1
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Holme JA, Vondráček J, Machala M, Lagadic-Gossmann D, Vogel CFA, Le Ferrec E, Sparfel L, Øvrevik J. Lung cancer associated with combustion particles and fine particulate matter (PM 2.5) - The roles of polycyclic aromatic hydrocarbons (PAHs) and the aryl hydrocarbon receptor (AhR). Biochem Pharmacol 2023; 216:115801. [PMID: 37696458 PMCID: PMC10543654 DOI: 10.1016/j.bcp.2023.115801] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/08/2023] [Accepted: 09/08/2023] [Indexed: 09/13/2023]
Abstract
Air pollution is the leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Increased risk associated with living near trafficked roads, occupational exposure to diesel exhaust, indoor coal combustion and cigarette smoking, suggest that combustion components in ambient fine particulate matter (PM2.5), such as polycyclic aromatic hydrocarbons (PAHs), may be central drivers of lung cancer. Activation of the aryl hydrocarbon receptor (AhR) induces expression of xenobiotic-metabolizing enzymes (XMEs) and increase PAH metabolism, formation of reactive metabolites, oxidative stress, DNA damage and mutagenesis. Lung cancer tissues from smokers and workers exposed to high combustion PM levels contain mutagenic signatures derived from PAHs. However, recent findings suggest that ambient air PM2.5 exposure primarily induces lung cancer development through tumor promotion of cells harboring naturally acquired oncogenic mutations, thus lacking typical PAH-induced mutations. On this background, we discuss the role of AhR and PAHs in lung cancer development caused by air pollution focusing on the tumor promoting properties including metabolism, immune system, cell proliferation and survival, tumor microenvironment, cell-to-cell communication, tumor growth and metastasis. We suggest that the dichotomy in lung cancer patterns observed between smoking and outdoor air PM2.5 represent the two ends of a dose-response continuum of combustion PM exposure, where tumor promotion in the peripheral lung appears to be the driving factor at the relatively low-dose exposures from ambient air PM2.5, whereas genotoxicity in the central airways becomes increasingly more important at the higher combustion PM levels encountered through smoking and occupational exposure.
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Affiliation(s)
- Jørn A Holme
- Department of Air Quality and Noise, Division of Climate and Environmental Health, Norwegian Institute of Public Health, PO Box PO Box 222 Skøyen, 0213 Oslo, Norway
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, 61265 Brno, Czech Republic
| | - Miroslav Machala
- Department of Pharmacology and Toxicology, Veterinary Research Institute, 62100 Brno, Czech Republic
| | - Dominique Lagadic-Gossmann
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Christoph F A Vogel
- Department of Environmental Toxicology and Center for Health and the Environment, University of California, Davis, CA 95616, USA
| | - Eric Le Ferrec
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Lydie Sparfel
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, F-35000, Rennes, France
| | - Johan Øvrevik
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway; Division of Climate and Environmental Health, Norwegian Institute of Public Health, PO Box 222 Skøyen, 0213 Oslo, Norway.
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2
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Sweeney C, Lazennec G, Vogel CFA. Environmental exposure and the role of AhR in the tumor microenvironment of breast cancer. Front Pharmacol 2022; 13:1095289. [PMID: 36588678 PMCID: PMC9797527 DOI: 10.3389/fphar.2022.1095289] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Activation of the aryl hydrocarbon receptor (AhR) through environmental exposure to chemicals including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDDs) can lead to severe adverse health effects and increase the risk of breast cancer. This review considers several mechanisms which link the tumor promoting effects of environmental pollutants with the AhR signaling pathway, contributing to the development and progression of breast cancer. We explore AhR's function in shaping the tumor microenvironment, modifying immune tolerance, and regulating cancer stemness, driving breast cancer chemoresistance and metastasis. The complexity of AhR, with evidence for both oncogenic and tumor suppressor roles is discussed. We propose that AhR functions as a "molecular bridge", linking disproportionate toxin exposure and policies which underlie environmental injustice with tumor cell behaviors which drive poor patient outcomes.
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Affiliation(s)
- Colleen Sweeney
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, CA, United States
| | - Gwendal Lazennec
- Centre National de la Recherche Scientifique, SYS2DIAG-ALCEN, Cap Delta, Montpellier, France
| | - Christoph F. A. Vogel
- Center for Health and the Environment, University of California Davis, Davis, CA, United States
- Department of Environmental Toxicology, University of California Davis, Davis, CA, United States
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3
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Grishanova AY, Perepechaeva ML. Aryl Hydrocarbon Receptor in Oxidative Stress as a Double Agent and Its Biological and Therapeutic Significance. Int J Mol Sci 2022; 23:ijms23126719. [PMID: 35743162 PMCID: PMC9224361 DOI: 10.3390/ijms23126719] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 12/02/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) has long been implicated in the induction of a battery of genes involved in the metabolism of xenobiotics and endogenous compounds. AhR is a ligand-activated transcription factor necessary for the launch of transcriptional responses important in health and disease. In past decades, evidence has accumulated that AhR is associated with the cellular response to oxidative stress, and this property of AhR must be taken into account during investigations into a mechanism of action of xenobiotics that is able to activate AhR or that is susceptible to metabolic activation by enzymes encoded by the genes that are under the control of AhR. In this review, we examine various mechanisms by which AhR takes part in the oxidative-stress response, including antioxidant and prooxidant enzymes and cytochrome P450. We also show that AhR, as a participant in the redox balance and as a modulator of redox signals, is being increasingly studied as a target for a new class of therapeutic compounds and as an explanation for the pathogenesis of some disorders.
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4
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Vogel CFA, Lazennec G, Kado SY, Dahlem C, He Y, Castaneda A, Ishihara Y, Vogeley C, Rossi A, Haarmann-Stemmann T, Jugan J, Mori H, Borowsky AD, La Merrill MA, Sweeney C. Targeting the Aryl Hydrocarbon Receptor Signaling Pathway in Breast Cancer Development. Front Immunol 2021; 12:625346. [PMID: 33763068 PMCID: PMC7982668 DOI: 10.3389/fimmu.2021.625346] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/11/2021] [Indexed: 01/09/2023] Open
Abstract
Activation of the aryl hydrocarbon receptor (AhR) through environmental exposure to known human carcinogens including dioxins can lead to the promotion of breast cancer. While the repressor protein of the AhR (AhRR) blocks the canonical AhR pathway, the function of AhRR in the development of breast cancer is not well-known. In the current study we examined the impact of suppressing AhR activity using its dedicated repressor protein AhRR. AhRR is a putative tumor suppressor and is silenced in several cancer types, including breast, where its loss correlates with shorter patient survival. Using the AhRR transgenic mouse, we demonstrate that AhRR overexpression opposes AhR-driven and inflammation-induced growth of mammary tumors in two different murine models of breast cancer. These include a syngeneic model using E0771 mammary tumor cells as well as the Polyoma Middle T antigen (PyMT) transgenic model. Further AhRR overexpression or knockout of AhR in human breast cancer cells enhanced apoptosis induced by chemotherapeutics and inhibited the growth of mouse mammary tumor cells. This study provides the first in vivo evidence that AhRR suppresses mammary tumor development and suggests that strategies which lead to its functional restoration and expression may have therapeutic benefit.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Antigens, Polyomavirus Transforming/genetics
- Antineoplastic Agents/pharmacology
- Apoptosis
- Basic Helix-Loop-Helix Transcription Factors/genetics
- Basic Helix-Loop-Helix Transcription Factors/metabolism
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Doxorubicin/pharmacology
- Drug Resistance, Neoplasm
- Etoposide/pharmacology
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- MCF-7 Cells
- Mice, Inbred C57BL
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Signal Transduction/drug effects
- Time Factors
- Tumor Burden
- Tumor Cells, Cultured
- Mice
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Affiliation(s)
- Christoph F. A. Vogel
- Department of Environmental Toxicology, University of California, Davis, Davis, CA, United States
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
| | | | - Sarah Y. Kado
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
| | - Carla Dahlem
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
| | - Yi He
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
| | - Alejandro Castaneda
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
| | - Yasuhiro Ishihara
- Center for Health and the Environment, University of California, Davis, Davis, CA, United States
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Christian Vogeley
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Andrea Rossi
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | | | - Juliann Jugan
- Department of Environmental Toxicology, University of California, Davis, Davis, CA, United States
| | - Hidetoshi Mori
- Center for Comparative Medicine, University of California, Davis, Davis, CA, United States
| | - Alexander D. Borowsky
- Center for Comparative Medicine, University of California, Davis, Davis, CA, United States
| | - Michele A. La Merrill
- Department of Environmental Toxicology, University of California, Davis, Davis, CA, United States
| | - Colleen Sweeney
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
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5
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AHR Signaling Interacting with Nutritional Factors Regulating the Expression of Markers in Vascular Inflammation and Atherogenesis. Int J Mol Sci 2020; 21:ijms21218287. [PMID: 33167400 PMCID: PMC7663825 DOI: 10.3390/ijms21218287] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022] Open
Abstract
There is strong evidence that exposure to fine particulate matter (PM2.5) and a high-fat diet (HFD) increase the risk of mortality from atherosclerotic cardiovascular diseases. Recent studies indicate that PM2.5 generated by combustion activates the Aryl Hydrocarbon Receptor (AHR) and inflammatory cytokines contributing to PM2.5-mediated atherogenesis. Here we investigate the effects of components of a HFD on PM-mediated activation of AHR in macrophages. Cells were treated with components of a HFD and AHR-activating PM and the expression of biomarkers of vascular inflammation was analyzed. The results show that glucose and triglyceride increase AHR-activity and PM2.5-mediated induction of cytochrome P450 (CYP)1A1 mRNA in macrophages. Cholesterol, fructose, and palmitic acid increased the PM- and AHR-mediated induction of proinflammatory cytokines in macrophages. Treatment with palmitic acid significantly increased the expression of inflammatory cytokines and markers of vascular injury in human aortic endothelial cells (HAEC) after treatment with PM2.5. The PM2.5-mediated activation of the atherogenic markers C-reactive protein (CRP) and S100A9, a damage-associated molecular pattern molecule, was found to be AHR-dependent and involved protein kinase A (PKA) and a CCAAT/enhancer-binding protein (C/EBP) binding element. This study identified nutritional factors interacting with AHR signaling and contributing to PM2.5-induced markers of atherogenesis and future cardiovascular risk.
