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Robarts DR, Paine-Cabrera D, Kotulkar M, Venneman KK, Gunewardena S, Foquet L, Bial G, Apte U. Identifying novel mechanisms of per- and polyfluoroalkyl substance-induced hepatotoxicity using FRG humanized mice. Arch Toxicol 2024; 98:3063-3075. [PMID: 38782768 DOI: 10.1007/s00204-024-03789-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/15/2024] [Indexed: 05/25/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and perfluoro-2-methyl-3-oxahexanoic acid (GenX), the new replacement PFAS, are major environmental contaminants. In rodents, these PFAS induce several adverse effects on the liver, including increased proliferation, hepatomegaly, steatosis, hypercholesterolemia, nonalcoholic fatty liver disease and liver cancers. Activation of peroxisome proliferator receptor alpha by PFAS is considered the primary mechanism of action in rodent hepatocyte-induced proliferation. However, the human relevance of this mechanism is uncertain. We investigated human-relevant mechanisms of PFAS-induced adverse hepatic effects using FRG liver-chimeric humanized mice with livers repopulated with functional human hepatocytes. Male FRG humanized mice were treated with 0.067 mg/L of PFOA, 0.145 mg/L of PFOS, or 1 mg/L of GenX in drinking water for 28 days. PFOS caused a significant decrease in total serum cholesterol and LDL/VLDL, whereas GenX caused a significant elevation in LDL/VLDL with no change in total cholesterol and HDL. All three PFAS induced significant hepatocyte proliferation. RNA-sequencing with alignment to the human genome showed a total of 240, 162, and 619 differentially expressed genes after PFOA, PFOS, and GenX exposure, respectively. Upstream regulator analysis revealed that all three PFAS induced activation of p53 and inhibition of androgen receptor and NR1D1, a transcriptional repressor important in circadian rhythm. Further biochemical studies confirmed NR1D1 inhibition and in silico modeling indicated potential interaction of all three PFAS with the DNA-binding domain of NR1D1. In conclusion, our studies using FRG humanized mice have revealed new human-relevant molecular mechanisms of PFAS including their previously unknown effect on circadian rhythm.
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Affiliation(s)
- Dakota R Robarts
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MS1018, Kansas City, KS, 66160, USA
| | - Diego Paine-Cabrera
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MS1018, Kansas City, KS, 66160, USA
| | - Manasi Kotulkar
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MS1018, Kansas City, KS, 66160, USA
| | - Kaitlyn K Venneman
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MS1018, Kansas City, KS, 66160, USA
| | - Sumedha Gunewardena
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | | | - Greg Bial
- Yecuris Corporation, Tualatin, OR, USA
| | - Udayan Apte
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MS1018, Kansas City, KS, 66160, USA.
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Ozcagli E, Kubickova B, Jacobs MN. Addressing chemically-induced obesogenic metabolic disruption: selection of chemicals for in vitro human PPARα, PPARγ transactivation, and adipogenesis test methods. Front Endocrinol (Lausanne) 2024; 15:1401120. [PMID: 39040675 PMCID: PMC11260640 DOI: 10.3389/fendo.2024.1401120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 06/10/2024] [Indexed: 07/24/2024] Open
Abstract
Whilst western diet and sedentary lifestyles heavily contribute to the global obesity epidemic, it is likely that chemical exposure may also contribute. A substantial body of literature implicates a variety of suspected environmental chemicals in metabolic disruption and obesogenic mechanisms. Chemically induced obesogenic metabolic disruption is not yet considered in regulatory testing paradigms or regulations, but this is an internationally recognised human health regulatory development need. An early step in the development of relevant regulatory test methods is to derive appropriate minimum chemical selection lists for the target endpoint and its key mechanisms, such that the test method can be suitably optimised and validated. Independently collated and reviewed reference and proficiency chemicals relevant for the regulatory chemical universe that they are intended to serve, assist regulatory test method development and validation, particularly in relation to the OECD Test Guidelines Programme. To address obesogenic mechanisms and modes of action for chemical hazard assessment, key initiating mechanisms include molecular-level Peroxisome Proliferator-Activated Receptor (PPAR) α and γ agonism and the tissue/organ-level key event of perturbation of the adipogenesis process that may lead to excess white adipose tissue. Here we present a critical literature review, analysis and evaluation of chemicals suitable for the development, optimisation and validation of human PPARα and PPARγ agonism and human white adipose tissue adipogenesis test methods. The chemical lists have been derived with consideration of essential criteria needed for understanding the strengths and limitations of the test methods. With a weight of evidence approach, this has been combined with practical and applied aspects required for the integration and combination of relevant candidate test methods into test batteries, as part of an Integrated Approach to Testing and Assessment for metabolic disruption. The proposed proficiency and reference chemical list includes a long list of negatives and positives (20 chemicals for PPARα, 21 for PPARγ, and 11 for adipogenesis) from which a (pre-)validation proficiency chemicals list has been derived.
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3
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Hansen HH, Pors S, Andersen MW, Vyberg M, Nøhr-Meldgaard J, Nielsen MH, Oró D, Madsen MR, Lewinska M, Møllerhøj MB, Madsen AN, Feigh M. Semaglutide reduces tumor burden in the GAN diet-induced obese and biopsy-confirmed mouse model of NASH-HCC with advanced fibrosis. Sci Rep 2023; 13:23056. [PMID: 38155202 PMCID: PMC10754821 DOI: 10.1038/s41598-023-50328-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 12/18/2023] [Indexed: 12/30/2023] Open
Abstract
Non-alcoholic steatohepatitis (NASH) is emerging as a major cause of hepatocellular carcinoma (HCC), however, it is not resolved if compounds in late-stage clinical development for NASH may have additional therapeutic benefits in NASH-driven HCC (NASH-HCC). Here, we profiled monotherapy with semaglutide (glucagon-like-receptor-1 receptor agonist) and lanifibranor (pan-peroxisome proliferator-activated receptor agonist) in a diet-induced obese (DIO) mouse model of NASH-HCC. Disease progression was characterized in male C57BL/6 J mice fed the GAN (Gubra Amylin NASH) diet high in fat, fructose and cholesterol for 12-72 weeks (n = 15 per group). Other GAN DIO-NASH-HCC mice fed the GAN diet for 54 weeks and with biopsy-confirmed NASH (NAFLD Activity Score ≥ 5) and advanced fibrosis (stage F3) received vehicle (n = 16), semaglutide (30 nmol/kg, s.c., n = 15), or lanifibranor (30 mg/kg, p.o., n = 15) once daily for 14 weeks. GAN DIO-NASH-HCC mice demonstrated progressive NASH, fibrosis and HCC burden. Tumors presented with histological and molecular signatures of poor prognostic HCC. Consistent with clinical trial outcomes in NASH patients, both lanifibranor and semaglutide improved NASH while only lanifibranor reduced fibrosis in GAN DIO-NASH-HCC mice. Notably, only semaglutide reduced tumor burden in GAN DIO-NASH-HCC mice. In conclusion, the GAN DIO-NASH-HCC mouse is a clinical translational model of NASH-HCC. Semaglutide improves both NASH and tumor burden in GAN DIO-NASH-HCC mice, highlighting the suitability of this preclinical model for profiling novel drug therapies targeting NASH-HCC.
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Affiliation(s)
| | - Susanne Pors
- Gubra, Hørsholm Kongevej 11B, DK-2970, Hørsholm, Denmark
| | | | - Mogens Vyberg
- Center for RNA Medicine, Department of Clinical Medicine, Aalborg University, Copenhagen, Denmark
| | | | | | - Denise Oró
- Gubra, Hørsholm Kongevej 11B, DK-2970, Hørsholm, Denmark
| | | | | | | | | | - Michael Feigh
- Gubra, Hørsholm Kongevej 11B, DK-2970, Hørsholm, Denmark
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4
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Yang J, Yang X, Zhang YF, Tian JN, Fan SC, Gao Y, Li HL, Cai CH, Huang M, Bi HC. Peroxisome proliferator-activated receptor α agonist induces mouse hepatomegaly through the spatial hepatocyte enlargement and proliferation. Acta Pharmacol Sin 2023; 44:2037-2047. [PMID: 37193756 PMCID: PMC10545716 DOI: 10.1038/s41401-023-01096-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 04/22/2023] [Indexed: 05/18/2023] Open
Abstract
Peroxisome proliferator-activated receptor alpha (PPARα) activation-induced hepatomegaly is accompanied by hepatocyte hypertrophy around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area. However, the molecular mechanisms underlying this spatial change of hepatocytes remains unclear. In this study, we examined the characteristics and possible reasons for the zonation distinction of hypertrophy and proliferation during PPARα activation-induced mouse liver enlargement. Mice were injected with corn oil or a typical mouse PPARα agonist WY-14643 (100 mg·kg-1·d-1, i.p.) for 1, 2, 3, 5 or 10 days. At each time point, the mice were sacrificed after the final dose, and liver tissues and serum were harvested for analysis. We showed that PPARα activation induced zonal changes in hepatocyte hypertrophy and proliferation in the mice. In order to determine the zonal expression of proteins related to hepatocyte hypertrophy and proliferation in PPARα-induced liver enlargement, we performed digitonin liver perfusion to separately destroy the hepatocytes around the CV or PV areas, and found that PPARα activation-induced increase magnitude of its downstream targets such as cytochrome P450 (CYP) 4 A and acyl-coenzyme A oxidase 1 (ACOX1) levels around the CV area were higher compared with those around the PV area. Upregulation of proliferation-related proteins such as cell nuclear antigen (PCNA) and cyclin A1 (CCNA1) after WY-14643-induced PPARα activation mainly occurred around the PV area. This study reveals that the zonal expression of PPARα targets and proliferation-related proteins is responsible for the spatial change of hepatocyte hypertrophy and proliferation after PPARα activation. These findings provide a new insight into the understanding of PPARα activation-induced liver enlargement and regeneration.
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Affiliation(s)
- Jie Yang
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Xiao Yang
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Yi-Fei Zhang
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Jia-Ning Tian
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Shi-Cheng Fan
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Yue Gao
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Hui-Lin Li
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Cheng-Hui Cai
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Min Huang
- Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Hui-Chang Bi
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China.
