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Kim K. The Role of Endocrine Disruption Chemical-Regulated Aryl Hydrocarbon Receptor Activity in the Pathogenesis of Pancreatic Diseases and Cancer. Int J Mol Sci 2024; 25:3818. [PMID: 38612627 PMCID: PMC11012155 DOI: 10.3390/ijms25073818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
The aryl hydrocarbon receptor (AHR) serves as a ligand-activated transcription factor crucial for regulating fundamental cellular and molecular processes, such as xenobiotic metabolism, immune responses, and cancer development. Notably, a spectrum of endocrine-disrupting chemicals (EDCs) act as agonists or antagonists of AHR, leading to the dysregulation of pivotal cellular and molecular processes and endocrine system disruption. Accumulating evidence suggests a correlation between EDC exposure and the onset of diverse pancreatic diseases, including diabetes, pancreatitis, and pancreatic cancer. Despite this association, the mechanistic role of AHR as a linchpin molecule in EDC exposure-related pathogenesis of pancreatic diseases and cancer remains unexplored. This review comprehensively examines the involvement of AHR in EDC exposure-mediated regulation of pancreatic pathogenesis, emphasizing AHR as a potential therapeutic target for the pathogenesis of pancreatic diseases and cancer.
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Affiliation(s)
- Kyounghyun Kim
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas Medical Sciences, Little Rock, AR 72225, USA
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2
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Kou Z, Tran F, Dai W. Heavy metals, oxidative stress, and the role of AhR signaling. Toxicol Appl Pharmacol 2024; 482:116769. [PMID: 38007072 PMCID: PMC10988536 DOI: 10.1016/j.taap.2023.116769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/12/2023] [Accepted: 11/18/2023] [Indexed: 11/27/2023]
Abstract
The Aryl Hydrocarbon Receptor (AhR) is a ligand-activated transcriptional factor pivotal in responding to environmental stress and maintaining cellular homeostasis. Exposure to specific xenobiotics or industrial compounds in the environment activates AhR and its subsequent signaling, inducing oxidative stress and related toxicity. Past research has also identified and characterized several classes of endogenous ligands, particularly some tryptophan (Trp) metabolic/catabolic products, that act as AhR agonists, influencing a variety of physiological and pathological states, including the modulation of immune responses and cell death. Heavy metals, being non-essential elements in the human body, are generally perceived as toxic and hazardous, originating either naturally or from industrial activities. Emerging evidence indicates that heavy metals significantly influence AhR activation and its downstream signaling. This review consolidates current knowledge on the modulation of the AhR signaling pathway by heavy metals, explores the consequences of co-exposure to AhR ligands and heavy metals, and investigates the interplay between oxidative stress and AhR activation, focusing on the regulation of immune responses and ferroptosis.
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Affiliation(s)
- Ziyue Kou
- Division of Environmental Medicine, Department of Medicine, Grossman School of Medicine, New York University, 341 East 25(th) Street, New York, NY 10010, United States of America
| | - Franklin Tran
- Division of Environmental Medicine, Department of Medicine, Grossman School of Medicine, New York University, 341 East 25(th) Street, New York, NY 10010, United States of America
| | - Wei Dai
- Division of Environmental Medicine, Department of Medicine, Grossman School of Medicine, New York University, 341 East 25(th) Street, New York, NY 10010, United States of America.
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3
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El-Ghiaty MA, El-Mahrouk SR, Alqahtani MA, El-Kadi AOS. Differential modulation of cytochrome P450 enzymes by arsenicals in non-human experimental models. Drug Metab Rev 2023; 55:405-427. [PMID: 37679937 DOI: 10.1080/03602532.2023.2254525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/24/2023] [Indexed: 09/09/2023]
Abstract
Arsenic is a hazardous heavy metalloid that imposes threats to human health globally. It is widely spread throughout the environment in various forms. Arsenic-based compounds are either inorganic compounds (iAs) or organoarsenicals (oAs), where the latter are biotically generated from the former. Exposure to arsenic-based compounds results in varying biochemical derangements in living systems, leading eventually to toxic consequences. One important target for arsenic in biosystems is the network of metabolic enzymes, especially the superfamily of cytochrome P450 enzymes (CYPs) because of their prominent role in both endobiotic and xenobiotic metabolism. Therefore, the alteration of the CYPs by different arsenicals has been actively studied in the last few decades. We have previously summarized the findings of former studies investigating arsenic associated modulation of different CYPs in human experimental models. In this review, we focus on non-human models to get a complete picture about possible CYPs alterations in response to arsenic exposure.
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Affiliation(s)
- Mahmoud A El-Ghiaty
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sara R El-Mahrouk
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Mohammed A Alqahtani
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ayman O S El-Kadi
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
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El-Ghiaty MA, Alqahtani MA, El-Kadi AOS. Arsenic trioxide (ATO) up-regulates cytochrome P450 1A (CYP1A) enzymes in murine hepatoma Hepa-1c1c7 cell line. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023:104214. [PMID: 37423394 DOI: 10.1016/j.etap.2023.104214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 07/03/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Arsenic trioxide (ATO) is a highly toxic arsenical which has been successfully exploited for treating acute promyelocytic leukemia (APL). Unfortunately, its therapeutic efficacy is accompanied by serious toxicities with undeciphered mechanisms. Cytochrome P450 1A (CYP1A) enzymes undergo modulation by arsenicals, with ensuing critical consequences regarding drug clearance or procarcinogen activation. Here, we investigated the potential of ATO to alter basal and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1A1/1A2 expressions. Mouse-derived hepatoma Hepa-1c1c7 cells were exposed to 0.63, 1.25, and 2.5μM ATO with or without 1nM TCDD. ATO increased TCDD-induced CYP1A1/1A2 mRNA, protein, and activity. Constitutively, ATO induced Cyp1a1/1a2 transcripts and CYP1A2 protein. ATO increased AHR nuclear accumulation and subsequently increased XRE-luciferase reporter activity. ATO enhanced CYP1A1 mRNA and protein stabilities. In conclusion, ATO up-regulates CYP1A in Hepa-1c1c7 cells transcriptionally, post-transcriptionally, and post-translationally. Therefore, ATO can be implicated in clearance-related interactions with CYP1A1/1A2 substrates, or in excessive activation of environmental procarcinogens.
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Affiliation(s)
- Mahmoud A El-Ghiaty
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Mohammed A Alqahtani
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ayman O S El-Kadi
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada.
