of testicular and ovarian development and function. Mice homozygous for a targeted deletion of the inhibin alpha subunit gene (Inha(-/-)) develop sex cord-stromal tumors in a gonadotropin-dependent manner. Here, we determine the contribution of LH to gonadal tumorigenesis by generating mice deficient in both inhibins and LH. Inha(-/-)Lhb(-/-) mice have increased survival and delayed tumor progression, and these observations correlate with lower serum FSH and estradiol levels compared to Inha(-/-) controls. Double mutant testicular tumors demonstrate decreased expression of cyclin D2, while double mutant ovarian tumors have elevated expression of p15(INK4b) and trend toward higher levels of p27(Kip1). We conclude that LH is not required for tumor formation in the absence of inhibins but promotes tumor progression, likely through alterations in serum hormone levels and cell cycle regulators.
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Affiliation(s)
- Ankur K Nagaraja
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
When methyl tertiary-butyl ether (MTBE) in gasoline was first introduced to reduce vehicle exhaust emissions and comply with the Clean Air Act, in the United States, a pattern of complaints emerged characterised by seven "key symptoms." Later, carefully controlled volunteer studies did not confirm the existence of the specific key symptoms, although one study of self-reported sensitive (SRS) people did suggest that a threshold at about 11-15% MTBE in gasoline may exist for SRSs in total symptom scores. Neurobehavioral and psychophysiological studies on volunteers, including SRSs, found no adverse responses associated with MTBE at likely exposure levels. MTBE is well and rapidly absorbed following oral and inhalation exposures. Cmax values for MTBE are achieved almost immediately after oral dosing and within 2 h of continuous inhalation. It is rapidly eliminated, either by exhalation as unchanged MTBE or by urinary excretion of its less volatile metabolites. Metabolism is more rapid humans than in rats, for both MTBE and tert-butyl alcohol (TBA), its more persistent primary metabolite. The other primary metabolite, formaldehyde, is detoxified at a rate very much greater than its formation from MTBE. MTBE has no specific effects on reproduction or development, or on genetic material. Neurological effects were observed only at very high concentrations. In carcinogenicity studies of MTBE, TBA, and methanol (included as an endogenous precursor of formaldehyde, without the presence of TBA), some increases in tumor incidence have been observed, but consistency of outcome was lacking and even some degree of replication was observed in only three cases, none of which had human relevance: alpha(2u)-globulin nephropathy-related renal tubule cell adenoma in male rats; Leydig-cell adenoma in male rats, but not in mice, which provide the better model of the human disease; and B-cell-derived lymphoma/leukemia of doubtful pathogenesis that arose mainly in lungs of orally dosed female rats. In addition, hepatocellular adenomas were significantly higher in female CD-1 mice and thyroid follicular-cell adenomas were increased in female B6C3F1 mice treated with TBA, but these results lack any independent confirmation, which would have been possible from a number of other studies.
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Harvey PW, Everett DJ, Springall CJ. Adverse effects of prolactin in rodents and humans: breast and prostate cancer. J Psychopharmacol 2008; 22:20-7. [PMID: 18709700 DOI: 10.1177/0269881107082624] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Drugs and chemicals shown to induce mammary carcinogenesis in the rat/rodent via prolactin excess have traditionally been argued to pose little or no risk to humans in a regulatory toxicology context. The basis for this assumption is reviewed and placed into context with new evidence in humans that prolactin may be a tumour promoter in the breast and prostate. This evidence includes epidemiology, patient studies involving endocrine evaluation and molecular biology in human cells. It is concluded that hyperprolactinaemia is associated with an increase in breast cancer risk in both post and premenopausal women, that rat carcinogenicity studies are predictive of the human response, and that in a regulatory toxicology context prolactin-induced mammary tumours from nongenotoxic drugs and chemicals are an adverse effect that should not be ignored. More evidence is required concerning prostate cancer risk but molecular biology indicates that prolactin also induces prostate cell proliferation and inhibits apoptosis, which are similar to the responses observed in breast cancer cells.
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Affiliation(s)
- Philip W Harvey
- Department of Toxicology, Covance Laboratories Ltd., Otley Road, Harrogate, North Yorkshire, UK.
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Akingbemi BT, Braden TD, Kemppainen BW, Hancock KD, Sherrill JD, Cook SJ, He X, Supko JG. Exposure to phytoestrogens in the perinatal period affects androgen secretion by testicular Leydig cells in the adult rat. Endocrinology 2007; 148:4475-88. [PMID: 17569756 DOI: 10.1210/en.2007-0327] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The use of soy-based products in the diet of infants has raised concerns regarding the reproductive toxicity of genistein and daidzein, the predominant isoflavones in soybeans with estrogenic activity. Time-bred Long-Evans dams were fed diets containing 0, 5, 50, 500, or 1000 ppm of soy isoflavones from gestational d 12 until weaning at d 21 postpartum. Male rats in all groups were fed soy-free diets from postnatal d 21 until 90 d of age. The mean +/- SD concentration of unconjugated (i.e. biologically active) genistein and daidzein in serum from the group of dams maintained on the diet containing the highest amount of isoflavones (1000 ppm) were 17 +/- 27 and 56 +/- 30 nM, respectively, at d 21 postpartum. The concentrations were considerably greater in male offspring (genistein: 73 +/- 46 nM; daidzein: 106 +/- 53 nM). Although steroidogenesis was decreased in individual Leydig cells, male rats from the highest exposure group (1000 ppm diet) exhibited elevated serum levels of the sex steroid hormones androsterone at 21 d (control: 15 +/- 1.5 vs.28 +/- 3.5 ng/ml; P < 0.05) and testosterone at 90 d of age (control: 7.5 +/- 1 vs.17 +/- 2 ng/ml; P < 0.05). Testosterone secretion by immature Leydig cells, isolated from 35-d-old male rats, decreased on exposure to 0.1 nm genistein in vitro (control: 175 +/- 5 vs. 117 +/- 3 ng/10(6) cells per 24 h; P < 0.05), indicative of direct phytoestrogen action. Thus, phytoestrogens have the ability to regulate Leydig cells, and additional studies to assess potential adverse effects of dietary soy-based products on reproductive tract development in neonates are warranted.