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5
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Landowski M, Bhute VJ, Grindel S, Haugstad Z, Gyening YK, Tytanic M, Brush RS, Moyer LJ, Nelson DW, Davis CR, Yen CLE, Ikeda S, Agbaga MP, Ikeda A. Transmembrane protein 135 regulates lipid homeostasis through its role in peroxisomal DHA metabolism. Commun Biol 2023; 6:8. [PMID: 36599953 PMCID: PMC9813353 DOI: 10.1038/s42003-022-04404-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 12/23/2022] [Indexed: 01/05/2023] Open
Abstract
Transmembrane protein 135 (TMEM135) is thought to participate in the cellular response to increased intracellular lipids yet no defined molecular function for TMEM135 in lipid metabolism has been identified. In this study, we performed a lipid analysis of tissues from Tmem135 mutant mice and found striking reductions of docosahexaenoic acid (DHA) across all Tmem135 mutant tissues, indicating a role of TMEM135 in the production of DHA. Since all enzymes required for DHA synthesis remain intact in Tmem135 mutant mice, we hypothesized that TMEM135 is involved in the export of DHA from peroxisomes. The Tmem135 mutation likely leads to the retention of DHA in peroxisomes, causing DHA to be degraded within peroxisomes by their beta-oxidation machinery. This may lead to generation or alteration of ligands required for the activation of peroxisome proliferator-activated receptor a (PPARa) signaling, which in turn could result in increased peroxisomal number and beta-oxidation enzymes observed in Tmem135 mutant mice. We confirmed this effect of PPARa signaling by detecting decreased peroxisomes and their proteins upon genetic ablation of Ppara in Tmem135 mutant mice. Using Tmem135 mutant mice, we also validated the protective effect of increased peroxisomes and peroxisomal beta-oxidation on the metabolic disease phenotypes of leptin mutant mice which has been observed in previous studies. Thus, we conclude that TMEM135 has a role in lipid homeostasis through its function in peroxisomes.
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Affiliation(s)
- Michael Landowski
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Vijesh J Bhute
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemical Engineering, Imperial College London, South Kensington, London, UK
| | - Samuel Grindel
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Zachary Haugstad
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Yeboah K Gyening
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Madison Tytanic
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Richard S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Lucas J Moyer
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - David W Nelson
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Christopher R Davis
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Chi-Liang Eric Yen
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Sakae Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Akihiro Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA.
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA.
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6
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Immunomodulation and exposure to per- and polyfluoroalkyl substances: an overview of the current evidence from animal and human studies. Arch Toxicol 2022; 96:2261-2285. [PMID: 35695909 DOI: 10.1007/s00204-022-03303-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 04/13/2022] [Indexed: 02/07/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) have been widely used and represent a class of environmental persistent chemicals. An association of a reduction of vaccination efficacy with PFAS serum levels in humans was used by the European Food Safety Authority as a key effect for PFAS risk assessment. The data support for using this association is reviewed by a critical analysis of the respective human epidemiology and the available animal studies on the immunomodulation of PFAS. Based on an analysis of the available human epidemiology, the overall level of evidence regarding associations between PFAS serum levels and reduced antibody response remains weak. Absence of an association between an increase in clinical infections and PFAS serum levels and the limited understanding of the importance of antibody levels as an isolated data point further support this conclusion. Animal toxicity studies with PFAS focusing on immunomodulation also provide only limited support for immunomodulation as an important endpoint in PFAS toxicity. While immunomodulation is observed after PFAS administration, generally at blood concentrations several orders of magnitude above those seen in environmentally exposed humans, the relevance of these observation is hampered by the high doses required to influence immune endpoints, the limited number of endpoints assessed, and inconsistent results. The limitations of the current database on associations of human PFAS exposures outlined here indicate that more evidence is required to select immunomodulation as a critical endpoint for human PFAS risk assessment.
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Møllerhøj MB, Veidal SS, Thrane KT, Oró D, Overgaard A, Salinas CG, Madsen MR, Pfisterer L, Vyberg M, Simon E, Broermann A, Vrang N, Jelsing J, Feigh M, Hansen HH. Hepatoprotective effects of semaglutide, lanifibranor and dietary intervention in the GAN diet‐induced obese and biopsy‐confirmed mouse model of NASH. Clin Transl Sci 2022; 15:1167-1186. [PMID: 35143711 PMCID: PMC9099137 DOI: 10.1111/cts.13235] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/23/2021] [Accepted: 01/18/2022] [Indexed: 11/30/2022] Open
Abstract
Non‐alcoholic steatohepatitis (NASH) has emerged as a major challenge for public health because of high global prevalence and lack of evidence‐based therapies. Most animal models of NASH lack sufficient validation regarding disease progression and pharmacological treatment. The Gubra‐Amylin NASH (GAN) diet‐induced obese (DIO) mouse demonstrate clinical translatability with respect to disease etiology and hallmarks of NASH. This study aimed to evaluate disease progression and responsiveness to clinically effective interventions in GAN DIO‐NASH mice. Disease phenotyping was performed in male C57BL/6J mice fed the GAN diet high in fat, fructose, and cholesterol for 28–88 weeks. GAN DIO‐NASH mice with biopsy‐confirmed NASH and fibrosis received low‐caloric dietary intervention, semaglutide (30 nmol/kg/day, s.c.) or lanifibranor (30 mg/kg/day, p.o.) for 8 and 12 weeks, respectively. Within‐subject change in nonalcoholic fatty liver disease (NAFLD) Activity Score (NAS) and fibrosis stage was evaluated using automated deep learning‐based image analysis. GAN DIO‐NASH mice showed clear and reproducible progression in NASH, fibrosis stage, and tumor burden with high incidence of hepatocellular carcinoma. Consistent with clinical trial outcomes, semaglutide and lanifibranor improved NAS, whereas only lanifibranor induced regression in the fibrosis stage. Dietary intervention also demonstrated substantial benefits on metabolic outcomes and liver histology. Differential therapeutic efficacy of semaglutide, lanifibranor, and dietary intervention was supported by quantitative histology, RNA sequencing, and blood/liver biochemistry. In conclusion, the GAN DIO‐NASH mouse model recapitulates various histological stages of NASH and faithfully reproduces histological efficacy profiles of compounds in advanced clinical development for NASH. Collectively, these features highlight the utility of GAN DIO‐NASH mice in preclinical drug development.
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Affiliation(s)
| | | | | | - Denise Oró
- Gubra, Hørsholm Kongevej 11B, DK‐2970 Hørsholm Denmark
| | | | | | | | - Larissa Pfisterer
- Boehringer‐Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88397, Biberach an der Riss Germany
| | - Mogens Vyberg
- Center for RNA Medicine, Department of Clinical Medicine, Aalborg University Copenhagen Denmark
| | - Eric Simon
- Boehringer‐Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88397, Biberach an der Riss Germany
| | - Andre Broermann
- Boehringer‐Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88397, Biberach an der Riss Germany
| | - Niels Vrang
- Gubra, Hørsholm Kongevej 11B, DK‐2970 Hørsholm Denmark
| | - Jacob Jelsing
- Gubra, Hørsholm Kongevej 11B, DK‐2970 Hørsholm Denmark
| | - Michael Feigh
- Gubra, Hørsholm Kongevej 11B, DK‐2970 Hørsholm Denmark
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8
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Hala D, Petersen LH, Huggett DB, Puchowicz MA, Brunengraber H, Zhang GF. Overcompensation of CoA Trapping by Di(2-ethylhexyl) Phthalate (DEHP) Metabolites in Livers of Wistar Rats. Int J Mol Sci 2021; 22:ijms222413489. [PMID: 34948286 PMCID: PMC8709406 DOI: 10.3390/ijms222413489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/14/2021] [Accepted: 12/14/2021] [Indexed: 11/16/2022] Open
Abstract
Di(2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in various industrial and household plastic products, ensuring widespread human exposures. Its routine detection in human bio-fluids and the propensity of its monoester metabolite to activate peroxisome proliferator activated receptor-α (PPARα) and perturb lipid metabolism implicate it as a metabolic disrupter. In this study we evaluated the effects of DEHP exposure on hepatic levels of free CoA and various CoA esters, while also confirming the metabolic activation to CoA esters and partial β-oxidation of a DEHP metabolite (2-ethyhexanol). Male Wistar rats were exposed via diet to 2% (w/w) DEHP for fourteen-days, following which hepatic levels of free CoA and various CoA esters were identified using liquid chromatography-mass spectrometry. DEHP exposed rats showed significantly elevated free CoA and increased levels of physiological, DEHP-derived and unidentified CoA esters. The physiological CoA ester of malonyl-CoA and DEHP-derived CoA ester of 3-keto-2-ethylhexanoyl-CoA were the most highly elevated, at eighteen- and ninety eight-times respectively. We also detected sixteen unidentified CoA esters which may be derivative of DEHP metabolism or induction of other intermediary metabolism metabolites. Our results demonstrate that DEHP is a metabolic disrupter which affects production and sequestration of CoA, an essential cofactor of oxidative and biosynthetic reactions.
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Affiliation(s)
- David Hala
- Department of Biology, University of North Texas, Denton, TX 76203, USA; (L.H.P.); (D.B.H.)
- Department of Marine Biology, Texas A&M at Galveston, Galveston, TX 77554, USA
- Correspondence: ; Tel.: +1-409-740-4535
| | - Lene H. Petersen
- Department of Biology, University of North Texas, Denton, TX 76203, USA; (L.H.P.); (D.B.H.)
- Department of Marine Biology, Texas A&M at Galveston, Galveston, TX 77554, USA
| | - Duane B. Huggett
- Department of Biology, University of North Texas, Denton, TX 76203, USA; (L.H.P.); (D.B.H.)
- Boehringer Ingelheim Animal Health, Athens, GA 30601, USA
| | - Michelle A. Puchowicz
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106, USA; (M.A.P.); (H.B.)
- Department of Pediatrics, The University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106, USA; (M.A.P.); (H.B.)
| | - Guo-Fang Zhang
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27705, USA;
- Department of Medicine, Division of Endocrinology, Metabolism Nutrition, Duke University Medical Center, Durham, NC 27710, USA
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9
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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Ntzani E, Petersen A, Sand S, Schwerdtle T, Vleminckx C, Wallace H, Brüschweiler B, Leonards P, Rose M, Binaglia M, Horváth Z, Ramos Bordajandi L, Nielsen E. Risk assessment of chlorinated paraffins in feed and food. EFSA J 2020; 18:e05991. [PMID: 32874241 PMCID: PMC7447893 DOI: 10.2903/j.efsa.2020.5991] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of chlorinated paraffins in feed and food. The data for experimental animals were reviewed and the CONTAM Panel identified the liver, kidney and thyroid as the target organs for the SCCP and MCCP mixtures tested in repeated dose toxicity studies. Decreased pup survival and subcutaneous haematoma/haemorrhage were also identified as critical effects for an MCCP mixture. For the LCCP mixtures tested, the liver was identified as the target organ. The Panel selected as reference points a BMDL 10 of 2.3 mg/kg bw per day for increased incidence of nephritis in male rats, and of 36 mg/kg bw per day for increased relative kidney weights in male and female rats for SCCPs and MCCPs, respectively. For LCCPs, a reference point relevant for humans could not be identified. Due to the limitations in the toxicokinetic and toxicological database, the Panel concluded that derivation of a health-based guidance value was not appropriate. Only limited data on the occurrence of SCCPs and MCCPs in some fish species were submitted to EFSA. No data were submitted for LCCPs. Thus, a robust exposure assessment and consequently a complete risk characterisation could not be performed. A preliminary risk characterisation based only on the consumption of fish was performed, and the calculated margins of exposure suggested no health concern for this limited scenario. The Panel noted that dietary exposure will be higher due to the contribution of CPs from other foods. The Panel was not able to identify reference points for farm animals, horses and companion animals. No occurrence data for feed were submitted to EFSA. Therefore, no risk characterisation could be performed for any of these animal species.