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5
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Hu C, Liu YX, Zhang SP, Wang YQ, Gao P, Li YT, Yang XQ. Transcription Factor AhR Regulates Glutathione S-Transferases Conferring Resistance to lambda-Cyhalothrin in Cydia pomonella. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:5230-5239. [PMID: 36943249 DOI: 10.1021/acs.jafc.3c00002] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Aryl hydrocarbon receptor (AhR) enhances insect resistance to insecticides by regulating the detoxification network. Our previous studies have confirmed that overexpressions of cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) are involved in lambda-cyhalothrin resistance in Cydia pomonella. Here, we report that CpAhR regulates the expression of GST and P450 genes, thus conferring resistance. Expression patterns indicated that the expression of CpAhR was highly induced by lambda-cyhalothrin exposure and upregulated in a lambda-cyhalothrin-resistant population. RNA interference (RNAi) of CpAhR decreases the expression of key resistance-related genes (CpGSTe3, CpCYP9A121, and CpCYP9A122) and the activity of the GST enzyme, reducing the tolerance to lambda-cyhalothrin. Furthermore, β-naphthoflavone, a novel agonist of AhR, was first proven to be effective in increasing CpAhR expression and larval tolerance to lambda-cyhalothrin. These results demonstrate that CpAhR regulates the expression of key detoxifying genes and GST activity, resulting in the development of resistance to lambda-cyhalothrin in C. pomonella.
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Affiliation(s)
- Chao Hu
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Yu-Xi Liu
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Shi-Pang Zhang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Ya-Qi Wang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Ping Gao
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Yu-Ting Li
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
| | - Xue-Qing Yang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
- Key Laboratory of Economical and Applied Entomology of Liaoning Province, Shenyang 110866, Liaoning, China
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Cap 'n' Collar C and Aryl Hydrocarbon Receptor Nuclear Translocator Facilitate the Expression of Glutathione S-Transferases Conferring Adaptation to Tannic Acid and Quercetin in Micromelalopha troglodyta (Graeser) (Lepidoptera: Notodontidae). Int J Mol Sci 2023; 24:ijms24032190. [PMID: 36768514 PMCID: PMC9916665 DOI: 10.3390/ijms24032190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
Micromelalopha troglodyta (Graeser) (Lepidoptera: Notodontidae) is a notorious pest of poplar. Coevolution with poplars rich in plant secondary metabolites prompts M. troglodyta to expand effective detoxification mechanisms against toxic plant secondary metabolites. Although glutathione S-transferases (GSTs) play an important role in xenobiotic detoxification in M. troglodyta, it is unclear how GSTs act in response to toxic secondary metabolites in poplar. In this study, five GST gene core promoters were accurately identified by a 5' loss luciferase reporter assay, and the core promoters were significantly induced by two plant secondary metabolites in vitro. Two transcription factors, cap 'n' collar C (CncC) and aryl hydrocarbon receptor nuclear translocator (ARNT), were cloned in M. troglodyta. MtCncC and MtARNT clustered well with other insect CncCs and ARNTs, respectively. In addition, MtCncC and MtARNT could bind the MtGSTt1 promoter and strongly improve transcriptional activity, respectively. However, MtCncC and MtARNT had no regulatory function on the MtGSTz1 promoter. Our findings revealed the molecular mechanisms of the transcription factors MtCncC and MtARNT in regulating the GST genes of M. troglodyta. These results provide useful information for the control of M. troglodyta.
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Wang Z. Mechanisms of the synergistic lung tumorigenic effect of arsenic and benzo(a)pyrene combined- exposure. Semin Cancer Biol 2021; 76:156-162. [PMID: 33971262 PMCID: PMC9000133 DOI: 10.1016/j.semcancer.2021.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/01/2021] [Indexed: 12/20/2022]
Abstract
Humans are often exposed to mixtures of environmental pollutants especially environmental chemical carcinogens, representing a significant environmental health issue. However, our understanding on the carcinogenic effects and mechanisms of environmental carcinogen mixture exposures is limited and mostly relies on the findings from studying individual chemical carcinogens. Both arsenic and benzo(a)pyrene (BaP) are among the most common environmental carcinogens causing lung cancer and other types of cancer in humans. Millions of people are exposed to arsenic via consuming arsenic-contaminated drinking water and even more people are exposed to BaP via cigarette smoking and consuming BaP-contaminated food. Thus arsenic and BaP combined-exposure in humans is common. Previous epidemiology studies indicated that arsenic-exposed people who were cigarette smokers had significantly higher lung cancer risk than those who were non-smokers. Since BaP is one of the major carcinogens in cigarette smoke, it has been speculated that arsenic and BaP combined-exposure may play important roles in the increased lung cancer risk observed in arsenic-exposed cigarette smokers. In this review, we summarize important findings and inconsistencies about the co-carcinogenic effects and underlying mechanisms of arsenic and BaP combined-exposure and propose new areas for future studies. A clear understanding on the mechanism of co-carcinogenic effects of arsenic and BaP combined exposure may identify novel targets to more efficiently treat and prevent lung cancer resulting from arsenic and BaP combined-exposure.
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Affiliation(s)
- Zhishan Wang
- Division of Cancer Biology, Department of Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, 44109, USA.
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8
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Phelps DW, Fletcher AA, Rodriguez-Nunez I, Balik-Meisner MR, Tokarz DA, Reif DM, Germolec DR, Yoder JA. In vivo assessment of respiratory burst inhibition by xenobiotic exposure using larval zebrafish. J Immunotoxicol 2021; 17:94-104. [PMID: 32407153 DOI: 10.1080/1547691x.2020.1748772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Currently, assessment of the potential immunotoxicity of a given agent involves a tiered approach for hazard identification and mechanistic studies, including observational studies, evaluation of immune function, and measurement of susceptibility to infectious and neoplastic diseases. These studies generally use costly low-throughput mammalian models. Zebrafish, however, offer an excellent alternative due to their rapid development, ease of maintenance, and homology to mammalian immune system function and development. Larval zebrafish also are a convenient model to study the innate immune system with no interference from the adaptive immune system. In this study, a respiratory burst assay (RBA) was utilized to measure reactive oxygen species (ROS) production after developmental xenobiotic exposure. Embryos were exposed to non-teratogenic doses of chemicals and at 96 h post-fertilization, the ability to produce ROS was measured. Using the RBA, 12 compounds with varying immune-suppressive properties were screened. Seven compounds neither suppressed nor enhanced the respiratory burst; five reproducibly suppressed global ROS production, but with varying potencies: benzo[a]pyrene, 17β-estradiol, lead acetate, methoxychlor, and phenanthrene. These five compounds have all previously been reported as immunosuppressive in mammalian innate immunity assays. To evaluate whether the suppression of ROS by these compounds was a result of decreased immune cell numbers, flow cytometry with transgenic zebrafish larvae was used to count the numbers of neutrophils and macrophages after chemical exposure. With this assay, benzo[a]pyrene was found to be the only chemical that induced a change in the number of immune cells by increasing macrophage but not neutrophil numbers. Taken together, this work demonstrates the utility of zebrafish larvae as a vertebrate model for identifying compounds that impact innate immune function at non-teratogenic levels and validates measuring ROS production and phagocyte numbers as metrics for monitoring how xenobiotic exposure alters the innate immune system.