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Affiliation(s)
- Benson T Akingbemi
- Department of Anatomy, Physiology and Pharmacology, 109 Greene Hall, Auburn University, Auburn, Alabama 36849, USA.
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Harvey PW, Everett DJ, Springall CJ. Hyperprolactinaemia as an adverse effect in regulatory and clinical toxicology: role in breast and prostate cancer. Hum Exp Toxicol 2007; 25:395-404. [PMID: 16898168 DOI: 10.1191/0960327106ht643oa] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Historically, hyperprolactinaemia has been considered of low toxicological relevance when detected in toxicity studies, and even mammary carcinogenesis induced in the rat by prolactin excess has been considered of no relevance to humans. However, recent findings from human epidemiology and molecular biology suggests that prolactin is a risk factor for human breast cancer, and probably prostate cancer. Therefore, this new evidence should be considered in the various decisions to develop and license a new drug or chemical if the compound causes hyperprolactinaemia. This emerging evidence suggests that prolactin can also be produced locally from human breast cancer cells, and that, regardless of source (ie, pituitary or autocrine/paracrine production from cancer cells), prolactin is mitogenic, stimulates proliferation and suppresses apoptosis in breast and prostate cancer cells. This review outlines the evidence that hyperprolactinaemia should be considered a toxicological adverse effect and concludes that prolactin-induced rodent mammary carcinogenesis is relevant to humans and is not species-specific. The effects of prolactin on the prostate gland are also discussed; hyperprolactinaemia may be an additional risk factor for prostate cancer and this also requires consideration in toxicological risk assessments. The implications of increased prolactin secretion as an adverse effect for regulatory toxicology of drugs and chemicals, and in high risk patients receiving therapeutic drugs with hyperprolactinaemic side effects, is discussed. Alteration of prolactin level is also a novel mechanism that requires consideration in endocrine disruption research, since both endogenous oestrogens and also xenoestrogens stimulate prolactin secretion or affect prolactin receptors.
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Affiliation(s)
- P W Harvey
- Department of Toxicology, Covance Laboratories Ltd., Harrogate, North Yorkshire, UK.
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31
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Shipp A, Lawrence G, Gentry R, McDonald T, Bartow H, Bounds J, Macdonald N, Clewell H, Allen B, Van Landingham C. Acrylamide: review of toxicity data and dose-response analyses for cancer and noncancer effects. Crit Rev Toxicol 2006; 36:481-608. [PMID: 16973444 DOI: 10.1080/10408440600851377] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Acrylamide (ACR) is used in the manufacture of polyacrylamides and has recently been shown to form when foods, typically containing certain nutrients, are cooked at normal cooking temperatures (e.g., frying, grilling or baking). The toxicity of ACR has been extensively investigated. The major findings of these studies indicate that ACR is neurotoxic in animals and humans, and it has been shown to be a reproductive toxicant in animal models and a rodent carcinogen. Several reviews of ACR toxicity have been conducted and ACR has been categorized as to its potential to be a human carcinogen in these reviews. Allowable levels based on the toxicity data concurrently available had been developed by the U.S. EPA. New data have been published since the U.S. EPA review in 1991. The purpose of this investigation was to review the toxicity data, identify any new relevant data, and select those data to be used in dose-response modeling. Proposed revised cancer and noncancer toxicity values were estimated using the newest U.S. EPA guidelines for cancer risk assessment and noncancer hazard assessment. Assessment of noncancer endpoints using benchmark models resulted in a reference dose (RfD) of 0.83 microg/kg/day based on reproductive effects, and 1.2 microg/kg/day based on neurotoxicity. Thyroid tumors in male and female rats were the only endpoint relevant to human health and were selected to estimate the point of departure (POD) using the multistage model. Because the mode of action of acrylamide in thyroid tumor formation is not known with certainty, both linear and nonlinear low-dose extrapolations were conducted under the assumption that glycidamide or ACR, respectively, were the active agent. Under the U.S. EPA guidelines (2005), when a chemical produces rodent tumors by a nonlinear or threshold mode of action, an RfD is calculated using the most relevant POD and application of uncertainty factors. The RfD was estimated to be 1.5 microg/kg/day based on the use of the area under the curve (AUC) for ACR hemoglobin adducts under the assumption that the parent, ACR, is the proximate carcinogen in rodents by a nonlinear mode of action. When the mode of action in assumed to be linear in the low-dose region, a risk-specific dose corresponding to a specified level of risk (e.g., 1 x 10-5) is estimated, and, in the case of ACR, was 9.5 x 10-2 microg ACR/kg/day based on the use of the AUC for glycidamide adduct data. However, it should be noted that although this review was intended to be comprehensive, it is not exhaustive, as new data are being published continuously.
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Affiliation(s)
- A Shipp
- ENVIRON International Corporation, 602 East Georgia Street, Ruston, LA 07290, USA.