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10
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Gore E, Bigaeva E, Oldenburger A, Jansen YJM, Schuppan D, Boersema M, Rippmann JF, Broermann A, Olinga P. Investigating fibrosis and inflammation in an ex vivo NASH murine model. Am J Physiol Gastrointest Liver Physiol 2020; 318:G336-G351. [PMID: 31905025 DOI: 10.1152/ajpgi.00209.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease, characterized by excess fat accumulation (steatosis). Nonalcoholic steatohepatitis (NASH) develops in 15-20% of NAFLD patients and frequently progresses to liver fibrosis and cirrhosis. We aimed to develop an ex vivo model of inflammation and fibrosis in steatotic murine precision-cut liver slices (PCLS). NASH was induced in C57Bl/6 mice on an amylin and choline-deficient l-amino acid-defined (CDAA) diet. PCLS were prepared from steatohepatitic (sPCLS) and control (cPCLS) livers and cultured for 48 h with LPS, TGFβ1, or elafibranor. Additionally, C57Bl/6 mice were placed on CDAA diet for 12 wk to receive elafibranor or vehicle from weeks 7 to 12. Effects were assessed by transcriptome analysis and procollagen Iα1 protein production. The diets induced features of human NASH. Upon culture, all PCLS showed an increased gene expression of fibrosis- and inflammation-related markers but decreased lipid metabolism markers. LPS and TGFβ1 affected sPCLS more pronouncedly than cPCLS. TGFβ1 increased procollagen Iα1 solely in cPCLS. Elafibranor ameliorated fibrosis and inflammation in vivo but not ex vivo, where it only increased the expression of genes modulated by PPARα. sPCLS culture induced inflammation-, fibrosis-, and lipid metabolism-related transcripts, explained by spontaneous activation. sPCLS remained responsive to proinflammatory and profibrotic stimuli on gene expression. We consider that PCLS represent a useful tool to reproducibly study NASH progression. sPCLS can be used to evaluate potential treatments for NASH, as demonstrated in our elafibranor study, and serves as a model to bridge results from rodent studies to the human system.NEW & NOTEWORTHY This study showed that nonalcoholic steatohepatitis can be studied ex vivo in precision-cut liver slices obtained from murine diet-induced fatty livers. Liver slices develop a spontaneous inflammatory and fibrogenic response during culture that can be augmented with specific modulators. Additionally, the model can be used to test the efficacy of pharmaceutical compounds (as shown in this investigation with elafibranor) and could be a tool for preclinical assessment of potential therapies.
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Affiliation(s)
- Emilia Gore
- Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands
| | - Emilia Bigaeva
- Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands
| | - Anouk Oldenburger
- CardioMetabolic Diseases Research, Boehringer Ingelheim Pharma, Biberach an der Riss, Germany
| | - Yvette J M Jansen
- Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands
| | - Detlef Schuppan
- Institute of Translational Immunology and Research Center for Immunotherapy, University Medical Center, Johannes Gutenberg University, Mainz, Germany.,Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Miriam Boersema
- Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands
| | - Jörg F Rippmann
- CardioMetabolic Diseases Research, Boehringer Ingelheim Pharma, Biberach an der Riss, Germany
| | - Andre Broermann
- CardioMetabolic Diseases Research, Boehringer Ingelheim Pharma, Biberach an der Riss, Germany
| | - Peter Olinga
- Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands
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11
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Lian X, Wang G, Zhou H, Zheng Z, Fu Y, Cai L. Anticancer Properties of Fenofibrate: A Repurposing Use. J Cancer 2018; 9:1527-1537. [PMID: 29760790 PMCID: PMC5950581 DOI: 10.7150/jca.24488] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/25/2018] [Indexed: 12/22/2022] Open
Abstract
Cancer is a leading cause of death throughout the world, and cancer therapy remains a big medical challenge in terms of both its therapeutic efficacy and safety. Therefore, to find out a safe anticancer drug has been long goal for oncologist and medical scientists. Among clinically used medicines with no or little toxicity, fenofibrate is a drug of the fibrate class that plays an important role in lowering the levels of serum cholesterol and triglycerides while elevating the levels of high-density lipoproteins. Recently, several studies have implied that fenofibrate may exert anticancer effects via a variety of pathways involved in apoptosis, cell-cycle arrest, invasion, and migration. Given the great potential that fenofibrate may have anticancer effects, this review was to investigate all published works which directly or indirectly support the anticancer activity of fenofibrate. These studies provide evidence that fenofibrate exerted antitumor effects in several human cancer cell lines, such as breast, liver, glioma, prostate, pancreas, and lung cancer cell lines. Among these studies some have further confirmed the possibility and efficacy of fenofibrate anticancer in xenograft mouse models. In the last part of this review, we also discuss the potential mechanisms of action of fenofibrate based on the available information. Overall, we may repurpose fenofibrate as an anticancer drug in cancer treatment, which urgently need further and comprehensively investigated.
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Affiliation(s)
- Xin Lian
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China.,Pediatric Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY 40202, USA
| | - Gang Wang
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China
| | - Honglan Zhou
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China
| | - Zongyu Zheng
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China.,Pediatric Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY 40202, USA
| | - Yaowen Fu
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China
| | - Lu Cai
- Department of Urology, the First Hospital of Jilin University; 71 Xinmin Street, Changchun 130021, China.,Pediatric Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY 40202, USA.,Departments of Radiation Oncology, Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
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12
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Ena L, Lim JS, Son JY, Park YJ, Lee YH, Kim JY, Kwack SJ, Lee BM, Ahn MY, Kim HS. Evaluation of subchronic exposure to triclosan on hepatorenal and reproductive toxicities in prepubertal male rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2018; 81:421-431. [PMID: 29557728 DOI: 10.1080/15287394.2018.1451188] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Triclosan (TCS), a common antimicrobial ingredient, is present in many consumer products, including soaps, shampoos, and toothpaste. Owing to its widespread use, potential adverse effects on animals and humans may arise from lifetime exposure, but data on chronic prepubertal exposure of TCS are still lacking. The aim of the present study was to investigate the influence of subchronic TCS exposure (0.25, 25, 250, or 750 mg/kg) on target organ toxicity in prepubertal male rats. After daily administration of TCS to rats by oral gavage for 60 d, a significant reduction in body weight and relative weights of liver, kidneys, testes, and adrenal glands was observed in the 750-mg/kg (high dose) group. Serum alanine aminotransferase and aspartate aminotransferase activities as well as levels of blood urea nitrogen, and creatinine were significantly increased at 750 mg/kg TCS. Further, TCS (750 mg/kg) elevated the protein expressions of hepatic CYP2B1, RXR/PPAR, and levels of malondialdehyde. High-dose TCS exposure induced histological changes as evidenced by reduction of Bowman's space, occlusion of the tubular lumen, and degeneration of tubular epithelial cells in the kidney. Tubular necrosis was confirmed as evidenced by a rise in expression of high mobility group box 1 renal protein. Daily sperm production was significantly diminished by high doses of TCS with marked inhibition of androgen receptor protein expression. Our results indicated that subchronic exposure to excessively high concentrations of 750 mg/kg TCS induced hepatorenal and reproductive toxicities in prepubertal male rats; however, the biological relevance of these findings is questionable as these drug levels are not encountered in the environment.
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Affiliation(s)
- Lee Ena
- a School of Pharmacy , Pusan National University , Busan , Republic of Korea
| | - Jong Seung Lim
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Ji Yeon Son
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Yu Jin Park
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Yong Hee Lee
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Ji Yeong Kim
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Seung Jun Kwack
- c Department of Biochemistry and Health Science , Changwon National University , Gyeongnam , Republic of Korea
| | - Byung Mu Lee
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
| | - Mee-Young Ahn
- d Major in Pharmaceutical Engineering, Division of Bio-industry, College of Medical and Life Sciences , Silla University , Busan , Republic of Korea
| | - Hyung Sik Kim
- b Division of Toxicology, School of Pharmacy , Sungkyunkwan University , Suwon , Republic of Korea
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13
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Shi Y, Tao T, Liu N, Luan W, Qian J, Li R, Hu Q, Wei Y, Zhang J, You Y. PPARα, a predictor of patient survival in glioma, inhibits cell growth through the E2F1/miR-19a feedback loop. Oncotarget 2018; 7:84623-84633. [PMID: 27835866 PMCID: PMC5356686 DOI: 10.18632/oncotarget.13170] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 10/28/2016] [Indexed: 12/04/2022] Open
Abstract
Nuclear receptors such as peroxisome proliferator-activated receptor α (PPARα) are potential therapeutic targets. In this study, we found that PPARα expression was lower in high grade gliomas and PPARα was an independent prognostic factor in GBM patients. PPARα agonism or overexpression inhibited glioma cell proliferation, invasion, and aerobic glycolysis as well as suppressed glioma growth in an orthotopic model. Bioinformatic analysis and luciferase reporter assays showed that miR-19a decreased PPARα expression. E2F1 knockdown up-regulated PPARα and inhibited cell proliferation, invasion, and aerobic glycolysis, but this activity was blocked by miR-19a. Knockdown of E2F1 decreased miR-19a by inhibiting the miR-19a promoter. Moreover, PPARα repressed E2F1 via the p21 pathwayby modulating the transcriptional complexes containing E2F1 and pRB proteins. These results suggest that the E2F1/miR19a/PPARα feedback loop is critical for glioma progression.