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Affiliation(s)
- Drake W Phelps
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.,Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
| | - Ashley A Fletcher
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Ivan Rodriguez-Nunez
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | | | - Debra A Tokarz
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
| | - David M Reif
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA.,Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - Dori R Germolec
- National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Jeffrey A Yoder
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.,Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA.,Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
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9
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Wang Z, Yang P, Xie J, Lin HP, Kumagai K, Harkema J, Yang C. Arsenic and benzo[a]pyrene co-exposure acts synergistically in inducing cancer stem cell-like property and tumorigenesis by epigenetically down-regulating SOCS3 expression. ENVIRONMENT INTERNATIONAL 2020; 137:105560. [PMID: 32062438 PMCID: PMC7099608 DOI: 10.1016/j.envint.2020.105560] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 05/23/2023]
Abstract
Arsenic and benzo[a]pyrene (BaP) are among the most common environmental carcinogens causing lung cancer. Millions of people are exposed to arsenic through consuming arsenic-contaminated drinking water. High levels of BaP are found in well-done barbecued meat and other food in addition to cigarette smoke. Hence, arsenic and BaP co-exposure in humans is common. However, the combined health effect and the underlying mechanism of arsenic and BaP co-exposure have not been well-understood. In this study we investigate the combined tumorigenic effect of arsenic and BaP co-exposure and the mechanism using both cell culture and mouse models. It was found that arsenic (sodium arsenite, 1.0 µM) and BaP (2.5 µM) co-exposure for 30 weeks synergizes in inducing malignant transformation of immortalized non-tumorigenic human bronchial epithelial cells and cancer stem cell (CSC)-like property to enhance their tumorigenicity. In animal studies, A/J mice were exposed to arsenic in drinking water (sodium arsenite, 20 ppm) starting from gestation day 18. After birth, the dams continuously received arsenic water throughout lactation. At weaning (3 weeks of age), male offspring were exposed to either arsenic alone via drinking the same arsenic water or exposed to arsenic plus BaP. BaP was administered via oral gavage (3 µmol per mouse per week) once a week starting from 3 weeks of age for 8 weeks. All mice were euthanized 34-weeks after the first BaP exposure. It was found that mice in control and arsenic exposure alone group did not develop lung tumors. All mice in BaP exposure alone group developed lung adenomas. However, arsenic and BaP co-exposure synergized in increasing lung tumor multiplicity and tumor burden. Furthermore, 30% of mice in arsenic and BaP co-exposure group also developed lung adenocarcinomas. Mechanistic studies revealed that arsenic and BaP co-exposure does not produce more BPDE-DNA adducts than BaP exposure alone; but acts synergistically in activating aryl hydrocarbon receptor (AhR) to up-regulate the expression of a histone H3 lysine 9 methyltransferase SUV39H1 and increase the level of suppressive H3 lysine 9 dimethylation (H3K9me2), which down-regulates the expression of tumor suppressive SOCS3 leading to enhanced activation of Akt and Erk1/2 to promote cell transformation, CSC-like property and tumorigenesis. Together, these findings suggest that arsenic and BaP co-exposure synergizes in causing epigenetic dysregulation to enhance cell transformation, CSC-like property and tumorigenesis.
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Affiliation(s)
- Zhishan Wang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, USA.
| | - Ping Yang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, USA; School of Public Health, Guangzhou Medical University, Guangzhou, Guangdong, PR China
| | - Jie Xie
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, USA; School of Health Sciences, Wuhan University, Wuhan, Hubei, PR China
| | - Hsuan-Pei Lin
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, USA
| | - Kazuyoshi Kumagai
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Jack Harkema
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Chengfeng Yang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, USA
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Hu B, Huang H, Wei Q, Ren M, Mburu DK, Tian X, Su J. Transcription factors CncC/Maf and AhR/ARNT coordinately regulate the expression of multiple GSTs conferring resistance to chlorpyrifos and cypermethrin in Spodoptera exigua. PEST MANAGEMENT SCIENCE 2019; 75:2009-2019. [PMID: 30610747 DOI: 10.1002/ps.5316] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/18/2018] [Accepted: 12/27/2018] [Indexed: 05/21/2023]
Abstract
BACKGROUND Glutathione S-transferases (GSTs) are a superfamily of multifunctional dimeric proteins existing in both prokaryotic and eukaryotic organisms. They are involved in the detoxification of both endogenous and exogenous electrophiles, including insecticides. However, the molecular mechanisms underlying the regulation of GST genes in insects are poorly understood. RESULTS We first identified at least three GST genes involved in resistance to the insecticides chlorpyrifos and cypermethrin. Analysis of upstream sequences revealed that three GSTs (SeGSTo2, SeGSTe6 and SeGSTd3) harbor the same cap 'n' collar C/muscle aponeurosis fibromatosis (CncC/Maf) binding site, and SeGSTo2 and SeGSTe6 contain the aryl hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator (AhR/ARNT) binding site. Luciferase reporter assay showed co-transfection of reporter plasmid containing the SeGSTe6 promoter with CncC and/or Maf expressing constructs significantly boosted transcription. Similarly, AhR and/or ARNT expressing constructs also significantly increased the promoter activities. The co-transfection of mutated reporter plasmid with CncC/Maf or AhR/ARNT did not increase transcription activity anymore. Constitutive over-expression of CncC, Maf and AhR was also found in the HZ16 strain, which might be the molecular mechanism for up-regulated expression of multiple detoxification genes conferring resistance to insecticides. CONCLUSION These results suggest that CncC/Maf and AhR/ARNT coordinately regulate the expression of multiple GST genes involved in insecticide resistance in Spodoptera exigua. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Bo Hu
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - He Huang
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Qi Wei
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Miaomiao Ren
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - David K Mburu
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Xiangrui Tian
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Jianya Su
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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11
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Genotoxicity evaluation of multi-component mixtures of polyaromatic hydrocarbons (PAHs), arsenic, cadmium, and lead using flow cytometry based micronucleus test in HepG2 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 827:9-18. [DOI: 10.1016/j.mrgentox.2018.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 12/16/2017] [Accepted: 01/09/2018] [Indexed: 01/09/2023]
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12
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Zhou B, Wang X, Li F, Wang Y, Yang L, Zhen X, Tan W. Mitochondrial activity and oxidative stress functions are influenced by the activation of AhR-induced CYP1A1 overexpression in cardiomyocytes. Mol Med Rep 2017; 16:174-180. [PMID: 28498411 PMCID: PMC5482149 DOI: 10.3892/mmr.2017.6580] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 01/12/2017] [Indexed: 11/17/2022] Open
Abstract
There is an endemic cardiomyopathy currently occurring in China, termed, Keshan disease (KD). The authors previously compared mitochondrial-associated gene expression profiles of peripheral blood mononuclear cells (PBMCs) derived from KD patients and normal controls, using mitochondria-focused cDNA microarray technology. The results detected an upregulation of the enzyme-associated CYP1A1 gene, (ratios ≥2.0). The aryl hydrocarbon receptor (AhR) regulates the expression of numerous cytochrome P450 (CYP) genes including members of the CYP1 family; CYP1A1 and CYP1A2. Several previous studies have suggested roles for the aryl hydrocarbon receptor (AhR) and the genes that it regulates. An example involves cytochrome P4501A1 (CYP1A1), in the pathogenesis of heart failure, cardiac hypertrophy and other cardiomyopathies. Mitochondria comprise ~30% of the intracellular volume in mammalian cardiomyocytes, and subtle alterations in mitochondria can markedly influence cardiomyopathies. The present study investigated alterations in the activity and functions of mitochondria following AhR-induced overexpression of CYP1A1. AC16 cells were treated with the CYP1A1 inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and cytotoxicity was then evaluated in MTT assays. Reverse transcription-quantitative polymerase chain reactions, western blot analysis and 7-ethoxyresorufin O-deacylase assays were performed to analyze the mRNA and protein levels, and the enzymatic activity of CYP1A1. Mitochondrial activity and mass were analyzed using an inverted fluorescence microscope and a fluorescence microplate reader. Reactive oxygen species (ROS) activity was analyzed using flow cytometry. The results of the current study demonstrated that TCDD gradually increased mRNA and protein levels of AhR and CYP1A1, in addition to the enzymatic activity. Mitochondrial activity and the quality of mitochondrial membranes were also significantly attenuated, and mitochondrial ROS levels were elevated in the TCDD-induced cardiomyocytes. The results indicate the involvement of the AhR/CYP1A1 signaling pathway in the mechanism of action of TCDD in human cardiomyocytes. The present findings may provide an explanation for myocardial injuries caused by polycyclic aromatic hydrocarbons. The authors conclude that exposure to TCDD results in regulatory alteration to the expression of detoxification genes that ultimately affect the metabolic activation and function of cardiomyocytes.