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6
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Choudhary M, Malek G. The Aryl Hydrocarbon Receptor: A Mediator and Potential Therapeutic Target for Ocular and Non-Ocular Neurodegenerative Diseases. Int J Mol Sci 2020; 21:ijms21186777. [PMID: 32947781 PMCID: PMC7555571 DOI: 10.3390/ijms21186777] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/10/2020] [Accepted: 09/11/2020] [Indexed: 02/06/2023] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, which senses environmental, dietary or metabolic signals to mount a transcriptional response, vital in health and disease. As environmental stimuli and metabolic products have been shown to impact the central nervous system (CNS), a burgeoning area of research has been on the role of the AHR in ocular and non-ocular neurodegenerative diseases. Herein, we summarize our current knowledge, of AHR-controlled cellular processes and their impact on regulating pathobiology of select ocular and neurodegenerative diseases. We catalogue animal models generated to study the role of the AHR in tissue homeostasis and disease pathogenesis. Finally, we discuss the potential of targeting the AHR pathway as a therapeutic strategy, in the context of the maladies of the eye and brain.
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Affiliation(s)
- Mayur Choudhary
- Department of Ophthalmology, Duke University School of Medicine, 2351 Erwin Road, P.O. Box 3802, Durham, NC 27705, USA
- Correspondence: (M.C.); (G.M.)
| | - Goldis Malek
- Department of Ophthalmology, Duke University School of Medicine, 2351 Erwin Road, P.O. Box 3802, Durham, NC 27705, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27705, USA
- Correspondence: (M.C.); (G.M.)
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7
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Ishihara Y, Haarmann-Stemmann T, Kado NY, Vogel CFA. Interleukin 33 Expression Induced by Aryl Hydrocarbon Receptor in Macrophages. Toxicol Sci 2020; 170:404-414. [PMID: 31093659 DOI: 10.1093/toxsci/kfz114] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) contained in airborne particulate matter have been identified as a contributing factor for inflammation in the respiratory tract. Recently, interleukin-33 (IL-33) is strongly suggested to be associated with airway inflammation. Aryl hydrocarbon receptor (AhR) is a receptor for PAHs to regulate several metabolic enzymes, but the relationships between AhR and airway inflammation are still unclear. In this study, we examined the role of AhR in the expression of IL-33 in macrophages. THP-1 macrophages mainly expressed IL-33 variant 5, which in turn was strongly induced by the AhR agonists 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) and kynurenine (KYN). AhR antagonist CH223191 suppressed the increase in IL-33 expression. Promoter analysis revealed that the IL-33 promoter has 2 dioxin response elements (DREs). AhR was recruited to both DREs after treatment with TCDD or KYN as assessed by gel shift and chromatin immunoprecipitation assays. A luciferase assay showed that one of the DREs was functional and involved in the expression of IL-33. Macrophages isolated from AhR-null mice expressed only low levels of IL-33 even in response to treatment with AhR ligands compared with wild-type cells. The treatment of THP-1 macrophages with diesel particulate matter and particle extracts increased the mRNA and protein expression of IL-33. Taken together, the results show that ligand-activated AhR mediates the induction of IL-33 in macrophages via a DRE located in the IL-33 promoter region. AhR-mediated IL-33 induction could be involved in the exacerbation and/or prolongation of airway inflammation elicited by toxic chemical substances.
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Affiliation(s)
- Yasuhiro Ishihara
- Center for Health and the Environment, University of California, Davis 95616, California.,Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8521, Japan
| | | | - Norman Y Kado
- Center for Health and the Environment, University of California, Davis 95616, California.,Department of Environmental Toxicology, University of California, Davis 95616, California.,Air Resources Board, California Environmental Protection Agency, Sacramento 95812, California
| | - Christoph F A Vogel
- Center for Health and the Environment, University of California, Davis 95616, California.,Department of Environmental Toxicology, University of California, Davis 95616, California
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8
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Vogel CFA, Van Winkle LS, Esser C, Haarmann-Stemmann T. The aryl hydrocarbon receptor as a target of environmental stressors - Implications for pollution mediated stress and inflammatory responses. Redox Biol 2020; 34:101530. [PMID: 32354640 PMCID: PMC7327980 DOI: 10.1016/j.redox.2020.101530] [Citation(s) in RCA: 204] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/20/2020] [Accepted: 03/31/2020] [Indexed: 02/08/2023] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor regulating the expression of genes, for instance encoding the monooxygenases cytochrome P450 (CYP) 1A1 and CYP1A2, which are important enzymes in metabolism of xenobiotics. The AHR is activated upon binding of polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (POPs), and related ubiquitous environmental chemicals, to mediate their biological and toxic effects. In addition, several endogenous and natural compounds can bind to AHR, thereby modulating a variety of physiological processes. In recent years, ambient particulate matter (PM) associated with traffic related air pollution (TRAP) has been found to contain significant amounts of PAHs. PM containing PAHs are of increasing concern as a class of agonists, which can activate the AHR. Several reports show that PM and AHR-mediated induction of CYP1A1 results in excessive generation of reactive oxygen species (ROS), causing oxidative stress. Furthermore, exposure to PM and PAHs induce inflammatory responses and may lead to chronic inflammatory diseases, including asthma, cardiovascular diseases, and increased cancer risk. In this review, we summarize findings showing the critical role that the AHR plays in mediating effects of environmental pollutants and stressors, which pose a risk of impacting the environment and human health. PAHs present on ambient air pollution particles are ligands of the cellular AHR. AHR-dependent induction of CYP1, AKR, NOX and COX-2 genes can be a source of ROS generation. AHR signaling and NRF2 signaling interact to regulate the expression of antioxidant genes. Air pollution and ROS can affect inflammation, which is partially triggered by AHR and associated immune responses. Skin, lung, and the cardiovascular system are major target sites for air pollution-induced inflammation.
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Affiliation(s)
- Christoph F A Vogel
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA, 95616, USA; Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Laura S Van Winkle
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA, 95616, USA; School of Veterinary Medicine Department of Anatomy, University of California, One Shields Avenue, Davis, CA, 5616, USA
| | - Charlotte Esser
- IUF - Leibniz-Research Institute for Environmental Medicine, 40225, Düsseldorf, Germany
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9
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Vogel CFA, Ishihara Y, Campbell CE, Kado SY, Nguyen-Chi A, Sweeney C, Pollet M, Haarmann-Stemmann T, Tuscano JM. A Protective Role of Aryl Hydrocarbon Receptor Repressor in Inflammation and Tumor Growth. Cancers (Basel) 2019; 11:cancers11050589. [PMID: 31035533 PMCID: PMC6563059 DOI: 10.3390/cancers11050589] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/19/2019] [Accepted: 04/25/2019] [Indexed: 01/02/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is known for mediating the toxicity of environmental pollutants such as dioxins and numerous dioxin-like compounds, and is associated with the promotion of various malignancies, including lymphoma. The aryl hydrocarbon receptor repressor (AhRR), a ligand-independent, transcriptionally inactive AhR-like protein is known to repress AhR signaling through its ability to compete with the AhR for dimerization with the AhR nuclear translocator (ARNT). While AhRR effectively blocks AhR signaling, several aspects of the mechanism of AhRR’s functions are poorly understood, including suppression of inflammatory responses and its putative role as a tumor suppressor. In a transgenic mouse that overexpresses AhRR (AhRR Tg) we discovered that these mice suppress 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)- and inflammation-induced tumor growth after subcutaneous challenge of EL4 lymphoma cells. Using mouse embryonic fibroblasts (MEF) we found that AhRR overexpression suppresses the AhR-mediated anti-apoptotic response. The AhRR-mediated inhibition of apoptotic resistance was associated with a suppressed expression of interleukin (IL)-1β and cyclooxygenase (COX)-2, which was dependent on activation of protein kinase A (PKA) and the CAAT-enhancer-binding protein beta (C/EBPβ). These results provide mechanistic insights into the role of the AhRR to suppress inflammation and highlight the AhRR as a potential therapeutic target to suppress tumor growth.
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Affiliation(s)
- Christoph F A Vogel
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA 95616, USA.
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Yasuhiro Ishihara
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8521, Japan.
| | - Claire E Campbell
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Sarah Y Kado
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Aimy Nguyen-Chi
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Colleen Sweeney
- Department of Biochemistry & Molecular Medicine, School of Medicine, University of California, Davis, CA 95817, USA.
| | - Marius Pollet
- Center for Health and the Environment, University of California, One Shields Avenue, Davis, CA 95616, USA.
- Leibniz Research Institute for Environmental Medicine, 40225 Düsseldorf, Germany.
| | | | - Joseph M Tuscano
- Division of Hematology & Oncology, Department of Internal Medicine, University of California Davis Comprehensive Cancer Center, Sacramento, CA 95817, USA.
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10
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Voriconazole-induced photocarcinogenesis is promoted by aryl hydrocarbon receptor-dependent COX-2 upregulation. Sci Rep 2018; 8:5050. [PMID: 29568008 PMCID: PMC5864729 DOI: 10.1038/s41598-018-23439-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/13/2018] [Indexed: 01/12/2023] Open
Abstract
Voriconazole (VRCZ) induces the development of UV-associated skin cancers. The mechanism underlying the VRCZ-induced carcinogenesis has been largely unknown. Here, we showed that VRCZ metabolites plus UVA generated reactive oxygen species and resultant DNA damage of the epidermis, but did not induce substantial apoptosis in human keratinocytes (KCs). Furthermore, VRCZ per se stimulates aryl hydrocarbon receptor (AhR) and upregulates COX-2, which is a pivotal enzyme for the promotion of UV-associated tumors, in an AhR-ARNT dependent manner of the classical (genomic) pathway. Our findings suggest that the phototoxic moieties of VRCZ metabolites may participate in the initiation phase of VRCZ skin cancer, while VRCZ per se promotes the tumor development. Therefore, during VRCZ therapy, sun exposure protection is essential to prevent photocarcinogenesis caused by VRCZ metabolites plus UV. Chemoprevention with selective COX-2 inhibitors may be helpful to repress the development of skin cancers derived from DNA-damaged KCs.