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Affiliation(s)
- Yan Shi
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Tao Tao
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Ning Liu
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - WenKang Luan
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jin Qian
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.,Department of Neurosurgery, People's Hospital of Xuancheng City, Anhui, China
| | - Rui Li
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qi Hu
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yan Wei
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Junxia Zhang
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yongping You
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
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14
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4',6-Dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) is a peroxisome proliferator-activated receptor α (PPARα) agonist in mouse hepatocytes. Mol Cell Biochem 2018; 446:35-41. [PMID: 29318455 DOI: 10.1007/s11010-018-3270-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 01/04/2018] [Indexed: 01/11/2023]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that regulate lipid and glucose metabolism. PPARα mainly affects fatty acid metabolism, and its activation lowers lipid levels. PPARγ is involved in the regulation of adipogenesis, insulin sensitivity, energy balance, and lipid biosynthesis. We have previously reported that 4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) can activate PPARγ. The purpose of the present study is to investigate the PPARα agonist activity of wistin. Using a luciferase reporter assay system of PPARα in monkey COS7 kidney cells, we showed that wistin could activate PPARα (P < 0.01 at 10 μg/mL) in a dose-dependent manner. Moreover, the addition of wistin upregulated the expression of PPARα (P < 0.01 at 10 μg/mL) and PPARα target genes including carnitine palmitoyltransferase 1a (P < 0.05 at 10 μg/mL), acyl-CoA oxidase (P < 0.01 at 10 μg/mL), acyl-CoA synthase (P < 0.05 at 10 μg/mL), PPARγ coactivator 1α (P < 0.05 at 10 μg/mL), uncoupling protein 2 (P < 0.05 at 1 μg/mL), and uncoupling protein 3 (P < 0.05 at 10 μg/mL), which are genes involved in lipid efflux and energy expenditure, in mouse primary hepatocytes. Furthermore, wistin inhibited cellular triglyceride accumulation in hepatocytes (P < 0.05 at 10 μg/mL) in a dose-dependent manner. These results indicate that wistin could suppress lipid accumulation through PPARα activation. The action of wistin on PPARα could be of interest for the amelioration of lipid metabolic disorders. To the best of our knowledge, wistin is the first reported isoflavonoid O-glycoside with PPARα agonist activity.
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15
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Corton JC, Peters JM, Klaunig JE. The PPARα-dependent rodent liver tumor response is not relevant to humans: addressing misconceptions. Arch Toxicol 2017; 92:83-119. [PMID: 29197930 DOI: 10.1007/s00204-017-2094-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/12/2017] [Indexed: 12/17/2022]
Abstract
A number of industrial chemicals and therapeutic agents cause liver tumors in rats and mice by activating the nuclear receptor peroxisome proliferator-activated receptor α (PPARα). The molecular and cellular events by which PPARα activators induce rodent hepatocarcinogenesis have been extensively studied elucidating a number of consistent mechanistic changes linked to the increased incidence of liver neoplasms. The weight of evidence relevant to the hypothesized mode of action (MOA) for PPARα activator-induced rodent hepatocarcinogenesis is summarized here. Chemical-specific and mechanistic data support concordance of temporal and dose-response relationships for the key events associated with many PPARα activators. The key events (KE) identified in the MOA are PPARα activation (KE1), alteration in cell growth pathways (KE2), perturbation of hepatocyte growth and survival (KE3), and selective clonal expansion of preneoplastic foci cells (KE4), which leads to the apical event-increases in hepatocellular adenomas and carcinomas (KE5). In addition, a number of concurrent molecular and cellular events have been classified as modulating factors, because they potentially alter the ability of PPARα activators to increase rodent liver cancer while not being key events themselves. These modulating factors include increases in oxidative stress and activation of NF-kB. PPARα activators are unlikely to induce liver tumors in humans due to biological differences in the response of KEs downstream of PPARα activation. This conclusion is based on minimal or no effects observed on cell growth pathways and hepatocellular proliferation in human primary hepatocytes and absence of alteration in growth pathways, hepatocyte proliferation, and tumors in the livers of species (hamsters, guinea pigs and cynomolgus monkeys) that are more appropriate human surrogates than mice and rats at overlapping dose levels. Despite this overwhelming body of evidence and almost universal acceptance of the PPARα MOA and lack of human relevance, several reviews have selectively focused on specific studies that, as discussed, contradict the consensus opinion and suggest uncertainty. In the present review, we systematically address these most germane suggested weaknesses of the PPARα MOA.
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Affiliation(s)
- J Christopher Corton
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Dr, MD-B105-03, Research Triangle Park, NC, 27711, USA.
| | - Jeffrey M Peters
- The Department of Veterinary and Biomedical Sciences and Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA, 16803, USA
| | - James E Klaunig
- Department of Environmental Health, Indiana University, Bloomington, IN, 47402, USA
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16
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Madureira TV, Pinheiro I, Malhão F, Lopes C, Urbatzka R, Castro LFC, Rocha E. Cross-interference of two model peroxisome proliferators in peroxisomal and estrogenic pathways in brown trout hepatocytes. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 187:153-162. [PMID: 28415051 DOI: 10.1016/j.aquatox.2017.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 03/16/2017] [Accepted: 04/04/2017] [Indexed: 06/07/2023]
Abstract
Peroxisome proliferators cause species-specific effects, which seem to be primarily transduced by peroxisome proliferator-activated receptor alpha (PPARα). Interestingly, PPARα has a close interrelationship with estrogenic signaling, and this latter has already been promptly activated in brown trout primary hepatocytes. Thus, and further exploring this model, we assess here the reactivity of two PPARα agonists in direct peroxisomal routes and, in parallel the cross-interferences in estrogen receptor (ER) mediated paths. To achieve these goals, three independent in vitro studies were performed using single exposures to clofibrate - CLF (50, 500 and 1000μM), Wy-14,643 - Wy (50 and 150μM), GW6471 - GW (1 and 10μM), and mixtures, including PPARα agonist or antagonist plus an ER agonist or antagonist. Endpoints included gene expression analysis of peroxisome/lipidic related genes (encoding apolipoprotein AI - ApoAI, fatty acid binding protein 1 - Fabp1, catalase - Cat, 17 beta-hydroxysteroid dehydrogenase 4 - 17β-HSD4, peroxin 11 alpha - Pex11α, PPARαBb, PPARαBa and urate oxidase - Uox) and those encoding estrogenic targets (ERα, ERβ-1 and vitellogenin A - VtgA). A quantitative morphological approach by using a pre-validated catalase immunofluorescence technique allowed checking possible changes in peroxisomes. Our results show a low responsiveness of trout hepatocytes to model PPARα agonists in direct target receptor pathways. Additionally, we unveiled interferences in estrogenic signaling caused by Wy, leading to an up-regulation VtgA and ERα at 150μM; these effects seem counteracted with a co-exposure to an ER antagonist. The present data stress the potential of this in vitro model for further exploring the physiological/toxicological implications related with this nuclear receptor cross-regulation.
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Affiliation(s)
- Tânia Vieira Madureira
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Laboratory of Histology and Embryology, Department of Microscopy, Rua Jorge Viterbo Ferreira 228, P 4050-313 Porto, Portugal.
| | - Ivone Pinheiro
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Laboratory of Histology and Embryology, Department of Microscopy, Rua Jorge Viterbo Ferreira 228, P 4050-313 Porto, Portugal
| | - Fernanda Malhão
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Laboratory of Histology and Embryology, Department of Microscopy, Rua Jorge Viterbo Ferreira 228, P 4050-313 Porto, Portugal
| | - Célia Lopes
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Laboratory of Histology and Embryology, Department of Microscopy, Rua Jorge Viterbo Ferreira 228, P 4050-313 Porto, Portugal
| | - Ralph Urbatzka
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal
| | - L Filipe C Castro
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Faculty of Sciences (FCUP), University of Porto (U. Porto), Department of Biology, Rua do Campo Alegre, P 4169-007 Porto, Portugal
| | - Eduardo Rocha
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto (U. Porto), Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Laboratory of Histology and Embryology, Department of Microscopy, Rua Jorge Viterbo Ferreira 228, P 4050-313 Porto, Portugal
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17
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Dubois V, Eeckhoute J, Lefebvre P, Staels B. Distinct but complementary contributions of PPAR isotypes to energy homeostasis. J Clin Invest 2017; 127:1202-1214. [PMID: 28368286 DOI: 10.1172/jci88894] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) regulate energy metabolism and hence are therapeutic targets in metabolic diseases such as type 2 diabetes and non-alcoholic fatty liver disease. While they share anti-inflammatory activities, the PPAR isotypes distinguish themselves by differential actions on lipid and glucose homeostasis. In this Review we discuss the complementary and distinct metabolic effects of the PPAR isotypes together with the underlying cellular and molecular mechanisms, as well as the synthetic PPAR ligands that are used in the clinic or under development. We highlight the potential of new PPAR ligands with improved efficacy and safety profiles in the treatment of complex metabolic disorders.
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18
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Asaoka Y, Togashi Y, Mutsuga M, Imura N, Miyoshi T, Miyamoto Y. Histopathological image analysis of chemical-induced hepatocellular hypertrophy in mice. ACTA ACUST UNITED AC 2016; 68:233-9. [DOI: 10.1016/j.etp.2015.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 11/27/2022]
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19
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Gureev A, Shmatkova M, Bashmakov V, Starkov A, Popov V. The effect of fenofibrate on expression of genes involved in fatty acids beta-oxidation and associated free-radical processes. ACTA ACUST UNITED AC 2016; 62:426-30. [DOI: 10.18097/pbmc20166204426] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Fenofibrate is a synthetic ligand for peroxisome proliferator-activated receptors subtype alpha (PPARa); it is used for the treatment of a wide range of metabolic diseases such as hypertriglyceridemia, dyslipidemia, diabetes and various neurodegenerative diseases. We have studied the effect of fenofibrate on b-oxidation of fatty acids and related free-radical processes. The most effective concentration of fenofibrate (0.3%) added to the chow caused a significant decrease of the body weight of mice. The data obtained by quantitative PCR demonstrated increased hepatic gene expression responsible for b-oxidation of fatty acids in peroxisomes and mitochondria. Enhancement of oxidative processes caused a 2-fold increase in the rate of reactive oxygen species (ROS) production, as evidenced by determination of the level of lipid peroxidation (LPO) products in the liver. Mitochondrial antioxidant systems are more sensitive to elevated ROS production, as they respond by increased expression of SOD2 and PRDX3 genes, than cytoplasmic and peroxisomal antioxidant systems, where expression of CAT1, SOD1, PRDX5 genes remained unaltered.