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Affiliation(s)
- Bing Zhou
- Key Laboratory of Trace Elements and Endemic Diseases, Xi'an Jiaotong University, Ministry of Health, Xi'an, Shaanxi 710061, P.R. China
| | - Xi Wang
- Key Laboratory of Trace Elements and Endemic Diseases, Xi'an Jiaotong University, Ministry of Health, Xi'an, Shaanxi 710061, P.R. China
| | - Feng Li
- Department of Orthopaedics, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yingting Wang
- Key Laboratory of Trace Elements and Endemic Diseases, Xi'an Jiaotong University, Ministry of Health, Xi'an, Shaanxi 710061, P.R. China
| | - Lei Yang
- Key Laboratory of Trace Elements and Endemic Diseases, Xi'an Jiaotong University, Ministry of Health, Xi'an, Shaanxi 710061, P.R. China
| | - Xiaolong Zhen
- Department of Otolaryngology, Wuqing People's Hospital of Tianjin, Tianjin 301700, P.R. China
| | - Wuhong Tan
- Key Laboratory of Trace Elements and Endemic Diseases, Xi'an Jiaotong University, Ministry of Health, Xi'an, Shaanxi 710061, P.R. China
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13
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Elshenawy OH, Abdelhamid G, Soshilov AA, Denison MS, El-Kadi AO. Down-regulation of cytochrome P450 1A1 by monomethylarsonous acid in human HepG2 cells. Toxicol Lett 2017; 270:34-50. [DOI: 10.1016/j.toxlet.2017.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/30/2017] [Accepted: 02/07/2017] [Indexed: 01/04/2023]
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14
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Chen YY, Chan KM. Differential effects of metal ions on TCDD-induced cytotoxicity and cytochrome P4501A1 gene expression in a zebrafish liver (ZFL) cell-line. Metallomics 2016; 8:236-51. [PMID: 26612010 DOI: 10.1039/c5mt00219b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Trace metal ions and trace organic compounds are common co-contaminants in the environment that pose risks to human health. We evaluated the effects of four metal ions (As(3+), Cu(2+), Hg(2+), and Zn(2+)) on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced cytotoxicity and the expression of the cytochrome P4501A1 gene (cyp1a1) in the zebrafish liver (ZFL) cell line. A metal accumulation study showed that Cu and Zn did not accumulate in ZFL cells. However, As and Hg did accumulate, which resulted in the inhibition of TCDD-mediated induction of cyp1a1 mRNA and protein expression, and 7-ethoxyresorufin O-deethylase activity. A luciferase assay showed that both As(3+) and Hg(2+) inhibited the TCDD-induced activity of gene constructs containing either synthetic 3XRE or a distal cyp1a1 promoter region, implying that the decreased levels of TCDD-induced cyp1a1 were due to transcriptional effects. A proteomic study showed that the toxic effects of As(3+) might be due to changes in cellular metabolic processes, the cellular stimulation response and the cellular redox state in ZFL cells.
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Affiliation(s)
- Ying Ying Chen
- School of Life Sciences, Chinese University, Sha Tin, Hong Kong SAR, China.
| | - King Ming Chan
- School of Life Sciences, Chinese University, Sha Tin, Hong Kong SAR, China.
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15
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Mohammadi-Bardbori A, Vikström Bergander L, Rannug U, Rannug A. NADPH Oxidase-Dependent Mechanism Explains How Arsenic and Other Oxidants Can Activate Aryl Hydrocarbon Receptor Signaling. Chem Res Toxicol 2015; 28:2278-86. [PMID: 26535918 DOI: 10.1021/acs.chemrestox.5b00415] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mechanisms explaining arsenic toxicity are not well understood, but physiological consequences of stimulated aryl hydrocarbon receptor (AHR) signaling both directly and through cross-talk with other pathways have been indicated. The aim of this study was to establish how arsenic interacts with AHR-mediated transcription. The human hepatoma cell line (HepG2-XRE-Luc) carrying a luciferase reporter under the control of two AHR response elements (AHREs) and immortalized human keratinocytes (HaCaT) were exposed to sodium arsenite (NaAsO2; As(3+)), alone or in combination with the endogenous high affinity AHR ligand 6-formylindolo[3,2-b]carbazole (FICZ). Luciferase activity, cytochrome P4501A1 (CYP1A1) activity, oxidative stress-related responses, metabolic clearance of FICZ, and NADPH oxidase (NOX) activity as well as nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent gene expression were measured. Arsenic inhibited CYP1A1 enzyme activity and reduced the metabolic clearance of FICZ. Arsenic also led to activated CYP1A1 transcription but only in cells grown in medium containing trace amounts of the endogenous ligand FICZ, pointing to an indirect mechanism of activation. Initially, arsenic caused dose-dependent inhibition of FICZ-activated AHR signaling, disturbed intracellular GSH status, and increased expression of oxidative stress-related genes. Silencing of NOX4, addition of N-acetylcystein, or pretreatment with arsenic itself attenuated the initial dose-dependent inhibition of AHR signaling. Arsenic pretreatment led to elevated GSH levels and sensitized the cells to ligand-dependent AHR signaling, while silencing of Nrf2 significantly reduced arsenic-mediated activation of the AHR. In addition, influence of NOX on AHR activation was also observed in cells treated with the SH-reactive metals cadmium, mercury, and nickel. Together, the results suggest that SH-reactive agents via a new and possibly general NOX/H2O2-dependent mechanism can interfere with the endogenous regulation of the AHR.