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11
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Yu Y, Liu Q, Guo S, Zhang Q, Tang J, Liu G, Kong D, Li J, Yan S, Wang R, Wang P, Su X, Yu Y. 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin promotes endothelial cell apoptosis through activation of EP3/p38MAPK/Bcl-2 pathway. J Cell Mol Med 2017; 21:3540-3551. [PMID: 28699682 PMCID: PMC5706494 DOI: 10.1111/jcmm.13265] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 05/02/2017] [Indexed: 12/18/2022] Open
Abstract
Endothelial injury or dysfunction is an early event in the pathogenesis of atherosclerosis. Epidemiological and animal studies have shown that 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD) exposure increases morbidity and mortality from chronic cardiovascular diseases, including atherosclerosis. However, whether or how TCDD exposure causes endothelial injury or dysfunction remains largely unknown. Cultured human umbilical vein endothelial cells (HUVECs) were exposed to different doses of TCDD, and cell apoptosis was examined. We found that TCDD treatment increased caspase 3 activity and apoptosis in HUVECs in a dose‐dependent manner,at doses from 10 to 40 nM. TCDD increased cyclooxygenase enzymes (COX)‐2 expression and its downstream prostaglandin (PG) production (mainly PGE2 and 6‐keto‐PGF1α) in HUVECs. Interestingly, inhibition of COX‐2, but not COX‐1, markedly attenuated TCDD‐triggered apoptosis in HUVECs. Pharmacological inhibition or gene silencing of the PGE2 receptor subtype 3 (EP3) suppressed the augmented apoptosis in TCDD‐treated HUVECs. Activation of the EP3 receptor enhanced p38 MAPK phosphorylation and decreased Bcl‐2 expression following TCDD treatment. Both p38 MAPK suppression and Bcl‐2 overexpression attenuated the apoptosis in TCDD‐treated HUVECs. TCDD increased EP3‐dependent Rho activity and subsequently promoted p38MAPK/Bcl‐2 pathway‐mediated apoptosis in HUVECs. In addition, TCDD promoted apoptosis in vascular endothelium and delayed re‐endothelialization after femoral artery injury in wild‐type (WT) mice, but not in EP3−/− mice. In summary, TCDD promotes endothelial apoptosis through the COX‐2/PGE2/EP3/p38MAPK/Bcl‐2 pathway. Given the cardiovascular hazard of a COX‐2 inhibitor, our findings indicate that the EP3 receptor and its downstream pathways may be potential targets for prevention of TCDD‐associated cardiovascular diseases.
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Affiliation(s)
- Yu Yu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Department of Pediatric Cardiology, Xinhua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qian Liu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shumin Guo
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qianqian Zhang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Juan Tang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guizhu Liu
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Deping Kong
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Juanjuan Li
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shuai Yan
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ruiguo Wang
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Peilong Wang
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoou Su
- Institute of Quality Standards and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ying Yu
- Department of Pharmacology, Tianjin Medical University, Tianjin, China.,Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Bekki K, Vogel H, Li W, Ito T, Sweeney C, Haarmann-Stemmann T, Matsumura F, Vogel CFA. The aryl hydrocarbon receptor (AhR) mediates resistance to apoptosis induced in breast cancer cells. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2015; 120:5-13. [PMID: 25987214 PMCID: PMC4438266 DOI: 10.1016/j.pestbp.2014.12.021] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 05/26/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is well known as a ligand binding transcription factor regulating various biological effects. Previously we have shown that long-term exposure to estrogen in breast cancer cells caused not only down regulation of estrogen receptor (ER) but also overexpression of AhR. The AhR interacts with several cell signaling pathways associated with induction of tyrosine kinases, cytokines and growth factors which may support the survival roles of AhR escaping from apoptosis elicited by a variety of apoptosis inducing agents in breast cancer. In this study, we studied the anti-apoptotic role of AhR in different breast cancer cells when apoptosis was induced by exposure to UV light and chemotherapeutic agents. Activation of AhR by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in AhR overexpressing breast cancer cells effectively suppressed the apoptotic response induced by UV-irradiation, doxorubicin, lapatinib and paclitaxel. The anti-apoptotic response of TCDD was uniformly antagonized by the treatment with 3'methoxy-4'nitroflavone (MNF), a specific antagonist of AhR. TCDD's survival action of apoptosis was accompanied with the induction of well-known inflammatory genes, such as cyclooxygenase-2 (COX-2) and NF-κB subunit RelB. Moreover, TCDD increased the activity of the immunosuppressive enzyme indoleamine 2, 3-dioxygenase (IDO), which metabolizes tryptophan to kynurenine (Kyn) and mediates tumor immunity. Kyn also acts as an AhR ligand like TCDD, and kyn induced an anti-apoptotic response in breast cancer cells. Accordingly, our present study suggests that AhR plays a pivotal role in the development of breast cancer via the suppression of apoptosis, and provides an idea that the use of AhR antagonists with chemotherapeutic agents may effectively synergize the elimination of breast cancer cells.
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Affiliation(s)
- Kanae Bekki
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Helena Vogel
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Wen Li
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Tomohiro Ito
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Colleen Sweeney
- Cancer Research Center, Basic Science Research, Medical School, University of California, Davis, CA 95817, USA
| | - Thomas Haarmann-Stemmann
- Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Fumio Matsumura
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Environmental Toxicology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Christoph F A Vogel
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Environmental Toxicology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA.
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13
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Frauenstein K, Tigges J, Soshilov AA, Kado S, Raab N, Fritsche E, Haendeler J, Denison MS, Vogel CFA, Haarmann-Stemmann T. Activation of the aryl hydrocarbon receptor by the widely used Src family kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d]pyrimidine (PP2). Arch Toxicol 2014; 89:1329-36. [PMID: 25082669 DOI: 10.1007/s00204-014-1321-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/21/2014] [Indexed: 01/16/2023]
Abstract
Small molecular weight protein kinase inhibitors are frequently used tools to unravel the complex network of cellular signal transduction under certain physiological and pathophysiological conditions. 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d]pyrimidine (PP2) is a widely used compound to block the activity of Src family kinases, the major group of non-receptor tyrosine kinases, which trigger multiple cellular signaling pathways. Here, we show that PP2 induces cytochrome P450 1A1 mRNA expression and enzyme activity in a dose-dependent manner in human HepG2 hepatoma cells and NCTC 2544 keratinocytes. By means of reporter gene assays, RNA interference, electrophoretic mobility shift assay, and competitive ligand-binding assay, we further demonstrate that PP2 is a ligand for the aryl hydrocarbon receptor (AHR), an intracellular chemosensor that regulates xenobiotic metabolism, environmental stress responses, and immune functions. Upon ligand-dependent activation, the AHR translocates into the nucleus and dimerizes with the AHR nuclear translocator (ARNT) to modulate the expression of its target genes. In addition, AHR activation is frequently accompanied by an activation of the tyrosine kinase c-Src, resulting in stimulation of cell-surface receptors and downstream signal transduction. As PP2 activates the AHR/ARNT pathway by simultaneously blocking c-Src-mediated alternative signaling routes, this compound may be a suitable tool to study the contribution of the different AHR-dependent signaling pathways to biological processes and adverse outcomes. On the other hand, the unexpected property of PP2 to stimulate AHR/ARNT signaling should be carefully taken into account in future investigations in order to avoid a false interpretation of experimental results and molecular interrelations.
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Affiliation(s)
- Katrin Frauenstein
- IUF - Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225, Düsseldorf, Germany
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14
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Jönsson ME, Kubota A, Timme-Laragy AR, Woodin B, Stegeman JJ. Ahr2-dependence of PCB126 effects on the swim bladder in relation to expression of CYP1 and cox-2 genes in developing zebrafish. Toxicol Appl Pharmacol 2012; 265:166-74. [PMID: 23036320 DOI: 10.1016/j.taap.2012.09.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 09/18/2012] [Accepted: 09/26/2012] [Indexed: 01/01/2023]
Abstract
The teleost swim bladder is assumed a homolog of the tetrapod lung. Both swim bladder and lung are developmental targets of persistent aryl hydrocarbon receptor (AHR(2)) agonists; in zebrafish (Danio rerio) the swim bladder fails to inflate with exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB126). The mechanism for this effect is unknown, but studies have suggested roles of cytochrome P450 1 (CYP1) and cyclooxygenase 2 (Cox-2) in some Ahr-mediated developmental effects in zebrafish. We determined relationships between swim bladder inflation and CYP1 and Cox-2 mRNA expression in PCB126-exposed zebrafish embryos. We also examined effects on β-catenin dependent transcription, histological effects, and Ahr2 dependence of the effect of PCB126 on swim bladder using morpholinos targeting ahr2. One-day-old embryos were exposed to waterborne PCB126 or carrier (DMSO) for 24h and then held in clean water until day 4, a normal time for swim bladder inflation. The effects of PCB126 were concentration-dependent with EC(50) values of 1.4 to 2.0 nM for induction of the CYP1s, 3.7 and 5.1 nM (or higher) for cox-2a and cox-2b induction, and 2.5 nM for inhibition of swim bladder inflation. Histological defects included a compaction of the developing bladder. Ahr2-morpholino treatment rescued the effect of PCB126 (5 nM) on swim bladder inflation and blocked induction of CYP1A, cox-2a, and cox-2b. With 2nM PCB126 approximately 30% of eleutheroembryos(3) failed to inflate the swim bladder, but there was no difference in CYP1 or cox-2 mRNA expression between those embryos and embryos showing inflated swim bladder. Our results indicate that PCB126 blocks swim bladder inflation via an Ahr2-mediated mechanism. This mechanism seems independent of CYP1 or cox-2 mRNA induction but may involve abnormal development of swim bladder cells.
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Affiliation(s)
- Maria E Jönsson
- Dept. of Environmental Toxicology, Evolutionary Biology, Centre, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden.
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Yoshioka W, Aida-Yasuoka K, Fujisawa N, Kawaguchi T, Ohsako S, Hara S, Uematsu S, Akira S, Tohyama C. Critical Role of Microsomal Prostaglandin E Synthase-1 in the Hydronephrosis Caused by Lactational Exposure to Dioxin in Mice. Toxicol Sci 2012; 127:547-54. [DOI: 10.1093/toxsci/kfs115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Abstract
The ligand-activated transcription factor AhR mediates the cutaneous stress response toward a variety of environmental noxae and is therefore currently of interest for modern preventive medicine. In this issue, Tsuji et al. identify the antifungal agent ketoconazole as an inducer of AhR signaling and the Nrf2 antioxidant response in human keratinocytes. Ketoconazole-stimulated nuclear translocation of Nrf2 and its cytoprotective effects against oxidative stress strongly depend on a functional AhR. This newly identified AhR-Nrf2 pathway opens up new opportunities to prevent and treat inflammatory skin diseases.