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Affiliation(s)
| | | | | | - A.A. Starkov
- Cornell university, Weill Cornell Medical College, New York
| | - V.N. Popov
- Voronezh State University, Voronezh, Russia
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20
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Janssen AWF, Betzel B, Stoopen G, Berends FJ, Janssen IM, Peijnenburg AA, Kersten S. The impact of PPARα activation on whole genome gene expression in human precision cut liver slices. BMC Genomics 2015; 16:760. [PMID: 26449539 PMCID: PMC4599789 DOI: 10.1186/s12864-015-1969-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/30/2015] [Indexed: 02/08/2023] Open
Abstract
Background Studies in mice have shown that PPARα is an important regulator of lipid metabolism in liver and key transcription factor involved in the adaptive response to fasting. However, much less is known about the role of PPARα in human liver. Methods Here we set out to study the function of PPARα in human liver via analysis of whole genome gene regulation in human liver slices treated with the PPARα agonist Wy14643. Results Quantitative PCR indicated that PPARα is well expressed in human liver and human liver slices and that the classical PPARα targets PLIN2, VLDLR, ANGPTL4, CPT1A and PDK4 are robustly induced by PPARα activation. Transcriptomics analysis indicated that 617 genes were upregulated and 665 genes were downregulated by PPARα activation (q value < 0.05). Many genes induced by PPARα activation were involved in lipid metabolism (ACSL5, AGPAT9, FADS1, SLC27A4), xenobiotic metabolism (POR, ABCC2, CYP3A5) or the unfolded protein response, whereas most of the downregulated genes were involved in immune-related pathways. Among the most highly repressed genes upon PPARα activation were several chemokines (e.g. CXCL9-11, CCL8, CX3CL1, CXCL6), interferon γ-induced genes (e.g. IFITM1, IFIT1, IFIT2, IFIT3) and numerous other immune-related genes (e.g. TLR3, NOS2, and LCN2). Comparative analysis of gene regulation by Wy14643 between human liver slices and primary human hepatocytes showed that down-regulation of gene expression by PPARα is much better captured by liver slices as compared to primary hepatocytes. In particular, PPARα activation markedly suppressed immunity/inflammation-related genes in human liver slices but not in primary hepatocytes. Finally, several putative new target genes of PPARα were identified that were commonly induced by PPARα activation in the two human liver model systems, including TSKU, RHOF, CA12 and VSIG10L. Conclusion Our paper demonstrates the suitability and superiority of human liver slices over primary hepatocytes for studying the functional role of PPARα in human liver. Our data underscore the major role of PPARα in regulation of hepatic lipid and xenobiotic metabolism in human liver and reveal a marked immuno-suppressive/anti-inflammatory effect of PPARα in human liver slices that may be therapeutically relevant for non-alcoholic fatty liver disease. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1969-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aafke W F Janssen
- Nutrition, Metabolism and Genomics Group, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Bark Betzel
- Department of Surgery, Rijnstate Hospital, Wagnerlaan 55, 6815 AD, Arnhem, The Netherlands.
| | - Geert Stoopen
- RIKILT-Institute of Food Safety, Wageningen UR, P.O. Box 230, 6700, AE, Wageningen, The Netherlands.
| | - Frits J Berends
- Department of Surgery, Rijnstate Hospital, Wagnerlaan 55, 6815 AD, Arnhem, The Netherlands.
| | - Ignace M Janssen
- Department of Surgery, Rijnstate Hospital, Wagnerlaan 55, 6815 AD, Arnhem, The Netherlands.
| | - Ad A Peijnenburg
- RIKILT-Institute of Food Safety, Wageningen UR, P.O. Box 230, 6700, AE, Wageningen, The Netherlands.
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
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Mukerji P, Rae JC, Buck RC, O'Connor JC. Oral repeated-dose systemic and reproductive toxicity of 6:2 fluorotelomer alcohol in mice. Toxicol Rep 2014; 2:130-143. [PMID: 28962345 PMCID: PMC5598097 DOI: 10.1016/j.toxrep.2014.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/01/2014] [Accepted: 12/01/2014] [Indexed: 01/28/2023] Open
Abstract
6:2 fluorotelomer alcohol (6:2 FTOH) was evaluated for potential systemic repeated-dose and reproductive toxicity in mice. 6:2 FTOH was administered by oral gavage to CD-1 mice as a suspension in 0.5% aqueous methylcellulose with 0.1% Tween-80 at dosages of 1, 5, 25, or 100 mg/kg/day. The no-observed-adverse-effect level (NOAEL) for systemic toxicity was 25 mg/kg/day (males) and 5 mg/kg/day (females), based on effects at higher doses on mortality, clinical observations, body weight, nutritional parameters, hematology (red and white blood cell), clinical chemistry (liver-related), liver weights, and histopathology (liver, teeth, reproductive tract, and mammary gland). However, 6:2 FTOH was not a selective reproductive toxicant. The NOAEL for reproductive toxicity was >100 mg/kg/day; no effects on reproductive outcome were observed at any dosage. The NOAEL for viability and growth of the offspring was 25 mg/kg/day, based on clinical signs of delayed maturation in pups, and reductions in pup survival and pup body weight during lactation at 100 mg/kg/day. While the severity of the effects was generally greater in mice than previously reported in CD rats, the overall NOAELs were identical in both species, 5 mg/kg/day for systemic toxicity and 25 mg/kg/day for offspring viability/growth. 6:2 FTOH was not a selective reproductive toxicant in either species; no effects on reproductive outcome occurred at any dose level, and any effects observed in offspring occurred at dose levels that induced mortality and severe toxicity in maternal animals.
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Affiliation(s)
- Pushkor Mukerji
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
| | - Jessica Caverly Rae
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
| | - Robert C Buck
- E I. duPont de Nemours and Company, Inc., Chemicals and Fluoroproducts, Wilmington, DE 19805, United States
| | - John C O'Connor
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
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22
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Liver tumor formation in female rat induced by fluopyram is mediated by CAR/PXR nuclear receptor activation. Regul Toxicol Pharmacol 2014; 70:648-58. [DOI: 10.1016/j.yrtph.2014.09.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 01/31/2023]
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23
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Abstract
Many of the environmental, occupational and industrial chemicals are able to generate reactive oxygen species (ROS) and cause oxidative stress. ROS may lead to genotoxicity, which is suggested to contribute to the pathophysiology of many human diseases, including inflammatory diseases and cancer. Phthalates are ubiquitous environmental chemicals and are well-known peroxisome proliferators (PPs) and endocrine disruptors. Several in vivo and in vitro studies have been conducted concerning the carcinogenic and mutagenic effects of phthalates. Di(2-ethylhexyl)-phthalate (DEHP) and several other phthalates are shown to be hepatocarcinogenic in rodents. The underlying factor in the hepatocarcinogenesis is suggested to be their ability to generate ROS and cause genotoxicity. Several methods, including chromosomal aberration test, Ames test, micronucleus assay and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutation test and Comet assay, have been used to determine genotoxic properties of phthalates. Comet assay has been an important tool in the measurement of the genotoxic potential of many chemicals, including phthalates. In this review, we will mainly focus on the studies, which were conducted on the DNA damage caused by different phthalate esters and protection studies against the genotoxicity of these chemicals.
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Affiliation(s)
- Pınar Erkekoglu
- Department of Toxicology, Faculty of Pharmacy, Hacettepe University , Ankara , Turkey
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24
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Tateno C, Yamamoto T, Utoh R, Yamasaki C, Ishida Y, Myoken Y, Oofusa K, Okada M, Tsutsui N, Yoshizato K. Chimeric Mice with Hepatocyte-humanized Liver as an Appropriate Model to Study Human Peroxisome Proliferator–activated Receptor-α. Toxicol Pathol 2014; 43:233-48. [DOI: 10.1177/0192623314544378] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peroxisome proliferator (PP)–activated receptor-α (PPARα) agonists exhibit species-specific effects on livers of the rodent and human (h), which has been considered to reside in the difference of PPARα gene structures. However, the contribution of h-hepatocytes (heps) to the species-specificity remains to be clarified. In this study, the effects of fenofibrate were investigated using a hepatocyte-humanized chimeric mouse (m) model whose livers were replaced with h-heps at >70%. Fenofibrate induced hepatocellular hypertrophy, cell proliferation, and peroxisome proliferation in livers of severe combined immunodeficiency (SCID) mice, but not in the h-hep of chimeric mouse livers. Fenofibrate increased the expression of the enzymes of β- and ω-hydroxylation and deoxygenation of lipids at both gene and protein levels in SCID mouse livers, but not in the h-heps of chimeric mouse livers, supporting the studies with h-PPARα-transgenic mice, a hitherto reliable model for studying the regulation of h-PPARα in the h-liver in most respects, except the induction of the peroxisome proliferation. This study indicates the importance of not only h-PPARα gene but also h-heps themselves to correctly predict effects of fibrates on h-livers, and, therefore, suggests that the chimeric mouse is a currently available, consistent, and reliable model to obtain pharmaceutical data concerning the effects of fibrates on h-livers.
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Affiliation(s)
- Chise Tateno
- Yoshizato Project, Cooperative Link of Unique Science and Technology for Economy Revitalization (CLUSTER), Hiroshima Prefectural Institute of Industrial Science and Technology, Higashihiroshima, Japan
- Liver Research Project Center, Hiroshima University, Hiroshima, Japan
- PhoenixBio Co., Ltd., Higashihiroshima, Japan
| | - Toshinobu Yamamoto
- Safety Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Kisarazu, Japan
| | - Rie Utoh
- Yoshizato Project, Cooperative Link of Unique Science and Technology for Economy Revitalization (CLUSTER), Hiroshima Prefectural Institute of Industrial Science and Technology, Higashihiroshima, Japan
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan
| | - Chihiro Yamasaki
- Yoshizato Project, Cooperative Link of Unique Science and Technology for Economy Revitalization (CLUSTER), Hiroshima Prefectural Institute of Industrial Science and Technology, Higashihiroshima, Japan
- PhoenixBio Co., Ltd., Higashihiroshima, Japan
| | - Yuji Ishida
- Liver Research Project Center, Hiroshima University, Hiroshima, Japan
- PhoenixBio Co., Ltd., Higashihiroshima, Japan
| | - Yuka Myoken
- Prophoenix Co., Ltd., Developmental Biology Laboratory, Higashihiroshima, Japan
| | - Ken Oofusa
- Prophoenix Co., Ltd., Developmental Biology Laboratory, Higashihiroshima, Japan
- Prophoenix Division, Idea Consultants, Osaka, Japan
| | - Miyoko Okada
- Safety Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Kisarazu, Japan
| | - Naohisa Tsutsui
- Safety Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Kisarazu, Japan
| | - Katsutoshi Yoshizato
- Yoshizato Project, Cooperative Link of Unique Science and Technology for Economy Revitalization (CLUSTER), Hiroshima Prefectural Institute of Industrial Science and Technology, Higashihiroshima, Japan
- Liver Research Project Center, Hiroshima University, Hiroshima, Japan
- PhoenixBio Co., Ltd., Higashihiroshima, Japan
- Hiroshima University 21st Century COE Program for Advanced Radiation Casualty Medicine, Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
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25
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Misra P, Reddy JK. Peroxisome proliferator-activated receptor-α activation and excess energy burning in hepatocarcinogenesis. Biochimie 2014; 98:63-74. [DOI: 10.1016/j.biochi.2013.11.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 11/14/2013] [Indexed: 01/23/2023]
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26
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Lyssimachou A, Thibaut R, Gisbert E, Porte C. Gemfibrozil modulates cytochrome P450 and peroxisome proliferation-inducible enzymes in the liver of the yellow European eel (Anguilla anguilla). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2014; 21:862-871. [PMID: 23828728 DOI: 10.1007/s11356-013-1944-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/17/2013] [Indexed: 06/02/2023]
Abstract
The human lipid regulator gemfibrozil (GEM) has been shown to induce peroxisome proliferation in rodents leading to hepatocarcinogenesis. Since GEM is found at biological active concentrations in the aquatic environment, the present study investigates the effects of this drug on the yellow European eel (Anguilla anguilla). Eels were injected with different concentrations of GEM (0.1 to 200 μg/g) and sampled 24- and 96-h post-injection. GEM was shown to inhibit CYP1A, CYP3A and CYP2K-like catalytic activities 24-h post-injection, but at 96-h post-injection, only CYP1A was significantly altered in fish injected with the highest GEM dose. On the contrary, GEM had little effect on the phase II enzymes examined (UDP-glucuronyltransferase and glutathione-S-transferase). Peroxisome proliferation inducible enzymes (liver peroxisomal acyl-CoA oxidase and catalase) were very weakly induced. No evidence of a significant effect on the endocrine system of eels was observed in terms of plasmatic steroid levels or testosterone esterification in the liver.