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Affiliation(s)
- Afshin Mohammadi-Bardbori
- Institute of Environmental Medicine, Karolinska Institutet , SE-171 77 Stockholm, Sweden.,Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences , Shiraz, Fars 71345-1583, Iran
| | | | - Ulf Rannug
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University , SE-106 91 Stockholm, Sweden
| | - Agneta Rannug
- Institute of Environmental Medicine, Karolinska Institutet , SE-171 77 Stockholm, Sweden
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16
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Esser C, Rannug A. The aryl hydrocarbon receptor in barrier organ physiology, immunology, and toxicology. Pharmacol Rev 2015; 67:259-79. [PMID: 25657351 DOI: 10.1124/pr.114.009001] [Citation(s) in RCA: 351] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The aryl hydrocarbon receptor (AhR) is an evolutionarily old transcription factor belonging to the Per-ARNT-Sim-basic helix-loop-helix protein family. AhR translocates into the nucleus upon binding of various small molecules into the pocket of its single-ligand binding domain. AhR binding to both xenobiotic and endogenous ligands results in highly cell-specific transcriptome changes and in changes in cellular functions. We discuss here the role of AhR for immune cells of the barrier organs: skin, gut, and lung. Both adaptive and innate immune cells require AhR signaling at critical checkpoints. We also discuss the current two prevailing views-namely, 1) AhR as a promiscuous sensor for small chemicals and 2) a role for AhR as a balancing factor for cell differentiation and function, which is controlled by levels of endogenous high-affinity ligands. AhR signaling is considered a promising drug and preventive target, particularly for cancer, inflammatory, and autoimmune diseases. Therefore, understanding its biology is of great importance.
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Affiliation(s)
- Charlotte Esser
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.)
| | - Agneta Rannug
- Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.)
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17
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Du J, Liao C, Zhou H, Diao X, Li Y, Zheng P, Wang F. Gene cloning and expression analysis of AhR and CYP4 from Pinctada martensii after exposed to pyrene. ECOTOXICOLOGY (LONDON, ENGLAND) 2015; 24:1574-1582. [PMID: 25666496 DOI: 10.1007/s10646-015-1424-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
Pyrene, a typical polycyclic aromatic hydrocarbon, is a common pollutant in the marine environment. Polycyclic aromatic hydrocarbons initiate cellular detoxification in an exposed organism via the activation of the aryl hydrocarbon receptor (AhR). Subsequent metabolism of these xenobiotics is mainly by the cytochrome P450 enzymes of the phase I detoxification system. Full-length complementary DNA sequences from the pearl oyster Pinctada martensii (pm) encoding AhR and cytochrome P4 were cloned. The P. martensii AhR complementary DNA sequence constitutes an open reading frame that encodes for 848 amino acids. Sequence analysis indicated PmAhR showed high similarity with its homologues of other bivalve species. The cytochrome P(CYP)4 complementary DNA sequence of P. martensii constitutes an open reading frame that encodes for 489 amino acids. Quantitative real-time analysis detected both PmAhR and PmCYP4 messenger RNA expressions in the mantle, gill, hepatapancreas and adductor muscle of P. martensii exposed to pyrene. The highest transcript-band intensities of PmAhR and PmCYP4 were observed in the gill. Temporal expression of PmAhR and PmCYP4 messenger RNAs induction was observed in gills and increased between 3 and 5 days post exposure; then returned to control level. These results suggest that messenger RNAs of PmAhR and PmCYP4 in pearl oysters might be useful parameters for monitoring marine environment pyrene pollution.
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Affiliation(s)
- Junqiao Du
- College of Environment and Plant Protection, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Hainan University, Haikou, 570228, China
| | - Chenghong Liao
- College of Agriculture, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
| | - Hailong Zhou
- College of Agriculture, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
| | - Xiaoping Diao
- College of Agriculture, Hainan University, Haikou, 570228, China.
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China.
| | - Yuhu Li
- College of Agriculture, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
| | - Pengfei Zheng
- College of Agriculture, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
| | - Fuqiang Wang
- College of Environment and Plant Protection, Hainan University, Haikou, 570228, China
- Haikou Key Laboratory of Environment Toxicology, Hainan University, Haikou, 570228, China
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Modulation of aryl hydrocarbon receptor-regulated enzymes by trimethylarsine oxide in C57BL/6 mice: In vivo and in vitro studies. Toxicol Lett 2015; 238:17-31. [PMID: 26144063 DOI: 10.1016/j.toxlet.2015.06.1646] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 06/19/2015] [Accepted: 06/28/2015] [Indexed: 01/10/2023]
Abstract
Arsenic is a worldwide environmental pollutant that is associated with skin and several types of internal cancers. Recent reports revealed that arsenic biomethylation could activate the toxic and carcinogenic potential of arsenic. Therefore, we investigated the effect of trimethylarsine oxide (TMAO) on the activation of AhR-regulated genes in vivo and in vitro. In vivo, C57BL/6 mice received TMAO (13mg/kg i.p.) with or without the prototypical AhR ligand, TCDD (15μg/kg), then the livers were harvested at 6 and 24h post-treatment. In vitro, isolated hepatocytes from C57BL/6 mice were treated with TMAO (5μM) in the absence and presence of TCDD (1nM) for 6 and 24h. Our in vivo results demonstrated that, TMAO alone increased Cyp1a1, Cyp1a2, Cyp1b1, Nqo1, Gsta1, and Ho-1 at mRNA level. Upon co-exposure to TMAO and TCDD, TMAO potentiated the TCDD-mediated induction of Cyp1a1, Cyp1b1, and Nqo1 mRNA levels. Western blotting revealed that, TMAO alone increased Cyp1a1, Cyp1a2, Nqo1, Gsta1/2, and Ho-1 protein levels, and potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1b1 protein level. In addition, TMAO alone significantly increased Cyp1a1, Cyp1a2, Nqo1, Gst, and Ho-1 activities and significantly potentiated the TCDD-mediated induction of Cyp1a1 activity. At the in vitro level, TMAO induced Cyp1a1 and potentiated the TCDD-mediated induction of Cyp1a1 at mRNA, protein and activity levels. In addition, TMAO increased the nuclear localization of AhR and AhR-dependent XRE-driven luciferase activity. Our results demonstrate that the TMAO, modulates AhR-regulated genes which could potentially participate, at least in part, in arsenic induced toxicity and carcinogenicity.