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Wu D, Li W, Lok P, Matsumura F, Vogel CFA. AhR deficiency impairs expression of LPS-induced inflammatory genes in mice. Biochem Biophys Res Commun 2011; 410:358-63. [PMID: 21683686 DOI: 10.1016/j.bbrc.2011.06.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Accepted: 06/01/2011] [Indexed: 11/19/2022]
Abstract
Recent reports suggest the participation of the aryl hydrocarbon receptor (AhR) in the induction mechanism of the NF-κB signaling pathway. In the current study we challenged C57BL/6 wild-type (WT) and AhR deficient (AhR(-/-)) mice with bacterial lipopolysaccharide (LPS) to investigate the role of the AhR in expression profiles of LPS and NF-κB target genes. Further, we analyzed the effect of LPS on the DNA binding activity of NF-κB, C/EBP and AP-1 transcription factors in liver and lung from WT and AhR(-/-) mice. The results show that the LPS-induced expression of several target genes was impaired in AhR(-/-) mice compared to WT mice. Depending on the target gene, the target tissue as well as the time of treatment, the deficiency of AhR may cause an inhibition or increase of the LPS-induced gene expression. The binding activity of NF-κB, C/EBP and AP-1 transcription factors was also affected in a time- and tissue-dependent manner. The current study shows that the AhR is implemented in LPS-induced inflammatory gene expression in vivo even in the absence of exogenous ligands of the AhR. The main implication of this finding is that the AhR functions in Toll-like receptor (TLR) and NF-κB signaling after activation by a classical stimulus, such as LPS.
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Affiliation(s)
- Dalei Wu
- Center for Health and the Environment, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
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18
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FRET analysis of protein tyrosine kinase c-Src activation mediated via aryl hydrocarbon receptor. Biochim Biophys Acta Gen Subj 2010; 1810:427-31. [PMID: 21145940 DOI: 10.1016/j.bbagen.2010.11.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 11/04/2010] [Accepted: 11/25/2010] [Indexed: 01/25/2023]
Abstract
BACKGROUND Activation of the protein tyrosine kinase c-Src (c-Src kinase) induced by the exposure to the environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown in various cell types. Most previous works used Western blot analysis to detect the phosphorylation on the Tyr416 residue, which activates c-Src kinase. METHODS Here we compared the results of c-Src tyrosine phosphorylation via aryl hydrocarbon receptor (AhR)-dependent mechanisms from Western blot analysis with fluorescent resonance energy transfer (FRET) assay detecting c-Src activation after treatment with TCDD to activate AhR in two different human cell types. RESULTS Western blot analyses show time-dependent phosphorylation of c-Src by TCDD in HepG2 and MCF-10A cells. Data from FRET assay visualized and quantified the activation of c-Src kinase induced by TCDD in living cells of both cell types. The FRET efficiency decreased by 20%, 5 min after TCDD treatment and continued decreasing until the end of the experiment, 25 min after TCDD treatment. PP2, a c-Src specific inhibitor, suppressed both TCDD- and epidermal growth factor- (EGF) induced c-Src activation. In contrast, the AhR antagonist 3'-methoxy-4'nitroflavone (MNF) blocked only TCDD- but not EGF-induced activation of c-Src. CONCLUSIONS The current study shows that the early activation of c-Src via EGF and AhR signaling pathways can be visualized in living cells using the FRET assay which is in line with Western blot analysis. GENERAL SIGNIFICANCE The FRET assay provides a useful tool to visualize and quantify c-Src kinase activation via AhR in living cells.
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19
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Dong B, Nishimura N, Vogel CF, Tohyama C, Matsumura F. TCDD-induced cyclooxygenase-2 expression is mediated by the nongenomic pathway in mouse MMDD1 macula densa cells and kidneys. Biochem Pharmacol 2009; 79:487-97. [PMID: 19782052 DOI: 10.1016/j.bcp.2009.08.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/21/2009] [Accepted: 08/24/2009] [Indexed: 01/15/2023]
Abstract
Cyclooxygenase-2 (Cox-2) plays a critical role in TCDD-induced hydronephrosis in mouse neonates. In this study we found that induction of Cox-2 by TCDD in MMDD1, a mouse macula densa cell line, is accompanied with a rapid increase in the enzymatic activity of cytosolic phospholipase A2 (cPLA2) as well as activation of protein kinases. Calcium serves as a trigger for such an action of TCDD in this cell line. These observations indicate that the basic mode of action of TCDD to induce the rapid inflammatory response in MMDD1 is remarkably similar to those mediated by the nongenomic pathway of aryl hydrocarbon receptor (AhR) found in other types of cells. Such an action of TCDD to induce Cox-2 in MMDD1 was not affected by "DRE decoy oligonucleotides" treatment or by introduction of a mutation on the DRE site of Cox-2 promoter, suggesting that this route of action of TCDD is clearly different from that mediated by the classical genomic pathway. An in vivo study with Ahr(nls) mouse model has shown that TCDD-induces Cox-2 and renin expression in the kidneys of the Ahr(nls) mice as well as Ahr(+/-) mice, but not in the Ahr(-/-) mice, indicating that this initial action of TCDD in mouse kidney does not require the translocation of AhR into the nucleus, supporting our conclusion that induction of Cox-2 by TCDD in mouse kidney is largely mediated by the nongenomic pathway of TCDD-activated AhR.
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Affiliation(s)
- Bin Dong
- Department of Environmental Toxicology, University of California, 4245 Meyer Hall, Davis, CA 95616, USA
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20
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Wangpradit O, Teesch LM, Mariappan SVS, Duffel MW, Norstrom K, Robertson LW, Luthe G. Oxidation of 4-chlorobiphenyl metabolites to electrophilic species by prostaglandin H synthase. Chem Res Toxicol 2009; 22:64-71. [PMID: 19105592 DOI: 10.1021/tx800300t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hormonally sensitive tissues, like the prostate, ovary, and breast, increasingly studied as targets of environmental chemicals, are sources of an enzyme potentially capable of transforming and activating xenobiotics to highly reactive metabolites. Our study specifically addresses the question of whether prostaglandin H synthase (PGHS) can activate phenolic metabolites of polychlorinated biphenyls (PCBs). We found that human recombinant PGHS-2 catalyzed the oxidation of ortho (2',3'- and 3',4'-) and para (2',5'-) dihydroxy 4-chlorobiphenyl metabolites to their corresponding quinones. These were trapped in situ with N-acetyl cysteine, and the reaction products were isolated and characterized by liquid chromatography coupled mass spectrometry and (1)H and heteronuclear ((1)H-(13)C) nuclear magnetic resonance spectroscopy. Both mono- and di-N-acetyl cysteine Michael addition adducts were identified, with the 2',3'- and 2',5'-dihydroxy metabolites predominantly forming mono-N-acetyl cysteine adducts, while the 3',4'-dihydroxy predominantly formed disubstituted N-acetyl cysteine adducts. These studies clearly demonstrate that the phenolic metabolites of these environmental pollutants are activated by PGHS, as cosubstrates, to highly reactive electrophilic PCB quinones, with a potential for protein and DNA damage, especially in nonhepatic tissues where the enzyme is found.
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Affiliation(s)
- Orarat Wangpradit
- Department of Occupational and Environmental Health, Interdisciplinary Graduate Program in Human Toxicology, College of Pharmacy, and Seamans Center for the Engineering Art and Sciences, University of Iowa, Iowa City, Iowa 52242, USA
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Sciullo EM, Dong B, Vogel CFA, Matsumura F. Characterization of the pattern of the nongenomic signaling pathway through which TCDD-induces early inflammatory responses in U937 human macrophages. CHEMOSPHERE 2009; 74:1531-1537. [PMID: 19162293 PMCID: PMC2879335 DOI: 10.1016/j.chemosphere.2008.11.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Revised: 10/17/2008] [Accepted: 11/06/2008] [Indexed: 05/27/2023]
Abstract
2,3,7,8-Tetrachlorodibenzo(p)dioxin (TCDD) has been known to induce inflammatory signaling in a number of cell types and tissues. We found that in U937 macrophages TCDD causes rapid activation of cytosolic phospholipase A2 (cPLA2) within 30min as judged by the increase in the serine 505 phosphorylated form of cPLA2 protein and the increased cellular release of free arachidonic acid. This initial action of TCDD is accompanied with the up-regulation of an important inflammation marker, COX-2 mRNA expression within 1h, and by 3h, several other markers become up-regulated. These effects appear to be dependent on the initial increase in the intracellular concentration of Ca(2+), and activation of cPLA2 and COX-2. A comparative study among three different human cell lines showed that activation of COX-2 within 1h of action of TCDD is a common feature exhibited by all cell lines. On the other hand, the U937 macrophage line appears to be unique among them with respect to its ability to activate TNF-alpha and IL-8 mRNA expressions, and not requiring Src kinase in propagating the initial signaling of cPLA2. Based on the rapidity of activation of cPLA2 and COX-2, which occurs within 1h of cell exposure to TCDD, when no change in mRNA expression of CYP1A1 has been observed, it is apparent that this unique action of TCDD is carried out through a distinct "nongenomic" pathway which, is clearly discernable from the classical, "genomic" action pathway of the AhR by not requiring the participation of ARNT.
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Affiliation(s)
- Eric M Sciullo
- Department of Environmental Toxicology, University of California Davis, Center for Health and the Environment, One Shields Ave., Old Davis Rd., Davis, CA 95616, USA
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22
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Matsumura F. The significance of the nongenomic pathway in mediating inflammatory signaling of the dioxin-activated Ah receptor to cause toxic effects. Biochem Pharmacol 2009; 77:608-26. [DOI: 10.1016/j.bcp.2008.10.013] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 09/26/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022]
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Li W, Matsumura F. Significance of the nongenomic, inflammatory pathway in mediating the toxic action of TCDD to induce rapid and long-term cellular responses in 3T3-L1 adipocytes. Biochemistry 2009; 47:13997-4008. [PMID: 19063610 DOI: 10.1021/bi801913w] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
TCDD (dioxin) induces a rapid inflammatory response from 3T3-L1 adipocytes as judged by prominent induction of the mRNA expression of prostaglandin-endperoxide synthase 2 (Cox-2) along with other inflammation markers within 1 h. This action of TCDD is clearly antagonized by cell pretreatment with AACOCF3 (an inhibitor of cPLA2), nifedipine (a Ca(2+) channel blocker), or 3'-methyl-4'-nitroflavone (MNF), an antagonist of the Ah receptor (AhR), suggesting the possible involvement of the nongenomic pathway of action of TCDD as shown previously in MCF10A cells [Dong, B., and Matsumura, F. (2008) Mol. Pharmacol. 74 (1), 255-263]. This early inflammatory action of TCDD is clearly different from that mediated by its classical action pathway in that the former is mediated by protein kinases such as PKC, PKA, and tyrosine kinases, but not by ARNT. Furthermore, the former is not blocked by two "DRE-decoy" treatments. Such an inflammatory effect of TCDD on 3T3-L1 adipocyes persists at least for 5 days, when the affected adipocytes exhibit significant reduction in their adipocyte characteristics. To assess the cause for the long-lasting influence of this nongenomic action of TCDD, we tested the effects of AACOCF3, exogenous arachidonic acid (AA), and H89 (an inhibitor of PKA) on the 5 day action of TCDD. These agents clearly antagonized all the long-term actions of TCDD except that on CYP1A1 induction, indicating that the influence of the nongenomic action of TCDD lasts a long time in this cell material. One of the major factors mediating its long-lasting effects has been identified to be PKA.