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32
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Harvey PW. Human relevance of rodent prolactin-induced non-genotoxic mammary carcinogenesis: prolactin involvement in human breast cancer and significance for toxicology risk assessments. J Appl Toxicol 2005; 25:179-83. [PMID: 15856525 DOI: 10.1002/jat.1063] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Prolactin-induced mammary carcinogenesis in rodents, particularly rats, is often stated to be of low toxicological relevance to humans. This opinion appears to have developed from a number of lines of cited evidence. Firstly, there had been long experience of use of dopamine antagonists (that increase prolactin) in human medicine and no evidence of an increase in breast cancer incidence or risk had been reported. Secondly, dopamine agonists (that lower prolactin) had been shown to have no effect in human breast cancer treatment. Thirdly, the actions of prolactin were considered different between rodents and humans. However, recent evidence now suggests that prolactin has a major role in human breast cancer, and the similarity of mechanism with the rodent suggests that prolactin-mediated mammary carcinogenesis in rodents could be of much higher toxicological relevance to humans than previously thought. Large epidemiology studies have upgraded a limited database and shown that dopamine antagonists (both antipsychotics and anti-emetics) increase breast cancer risk, that hyperprolactinaemia is consistently associated with human breast cancer growth, development and poor prognosis, and that prolactin is indeed a mitogen in human breast cancer cells that suppresses apoptosis and upregulates BRCA1. It is now clear that initial studies giving dopamine agonists to breast cancer patients had no effect because breast cancer cells also produced prolactin independently of the pituitary, which remained uncontrolled and unrecognized in early clinical studies. The evidence for the role of prolactin in human breast cancer is now strong and consistent, and is discussed and related to the risk assessment of drugs and chemicals. The conclusion is that it is invalid to suggest that prolactin-induced mammary carcinogenesis in rodents is of low relevance to humans because prolactin can induce an adverse response in the mammary tissue of both rodents and humans alike. Drugs and chemicals causing rodent prolactin-induced mammary carcinogenesis may therefore pose a risk to humans via the same mechanism if exposures also increase prolactin secretion in humans.
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Affiliation(s)
- Philip W Harvey
- Department of Toxicology, Covance Laboratories, Otley Road, Harrogate, North Yorkshire HG3 1PY, UK.
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Akingbemi BT, Ge R, Klinefelter GR, Zirkin BR, Hardy MP. Phthalate-induced Leydig cell hyperplasia is associated with multiple endocrine disturbances. Proc Natl Acad Sci U S A 2004; 101:775-80. [PMID: 14715905 PMCID: PMC321757 DOI: 10.1073/pnas.0305977101] [Citation(s) in RCA: 258] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Indexed: 11/18/2022] Open
Abstract
The possibility that exposures to environmental agents are associated with reproductive disorders in human populations has generated much public interest recently. Phthalate esters are used most commonly as plasticizers in the food and construction industry, and di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate in the environment. Daily human exposure to DEHP in the U.S. is significant, and occupational and clinical exposures from DEHP-plasticized medical devices, e.g., blood bags, hemodialysis tubing, and nasogastric feeding tubes, increase body burden levels. We investigated the effects of chronic exposures to low environmentally relevant DEHP levels on testicular function. Our data show that prolonged exposures to this agent induced high levels of the gonadotropin luteinizing hormone and increased the serum concentrations of sex hormones [testosterone and 17beta-estradiol (E2)] by >50%. Increased proliferative activity in Leydig cells was evidenced by enhanced expression of cell cycle proteins, as determined by RT-PCR. The numbers of Leydig cells in the testis of DEHP-treated rats were 40-60% higher than in control rats, indicating induction of Leydig cell hyperplasia. DEHP-induced elevations in serum testosterone and E2 levels suggest the possibility of multiple crosstalks between androgen, estrogen, and steroid hormone receptors, whereas the presence of estrogen receptors in nonreproductive tissues, e.g., cardiovascular system and bones, implies that the increases in serum E2 levels have implications beyond reproduction, including systemic physiology. Analysis of the effects of phthalate exposures on gonadotropin and steroid hormone levels should form part of overall risk assessment in human populations.
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Affiliation(s)
- Benson T Akingbemi
- Center for Biomedical Research, Population Council, New York, NY 10021, USA
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Mikola M, Kero J, Nilson JH, Keri RA, Poutanen M, Huhtaniemi I. High levels of luteinizing hormone analog stimulate gonadal and adrenal tumorigenesis in mice transgenic for the mouse inhibin-alpha-subunit promoter/Simian virus 40 T-antigen fusion gene. Oncogene 2003; 22:3269-78. [PMID: 12761497 DOI: 10.1038/sj.onc.1206518] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Transgenic (TG) mice expressing the Simian virus 40 T-antigen under the control of the murine inhibin-alpha promoter (Inhalpha/Tag) develop granulosa and Leydig cell tumors at the age of 5-6 months, with 100% penetrance. When these mice are gonadectomized, they develop adrenocortical tumors. Suppression of gonadotropin secretion inhibits the tumorigenesis in the gonads of intact animals and in the adrenals after gonadectomy. To study further the role of luteinizing hormone (LH) in gonadal and adrenal tumorigenesis, a double TG mouse model was generated by crossing the Inhalpha/Tag mice with mice producing constitutively elevated levels of LH (bLHbeta-CTP mice). Our results show that in double TG mice (bLHbeta-CTP/Inhalpha/Tag), gonadal tumorigenesis starts earlier and progresses faster than in Inhalpha/Tag mice. Both ovarian and testicular tumors were histologically comparable with the tumors found in Inhalpha/Tag mice. In addition, adrenal tumorigenesis was found in intact double TG females, but not in Inhalpha/Tag females. Inhibin-alpha and LH receptor (LHR) were highly expressed in tumorigenic gonadal tissues, and the elevated LH levels were shown to be associated with ectopic LHR and high inhibin-alpha expression in the female adrenals. We conclude that in the Inhalpha/Tag tumor mouse model, elevated LH levels act as a tumor promoter, advancing gonadal and adrenal tumorigenesis.