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Affiliation(s)
- Angeliki Lyssimachou
- Environmental Chemistry Department, IDAEA-CSIC, Jordi Girona 18, 08034, Barcelona, Spain
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27
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Corton JC, Cunningham ML, Hummer BT, Lau C, Meek B, Peters JM, Popp JA, Rhomberg L, Seed J, Klaunig JE. Mode of action framework analysis for receptor-mediated toxicity: The peroxisome proliferator-activated receptor alpha (PPARα) as a case study. Crit Rev Toxicol 2013; 44:1-49. [PMID: 24180432 DOI: 10.3109/10408444.2013.835784] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Several therapeutic agents and industrial chemicals induce liver tumors in rodents through the activation of the peroxisome proliferator-activated receptor alpha (PPARα). The cellular and molecular events by which PPARα activators induce rodent hepatocarcinogenesis has been extensively studied and elucidated. This review summarizes the weight of evidence relevant to the hypothesized mode of action (MOA) for PPARα activator-induced rodent hepatocarcinogenesis and identifies gaps in our knowledge of this MOA. Chemical-specific and mechanistic data support concordance of temporal and dose-response relationships for the key events associated with many PPARα activators including a phthalate ester plasticizer di(2-ethylhexyl) phthalate (DEHP) and the drug gemfibrozil. While biologically plausible in humans, the hypothesized key events in the rodent MOA, for PPARα activators, are unlikely to induce liver tumors in humans because of toxicodynamic and biological differences in responses. This conclusion is based on minimal or no effects observed on growth pathways, hepatocellular proliferation and liver tumors in humans and/or species (including hamsters, guinea pigs and cynomolgous monkeys) that are more appropriate human surrogates than mice and rats at overlapping dose levels. Overall, the panel concluded that significant quantitative differences in PPARα activator-induced effects related to liver cancer formation exist between rodents and humans. On the basis of these quantitative differences, most of the workgroup felt that the rodent MOA is "not relevant to humans" with the remaining members concluding that the MOA is "unlikely to be relevant to humans". The two groups differed in their level of confidence based on perceived limitations of the quantitative and mechanistic knowledge of the species differences, which for some panel members strongly supports but cannot preclude the absence of effects under unlikely exposure scenarios.
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28
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Rosen MB, Das KP, Wood CR, Wolf CJ, Abbott BD, Lau C. Evaluation of perfluoroalkyl acid activity using primary mouse and human hepatocytes. Toxicology 2013; 308:129-37. [DOI: 10.1016/j.tox.2013.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 01/09/2023]
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29
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Benigni R, Bossa C, Tcheremenskaia O. Nongenotoxic carcinogenicity of chemicals: mechanisms of action and early recognition through a new set of structural alerts. Chem Rev 2013; 113:2940-57. [PMID: 23469814 DOI: 10.1021/cr300206t] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Romualdo Benigni
- Istituto Superiore di Sanita' Environment and Health Department, Viale Regina Elena 299, 00161 Rome, Italy.
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30
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Sozmen M, Kabak YB, Gulbahar MY, Gacar A, Karayigit MO, Guvenc T, Yarim M. Immunohistochemical characterization of peroxisome proliferator-activated receptors in canine normal testis and testicular tumours. J Comp Pathol 2012; 149:10-8. [PMID: 23219070 DOI: 10.1016/j.jcpa.2012.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/05/2012] [Accepted: 09/25/2012] [Indexed: 11/19/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. Recent studies have demonstrated that PPARs regulate lipid metabolism and are expressed in various cancers. The aim of the present study was to investigate the expression of PPAR-α, -β and -γ in normal canine testicular tissue and canine testicular tumours (CTTs). Expression of PPAR-α, -β and -γ was greater (P <0.05) than in normal testicular tissue. PPARs were therefore induced in CTTs and they may play a role in the biology of these tumours.
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Affiliation(s)
- M Sozmen
- Department of Pathology, Faculty of Veterinary Medicine, Ondokuz Mayis University, TR-55139 Samsun, Turkey.
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31
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Penna F, Pin F, Costamagna D, Reffo P, Baccino FM, Bonelli G, Costelli P. Caspase 2 activation and ER stress drive rapid Jurkat cell apoptosis by clofibrate. PLoS One 2012; 7:e45327. [PMID: 23028936 PMCID: PMC3445471 DOI: 10.1371/journal.pone.0045327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Accepted: 08/20/2012] [Indexed: 01/10/2023] Open
Abstract
Differently from the antiapoptotic action most commonly assigned to peroxisome proliferators (PPs), we demonstrated that some of them, clofibrate (CF) in particular, display clearcut apoptogenic properties on rat hepatoma cell lines. We and others could confirm that CF as well as various other PPs can induce apoptosis in a variety of cells, including human liver, breast and lung cancer cell lines. The present study was aimed at investigating the cytotoxic action of CF on a neoplastic line of different origin, the human T leukemia Jurkat cells. We observed that CF rapidly triggers an extensive and morphologically typical apoptotic process on Jurkat cells, though not in primary T cells, which is completely prevented by the polycaspase inhibitor zVADfmk. Gene silencing studies demonstrated that CF-induced apoptosis in Jurkat cells is partially dependent on activation of caspase 2. Looking for a possible trigger of caspase 2 activation, we observed increased levels of phosphorylated eIF2α and JNK in CF-treated cells. Moreover, intracellular Ca(2+) homeostasis was perturbed. Together, these findings are suggestive for the occurrence of ER stress, an event that is known to have the potential to activate caspase 2. The present observations demonstrate that CF induces in Jurkat cells a very fast and extensive apoptosis, that involves induction of ER stress and activation of caspases 2 and 3. Since apoptosis in Jurkat cells occurs at pharmacologically relevant concentrations of CF, the present findings encourage further in depth analysis in order to work out the potential implications of CF cytotoxcity on leukemic cells.
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Affiliation(s)
- Fabio Penna
- Department of Experimental Medicine and Oncology, University of Torino, Torino, Italy
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32
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Hall AP, Elcombe CR, Foster JR, Harada T, Kaufmann W, Knippel A, Küttler K, Malarkey DE, Maronpot RR, Nishikawa A, Nolte T, Schulte A, Strauss V, York MJ. Liver hypertrophy: a review of adaptive (adverse and non-adverse) changes--conclusions from the 3rd International ESTP Expert Workshop. Toxicol Pathol 2012; 40:971-94. [PMID: 22723046 DOI: 10.1177/0192623312448935] [Citation(s) in RCA: 289] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Preclinical toxicity studies have demonstrated that exposure of laboratory animals to liver enzyme inducers during preclinical safety assessment results in a signature of toxicological changes characterized by an increase in liver weight, hepatocellular hypertrophy, cell proliferation, and, frequently in long-term (life-time) studies, hepatocarcinogenesis. Recent advances over the last decade have revealed that for many xenobiotics, these changes may be induced through a common mechanism of action involving activation of the nuclear hormone receptors CAR, PXR, or PPARα. The generation of genetically engineered mice that express altered versions of these nuclear hormone receptors, together with other avenues of investigation, have now demonstrated that sensitivity to many of these effects is rodent-specific. These data are consistent with the available epidemiological and empirical human evidence and lend support to the scientific opinion that these changes have little relevance to man. The ESTP therefore convened an international panel of experts to debate the evidence in order to more clearly define for toxicologic pathologists what is considered adverse in the context of hepatocellular hypertrophy. The results of this workshop concluded that hepatomegaly as a consequence of hepatocellular hypertrophy without histologic or clinical pathology alterations indicative of liver toxicity was considered an adaptive and a non-adverse reaction. This conclusion should normally be reached by an integrative weight of evidence approach.
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Affiliation(s)
- A P Hall
- AstraZeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire, UK.
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33
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Butenhoff JL, Kennedy GL, Chang SC, Olsen GW. Chronic dietary toxicity and carcinogenicity study with ammonium perfluorooctanoate in Sprague-Dawley rats. Toxicology 2012; 298:1-13. [PMID: 22531602 DOI: 10.1016/j.tox.2012.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/29/2012] [Accepted: 04/03/2012] [Indexed: 11/25/2022]
Abstract
In order to assess the potential chronic toxicity and tumorigenicity of ammonium perfluorooctanoate (APFO), a 2-year dietary study was conducted with male and female rats fed 30 ppm or 300 ppm (approximately 1.5 and 15 mg/kg). In males fed 300 ppm, mean body weights were lower across most of the test period and survival in these rats was greater than that seen either in the 30 ppm or the control group. Non-neoplastic effects were observed in liver in rats fed 300 ppm and included elevated liver weight, an increase in the incidence of diffuse hepatocellular hypertrophy, portal mononuclear cell infiltration, and mild hepatocellular vacuolation without an increase in hepatocellular necrosis. Mean serum activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were elevated up to three times the control means, primarily at the 300 ppm dose. A significant increase in Leydig cell tumors of the testes was seen in the males fed 300 ppm, and tumors of the liver and acinar pancreas, which are often observed in rats from chronic exposure to peroxisome proliferating agents, were not observed in this study. All other tumor types were those seen spontaneously in rats of this stock and age and were not associated with feeding of APFO.
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Affiliation(s)
- John L Butenhoff
- 3M Company, Medical Department, 3M Center 220-06-W-08, Saint Paul, MN 55144, USA.