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Affiliation(s)
- Wen Li
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, California 95616, USA
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Vogel CFA, Matsumura F. A new cross-talk between the aryl hydrocarbon receptor and RelB, a member of the NF-kappaB family. Biochem Pharmacol 2008; 77:734-45. [PMID: 18955032 DOI: 10.1016/j.bcp.2008.09.036] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 09/19/2008] [Accepted: 09/25/2008] [Indexed: 11/17/2022]
Abstract
The discovery of the new crosstalk between the aryl hydrocarbon receptor (AhR) and the NF-kappaB subunit RelB may extend our understanding of the biological functions of the AhR and at the same time raises a number of questions, which will be addressed in this review. The characteristics of this interaction differ from that of AhR with RelA in that the latter appears to be mostly negative unlike the collaborative interactions of AhR/RelB. The AhR/RelB dimer is capable of binding to DNA response elements including the dioxin response element (DRE) as well as NF-kappaB binding sites supporting the activation of target genes of the AhR as well as NF-kappaB pathway. Further studies show that AhR/RelB complexes can be found not only in lymphoid cells but also in a human hepatoma cell line (HepG2) or breast cancer cell line (MDA-MB-231). RelB has been implicated in carcinogenesis of breast cancer for instance and RelB is known to be a critical factor for the function and differentiation of dendritic cells; interestingly the participation of AhR in both processes has been suggested recently, which offers the great potential to expand the scope of the physiological roles of the AhR. There is evidence indicating that RelB may serve as a pro-survival factor, including its ability to promote "inflammation resolution" besides the association of RelB with inflammatory disorders. Based on such information, a hypothesis has been proposed in this review that AhR together with RelB functions as a coordinator of inflammatory responses.
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Affiliation(s)
- Christoph F A Vogel
- Department of Environmental Toxicology, University of California Davis, Davis, CA 95616, USA.
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25
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Teraoka H, Kubota A, Dong W, Kawai Y, Yamazaki K, Mori C, Harada Y, Peterson RE, Hiraga T. Role of the cyclooxygenase 2-thromboxane pathway in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced decrease in mesencephalic vein blood flow in the zebrafish embryo. Toxicol Appl Pharmacol 2008; 234:33-40. [PMID: 18952116 DOI: 10.1016/j.taap.2008.09.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/26/2008] [Accepted: 09/22/2008] [Indexed: 10/21/2022]
Abstract
Previously, we reported that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) evoked developmental toxicity required activation of aryl hydrocarbon receptor type 2 (AHR2), using zebrafish embryos. However, the downstream molecular targets of AHR2 activation are largely unknown and are the focus of the present investigation. TCDD induces cyclooxygenase 2 (COX2), a rate-limiting enzyme for prostaglandin synthesis in certain cells. In the present study, we investigated the role of the COX2-thromboxane pathway in causing a specific endpoint of TCDD developmental toxicity in the zebrafish embryo, namely, a decrease in regional blood flow in the dorsal midbrain. It was found that the TCDD-induced reduction in mesencephalic vein blood flow was markedly inhibited by selective COX2 inhibitors, NS-398 and SC-236, and by a general COX inhibitor, indomethacin, but not by a selective COX1 inhibitor, SC-560. Gene knock-down of COX2 by two different types of morpholino antisense oligonucleotides, but not by their negative homologs, also protected the zebrafish embryos from mesencephalic vein circulation failure caused by TCDD. This inhibitory effect of TCDD on regional blood flow in the dorsal midbrain was also blocked by selective antagonists of the thromboxane receptor (TP). Treatment of control zebrafish embryos with a TP agonist also caused a reduction in mesencephalic vein blood flow and it too was blocked by a TP antagonist, without any effect on trunk circulation. Finally, gene knock-down of thromboxane A synthase 1 (TBXS) with morpholinos but not by the morpholinos' negative homologs provided significant protection against TCDD-induced mesencephalic circulation failure. Taken together, these results point to a role of the prostanoid synthesis pathway via COX2-TBXS-TP in the local circulation failure induced by TCDD in the dorsal midbrain of the zebrafish embryo.
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Affiliation(s)
- Hiroki Teraoka
- Department of Toxicology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
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26
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Beischlag TV, Luis Morales J, Hollingshead BD, Perdew GH. The aryl hydrocarbon receptor complex and the control of gene expression. Crit Rev Eukaryot Gene Expr 2008; 18:207-50. [PMID: 18540824 DOI: 10.1615/critreveukargeneexpr.v18.i3.20] [Citation(s) in RCA: 530] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that controls the expression of a diverse set of genes. The toxicity of the potent AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin is almost exclusively mediated through this receptor. However, the key alterations in gene expression that mediate toxicity are poorly understood. It has been established through characterization of AhR-null mice that the AhR has a required physiological function, yet how endogenous mediators regulate this orphan receptor remains to be established. A picture as to how the AhR/ARNT heterodimer actually mediates gene transcription is starting to emerge. The AhR/ARNT complex can alter transcription both by binding to its cognate response element and through tethering to other transcription factors. In addition, many of the coregulatory proteins necessary for AhR-mediated transcription have been identified. Cross talk between the estrogen receptor and the AhR at the promoter of target genes appears to be an important mode of regulation. Inflammatory signaling pathways and the AhR also appear to be another important site of cross talk at the level of transcription. A major focus of this review is to highlight experimental efforts to characterize nonclassical mechanisms of AhR-mediated modulation of gene transcription.
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Affiliation(s)
- Timothy V Beischlag
- Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA
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27
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Degner SC, Kemp MQ, Hockings JK, Romagnolo DF. Cyclooxygenase-2 Promoter Activation by the Aromatic Hydrocarbon Receptor in Breast Cancer MCF-7 Cells: Repressive Effects of Conjugated Linoleic Acid. Nutr Cancer 2007; 59:248-57. [DOI: 10.1080/01635580701485585] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Vogel CFA, Li W, Sciullo E, Newman J, Hammock B, Reader JR, Tuscano J, Matsumura F. Pathogenesis of aryl hydrocarbon receptor-mediated development of lymphoma is associated with increased cyclooxygenase-2 expression. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1538-48. [PMID: 17823287 PMCID: PMC2043515 DOI: 10.2353/ajpath.2007.070406] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epidemiological studies indicate that exposure to environmental pollutants such as pesticides and dioxins leads to the pathogenesis of lymphoma and leukemia. Here, we show that activation of the aryl hydrocarbon receptor (AhR) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) resulted in loss of the programmed cell death (apoptosis) response in three different lymphoma cell lines, which plays a key role in the development of cancer, especially lymphoma and leukemia. The AhR-mediated inhibition of apoptosis in vitro was associated with a clear increase of cyclooxygenase-2 (COX-2) and deregulation of genes of the B-cell lymphoma-2 (Bcl-2) family involved in apoptosis including Bcl-xl and Mcl-1 in several lymphoma cell lines. Treatment with the COX-2 inhibitor NS-398 and the AhR antagonist 3'-methoxy-4'-nitroflavone abolished the TCDD-induced resistance of apoptosis in vitro. Furthermore, using micropositron emission tomography imaging, in vivo findings demonstrated that exposure to TCDD promotes the development of lymphoma in superficial lymph nodes of C57BL/10J mice, which was associated with a marked increase of COX-2 expression in the affected lymph nodes. The results indicate that AhR activation and COX-2 overexpression likely represent a mechanism of resistance to apoptosis in lymphoma cell lines that might be relevant for the development of lymphoma in vivo.
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Affiliation(s)
- Christoph F A Vogel
- Department of Environmental Toxicology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA.
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29
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Lee JA, Hwang JA, Sung HN, Jeon CH, Gill BC, Youn HJ, Park JH. 2,3,7,8-Tetrachlorodibenzo-p-dioxin modulates functional differentiation of mouse bone marrow-derived dendritic cells Downregulation of RelB by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Lett 2007; 173:31-40. [PMID: 17681673 DOI: 10.1016/j.toxlet.2007.06.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 06/21/2007] [Accepted: 06/21/2007] [Indexed: 01/22/2023]
Abstract
We have previously shown that benzo(a)pyrene inhibits the growth and functional differentiation of mouse bone marrow (BM)-derived dendritic cells (DCs) [Hwang, J.A., Lee, J.A., Cheong, S.W., Youn, H.J., Park, J.H., 2007. Benzo(a)pyrene inhibits growth and functional differentiation of mouse bone marrow-derived dendritic cells. Downregulation of RelB and eIF3 p170 by benzo(a)pyrene. Toxicol. Lett. 169, 82-90]. Since the toxic effects of benzo(a)pyrene are aryl hydrocarbon receptor (AhR)-dependent, we examined the effects of the very potent AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the growth and functional differentiation of mouse BM-derived DCs. Ten nanomolars of TCDD had significant effects on functional differentiation of mouse DCs derived from BM cultured in the presence of GM-CSF and IL-4. The yields of DCs, flow-cytometrically analyzed for co-expression of CD11c/MHCII or CD11c/CD86, were reduced for TCDD-treated cultures, but TCDD itself had no effect on the growth of BM. DCs from TCDD-treated cultures expressed higher levels of MHCII and CD86, whereas expression of CD11c was reduced, compared with vehicle-treated cultures. Production of IL-10, but not IL-12, by the DCs from TCDD-treated cultures was decreased. Allogeneic T-cell stimulating ability of TCDD-treated DCs was increased compared to control DCs. The effects of TCDD were dependent on aryl hydrocarbon receptor (AhR), because alpha-naphthoflavone, an AhR antagonist, suppressed the effects of TCDD on IL-10 production and T-cell stimulating ability. RT-PCR revealed the downregulation of RelB, a transcription factor necessary for DCs differentiation and function. Taken together, although benzo(a)pyrene and TCDD exert their effects via binding to AhR, their effects on the growth and functional differentiation of bone marrow-derived DCs are different.