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MESH Headings
- Adrenal Cortex Neoplasms/etiology
- Adrenal Cortex Neoplasms/metabolism
- Adrenal Cortex Neoplasms/pathology
- Adrenal Glands/metabolism
- Animals
- Antigens, Polyomavirus Transforming/genetics
- Artificial Gene Fusion
- Chorionic Gonadotropin, beta Subunit, Human/genetics
- Female
- Granulosa Cell Tumor/etiology
- Granulosa Cell Tumor/metabolism
- Granulosa Cell Tumor/pathology
- Hormones/blood
- Inhibins/biosynthesis
- Inhibins/genetics
- Leydig Cell Tumor/etiology
- Leydig Cell Tumor/metabolism
- Leydig Cell Tumor/pathology
- Luteinizing Hormone/biosynthesis
- Luteinizing Hormone, beta Subunit/genetics
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Transgenic
- Ovarian Neoplasms/etiology
- Ovarian Neoplasms/metabolism
- Ovarian Neoplasms/pathology
- Promoter Regions, Genetic
- RNA, Messenger/biosynthesis
- Receptors, LH/biosynthesis
- Receptors, LH/genetics
- Simian virus 40/immunology
- Testicular Neoplasms/etiology
- Testicular Neoplasms/metabolism
- Testicular Neoplasms/pathology
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Affiliation(s)
- Maarit Mikola
- Department of Physiology, University of Turku, FIN-20520 Turku, Finland
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35
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Abstract
Currently, the majority of substances tested in lifetime bioassays in rodents are not mutagenic and, therefore, at the most weakly carcinogenic, generally by epigenetic mechanisms. It thus appears obvious that only marginal increases of tumour incidences can be expected in lifetime bioassays and that, therefore, every aspect of a potential carcinogenic effect must be thoroughly evaluated. This paper describes a series of key factors, which should be looked at in order to exclude that the lifetime bioassay in question is flawed for design, technical or qualification reasons. It also provides some hints whether there is indeed a real effect and not just a variation of the spontaneous tumour incidences. Tumour findings must be seen in the context of the animal model, the pharmcokinetics and pharmcodynamics of the test substance, as well as any other observation in the present or other studies with the test substance, including non-tumour findings and--in particular--potential precursor lesions and effects on feed intake and survival. The possibility that the observed carcinogenic effects may be species-specific and not relevant for man is discussed. It is also important to check what findings are reported with similar substances or substances with the same pharmacological effect. Data from additional investigations on material of the same study and/or mechanistic studies are often needed to support the final risk assessment.
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Affiliation(s)
- R A Ettlin
- Novartis Pharma AG, WKL-125.1514, CH-4002 Basel, Switzerland.
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36
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Osamura RY, Iwasaka T, Umemura S. Endocrine System and Endocrine Disrupting Chemicals(EDCs). J Toxicol Pathol 2001. [DOI: 10.1293/tox.14.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
| | - Toshiki Iwasaka
- Department of Pathology, Tokai University School of Medicine
| | - Shinobu Umemura
- Department of Pathology, Tokai University School of Medicine
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37
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O'Connor JC, Plowchalk DR, Van Pelt CS, Davis LG, Cook JC. Role of prolactin in chloro-S-triazine rat mammary tumorigenesis. Drug Chem Toxicol 2000; 23:575-601. [PMID: 11071396 DOI: 10.1081/dct-100101972] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Chloro-S-triazine herbicides [cyanazine (CZ), atrazine (AZ), simazine (SZ)] increase mammary tumors in Crl:CD BR rats but not in F-344 rats or in mice. A nongenotoxic mechanism was investigated since the chloro-S-triazines are negative in short-term tests for genotoxicity. An in vivo battery was used to assess the chloro-S-triazines for estrogenic activity or for their ability to increase prolactin (PRL) levels, both of which play important roles in enhancing mammary gland tumorigenesis in rodents. Ovariectomized (OVX) female rats were treated with AZ, CZ, SZ, or three CZ metabolites for 4 days via intraperitoneal injection. The pattern of responses between the chloro-S-triazines and four controls (estradiol, estriol, haloperidol, reserpine) was compared. For the 6 end-points examined, the responses from rats treated with AZ, CZ, SZ, and the metabolites of CZ most closely matched the responses from the reserpine-treated rats (a PRL rather than estrogenic mechanism). In addition, AZ, CZ, and SZ were tested in several other in vitro models (estrogen/biogenic amine receptor competition assays and a yeast-expressed human estrogen receptor transcription assay) as well as an in vivo 24 h time-course experiment to characterize the CZ-induced increases in PRL levels. AZ, CZ, and SZ are not estrogen receptor (ER) activating compounds based on yeast transactivation and receptor competition data. CZ and AZ demonstrated marginal competition (at mM levels) to the D and alpha2 adrenergic receptors. Ligands to the D2 receptor, but not the alpha2 adrenergic receptor, are known to induce mammary tumors. CZ was also found to produce elevated PRL levels in a time-course similar to that seen with reserpine and haloperidol. Overall, the pattern of responses obtained with the chloro-S-triazines most closely matched the responses observed for reserpine. Taken together, these data suggest chloro-S-triazine-induced mammary tumors in rats are mediated through a PRL mechanism, which is thought to be of low relevance to humans.