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19
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Elshenawy OH, El-Kadi AOS. Modulation of aryl hydrocarbon receptor regulated genes by acute administration of trimethylarsine oxide in the lung, kidney and heart of C57BL/6 mice. Xenobiotica 2015; 45:930-43. [DOI: 10.3109/00498254.2015.1032385] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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20
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Cai Y, Pan L, Hu F, Jin Q, Liu T. Deep sequencing-based transcriptome profiling analysis of Chlamys farreri exposed to benzo[a]pyrene. Gene 2014; 551:261-70. [DOI: 10.1016/j.gene.2014.09.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/11/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
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21
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Gauthier PT, Norwood WP, Prepas EE, Pyle GG. Metal-PAH mixtures in the aquatic environment: a review of co-toxic mechanisms leading to more-than-additive outcomes. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 154:253-69. [PMID: 24929353 DOI: 10.1016/j.aquatox.2014.05.026] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 05/10/2023]
Abstract
Mixtures of metals and polycyclic aromatic hydrocarbons (PAHs) occur ubiquitously in aquatic environments, yet relatively little is known regarding their combined toxicities. Emerging reports investigating the additive mortality in metal-PAH mixtures have indicated that more-than-additive effects are equally as common as strictly-additive effects, raising concern for ecological risk assessment typically based on the summation of individual toxicities. Moreover, the current separation of focus between in vivo and in vitro studies, and fine- and coarse-scale endpoints, creates uncertainty regarding the mechanisms of co-toxicity involved in more-than-additive effects on whole organisms. Drawing from literature on metal and PAH toxicity in bacteria, protozoa, invertebrates, fish, and mammalian models, this review outlines several key mechanistic interactions likely to promote more-than-additive toxicity in metal-PAH mixtures. Namely, the deleterious effects of PAHs on membrane integrity and permeability to metals, the potential for metal-PAH complexation, the inhibitory nature of metals to the detoxification of PAHs via the cytochrome P450 pathway, the inhibitory nature of PAHs towards the detoxification of metals via metallothionein, and the potentiated production of reactive oxygenated species (ROS) in certain metal (e.g. Cu) and PAH (e.g., phenanthrenequinone) mixtures. Moreover, the mutual inhibition of detoxification suggests the possibility of positive feedback among these mechanisms. The individual toxicities and interactive aspects of contaminant transport, detoxification, and the production of ROS are herein discussed.
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Affiliation(s)
- Patrick T Gauthier
- Faculty of Natural Resources Management, Lakehead University, Thunder Bay, ON, Canada P7B 5E1.
| | - Warren P Norwood
- Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6
| | - Ellie E Prepas
- Faculty of Natural Resources Management, Lakehead University, Thunder Bay, ON, Canada P7B 5E1
| | - Greg G Pyle
- Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4
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22
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Banerjee M, Carew MW, Roggenbeck BA, Whitlock BD, Naranmandura H, Le XC, Leslie EM. A Novel Pathway for Arsenic Elimination: Human Multidrug Resistance Protein 4 (MRP4/ABCC4) Mediates Cellular Export of Dimethylarsinic Acid (DMAV) and the Diglutathione Conjugate of Monomethylarsonous Acid (MMAIII). Mol Pharmacol 2014; 86:168-79. [DOI: 10.1124/mol.113.091314] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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23
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Wang BJ, Liao YF, Tung YT, Yih LH, Hu CC, Lee H. Establishment of a bioluminescence-based bioassay for the detection of dioxin-like compounds. Toxicol Mech Methods 2013. [DOI: 10.3109/15376516.2012.745105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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24
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Chung CJ, Huang CY, Pu YS, Shiue HS, Su CT, Hsueh YM. The effect of cigarette smoke and arsenic exposure on urothelial carcinoma risk is modified by glutathione S-transferase M1 gene null genotype. Toxicol Appl Pharmacol 2013; 266:254-9. [DOI: 10.1016/j.taap.2012.11.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/16/2012] [Accepted: 11/06/2012] [Indexed: 01/07/2023]
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25
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Ayed-Boussema I, Pascussi JM, Rjiba K, Maurel P, Bacha H, Hassen W. The mycotoxin, patulin, increases the expression of PXR and AhR and their target cytochrome P450s in primary cultured human hepatocytes. Drug Chem Toxicol 2011; 35:241-50. [PMID: 21939362 DOI: 10.3109/01480545.2011.592194] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The mycotoxin, patulin (PAT), which is frequently found in apples, grapes, oranges, pear, peaches, and in apple juices, has previously been shown to be cytotoxic, genotoxic, and mutagenic. In this study, we have investigated the effect of PAT on mRNA level of pregnane X receptor (PXR), constitutive androstane receptor (CAR), aryl hydrocarbon receptor (AhR), and their corresponding target cytochrome P450s. Using primary cultures of adult human hepatocytes, we evaluated PAT cytotoxicity on hepatocytes after 24 hours of treatment. Real time reverse-transcriptase polymerase chain reaction procedure was employed to determine the effect of PAT on receptors (PXR, CAR, and AhR) and cytochrome (CYP3A4, 2B6, 3A5, 2C9, 1A1, and 1A2) genes. Our results showed that PAT reduced hepatocyte viability. At a noncytotoxic range of PAT concentrations, PAT induced an upregulation of the PXR gene in the three treated hepatocytes cultures, whereas CAR was overexpressed in only 1 treated liver. PXR gene induction was accompanied by the enhancement of CYP2B6, 3A5, 2C9, and 3A4 expression. PAT was also found to induce an overexpression of AhR and CYP1A1 and CYP1A2 mRNA expression. These findings suggested that PAT may activate PXR and/or CAR and AhR. However, further investigations are needed to confirm nuclear receptor activation by PAT and to elucidate the molecular mechanism of PAT action.
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Affiliation(s)
- Imen Ayed-Boussema
- Laboratory of Research on Biologically Compatible Compounds, Faculty of Dentistry, Monastir, Tunisia
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26
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Shen M, Bunaciu RP, Congleton J, Jensen HA, Sayam LG, Varner JD, Yen A. Interferon regulatory factor-1 binds c-Cbl, enhances mitogen activated protein kinase signaling and promotes retinoic acid-induced differentiation of HL-60 human myelo-monoblastic leukemia cells. Leuk Lymphoma 2011; 52:2372-9. [PMID: 21740303 DOI: 10.3109/10428194.2011.603449] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
All-trans retinoic acid (RA) and interferons (IFNs) have efficacy in treating certain leukemias and lymphomas, respectively, motivating interest in their mechanism of action to improve therapy. Both RA and IFNs induce interferon regulatory factor-1 (IRF-1). We find that in HL-60 myeloblastic leukemia cells which undergo mitogen activated protien kinase (MAPK)-dependent myeloid differentiation in response to RA, IRF-1 propels differentiation. RA induces MAPK-dependent expression of IRF-1. IRF-1 binds c-Cbl, a MAPK related adaptor. Ectopic IRF-1 expression causes CD38 expression and activation of the Raf/MEK/ERK axis, and enhances RA-induced differentiation by augmenting CD38, CD11b, respiratory burst and G0 arrest. Ectopic IRF-1 expression also decreases the activity of aldehyde dehydrogenase 1, a stem cell marker, and enhances RA-induced ALDH1 down-regulation. Interestingly, expression of aryl hydrocarbon receptor (AhR), which is RA-induced and known to down-regulate Oct4 and drive RA-induced differentiation, also enhances IRF-1 expression. The data are consistent with a model whereby IRF-1 acts downstream of RA and AhR to enhance Raf/MEK/ERK activation and propel differentiation.