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Affiliation(s)
- Jin-Ah Lee
- Department of Biology, Changwon National University, #9 Sarim-dong, Changwon, Kyungnam 641-773, South Korea
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Lovgren AK, Kovarova M, Koller BH. cPGES/p23 is required for glucocorticoid receptor function and embryonic growth but not prostaglandin E2 synthesis. Mol Cell Biol 2007; 27:4416-30. [PMID: 17438133 PMCID: PMC1900037 DOI: 10.1128/mcb.02314-06] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 01/10/2007] [Accepted: 03/24/2007] [Indexed: 11/20/2022] Open
Abstract
A number of studies have identified cytosolic prostaglandin E(2) synthase (cPGES)/p23 as a cytoplasmic protein capable of metabolism of prostaglandin E(2) (PGE(2)) from the cyclooxygenase metabolite prostaglandin endoperoxide (PGH(2)). However, this protein has also been implicated in a number of other pathways, including stabilization of the glucocorticoid receptor (GR) complex. To define the importance of the functions assigned to this protein, mice lacking detectible cPGES/p23 expression were generated. cPGES/p23(-/-) pups die during the perinatal period and display retarded lung development reminiscent of the phenotype of GR-deficient neonates. Furthermore, GR-sensitive gluconeogenic enzymes are not induced in the prenatal period. However, unlike GR-deficient embryos, cPGES/p23(-/-) embryos are small and a proliferation defect is observed in cPGES/p23(-/-) fibroblasts. Analysis of arachidonic acid metabolites in embryonic tissues and primary fibroblasts failed to support a function for this protein in PGE(2) biosynthesis. Thus, while the growth retardation of the cPGES/p23(-/-) pups and decreased proliferation of primary fibroblasts identify functions for this protein in addition to GR stabilization, it is unlikely that these functions include metabolism of PGH(2) to PGE(2).
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Affiliation(s)
- Alysia Kern Lovgren
- University of North Carolina, Department of Genetics, Chapel Hill, NC 27599, USA
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31
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Fritsche E, Schäfer C, Calles C, Bernsmann T, Bernshausen T, Wurm M, Hübenthal U, Cline JE, Hajimiragha H, Schroeder P, Klotz LO, Rannug A, Fürst P, Hanenberg H, Abel J, Krutmann J. Lightening up the UV response by identification of the arylhydrocarbon receptor as a cytoplasmatic target for ultraviolet B radiation. Proc Natl Acad Sci U S A 2007; 104:8851-6. [PMID: 17502624 PMCID: PMC1885591 DOI: 10.1073/pnas.0701764104] [Citation(s) in RCA: 326] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
UVB radiation-induced signaling in mammalian cells involves two major pathways: one that is initiated through the generation of DNA photoproducts in the nucleus and a second one that occurs independently of DNA damage and is characterized by cell surface receptor activation. The chromophore for the latter one has been unknown. Here, we report that the UVB response involves tryptophan as a chromophore. We show that through the intracellular generation of photoproducts, such as the arylhydrocarbon receptor (AhR) ligand 6-formylindolo[3,2-b]carbazole, signaling events are initiated, which are transferred to the nucleus and the cell membrane via activation of the cytoplasmatic AhR. Specifically, AhR activation by UVB leads to (i) transcriptional induction of cytochrome P450 1A1 and (ii) EGF receptor internalization with activation of the EGF receptor downstream target ERK1/2 and subsequent induction of cyclooxygenase-2. The role of the AhR in the UVB stress response was confirmed in vivo by studies employing AhR KO mice.
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Affiliation(s)
- Ellen Fritsche
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Claudia Schäfer
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Christian Calles
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Thorsten Bernsmann
- Chemical and Veterinary Control Laboratory, Josef-König-Strasse 40, 48147 Münster, Germany
| | - Thorsten Bernshausen
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Melanie Wurm
- Department of Pediatric Oncology, Hematology, and Immunology, Children's Hospital, Heinrich Heine University Medical Center, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Ulrike Hübenthal
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Jason E. Cline
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Hossein Hajimiragha
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Peter Schroeder
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Lars-Oliver Klotz
- Institute for Biochemistry und Molecular Biology I, Heinrich Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Agneta Rannug
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden; and
| | - Peter Fürst
- Chemical and Veterinary Control Laboratory, Josef-König-Strasse 40, 48147 Münster, Germany
| | - Helmut Hanenberg
- Department of Pediatric Oncology, Hematology, and Immunology, Children's Hospital, Heinrich Heine University Medical Center, Moorenstrasse 5, 40225 Düsseldorf, Germany
| | - Josef Abel
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Jean Krutmann
- *Institut für Umweltmedizinische Forschung (IUF), Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
- To whom correspondence should be addressed. E-mail:
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Matsumura F, Vogel CFA. Evidence supporting the hypothesis that one of the main functions of the aryl hydrocarbon receptor is mediation of cell stress responses. Biol Chem 2006; 387:1189-94. [PMID: 16972785 DOI: 10.1515/bc.2006.146] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We have previously proposed that one of the major consequences of activation of the aryl hydrocarbon receptor (AhR) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) could be elicitation of ‘cell stress response’ reactions [Matsumura, Biochem. Pharmacol. 66 (2003), 527–540]. This hypothesis was based mainly on the similarity between the toxic symptoms, particularly those related to the wasting syndrome, and those induced by bacterial endotoxins, namely lipopolysaccharides (LPS) in vivo, as well as the biochemical and molecular consequences of their toxic actions in vitro. Since the basic action mechanism of LPS as an inducer of cell stress responses (CSR) is known to some extent, including knowledge of their specific receptors (i.e., toll-like receptors) and their signaling process through the inflammatory response messengers, the above comparison offered a good point of reference to this subject. Furthermore, the process of constructing this hypothesis itself has provided us with a good opportunity to give a fresh view on the toxic action patterns of TCDD.
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Affiliation(s)
- Fumio Matsumura
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA 95616, USA.
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33
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Bock KW, Köhle C. Ah receptor: Dioxin-mediated toxic responses as hints to deregulated physiologic functions. Biochem Pharmacol 2006; 72:393-404. [PMID: 16545780 DOI: 10.1016/j.bcp.2006.01.017] [Citation(s) in RCA: 264] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2005] [Revised: 01/23/2006] [Accepted: 01/24/2006] [Indexed: 01/28/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and member of the bHLH/PAS (basic Helix-Loop-Helix/Per-Arnt-Sim) family of chemosensors and developmental regulators. It represents a multifunctional molecular switch regulating endo- and xenobiotic metabolism as well as cell proliferation and differentiation. Physiologic functions of the AhR are beginning to be understood, including functions in vascular development, and in detoxification of endo- and xenobiotics. The AhR is also recognized as the culprit for most toxic responses observed after exposure to dioxins and related compounds such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The non-metabolizable AhR agonist TCDD has to be distinguished from the myriad of metabolizable agonists present as dietary contaminants and plant constituents as well as endogenous toxins. The hypothesis is emerging that the diverse tissue-specific, TCDD-mediated toxicities are due to sustained and inappropriate AhR activation leading to deregulated physiologic functions. In support of this hypothesis recent observations in the context of some TCDD-mediated toxic responses are discussed, such as chloracne, cleft palate, thymus involution and in particular carcinogenesis. Major open questions are addressed, such as ligand-independent AhR activation by phosphorylation and the large differences in species-dependent susceptibility to toxic responses. Though important issues remain unresolved, the commentary is intended to stimulate efforts to understand dioxin-mediated toxic responses with emphasis on carcinogenesis in comparison with AhR-mediated physiologic functions.
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Affiliation(s)
- Karl Walter Bock
- Department of Toxicology, Institute of Pharmacology and Toxicology, University of Tübingen, Tübingen, Germany.
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Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that has been intensively studied with respect to the toxicity of xenobiotics. However, its function in response to light has never been summarized. Here, we provide an overview of AhR activation by light with a focus on the role of tryptophan in light-induced AhR activation. We discuss the involvement of the AhR in different biological rhythms and speculate on the possible role of the AhR in UV-induced responses in skin. Furthermore, this review points out future research needs in this field.
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Affiliation(s)
- Agneta Rannug
- Karolinska Institute, Institute of Environmental Medicine, P.O. Box 210, S-171 77 Stockholm, Sweden.
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35
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Schwarz M, Appel KE. Carcinogenic risks of dioxin: Mechanistic considerations. Regul Toxicol Pharmacol 2005; 43:19-34. [PMID: 16054739 DOI: 10.1016/j.yrtph.2005.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Indexed: 12/01/2022]
Abstract
Dioxins and dioxin-like chemicals demonstrate high affinity binding to the aryl hydrocarbon receptor (AhR), a ligand activated transcription factor, which mediates most, if not all, of the toxic responses of these agents. Since dioxins are not directly genotoxic their carcinogenic effect is likely the result of their tumor promoting activity produced by activation of the AhR. For the purpose of risk assessment extrapolation from effects in the observable high dose range to background dietary exposure is necessary. In the present review, we discuss various aspects of low-dose-response of receptor-mediated processes in general, including threshold phenomena with regard to tumor promotion during multi-stage carcinogenesis. In this connection the reversibility of tumor promotion plays an important role but this may not be valid for dioxins due to their long half life. The relevance of cytochrome P 4501 A-induction as biomarker for prediction of carcinogenic effects of dioxins at low doses is considered. Dioxins may act in concert with endogenous ligands of the AhR, an effect which becomes particularly relevant at low toxicant concentrations. At present, however, the nature and role of these postulated ligands are unknown. Furthermore, it is unclear whether dioxins produce synergistic tumor promotional effects with non-dioxin-like chemicals to which humans are also exposed. Dioxins and, e.g., non-dioxin-like PCBs act through different receptors and there is, albeit yet limited, experimental evidence from experimental studies to suggest that they may act on different target cell populations within the same target organ. From the available data the existence of a (physiological) threshold of effects cannot be proven and may not even exist. For regulatory purposes the application of a so called "practical threshold" for the carcinogenic effect of dioxins is proposed. Further mechanistic studies should be conducted to get insight into the dose-response characteristics of relevant events of dioxin-like and non-dioxin-like agents and into the consequences of potential interactions between both group of compounds during carcinogenesis.