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Affiliation(s)
- J C O'Connor
- DuPont Haskell Laboratory for Toxicology and Industrial Medicine, Newark, DE 19714, USA.
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38
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Ishikawa T, Inoue S, Kakinuma C, Kuwayama C, Hamada Y, Shibutani Y. Growth-stimulating effect of dienogest, a synthetic steroid, on rodent, canine, and primate mammary glands. Toxicology 2000; 151:91-101. [PMID: 11074304 DOI: 10.1016/s0300-483x(00)00318-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We observed hyperplasia of the mammary gland in female beagle dogs, but not in female rats and monkeys, in 91-day toxicity studies on dienogest. In order to elucidate a possible mechanism for its development and to account for this species difference, we determined the plasma level of growth hormone (GH) in dogs, rats, and monkeys treated orally with dienogest for 91 days. As a result, dogs with mammary hyperplasia showed a prominent, dose-dependent increase in their GH level; and, contrarily, rats and monkeys without the hyperplasia of this organ failed to show any such increase. These results were supported by evidence from immunohistochemical and morphometric analysis of the pituitary gland. In addition, dienogest and medroxyprogesterone acetate (MPA) stimulated the growth of canine mammary epithelial cells in the presence of estradiol in vitro, but had no effect on rat and human mammary epithelial cells incubated under the same conditions. In conclusion, dienogest with progestational activity caused proliferation of the mammary gland in beagle dogs by increasing the secretion of GH, as do other progestational compounds. This change may be partially dependent on the direct effect of the drug.
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Affiliation(s)
- T Ishikawa
- Toxicology Laboratory, Research Center, Mochida Pharmaceutical Co., Ltd., 342 Gensuke, Fujieda, 426-8640, Shizuoka, Japan.
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39
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Davies TS, Lynch BS, Monro AM, Munro IC, Nestmann ER. Rodent carcinogenicity tests need be no longer than 18 months: an analysis based on 210 chemicals in the IARC monographs. Food Chem Toxicol 2000; 38:219-35. [PMID: 10717362 DOI: 10.1016/s0278-6915(99)00150-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The IARC Monographs (Vols 1-70) were studied to determine the time of onset of treatment-related tumorigenicity in long-term rodent studies for chemicals classified by IARC as having sufficient evidence of carcinogenicity in animals. The analysis excluded studies on metals and their salts, studies on particulates, studies by parenteral routes of administration that resulted in tumours only at the site of exposure, and studies that did not approximate to the current standard long-term rodent carcinogenicity bioassay, for instance transplacental or multigeneration studies, initiator-promoter studies, lung tumour assays in Strain A mice and studies in newborn animals. Data from a total of 210 chemicals revealed that, overall, evidence of treatment-related tumorigenicity was first apparent within 12 months for 66% of the chemicals and for only 7% were studies of longer than 18 months necessary. All IARC Group 1 chemicals were detected in animals within 18 months, and most within 12 months. Most of the tumour types that required more than 18 months for detection were of dubious relevance to human risk assessment. Termination of rodent carcinogenicity studies at 18 months or earlier would greatly reduce the complications that arise in interpreting the findings in aged animals which often have defective hepatic or renal function and would also markedly reduce the time required for histopathological examination of dozens of tissues taken from the approximately 500 animals routinely employed in these studies.
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Affiliation(s)
- T S Davies
- Pfizer Central Research, Groton, CT 06340, USA
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40
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Iwasaka T, Umemura S, Miyajima K, Shoda T, Takahashi A, Kakimoto K, Koizumi H, Miyakawa Y, Osamura YR. Lack of Prolactin (PRL) mRNA Expression in Estrogen-treated Rat Mammary Glands. J Toxicol Pathol 2000. [DOI: 10.1293/tox.13.151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Toshiki Iwasaka
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Shinobu Umemura
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
| | - Katsuhiro Miyajima
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Toshiyuki Shoda
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Akemi Takahashi
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Kochi Kakimoto
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Haruko Koizumi
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Yoshifumi Miyakawa
- Toxicology Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 23-Nakogi, Hadano, Kanagawa, 257-0024, Japan
| | - Yoshiyuki R Osamura
- Department of Pathology, Tokai University School of Medicine, Isehara, Kanagawa, 259-1193, Japan
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41
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Clegg ED, Cook JC, Chapin RE, Foster PM, Daston GP. Leydig cell hyperplasia and adenoma formation: mechanisms and relevance to humans. Reprod Toxicol 1997; 11:107-21. [PMID: 9138629 DOI: 10.1016/s0890-6238(96)00203-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Leydig cell adenomas are observed frequently in studies evaluating the chronic toxicity of chemical agents in laboratory animals. Doubts have been raised about the relevance of such responses for human risk assessment, but the question of relevance has not been evaluated and presented in a comprehensive manner by a broad group of experts. This article reports the consensus conclusions from a workshop on rodent Leydig cell adenomas and human relevance. Five aspects of Leydig cell biology and toxicology were discussed: 1) control of Leydig cell proliferation; 2) mechanisms of toxicant-induced Leydig cell hyperplasia and tumorigenesis; 3) pathology of Leydig cell adenomas; 4) epidemiology of Leydig cell adenomas; and 5) risk assessment for Leydig cell tumorigens. Important research needs also were identified. Uncertainty exists about the true incidence of Leydig cell adenomas in men, although apparent incidence is rare and restricted primarily to white males. Also, surveillance databases for specific therapeutic agents as well as nicotine and lactose that have induced Leydig cell hyperplasia or adenoma in test species have detected no increased incidence in humans. Because uncertainties exist about the true incidence in humans, induction of Leydig cell adenomas in test species may be of concern under some conditions. Occurrence of Leydig cell hyperplasia alone in test species after lifetime exposure to a chemical does not constitute a cause for concern in a risk assessment for carcinogenic potential, but early occurrence may indicate a need for additional testing. Occurrence of Leydig cell adenomas in test species is of potential concern as both a carcinogenic and reproductive effect if the mode of induction and potential exposures cannot be ruled out as relevant for humans. The workgroup focused on seven hormonal modes of induction of which two, GnRH agonism and dopamine agonism, were considered not relevant to humans. Androgen receptor antagonism, 5 alpha-reductase inhibition, testosterone biosynthesis inhibition, aromatase inhibition, and estrogen agonism were considered to be relevant or potentially relevant, but quantitative differences may exist across species, with rodents being more sensitive. A margin of exposure (MOE; the ratio of the lowest exposure associated with toxicity to the human exposure level) approach should be used for compounds causing Leydig cell adenoma by a hormonal mode that is relevant to humans. For agents that are positive for mutagenicity, the decision regarding a MOE or linear extrapolation approach should be made on a case-by-case basis. In the absence of information about mode of induction, it is necessary to utilize default assumptions, including linear behavior below the observable range. All of the evidence should be weighed in the decision-making process.