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Affiliation(s)
- Miaoqing Shen
- Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA
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27
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Lin X, Yang H, Zhou L, Guo Z. Nrf2-dependent induction of NQO1 in mouse aortic endothelial cells overexpressing catalase. Free Radic Biol Med 2011; 51:97-106. [PMID: 21569840 PMCID: PMC3109219 DOI: 10.1016/j.freeradbiomed.2011.04.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/28/2011] [Accepted: 04/11/2011] [Indexed: 11/17/2022]
Abstract
Overexpression of catalase has been shown to accelerate benzo(a)pyrene (BaP) detoxification in mouse aortic endothelial cells (MAECs). NAD(P)H:quinone oxidoreductase-1 (NQO1) is an enzyme that catalyzes BaP-quinone detoxification. Aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor-2 (Nrf2) are transcription factors that control NQO1 expression. Here, we investigated the effects of catalase overexpression on NQO1, Nrf2, and AhR expression. The levels of NQO1 mRNA and protein were comparable in MAECs isolated from wild-type and transgenic mice that overexpress human catalase (hCatTg). BaP treatment increased NQO1 mRNA and protein levels in both groups, with a significantly greater induction in hCatTg MAECs than in wild-type cells. BaP-induced NQO1 promoter activity was dramatically higher in hCatTg MAECs than in wild-type cells. Our data also showed that the basal level of AhR and the BaP-induced level of Nrf2 were significantly higher in hCatTg MAECs than in wild-type cells. Inhibition of specificity protein-1 (Sp1) binding to the AhR promoter region by mithramycin A reversed the enhancing effect of catalase overexpression on AhR expression. Knockdown of AhR by RNA interference diminished BaP-induced expression of Nrf2 and NQO1. Knockdown of Nrf2 significantly decreased NQO1 mRNA and protein levels in cells with or without BaP treatment. NQO1 promoter activity was abrogated by mutation of the Nrf2-binding site in this promoter. In contrast, mutation of the AhR-binding site in the NQO1 promoter did not affect the promoter activity. These results suggest that catalase overexpression upregulates BaP-induced NQO1 expression by enhancing the Sp1-AhR-Nrf2 signaling cascade.
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Affiliation(s)
| | | | | | - ZhongMao Guo
- Correspondence author: Department of Physiology Meharry Medical College Nashville, TN 37208 Phone: (615) 327-6804 Fax: (615) 321-2949
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28
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Fragou D, Fragou A, Kouidou S, Njau S, Kovatsi L. Epigenetic mechanisms in metal toxicity. Toxicol Mech Methods 2011; 21:343-52. [DOI: 10.3109/15376516.2011.557878] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Liu N, Pan L, Miao J, Xu C, Zhang L. Molecular cloning and sequence analysis and the response of a aryl hydrocarbon receptor homologue gene in the clam Ruditapes philippinarum exposed to benzo(a)pyrene. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:279-87. [PMID: 20624694 DOI: 10.1016/j.cbpc.2010.05.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 05/12/2010] [Accepted: 05/13/2010] [Indexed: 11/25/2022]
Abstract
The aryl hydrocarbon receptor (AhR) is a member of the basic helix-loop-helix/Per-Arnt-Sim (bHLH/PAS) family of transcription factors. In the present study, a cDNA encoding an AhR homologue was initially cloned and sequenced from the clam, Ruditapes philippinarum. The predicted amino acid sequences contain regions characteristic of AhRs from other species including basic helix-loop-helix (bHLH) and Per-ARNT-Sim (PAS) domains, but it does not contain distinct Q-rich domain as found in the mammalian AhRs. The clam AhR homologue cDNA coded for a 765 amino acids protein and phylogenetic analysis demonstrated that it was clustered within the invertebrate AhRs branch. The clam AhR homologue mRNA expression was detected in all the adult tissues tested (gill, digestive gland, adductor muscle and mantle) and highest transcription level were observed in gill compared to other tissues. Quantitative real-time RT-PCR analysis revealed that the clam AhR homologue mRNA expression levels in gill and digestive gland of R. philippinarum were induced by benzo(a)pyrene (BaP) and the absolute expression levels of the gene showed temporal and dose-dependent response.
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Affiliation(s)
- Na Liu
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, PR China
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30
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Thompson ED, Burwinkel KE, Chava AK, Notch EG, Mayer GD. Activity of Phase I and Phase II enzymes of the benzo[a]pyrene transformation pathway in zebrafish (Danio rerio) following waterborne exposure to arsenite. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:371-8. [PMID: 20547244 DOI: 10.1016/j.cbpc.2010.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/07/2010] [Accepted: 06/08/2010] [Indexed: 12/15/2022]
Abstract
The environmental pollutants inorganic arsenic (iAs) and benzo[a]pyrene (B[a]P) are carcinogens often found together in groundwater. The hepatic metabolism of B[a]P is a multi-step process requiring several Phase I and Phase II enzymes, notably cytochrome p450 1A (CYP1A), epoxide hydrolase (EH), and glutathione S-transferase (GST). The purpose of this study was to examine the effect of arsenite (As(III)) on the activity of these enzymes in vivo utilizing adult zebrafish (Danio rerio). Zebrafish were exposed to either 0.4 microM B[a]P, 0.4 microM B[a]P+0.4 microM As(III), 0.4 microM B[a]P+8 microM As(III), 0.4 microM As(III), or 8 microM As(III) for 7 days. Co-exposures to As(III) and B[a]P led to significant decreases in CYP1A enzyme activity (approximately 3-fold) when compared to exposure to B[a]P alone. No similar effects occurred with EH or GST, although B[a]P exposure did significantly increase EH activity. Furthermore As(III) and B[a]P co-exposures significantly decreased CYP1A transcript levels (up to 35-fold) when compared to B[a]P. However, B[a]P-induced CYP1A protein levels remained elevated following co-exposures to As(III). This evidence suggests that As(III) has the potential to modify components of the B[a]P biotransformation pathway in vivo via a disruption of CYP1A activity by way of both pre- and post-translational mechanisms.
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Affiliation(s)
- E David Thompson
- Department of Biological Sciences, 204D Natural Science Center, Northern Kentucky University, Highland Heights, KY 41099, USA.