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Affiliation(s)
- Michael Schwarz
- Institute of Pharmacology and Toxicology, Department of Toxicology, University of Tübingen, Wilhelmstr. 56, 72074 Tübingen, Germany
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36
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Clausen I, Kietz S, Fischer B. Lineage-specific effects of polychlorinated biphenyls (PCB) on gene expression in the rabbit blastocyst. Reprod Toxicol 2005; 20:47-56. [PMID: 15808785 DOI: 10.1016/j.reprotox.2004.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Revised: 10/05/2004] [Accepted: 11/12/2004] [Indexed: 11/26/2022]
Abstract
The ubiquitous toxic environmental contaminants polychlorinated biphenyls (PCBs) change gene expression in preimplantation embryos. Cell lineage-specific effects of PCB are not known. Rabbit day 6 blastocysts were exposed in vitro to low (0.1 ng/congener/mL medium) and high (1 microg) PCB levels of coplanar (PCB 77, 126, and 169) or non-coplanar PCBs (PCB 28, 52, 101, 118, 138, 153, and 180). Embryoblast (ICM) and trophoblast cells (TE) were separated and analyzed for transcriptional changes of PCB-and implantation-associated genes by semiquantitative RT-PCR. PCBs increased CYP 1A1 mRNA only in the ICM. CYP 1B1, VEGFR2, and COX-2 transcript numbers were elevated in both ICM and TE. Transcripts for HIF-1alpha were decreased in the ICM. No obvious differences in gene expression following exposure to coplanar and non-coplanar PCBs were detected. Our results show that transcriptional responses to PCBs differ between the cell lineages of the rabbit blastocyst, indicating that PCBs can influence the highly sensitive process of early mammalian development.
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Affiliation(s)
- Ina Clausen
- Department of Anatomy and Cell Biology, Martin Luther University Faculty of Medicine, Grosse Steinstrasse 52, D-06097 Halle (Saale), Germany
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Mazina O, Park S, Sano H, Wong P, Matsumura F. Studies on the mechanism of rapid activation of protein tyrosine phosphorylation activities, particularly c-Src kinase, by TCDD in MCF10A. J Biochem Mol Toxicol 2005; 18:313-21. [PMID: 15674841 DOI: 10.1002/jbt.20041] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
While the process of the Ah receptor activation leading to cytochrome P450 induction has been well studied, the mechanism and the process through which the Ah receptor activates tyrosine kinases, within a few minutes of its ligand binding, is not known. Previously, it was reported by Tannheimer et al. (Carcinogenesis 1998; 19:1291-1297) that TCDD causes rapid induction of tyrosine phosphorylation activities in the MCF10A human mammary epithelial cell line. To study the mechanistic aspect of this phenomenon, particularly that occurs within a few minutes after administration, we first studied the effect of insulin on MCF10A under serum free conditions with added EGF. The addition of insulin induced a rapid (5 min) tyrosine phosphorylation on several 160-190 kDa proteins which was followed by significant dephosphorylation activities on these proteins by 15 min. TCDD increased the rate of tyrosine phosphorylation on those proteins but at 15 min, the level of phosphorylation was still high. When insulin and TCDD were added together, the ability of insulin to induce de-phosphorylation by 15 min disappeared. Such an action of TCDD was accompanied by an increase in the titer of the activated form of Src kinase (i.e. c-Src protein with 418 tyrosine phosphorylation), and a concomitant decrease in the level of 529 tyrosine phosphorylated form (an inactivated form). The TCDD-induced activation of c-Src could be blocked by pretreated MCF10A cells with antisense oligonucleotides against c-src or with a specific inhibitor of Src kinase, PP-2. These results support the conclusion that c-Src kinase is at least one of the earliest and the most upstream components of toxic signaling of the Ah-receptor activated by TCDD through the post-transcriptional process.
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Affiliation(s)
- Olga Mazina
- Department of Environmental Toxicology and the Center for Environmental Health Sciences, University of California, One Shields Ave, Davis, CA 95616, USA
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38
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Billi de Catabbi SC, Faletti A, Fuentes F, San Martín de Viale LC, Cochón AC. Hepatic arachidonic acid metabolism is disrupted after hexachlorobenzene treatment. Toxicol Appl Pharmacol 2005; 204:187-95. [PMID: 15808524 DOI: 10.1016/j.taap.2004.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Accepted: 09/01/2004] [Indexed: 11/21/2022]
Abstract
Hexaclorobenzene (HCB), one of the most persistent environmental pollutants, can cause a wide range of toxic effects including cancer in animals, and hepatotoxicity and porphyria both in humans and animals. In the present study, liver microsomal cytochrome P450 (CYP)-dependent arachidonic acid (AA) metabolism, hepatic PGE production, and cytosolic phospholipase A2 (cPLA2) activity were investigated in an experimental model of porphyria cutanea tarda induced by HCB. Female Wistar rats were treated with a single daily dose of HCB (100 mg kg(-1) body weight) for 5 days and were sacrificed 3, 10, 17, and 52 days after the last dose. HCB treatment induced the accumulation of hepatic porphyrins from day 17 and increased the activities of liver ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and aminopyrine N-demethylase (APND) from day 3 after the last dose. Liver microsomes from control and HCB-treated rats generated, in the presence of NADPH, hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs), 11,12-Di HETE, and omega-OH/omega-1-OH AA. HCB treatment caused an increase in total NADPH CYP-dependent AA metabolism, with a higher response at 3 days after the last HCB dose than at the other time points studied. In addition, HCB treatment markedly enhanced PGE production and release in liver slices. This HCB effect was time dependent and reached its highest level after 10 days. At this time cPLA2 activity was shown to be increased. Unexpectedly, HCB produced a significant decrease in cPLA2 activity on the 17th and 52nd day. Our results demonstrated for the first time that HCB induces both the cyclooxygenase and CYP-dependent AA metabolism. The effects of HCB on AA metabolism were previous to the onset of a marked porphyria and might contribute to different aspects of HCB-induced liver toxicity such as alterations of membrane fluidity and membrane-bound protein function. Observations also suggested that a possible role of cPLA2 in the early increase of AA metabolism cannot be excluded. However, the existence of other pathway(s) for metabolizable AA generation different from cPLA2 activation is also proposed.
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Affiliation(s)
- Silvia C Billi de Catabbi
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Laboratorio de Disturbios Metabólicos por Xenobióticos, Salud Humana y Medio Ambiente (DIMXSA), Universidad de Buenos Aires, Ciudad Universitaria 1428 Buenos Aires, Argentina
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Lecureur V, Ferrec EL, N'diaye M, Vee ML, Gardyn C, Gilot D, Fardel O. ERK-dependent induction of TNFalpha expression by the environmental contaminant benzo(a)pyrene in primary human macrophages. FEBS Lett 2005; 579:1904-10. [PMID: 15792794 DOI: 10.1016/j.febslet.2005.01.081] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 12/22/2004] [Accepted: 01/31/2005] [Indexed: 02/06/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BP) are toxic environmental contaminants known to enhance production of pro-inflammatory cytokines such as IL-1beta. The present study was designed in order to determine whether TNFalpha, another cytokine acting in inflammation, may also constitute a target for these chemicals. Both TNFalpha mRNA and TNFalpha secretion levels were found to be enhanced in human BP-treated macrophages. Dioxin, a contaminant activating the aryl hydrocarbon receptor (AhR) like PAHs, was also shown to increase TNFalpha expression. BP-mediated TNFalpha induction was however not suppressed by AhR antagonists, making unlikely the involvement of the typical AhR signalling pathway. BP-exposure of macrophages did not enhance NF-kappaB DNA binding activity, but it activated the MAP kinase ERK1/2. In addition, the use of chemical inhibitors of extracellular signal-regulated protein kinase (ERK) activation fully abrogated induction of TNFalpha production in BP-treated macrophages. These data likely indicate that PAHs enhance TNFalpha expression in human macrophages through an ERK-related mechanism. Such a regulation may contribute to confer pro-inflammatory properties to these widely-distributed environmental contaminants.
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Affiliation(s)
- Valérie Lecureur
- INSERM U620, Faculté de Pharmacie, 2 avenue du Pr. Léon Bernard, 35043 Rennes, France.
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Vogel CFA, Zhao Y, Wong P, Young NF, Matsumura F. The use of c-src knockout mice for the identification of the main toxic signaling pathway of TCDD to Induce wasting syndrome. J Biochem Mol Toxicol 2003; 17:305-15. [PMID: 14708085 DOI: 10.1002/jbt.10096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of single intraperitoneal injection of 115 microg/kg of TCDD (i.e., approximately 1/2 of LD50) to male C57BL/6 mice on the liver mRNA expression changes of several growth factor related genes was assessed at 3 h, 24 h, 10 days, and 30 days posttreatment. The results revealed that the most consistently elevated mRNAs during the entire test period were those of c-Src, TGFalpha, and PDGFa. In contrast, those observed to be consistently suppressed were mRNAs for EGF receptor (EGFR), Ki-Ras, SAPKK, Sp-1, C/EBPbeta, and NFkB. Elevation of mRNAs for TGFbeta and STAT3 was observed only on day 10 and day 30. To assess the role of c-Src in the above action of TCDD, we conducted a parallel study with congenic C57BL/6 male c-src -/- mice. The results showed that in scr -/- mice the effect of TCDD was less in the case of mRNA expression of PDGF(AA), STAT3, C/EPBbeta, NMT-1, and AP-2gamma in addition to c-src as compared to scr +/+ mice. Those affected least by the absence of c-Src were SAPKK, and surprisingly, EGF receptor mRNAs, both of which were consistently downregulated in both strains. In most of the other cases, the extent of TCDD-induced changes were generally less pronounced in src -/- mice as compared to +/+ mice. These observations support the notion that c-Src is an important mediator of the effects of TCDD on TGFalpha, PDGF(AA), and C/EBPalpha, beta.
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Affiliation(s)
- Christoph F A Vogel
- Department of Environmental Toxicology and the Center for Environmental Health Sciences, University of California, Davis, CA 95616, USA
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Vogel CFA, Sciullo E, Park S, Liedtke C, Trautwein C, Matsumura F. Dioxin increases C/EBPbeta transcription by activating cAMP/protein kinase A. J Biol Chem 2003; 279:8886-94. [PMID: 14684744 DOI: 10.1074/jbc.m310190200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD = dioxin) has been shown to increase the expression of C/EBPbeta. The modulated expression of C/EBPbeta has been suggested to be associated with toxic responses of TCDD such as wasting syndrome, diabetes, and inhibition of adipocyte differentiation. This study focused on the regulatory mechanism of TCDD-mediated transcriptional activation of C/EBPbeta. Elevated C/EBPbeta mRNA and protein levels in mouse embryonic fibroblasts (C3H10T(1/2)) and in mouse hepatoma cells (Hepa1c1c7) were correlated with increased binding affinity of the C/EBPbeta protein. Transfection studies with different deletion constructs of the CCAAT/enhancer-binding protein promoter indicated that a small region located 60-120 bp upstream of the start site of transcription is required for activation of the C/EBPbeta gene by TCDD in both cell lines tested. Further analysis using mutation constructs of the C/EBPbeta promoter demonstrated that activation of the C/EBPbeta promoter is mediated through incomplete cAMP-response element-binding protein (CREB) sites located close to the TATA box of the C/EBPbeta gene. The protein kinase A (PKA) inhibitor H89 completely blocks the TCDD-dependent effect on C/EBPbeta promoter activity, indicating that TCDD activates CREB binding via a cAMP/PKA pathway, which is supported by the increased cAMP level and PKA activity observed after TCDD treatment. Gel shift analyses demonstrated that CREB itself binds to the putative CREB motif that mediates the TCDD-dependent effect on C/EBPbeta gene transcription. Cotransfection experiments with CREB and PKA expression plasmids further supported our conclusions that the TCDD-dependent effect on C/EBPbeta transcription is mediated via PKA-dependent CREB activation.