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Affiliation(s)
- E D Clegg
- U.S. Environmental Protection Agency, National Center for Environmental Assessment, Washington, DC 20460, USA
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42
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Monro A. Are lifespan rodent carcinogenicity studies defensible for pharmaceutical agents? EXPERIMENTAL AND TOXICOLOGIC PATHOLOGY : OFFICIAL JOURNAL OF THE GESELLSCHAFT FUR TOXIKOLOGISCHE PATHOLOGIE 1996; 48:155-66. [PMID: 8672869 DOI: 10.1016/s0940-2993(96)80036-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
For most pharmaceuticals, the assessment of carcinogenic risk to humans can be made from information available from a) genotoxicity studies in vivo, b) 3-6 month toxicology studies in two or more animal species and c) clinical investigations in Phase I and II studies aimed at assessing the existence of risk factors (genotoxicity, immune suppression, hormonal activity and chronic irritation/inflammation) associated with cancer in humans caused by pharmaceuticals. The rodent carcinogenicity bioassay is redundant for compounds with such properties. In considering the utility of a bioassay, one must recognize that the outcome of the bioassay has been shown to be predictable for about half of a random selection of chemicals in the US National Toxicology Program (NTP). The predictability of bioassay outcomes for many pharmaceuticals should be even better, given the availability of extensive knowledge on genotoxic potential in vivo and of pharmacological mechanisms, this adding to the redundancy of the bioassay. Furthermore, the value of the bioassay is itself questionable. The inconsistencies in tumor responses between rodent species and strains, the simultaneous tumor increase and decreases within a study and the susceptibility to tumorigenicity from non-genotoxic chemicals by mechanisms now shown to be of no relevance to humans, together make the use of rodents highly misleading as predictors of human cancer risk. For pharmaceuticals with a novel or poorly-understood pharmacodynamic mechanism, useful information on long-term adverse effects that might presage a carcinogenic hazard to humans may be obtained from a 12 month study, usually in rats, conducted at clinically relevant dose levels.
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Affiliation(s)
- A Monro
- Pfizer Central Research, Groton, CT 06340, USA
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Prentice DE, Meikle AW. A review of drug-induced Leydig cell hyperplasia and neoplasia in the rat and some comparisons with man. Hum Exp Toxicol 1995; 14:562-72. [PMID: 7576816 DOI: 10.1177/096032719501400703] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This paper describes control of normal Leydig cell function and testosterone production. The macroscopic and histopathological appearances of spontaneous Leydig cell hyperplasias and tumors (LCT) in the rat are reviewed together with their incidence and hormonal status. Drugs which induce LCTs in chronic studies are discussed and include busereline, carbamazepine, cimetidine, finasteride, flutamide, gemfibrozil, histrelin, hydralazine, indomethacin, isradipine, lactitol, leuprolide, metronidazole, mesulergine, nafarelin, norprolac and vidarabine. The known mechanisms of LCT induction in the rat are reviewed together with other possible etiological factors. The incidence, clinical picture and etiological factors of LCTs in man are also surveyed. Hormone production in Leydig cells and LCTs in rats and man are compared. Differences between the two species are considered, particularly with regard to Leydig cell control mechanisms. The paper concludes that drug-induced LCTs in rats are most probably not predictive for man and their occurrence has little relevance in human safety assessment.