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34
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Elcombe CR, Elcombe BM, Foster JR, Chang SC, Ehresman DJ, Butenhoff JL. Hepatocellular hypertrophy and cell proliferation in Sprague–Dawley rats from dietary exposure to potassium perfluorooctanesulfonate results from increased expression of xenosensor nuclear receptors PPARα and CAR/PXR. Toxicology 2012; 293:16-29. [DOI: 10.1016/j.tox.2011.12.014] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/27/2011] [Accepted: 12/28/2011] [Indexed: 10/14/2022]
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35
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Hrach J, Mueller S, Hewitt P. Development of an in vitro liver toxicity prediction model based on longer term primary rat hepatocyte culture. Toxicol Lett 2011; 206:189-96. [DOI: 10.1016/j.toxlet.2011.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 07/13/2011] [Accepted: 07/14/2011] [Indexed: 02/05/2023]
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36
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Gentry PR, Clewell HJ, Clewell R, Campbell J, Van Landingham C, Shipp AM. Challenges in the application of quantitative approaches in risk assessment: a case study with di-(2-ethylhexyl)phthalate. Crit Rev Toxicol 2011; 41 Suppl 2:1-72. [DOI: 10.3109/10408444.2011.599366] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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37
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Vidyashankar S, Varma SR, Azeemudin M, Godavarthi A, Krishna NS, Patki PS. A novel herbal formulation "LiverCare" differentially regulates primary rat hepatocyte and hepatocarcinoma cell proliferation in vitro. J Med Food 2011; 14:1023-31. [PMID: 21812649 DOI: 10.1089/jmf.2010.1338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hepatocyte growth factor (HGF) plays an important role in hepatocyte proliferation. HGF expression is regulated by various signaling molecules and nuclear receptors. In the present study, LiverCare(®) (LC), a novel polyherbal formulation (The Himalaya Drug Company, Bangalore, India), was evaluated for its efficacy, using co-cultures of primary rat hepatocytes-non-parenchymal cells (NPCs) and human hepatocellular carcinoma cells (HepG2). The rate of primary hepatocyte co-culture proliferation was significantly and dose-dependently increased by LC as determined by [(3)H]thymidine incorporation into newly synthesized DNA and cell proliferation assay. LC also increased HGF expression in primary hepatocyte co-culture. Albumin and urea content remained constant during proliferation of hepatocyte co-cultures in the presence of LC with decreased activity of alanine aminotransferase. It is interesting that LC inhibited incorporation of [(3)H]thymidine into DNA in HepG2 cells. LC enhanced peroxisome proliferator-activated receptor-α expression during hepatocyte proliferation, whereas tumor necrosis factor-α expression remained unaffected. In conclusion, our study clearly showed that LC differentially regulates primary rat hepatocytes and human hepatocarcinoma cell proliferation. LC may be a promising candidate for treating degenerative liver diseases by enhancing liver regeneration.
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Affiliation(s)
- Satyakumar Vidyashankar
- Department of Cell Biology and Biochemistry, The Himalaya Drug Company, Makali, Bangalore, India.
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38
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Peroxisome proliferator-activated receptors in lung cancer. PPAR Res 2011; 2007:90289. [PMID: 18274632 PMCID: PMC2220082 DOI: 10.1155/2007/90289] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 07/03/2007] [Indexed: 01/11/2023] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. Their discovery in the 1990s provided insights into the cellular mechanisms involved in the control of energy homeostasis; the regulation of cell differentiation, proliferation, and apoptosis; and the modulation of important biological and pathological processes related to inflammation, among others. Since then, PPARs have become an exciting therapeutic target for several diseases. PPARs are expressed by many tumors including lung carcinoma cells, and their function has been linked to the process of carcinogenesis in lung. Consequently, intense research is being conducted in this area with the hope of discovering new PPAR-related therapeutic targets for the treatment of lung cancer. This review summarizes the research being conducted in this area and focuses on the mechanisms by which PPARs are believed to affect lung tumor cell biology.
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39
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Burri L, Bjørndal B, Wergedahl H, Berge K, Bohov P, Svardal A, Berge RK. Tetradecylthioacetic acid increases hepatic mitochondrial β-oxidation and alters fatty acid composition in a mouse model of chronic inflammation. Lipids 2011; 46:679-89. [PMID: 21479675 PMCID: PMC3131506 DOI: 10.1007/s11745-011-3536-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 01/10/2011] [Indexed: 12/23/2022]
Abstract
The administration of tetradecylthioacetic acid (TTA), a hypolipidemic and anti-inflammatory modified bioactive fatty acid, has in several experiments based on high fat diets been shown to improve lipid transport and utilization. It was suggested that increased mitochondrial and peroxisomal fatty acid oxidation in the liver of Wistar rats results in reduced plasma triacylglycerol (TAG) levels. Here we assessed the potential of TTA to prevent tumor necrosis factor (TNF) α-induced lipid modifications in human TNFα (hTNFα) transgenic mice. These mice are characterized by reduced β-oxidation and changed fatty acid composition in the liver. The effect of dietary treatment with TTA on persistent, low-grade hTNFα overexpression in mice showed a beneficial effect through decreasing TAG plasma concentrations and positively affecting saturated and monounsaturated fatty acid proportions in the liver, leading to an increased anti-inflammatory fatty acid index in this group. We also observed an increase of mitochondrial β-oxidation in the livers of TTA treated mice. Concomitantly, there were enhanced plasma levels of carnitine, acetyl carnitine, propionyl carnitine, and octanoyl carnitine, no changed levels in trimethyllysine and palmitoyl carnitine, and a decreased level of the precursor for carnitine, called γ-butyrobetaine. Nevertheless, TTA administration led to increased hepatic TAG levels that warrant further investigations to ascertain that TTA may be a promising candidate for use in the amelioration of inflammatory disorders characterized by changed lipid metabolism due to raised TNFα levels.
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Affiliation(s)
- Lena Burri
- Section of Medical Biochemistry, Institute of Medicine, Haukeland University Hospital, University of Bergen, N-5021, Bergen, Norway.
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40
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Maggiora M, Oraldi M, Muzio G, Canuto RA. Involvement of PPARα and PPARγ in apoptosis and proliferation of human hepatocarcinoma HepG2 cells. Cell Biochem Funct 2011; 28:571-7. [PMID: 20862655 DOI: 10.1002/cbf.1691] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Peroxisome proliferator-activated receptors (PPARs) mediate the effects of various ligands, known as peroxisome proliferators, a heterogeneous class of compounds including industrial chemicals, pharmaceuticals, and biomolecules such as fatty acids and eicosanoids. Among peroxisome proliferators, fibrate derivatives are considered specific ligands for PPARα, whereas eicosanoids, such as PGJ2, for PPARγ. The study aimed to clarify the relation between PPARs and apoptosis or proliferation on the same type of cells, using clofibrate as specific ligand of PPARα and PGJ2 as specific ligand of PPARγ. The cells used were human hepatocarcinoma HepG2 cells. The results showed that PPARα protein content increased in HepG2 cells treated with clofibrate, causing apoptosis in a time- and concentration-dependent way, as evidenced by the citofluorimetric assay and determination of BAD, myc and protein phosphatase 2A protein content. It also emerged that PPARγ increased in the same cells when treated with a specific ligand of this PPAR; in this case the increase of PPARγ did not cause an increase of apoptosis, but a time- and concentration-dependent inhibition of cell proliferation, evidenced by decreased cell numbers and increased number of cells in the G0/G1 phase of the cycle. It may be concluded that PPARα is chiefly related to apoptosis and PPARγ to cell proliferation.
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Affiliation(s)
- Marina Maggiora
- Dipartimento di Medicina ed Oncologia Sperimentale, Università di Torino, Corso Raffaello, Turin, Italy
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Abstract
PPARα is one of three members of the soluble nuclear receptor family called peroxisome proliferator-activated receptor (PPAR). It is a sensor for changes in levels of fatty acids and their derivatives that responds to ligand binding with PPAR target gene transcription, inasmuch as it can influence physiological homeostasis, including lipid and carbohydrate metabolism in various tissues. In this paper we summarize the involvement of PPARα in the metabolically active tissues liver and skeletal muscle and provide an overview of the risks and benefits of ligand activation of PPARα, with particular consideration to interspecies differences.
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Pavlikova N, Kortner TM, Arukwe A. Peroxisome proliferator-activated receptors, estrogenic responses and biotransformation system in the liver of salmon exposed to tributyltin and second messenger activator. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 99:176-85. [PMID: 20466441 DOI: 10.1016/j.aquatox.2010.04.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 04/06/2010] [Accepted: 04/17/2010] [Indexed: 05/24/2023]
Abstract
The mechanisms by which organotin compounds produce modulations of the endocrine systems and other biological responses are not fully understood. In this study, juvenile salmon were force-fed diet containing TBT (0: solvent control, 0.1, 1 and 10mg/kg fish) for 72 h. Subsequently, fish exposed to solvent control and 10mg TBT were exposed to waterborne concentration (200 microg/l) of the adenylate cyclase (AC) stimulator, forskolin for 2 and 4h. The overall aim of the study was to explore whether TBT endocrine disruptive effects involve second messenger activation. Liver was sampled from individual fish (n=8) at the end of the exposures. The transcription patterns of peroxisome proliferator-activated receptor (PPAR) isotype and acyl-coenzyme A oxidase 1 (ACOX1), aromatase isoform, estrogen receptor-alpha (ER alpha), pregnane X receptor (PXR), CYP3A and glutathione S-transferase (GST) genes were measured by quantitative polymerase chain reaction (qPCR). Our data showed a consistent increase in PPAR alpha, PPAR beta and PPAR gamma mRNA and protein expression after TBT exposure that were inversely correlated with ACOX1 mRNA levels. Forskolin produced PPAR isotype-specific mRNA and protein effects that were modulated by TBT. ACOX1 expression was decreased (at 2h) and increased (at 4h) by forskolin and the presence of TBT potentiated these effects. TBT apparently increased mRNA and protein levels of cyp19a, compared to the solvent control, whereas cyp19b mRNA levels were unaffected by TBT treatment. Combined TBT and forskolin exposure produced respective decrease and increase of mRNA levels of cyp19a and cyp19b, compared with control. TBT decreased ER alpha mRNA at low dose (1mg/kg) and forskolin exposure alone produced a consistent decrease of ER alpha mRNA levels that were not affected by the presence of TBT. Interestingly, PXR and CYP3A mRNA levels were differentially affected, either decreased or increased, after exposure to TBT and forskolin, singly and also in combination. GST mRNA was increased by TBT exposure. Exposure to forskolin alone increased GST expression with time, and combined exposure with TBT potentiated these respective effects. Overall, the present study demonstrates multiple biological effects of TBT given singly or in combination with cAMP activator. There are no studies known to us that have evaluated the endocrine disruptive effects of TBT in the presence of a second messenger activator, and our data suggest that TBT may exert endocrine, biotransformation and lipid peroxidative effects through modulation of cAMP/PKA second messenger signaling with overt physiological consequences.