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Affiliation(s)
- Christoph F A Vogel
- Department of Environmental Toxicology, University of California, Davis, California 95616, USA
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Matsumura F. On the significance of the role of cellular stress response reactions in the toxic actions of dioxin. Biochem Pharmacol 2003; 66:527-40. [PMID: 12906918 DOI: 10.1016/s0006-2952(03)00157-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dioxin is known to cause many toxic effects that vary greatly in different tissues, ages, genders, and species. In this review, an attempt has been made to sort out major signaling pathways involved in the expression of the toxicities of dioxin. The major strategy adopted in analyzing its major signaling pathways is to view the toxic actions of dioxin as the result of the Ah receptor-mediated expression of a major cellular emergency stress response signal. Evidence pointing to the similarities between the symptoms of poisoning by dioxin and those produced by chronic administration of typical stressors, particularly lipopolysaccharides (LPS), bacterial endotoxins, has been assembled and analyzed. The common symptoms are wasting syndrome, atherosclerosis, fatty liver, and thymic atrophy. On the other hand, oxidative stress caused by cytochrome P450 induction is one of the typical stresses of dioxin poisoning, but not LPS poisoning. One of the major means through which dioxin triggers stress responses via "stress-activated kinase pathways" is stimulation of the cellular production of cytokines/autocrines, particularly growth factors. In the case of hepatocytes for instance, transforming growth factor-alpha plays a pivotal role in the dioxin-induced activation of the epidermal growth factor receptor and the extracellular signal-related kinase pathway, which acts as a signal to suppress apoptosis induced by cellular stress. These observations as well as additional experimental data support the idea that one of the major functions of the Ah receptor could be the elicitation of cellular stress response reactions. Another key point in understanding the toxic action of dioxin is that, unlike other cases of stressors, dioxin signaling becomes chronically sustained because of its extreme persistence in the human body, its half-life of 7-10 years, and its selective accumulation in fatty target tissues.
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Affiliation(s)
- Fumio Matsumura
- Department of Environmental Toxicology, University of California, One Shields Avenue, Davis, CA, USA.
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Elder DJE, Baker JA, Banu NA, Moorghen M, Paraskeva C. Human colorectal adenomas demonstrate a size-dependent increase in epithelial cyclooxygenase-2 expression. J Pathol 2002; 198:428-34. [PMID: 12434411 DOI: 10.1002/path.1232] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Non-steroidal anti-inflammatory drugs are chemopreventive for colorectal cancer. This effect is due in part to their ability to inhibit the inducible isoform of cyclooxygenase (COX-2). However, the cellular expression and role of COX-2 in the premalignant stages of colorectal tumourigenesis is unclear. COX-2 expression was assessed in 35 human colorectal adenomas and 38 sporadic invasive colorectal adenocarcinomas. Adenomas were classified as small (<5 mm in diameter), medium (5-10 mm), and large (>10 mm). All tissues were paraffin-embedded and formalin-fixed. COX-2 protein expression was determined using immunohistochemistry. COX-2 was detected in the epithelial cells in 35 of 38 carcinomas (92%) and in 8 of 8 (100%) lymph node metastases. All of the epithelial cells expressed COX-2 in 30 of 35 (86%) carcinomas and in 100% of the lymph node metastases. Twenty-three of 35 (66%) adenomas expressed COX-2 in the tumour epithelium. With an increase in the size of adenoma (<5 mm, 5-10 mm, >10 mm), there was an increase in (i) the proportion of adenomas with immunoreactive COX-2 in the epithelium (p = 0.036)-this was 38% in small adenomas and 82% in large adenomas; (ii) the extent of epithelial COX-2 staining within a given tumour (p = 0.003)-100% of epithelial cells were COX-2-positive in 15% of small adenomas and in 73% of large adenomas; and (iii) the intensity of epithelial COX-2 staining (p = 0.009)-strong COX-2 staining occurred in 8% of small adenomas and in 36% of large adenomas. COX-2 immunoreactivity was not detected in adjacent normal epithelium but was apparent in fibroblasts and inflammatory mononuclear cells of adjacent normal, adenoma, and carcinoma tissue. These results suggest that epithelial COX-2 activity is important for the growth and/or survival of adenomatous epithelial cells from an adenoma diameter of less than 5 mm and that there is a selective advantage for adenoma epithelial cells expressing higher levels of COX-2.
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Affiliation(s)
- Douglas J E Elder
- Department of Pathology and Microbiology, School of Medical Sciences, University of Bristol, Bristol, UK
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Lamb JG, Franklin MR. Cell-based studies reveal differences in glutathione S-transferase induction between oltipraz and tert-butylhydroquinone. J Biochem Mol Toxicol 2002; 16:154-61. [PMID: 12242683 DOI: 10.1002/jbt.10033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Selective induction of Phase II over Phase I drug-metabolizing enzymes has been proposed as a mechanism for reduction of chemical carcinogenesis. Enzymes likely to play a role in this amelioration include the glutathione S-transferases (GSTs) and among compounds that selectively induce key GSTs are tert-butylhydroquinone (tBHQ) and oltipraz [4-methyl-5-(2-pyrazinyl)-3H-1,2-dithiole-3-thione]. In vivo, and in hepatoma cells (H4IIE), these two agents induce rat GSTA2 mRNA to a similar extent. However, with a luciferase reporter construct containing 1651 bp of the proximal 5' flanking region of the rGSTA2 gene in the same cell line and under similar conditions, luciferase activity was induced to a much greater extent by tBHQ than by oltipraz. A similar large intercompound differential was seen with reporter constructs containing either the rGSTA2 ARE enhancer and HNF1 site (-872 to -582) or XRE enhancer and HNF1 site (-1110 to -812). In H4IIE cells, the rGSTA2 mRNA response to each agent was completely inhibited by 1 microM actinomycin-D cotreatment. With 1 microM cycloheximide cotreatment however, some induction by tBHQ remained, while induction by oltipraz was completely abolished. The induction response to tBHQ but not oltipraz was augmented by pretreatment with PD98059, a MEK1/2 specific inhibitor. Notwithstanding induction characteristics in common, oltipraz, and tBHQ have sufficient dissimilarities to indicate that rGSTA2 upregulation by the two agents is not identical.
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Affiliation(s)
- John G Lamb
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, USA
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Dunlap DY, Ikeda I, Nagashima H, Vogel CFA, Matsumura F. Effects of src-deficiency on the expression of in vivo toxicity of TCDD in a strain of c-src knockout mice procured through six generations of backcrossings to C57BL/6 mice. Toxicology 2002; 172:125-41. [PMID: 11882352 DOI: 10.1016/s0300-483x(02)00006-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The effect of TCDD was studied in c-src-deficient C57BL6-src(tm1sor) (N6 src -/- and -/+) mice, and their wild-type littermate mice (N6 src +/+). The former was created from the original strain of B6, 129-src(tm1sor) mice through six generations of backcrossings with C57BL6 mice. The results of a high dose TCDD toxicity tests in male mice indicated that N6 src-/+ mice were significantly less responsive to the toxic action of TCDD (115 microg/kg single i.p. injection) than N6 src+/+ mice in terms of reduced % body weight gain, the increase in the liver to body weight ratio, and the decrease in the adipose tissue to liver weight ratio and in the weight of pancreas. To understand the cause for these differential effects of TCDD we studied TCDD-induced changes in several biochemical parameters at day 10 and found that most drastically affected ones were glycogen depletion and phosphoenolpyruvate carboxykinase (PEPCK) downregulation. In addition, the degree of triglyceride accumulation in liver was less pronounced in N6-/+ than in N6+/+ mice. These findings suggest that the absence of c-src expression indeed affects the development of selected, TCDD-induced toxic endpoints that are related to wasting syndrome.
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Affiliation(s)
- Debra Y Dunlap
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
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Ziemann C, Schäfer D, Rüdell G, Kahl GF, Hirsch-Ernst KI. The cyclooxygenase system participates in functional mdr1b overexpression in primary rat hepatocyte cultures. Hepatology 2002; 35:579-88. [PMID: 11870370 DOI: 10.1053/jhep.2002.31778] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Overexpression of mdr1-type P-glycoproteins (P-gps) is thought to contribute to primary chemotherapy resistance of untreated hepatocellular carcinoma. However, mechanisms of endogenous multidrug resistance 1 (mdr1) gene activation still remain unclear. Because recent studies have demonstrated overexpression of cyclooxygenase-2 (COX-2) in hepatocytes during early stages of hepatocarcinogenesis, we investigated whether the COX system, which catalyzes the rate-limiting step in prostaglandin synthesis, participates in mdr1 gene regulation. In the present study, primary rat hepatocyte cultures, exhibiting time-dependent mdr1b overexpression, demonstrated basal COX-2 and COX-1 mRNA expression and liberation of prostaglandin E(2) (PGE(2)), indicative of an active COX-dependent arachidonic acid metabolism. PGE(2) accumulation in culture supernatants was further enhanced by arachidonic acid (1mumol/L) and epidermal growth factor (EGF) (16 nmol/L). PGE(2) and prostaglandin F(2alpha) (PGF(2)alpha) (3-6mug/mL), added directly to the culture medium, significantly up-regulated intrinsic mdr1b mRNA overexpression and mdr1-dependent transport activity. Up-regulation was maximal after 3 days of culture. Like prostaglandins, the COX substrate, arachidonic acid, also induced mdr1b gene expression. Apart from this, structurally different COX inhibitors (indomethacin, meloxicam, NS-398) mediated significant inhibition of time-dependent and EGF-induced mdr1b mRNA overexpression, resulting in enhanced intracellular accumulation of the mdr1 substrate, rhodamine 123 (Rho123). Thus, the present data support the conclusion that the release of prostaglandins through activation of the COX system participates in endogenous mdr1b gene regulation. COX-2 inhibition might constitute a new strategy to counteract primary mdr1-dependent chemotherapy resistance.
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Affiliation(s)
- Christina Ziemann
- Department of Toxicology, Institute of Pharmacology and Toxicology, University of Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany.
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