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Affiliation(s)
- D E Prentice
- Pre-Clinical Safety Consultants Est., Godmanchester, Huntingdon, Cambs. UK
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Keenan KP, Soper KA, Smith PF, Ballam GC, Clark RL. Diet, overfeeding, and moderate dietary restriction in control Sprague-Dawley rats: I. Effects on spontaneous neoplasms. Toxicol Pathol 1995; 23:269-86. [PMID: 7659952 DOI: 10.1177/019262339502300305] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study was designed to compare the effects of ad libitum (AL) overfeeding and moderate dietary restriction (DR) of two different diets on Sprague-Dawley (SD) rat 2-yr survival and the development of spontaneous neoplasms. SD rats were fed Purina Rodent Chow 5002 or a modified Rodent Chow 5002-9 containing lower protein, fat, metabolizable energy and increased fiber by AL or by DR at 65% of the AL amount by measurement or time (6.5 hr). At 106 wk, rats fed the 5002-9 diet AL did not have significantly improved survival over rats fed the 5002 diet AL. The 5002 diet fed DR by time (6.5 hr) improved survival for males but not females. Only DR by measurement of both diets resulted in lower mortality for both sexes. The most common cause of death in rats of both sexes fed either diet AL was pituitary tumors followed by mammary gland tumors in females and renal and cardiovascular disease in males. The overall tumor incidence by 106 wk was remarkably similar between AL and DR groups. However, compared to the 5002 AL group, a decrease in the age-adjusted (Peto analysis) incidence of pituitary adenoma was observed in all other male groups. This effect was noted in the female DR by measurement groups only. For males, compared to the 5002 AL group, a decrease in the age-adjusted incidence of pancreatic islet carcinoma was observed in the DR by measurement groups only. In females, compared to the 5002 AL group, the only other difference in tumor incidence was the mammary gland tumors, which showed a significant decrease in the age-adjusted tumor incidence or multiplicity in the 5002-9 AL, 5002-9 DR, and 5002 DR groups. Additional analyses of mammary gland tumors showed growth time (time from initial palpation until death), tumor doubling time, and tumor volume were generally not statistically significantly different between AL and DR groups, although AL females could sustain larger tumor volumes. Compared to the 5002 AL group, there were no other significant differences in the age-adjusted incidence of any other tumor site in animals fed a modified diet or subjected to moderate DR of either diet. The conclusion from this study is that moderate DR delays death due to fatal cardiovascular or renal degenerative disease and spontaneous tumors, particularly those of the pituitary and mammary gland.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K P Keenan
- Department of Safety Assessment, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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Nandi S, Guzman RC, Yang J. Hormones and mammary carcinogenesis in mice, rats, and humans: a unifying hypothesis. Proc Natl Acad Sci U S A 1995; 92:3650-7. [PMID: 7731959 PMCID: PMC42019 DOI: 10.1073/pnas.92.9.3650] [Citation(s) in RCA: 276] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
An attempt has been made to put forward a unifying hypothesis explaining the role hormones play in the genesis of mammary cancers of different phenotypes and genotypes in mice, rats, and humans. Most mammary cancers in these species originate in luminal mammary epithelial cells lining the mammary ducts and alveoli. These cancers are histopathologically diverse and are classified on the basis of growth requirements as hormone-dependent or hormone-independent tumors. In most strains of mice, mammary cancers at the time of detection are largely of the hormone-independent type; in rats, almost all mammary cancers are hormone-dependent, while humans have both phenotypes. In spite of these differences, in vivo studies show that hormones (ovarian and pituitary) are essential for luminal mammary epithelial cell proliferation and also for the development of mammary cancers of both hormone-independent and hormone-dependent types. This article, based on our extensive in vivo and in vivo studies and on current literature, proposes a model to explain the central role of hormones in the genesis of all types of mammary cancers. The model attempts to address the following questions: (i) how hormones regulate luminal mammary epithelial cell proliferation, (ii) why hormones are required for the genesis of mammary cancers of all phenotypes and genotypes, including those which are always classified as hormone-independent tumors, and (iii) why the three species (mouse, rat, and human) have consistently different ratios of hormone-dependent to hormone-independent tumors.
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Affiliation(s)
- S Nandi
- Cancer Research Laboratory, University of California, Berkeley 94720, USA
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Monro A, Mordenti J. Expression of exposure in negative carcinogenicity studies: dose/body weight, dose/body surface area, or plasma concentrations? Toxicol Pathol 1995; 23:187-98. [PMID: 7569674 DOI: 10.1177/019262339502300213] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Evaluation of positive findings in a rodent carcinogenicity study and the subsequent extrapolation to humans is based on chemical structure, mutagenicity, pharmacology, hormone changes, chronic toxicity, and the nature of the tumors induced. For negative studies, adequacy of exposure may become an issue. The use of plasma concentrations as a metric for exposure assumes that each species responds in a similar manner to a given concentration; data are now available that demonstrate that this is not generally true for carcinogenicity. The use of the body surface area metric (i.e., mg/m2) is a special case of interspecies allometric scaling (i.e., W0.67). For a chemical to be amenable to such scaling in toxicology, it must satisfy 3 criteria: (a) the concentration-time profile of the putative toxicant at the site of action must be governed by a scalable pharmacokinetic process (e.g., glomerular filtration); (b) the mechanism of action and the susceptibility of each species to a given systemic exposure must be the same and, for example, be independent of lifespan, cellular repair mechanism/rate, and so forth; and (c) the biological response must depend only on size (e.g., not on race, strain, gender, age, or parity). Carcinogens rarely, if ever, meet these criteria. An empirical analysis of carcinogenic potency data in rodents and in humans shows that, in general, exposure is best expressed in terms of mg/kg body weight.