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Affiliation(s)
- Nela Pavlikova
- Department of Biology, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, 7491 Trondheim, Norway
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Rodricks JV, Swenberg JA, Borzelleca JF, Maronpot RR, Shipp AM. Triclosan: a critical review of the experimental data and development of margins of safety for consumer products. Crit Rev Toxicol 2010; 40:422-84. [PMID: 20377306 DOI: 10.3109/10408441003667514] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Triclosan (2,4,4'-trichloro-2'-hydroxy-diphenyl ether) is an antibacterial compound that has been used in consumer products for about 40 years. The tolerability and safety of triclosan has been evaluated in human volunteers with little indication of toxicity or sensitization. Although information in humans from chronic usage of personal care products is not available, triclosan has been extensively studied in laboratory animals. When evaluated in chronic oncogenicity studies in mice, rats, and hamsters, treatment-related tumors were found only in the liver of male and female mice. Application of the Human Relevance Framework suggested that these tumors arose by way of peroxisome proliferator-activated receptor alpha (PPARalpha) activation, a mode of action not considered to be relevant to humans. Consequently, a Benchmark Dose (BMDL(10)) of 47 mg/kg/day was developed based on kidney toxicity in the hamster. Estimates of the amount of intake from in the use of representative personal care products for men, women, and children were derived in two ways: (1) using known or assumed triclosan levels in various consumer products and assumed usage patterns (product-based estimates); and (2) using upper bound measured urinary triclosan levels from human volunteers (biomonitoring-based estimates) using data from the Centers for Disease Control and Prevention. For the product-based estimates, the margin of safety (MOS) for the combined exposure estimates of intake from the use of all triclosan-containing products considered were approximately 1000, 730, and 630 for men, women, and children, respectively. The MOS calculated from the biomonitoring-based estimated intakes were 5200, 6700, and 11,750 for men, women, and children, respectively. Based on these results, exposure to triclosan in consumer products is not expected to cause adverse health effects in children or adults who use these products as intended.
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Hepatocellular hypertrophy and cell proliferation in Sprague–Dawley rats following dietary exposure to ammonium perfluorooctanoate occurs through increased activation of the xenosensor nuclear receptors PPARα and CAR/PXR. Arch Toxicol 2010; 84:787-98. [DOI: 10.1007/s00204-010-0572-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 06/22/2010] [Indexed: 02/02/2023]
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Kennedy GL, Butenhoff JL, Olsen GW, O'Connor JC, Seacat AM, Perkins RG, Biegel LB, Murphy SR, Farrar DG. The Toxicology of Perfluorooctanoate. Crit Rev Toxicol 2010; 34:351-84. [PMID: 15328768 DOI: 10.1080/10408440490464705] [Citation(s) in RCA: 555] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PFOA is a peroxisome proliferator (PPAR agonist) and exerts morphological and biochemical effects characteristic of PPAR agonists. These effects include increased beta-oxidation of fatty acids, increases in several cytochrome P-450 (CYP450)-mediated reactions, and inhibition of the secretion of very low-density lipoproteins and cholesterol from the liver. These effects on lipid metabolism and transport result in a reduction of cholesterol and triglycerides in serum and an accumulation of lipids in the liver. The triad of tumors observed (liver, Leydig cell, and pancreatic acinar-cell) is typical of many PPAR agonists and is believed to involve nongenotoxic mechanisms. The hepatocellular tumors observed in rats are likely to have been the result of the activation of the peroxisome proliferator activated receptor alpha (PPARalpha). The tumors observed in the testis (Leydig-cell) have been hypothesized to be associated with an increased level of serum estradiol in concert with testicular growth factors. The mechanism responsible for the acinar-cell tumors of the pancreas in rats remains the subject of active investigation. The mechanism resulting in the hepatocellular tumors in rats (PPARalpha activation) is not likely to be relevant to humans. Similarly, the proposed mechanism for Leydig-cell tumor formation is of questionable relevance to humans. Acinar tumors of the pancreas are rare in humans, and the relevance of the these tumors, as found in rats, to humans is uncertain. Epidemiological investigations and medical surveillance of occupationally exposed workers have not found consistent associations between PFOA exposure and adverse health effects.
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Maronpot RR, Yoshizawa K, Nyska A, Harada T, Flake G, Mueller G, Singh B, Ward JM. Hepatic Enzyme Induction. Toxicol Pathol 2010; 38:776-95. [DOI: 10.1177/0192623310373778] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Hepatic enzyme induction is generally an adaptive response associated with increases in liver weight, induction of gene expression, and morphological changes in hepatocytes. The additive growth and functional demands that initiated the response to hepatic enzyme induction cover a wide range of stimuli including pregnancy and lactation, hormonal fluctuations, dietary constituents, infections associated with acute-phase proteins, as well as responses to exposure to xenobiotics. Common xenobiotic enzyme inducers trigger pathways involving the constitutive androstane receptor (CAR), the peroxisome proliferator-activated receptor (PPAR), the aryl hydrocarbon receptor (AhR), and the pregnane-X-receptor (PXR). Liver enlargement in response to hepatic enzyme induction is typically associated with hepatocellular hypertrophy and often, transient hepatocyte hyperplasia. The hypertrophy may show a lobular distribution, with the pattern of lobular zonation and severity reflecting species, strain, and sex differences in addition to effects from specific xenobiotics. Toxicity and hepatocarcinogenicity may occur when liver responses exceed adaptive changes or induced enzymes generate toxic metabolites. These undesirable consequences are influenced by the type and dose of xenobiotic and show considerable species differences in susceptibility and severity that need to be understood for assessing the potential effects on human health from similar exposures to specific xenobiotics.
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Affiliation(s)
| | | | | | | | - Gordon Flake
- National Institute for Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | | | - Bhanu Singh
- DuPont Haskell Global Centers for Health and Environmental Science, Newark, Delaware, USA
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Lalloyer F, Staels B. Fibrates, glitazones, and peroxisome proliferator-activated receptors. Arterioscler Thromb Vasc Biol 2010; 30:894-9. [PMID: 20393155 DOI: 10.1161/atvbaha.108.179689] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Several decades ago, fibrates were approved for the treatment of dyslipidemia, whereas thiazolidinediones were screened in animal models to improve glucose homeostasis and were subsequently developed for the treatment of type 2 diabetes mellitus. Relatively recently, these drugs were found to act via peroxisome proliferator-activated receptors, nuclear receptors that control lipid metabolism and glucose homeostasis. In this historical perspective, we discuss the history of discovery of the peroxisome proliferator-activated receptors, from the clinical development of their agonists to the subsequent discovery of these receptors and their mechanisms of action, to finally evoke possibilities of targeted pharmacology for future development of selective peroxisome proliferator-activated receptor modulators.
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Ross J, Plummer SM, Rode A, Scheer N, Bower CC, Vogel O, Henderson CJ, Wolf CR, Elcombe CR. Human Constitutive Androstane Receptor (CAR) and Pregnane X Receptor (PXR) Support the Hypertrophic but not the Hyperplastic Response to the Murine Nongenotoxic Hepatocarcinogens Phenobarbital and Chlordane In Vivo. Toxicol Sci 2010; 116:452-66. [PMID: 20403969 DOI: 10.1093/toxsci/kfq118] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Jillian Ross
- CXR Biosciences Ltd, 2 James Lindsay Place, Dundee DD1 5JJ, UK
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Osimitz TG, Lake BG. Mode-of-action analysis for induction of rat liver tumors by pyrethrins: relevance to human cancer risk. Crit Rev Toxicol 2010; 39:501-11. [PMID: 19463055 DOI: 10.1080/10408440902914014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
High doses of pyrethrins have been shown to produce liver tumors in female rats. Pyrethrins are not genotoxic agents. Pyrethrins produce liver tumors in rats by a mode of action (MOA) involving induction of hepatic xenobiotic metabolising enzymes, hypertrophy, increased cell proliferation, and the development of altered hepatic foci. The relevance of pyrethrins-induced rat liver tumors to human health was assessed by using the 2006 International Programme on Chemical Safety Human Relevance Framework. The postulated rodent tumor MOA was tested against the Bradford Hill criteria and was found to satisfy the conditions of dose and temporal concordance, biological plausibility, coherence, strength, consistency, and specificity that fit with an established mode of action for rodent liver tumor formation by phenobarbital and related compounds, which are activators of the constitutive androstane receptor. Other possible MOAs including mutagenicity, cytotoxicity, hepatic peroxisome proliferation, porphyria, and hormonal pertubation were excluded. The proposed MOA is considered not to be plausible in humans because pyrethrins, like phenobarbital, do not induce cell proliferation in human hepatocytes. Moreover, epidemiological studies with phenobarbital demonstrate that such compounds do not increase the risk of liver tumors in humans. It is concluded that pyrethrins do not pose a hepatocarcinogenic hazard for humans.
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Affiliation(s)
- Thomas G Osimitz
- Science Strategies LLC, 600 East Water Street, Suite G, Charlottesville, VA 22902, USA.
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Makino T, Kinoshita J, Arakawa S, Ito K, Ando Y, Yamoto T, Teranishi M, Sanbuissho A, Nakayama H. Comprehensive analysis of hepatic gene and protein expression profiles on phenobarbital- or clofibrate-induced hepatic hypertrophy in dogs. J Toxicol Sci 2010; 34:647-61. [PMID: 19952500 DOI: 10.2131/jts.34.647] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In order to characterize the hepatic effects of phenobarbital (PB) and clofibrate (CPIB) in dogs, PB and CPIB were administered to male beagle dogs for 14 days, and biochemical and histopathological examinations and comprehensive genomic and proteomic analyses, including GeneChip analysis and proteomics analysis using the 2-dimension difference gel electrophoresis (2D-DIGE) technique, were performed. Both compounds caused centrilobular hepatocellular hypertrophy, which were related to smooth endoplasmic reticulum (SER) proliferation in PB-treated dogs and to mitochondrial proliferation in CPIB-treated dogs. In the PB-treated dogs, drug-metabolizing enzyme induction was observed by Western blot and genomic analyses. CYP proteins could not be detected by the 2D-DIGE analysis, but increases in several endoplasmic reticulum (ER)-related proteins were observed. In the CPIB-treated dogs, drug-metabolizing enzyme induction was not clearly observed by any of Western blot, genomic and proteomic analyses. Genomic and proteomic analyses revealed that mitochondrial genes and proteins, including carnitine palmytoiltransferase II, acyl-CoA deheydrogenase and hydroxyacyl-CoA dehydrogenase, pyruvate carboxylase and ATP synthase beta chain were induced. There is a relatively good correlation among the morphology and the genomic and proteomic data, but some differences exist between the genomic and proteomic data. Comprehensive evaluation using these techniques in addition to morphological evaluation may provide a useful tool for safety assessment of the liver.
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Affiliation(s)
- Toshihiko Makino
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Shizuoka, Japan.
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