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Affiliation(s)
- A Monro
- Pfizer Central Research, Groton, Connecticut 06340, USA
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Keenan KP, Smith PF, Hertzog P, Soper K, Ballam GC, Clark RL. The effects of overfeeding and dietary restriction on Sprague-Dawley rat survival and early pathology biomarkers of aging. Toxicol Pathol 1994; 22:300-15. [PMID: 7817120 DOI: 10.1177/019262339402200308] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A significant correlation exists between average daily food consumption and 2-yr survival in control ad libitum (AL)-fed Sprague-Dawley (SD) rats. SD rats were fed Purina Rodent Chow 5002 or a modified chow, 5002-9, with lower protein, fat, metabolizable energy and increased fiber AL or by dietary restriction (DR) to 65% of the AL amount by measurement or time (6.5 hr). At 52 wk, food consumption and key pathology biomarkers correlated with 106-wk survival. The modified chow, 5002-9 fed AL, did not significantly improve survival. SD rats fed either diet AL consumed the greatest amount of feed and kcal/rat but consumed the same amount of feed per gram body weight as DR-fed rats. At 52 wk, AL rats fed either diet had the same brain weights as DR rats, but the AL-fed rats had greater body weight and body fat content and increased heart, lung, kidney, liver, adrenal, thyroid, and pituitary weights as well as an increased incidence and severity of degenerative and/or proliferative lesions in these organs. This study demonstrates that overfeeding best correlates with low 2-yr survival in SD rats and that simple DR by caloric restriction modifies key pathology biomarkers in the pituitary, mammary gland, kidney, and heart of SD rats at 52 wk that are predictive of 106-wk survival.
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Affiliation(s)
- K P Keenan
- Department of Safety Assessment, Merck Research Laboratories, West Point, Pennsylvania 19486
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48
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Abstract
Many compounds giving a positive result in animal carcinogenicity studies through mechanisms involving secondary carcinogenesis pose little or no risk to humans. This article provides an overview of current understanding, with particular reference to renal tumors in male rats with alpha 2mu-globulin nephropathy, urinary bladder neoplasia in rodents, mesovarian leiomyomas induced in rats by beta 2-receptor stimulants, carcinoid tumors in the rodent stomach induced by prolonged suppression of acid secretion, thyroid follicular cell tumors in rodents, canine mammary neoplasia due to administration of progestagens, rodent mammary neoplasia induced by estrogens, uterine endometrial carcinomas of rats induced by dopamine agonists, Leydig cell tumors in the testis of rats, and ovarian tubulostromal adenomas in mice. A positive result on a rodent carcinogenicity study should not automatically preclude further development of a compound; future progress in this field should increase the accuracy of the rodent carcinogenicity study as a tool in human safety assessment.
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Affiliation(s)
- R H Alison
- Department of Veterinary Pathobiology, Ohio State University, Columbus 43210
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Purchase IF. Current knowledge of mechanisms of carcinogenicity: genotoxins versus non-genotoxins. Hum Exp Toxicol 1994; 13:17-28. [PMID: 8198825 DOI: 10.1177/096032719401300104] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- I F Purchase
- ZENECA Central Toxicology Laboratory, Macclesfield, Cheshire, UK
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Cook JC, Murray SM, Frame SR, Hurtt ME. Induction of Leydig cell adenomas by ammonium perfluorooctanoate: a possible endocrine-related mechanism. Toxicol Appl Pharmacol 1992; 113:209-17. [PMID: 1561629 DOI: 10.1016/0041-008x(92)90116-a] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ammonium perfluorooctanoate (C8) produced an increased incidence of Leydig cell adenomas in Crl:CD BR (CD) rats fed 300 ppm for 2 years. A hormonal (nongenotoxic) mechanism was examined since C8 was negative in short-term tests for genotoxicity. Adult male CD rats were gavaged with either 0, 1, 10, 25, or 50 mg/kg C8 for 14 days. In addition, a control group was pair-fed to the 50 mg/kg C8 group. A dose-dependent decrease in body and relative accessory sex organ (ASO) weights was seen, with the relative ASO weights of the 50 mg/kg group significantly less than those of the pair-fed control. Serum estradiol levels were elevated in the 10, 25, and 50 mg/kg C8-treated animals. Estradiol levels in the 50 mg/kg C8 group were 2.7-fold greater than those in the pair-fed control. The increase in serum estradiol levels occurred at the same dose levels as the increase in hepatic beta-oxidation activity. A statistically significant downward trend with dose was seen in serum testosterone levels when compared with the ad libitum control. However, when the 50 mg/kg C8-treated rats were compared with their pair-fed control, no significant differences were seen. Challenge experiments, which can identify the presence and location of a lesion in an endocrine axis, were undertaken to clarify the significance of this downward trend in serum testosterone following C8 exposure. In the challenge experiments, adult CD rats were gavaged with either 0 or 50 mg/kg C8 for 14 days. One hour before termination, rats received either a human chorionic gonadotropin (hCG), gonadotropin-releasing hormone (GnRH), or naloxone challenge. Following hCG challenge, serum testosterone levels in the 50 mg/kg C8 were significantly decreased (50%) from those in the ad libitum controls. Similar decreases, although not significant, were seen in serum testosterone following GnRH and naloxone challenge. The challenge experiments suggest that the decrease in serum testosterone following C8 exposure is due to a lesion at the level of the testis. In addition, progesterone, 17 alpha-hydroxyprogesterone, and androstenedione were examined in the 50 mg/kg C8-treated males following hCG challenge. A 60% decrease was observed in androstenedione levels in the C8-treated animals from those in the ad libitum controls; no other differences were seen. These data suggest that the decrease in serum testosterone following hCG challenge may be due to a decrease in the conversion of 17 alpha-hydroxyprogesterone to androstenedione. The observed effects described above can be attributed to the elevated serum estradiol levels.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J C Cook
- Haskell Laboratory for Toxicology and Industrial Medicine, E. I. du Pont de Nemours & Company, Newark, Delaware 19714
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