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31
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Abstract
Arsenic is a nonmutagenic human carcinogen that induces tumors through unknown mechanisms. A growing body of evidence suggests that its carcinogenicity results from epigenetic changes, particularly in DNA methylation. Changes in gene methylation status, mediated by arsenic, have been proposed to activate oncogene expression or silence tumor suppressor genes, leading to long-term changes in the activity of genes controlling cell transformation. Mostly descriptive, and often contradictory, studies have demonstrated that arsenic exposure is associated with both hypo- and hyper-methylation at various genetic loci in vivo or in vitro. This ambiguity has made it difficult to assess whether the changes induced by arsenic are causally involved in the transformation process or are simply a reflection of the altered physiology of rapidly dividing cancer cells. Here, we discuss the evidence supporting changes in DNA methylation as a cause of arsenic carcinogenesis and highlight the strengths and limitations of these studies, as well as areas where consistencies and inconsistencies exist.
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Affiliation(s)
- John F Reichard
- Department of Environmental Health & Center for Environmental Genetics, University of Cincinnati College of Medicine, 3223 Eden Avenue, Cincinnati, OH 45267-0056, USA.
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Hu Q, Li L, Wang Y, Zhao W, Qi H, Zhuang G. Construction of WCB-11: a novel phiYFP arsenic-resistant whole-cell biosensor. J Environ Sci (China) 2010; 22:1469-1474. [PMID: 21174981 DOI: 10.1016/s1001-0742(09)60277-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The prediction and assessment of environmental pollution by arsenic are important preconditions of advocating environmental protection and human health risk assessment. A yellow fluorescent protein-based whole-cell biosensor for the detection of arsenite and arsenate was constructed and tested. An arsenic-resistant promoter and the regulatory gene arsR were obtained by PCR from the genome of Escherichia coli DH5alpha, and phiYFP was introduced into E. coli DH5alpha as a reporter gene to construct an arsenic-resistant whole-cell biosensor (WCB-11) in which phiYFP was expressed well for the first time. Experimental results demonstrated that the biosensor has a good response to arsenic and the expression of phiYFP. When strain WCB-11 was exposed to As3+ and As5+, the expression of yellow fluorescence was time-dependent and dose-dependent. This engineered construct is expected to become established as an inexpensive and convenient method for the detection of arsenic in the field.
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Affiliation(s)
- Qing Hu
- Department of Environmental Bio-Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Chen Y, Johansson E, Fan Y, Shertzer HG, Vasiliou V, Nebert DW, Dalton TP. Early onset senescence occurs when fibroblasts lack the glutamate-cysteine ligase modifier subunit. Free Radic Biol Med 2009; 47:410-8. [PMID: 19427898 PMCID: PMC2773044 DOI: 10.1016/j.freeradbiomed.2009.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 05/05/2009] [Accepted: 05/05/2009] [Indexed: 12/23/2022]
Abstract
Cellular senescence is the irreversible entry of cells into growth arrest. Senescence of primary cells in culture has long been used as an in vitro model for aging. Glutamate-cysteine ligase (GCL) controls the synthetic rate of the important cellular antioxidant glutathione (GSH). The catalytic subunit of GCL, GCLC, is catalytically active and essential for life. By contrast the modifier subunit of GCL, GCLM, is dispensable in mice. Although it is recognized that GCLM increases the rate of GSH synthesis, its physiological role is unclear. Herein, we show that loss of Gclm leads to premature senescence of primary murine fibroblasts as characterized by: (a) diminished growth rate, (b) cell morphology consistent with senescence, (c) increases in senescence-associated beta-galactosidase activity, and (d) cell cycle arrest at the G(1)/S and G(2)/M boundaries. These changes are accompanied by increased intracellular ROS, accumulation of DNA damage, and induction of p53 and p21 proteins. We also found that N-acetylcysteine increases intracellular GSH and prevents premature senescence in Gclm(-/-) cells. These results suggest that the control of GCLM, which in turn controls aspects of the cellular redox environment via GSH, is important in determining the replicative capacity of the cell.
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Affiliation(s)
- Ying Chen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, OH 45267-0056, USA.
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34
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Anwar-Mohamed A, Elbekai RH, El-Kadi AOS. Regulation of CYP1A1 by heavy metals and consequences for drug metabolism. Expert Opin Drug Metab Toxicol 2009; 5:501-21. [DOI: 10.1517/17425250902918302] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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35
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Wu JP, Chang LW, Yao HT, Chang H, Tsai HT, Tsai MH, Yeh TK, Lin P. Involvement of Oxidative Stress and Activation of Aryl Hydrocarbon Receptor in Elevation of CYP1A1 Expression and Activity in Lung Cells and Tissues by Arsenic: An In Vitro and In Vivo Study. Toxicol Sci 2008; 107:385-93. [DOI: 10.1093/toxsci/kfn239] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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36
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Abstract
Trace metals and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental co-contaminants and the trace metals could influence the carcinogenicity of the PAHs by altering their extent of induction of cytochromes P4501A1, 1A2, and 1B1 (CYP). Studies in cell lines from humans, rodents, chickens, and fish, and in cell culture generally indicate that trace metals diminish the inductive potency of PAHs for these CYPs. The extent of the effect is species-, metal-, PAH-, and metal dose-dependent. Both transcriptional and post-translational mechanisms are involved in the trace metal-mediated down regulation of the CYP1 forms. The latter mechanism incorporates induction of heme oxygenase-1 by the metals, with resultant heme catabolism. Thus, trace metals could diminish the carcinogenicity of PAHs.
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Affiliation(s)
- Laurence Kaminsky
- Wadsworth Center, New York State Department of Health, Albany, 12201, USA.
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37
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Staal YCM, Pushparajah DS, van Herwijnen MHM, Gottschalk RWH, Maas LM, Ioannides C, van Schooten FJ, van Delft JHM. Interactions between polycyclic aromatic hydrocarbons in binary mixtures: effects on gene expression and DNA adduct formation in precision-cut rat liver slices. Mutagenesis 2008; 23:491-9. [PMID: 18711122 DOI: 10.1093/mutage/gen041] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although exposure to polycyclic aromatic hydrocarbons (PAHs) occurs mostly through mixtures, hazard and risk assessment are mostly based on the effects caused by individual compounds. The objective of the current study was to investigate whether interactions between PAHs occur, focusing on gene expression (as measured by cDNA microarrays) and DNA adduct formation. The effects of benzo[a]pyrene or dibenzo[a,h]anthracene (DB[a,h]A) alone and in binary mixtures with another PAH (DB[a,h]A, benzo[b]fluoranthene, fluoranthene or dibenzo[a,l]pyrene) were investigated using precision-cut rat liver slices. All compounds significantly modulated the expression of several genes, but overlap between genes affected by the mixture and by the individual compounds was relatively small. All mixtures showed an antagonistic response on total gene expression profiles. Moreover, at the level of individual genes, mostly antagonism was evident, with additivity and synergism observed for only a few genes. As far as DNA adduct formation is concerned, the binary mixtures generally caused antagonism. The effects in liver slices suggest a lower carcinogenic potency of PAH mixtures than estimated based on additivity of individual compounds.
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Affiliation(s)
- Yvonne C M Staal
- Department of Health Risk Analysis and Toxicology, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands
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38
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Folate deficiency enhances arsenic effects on expression of genes involved in epidermal differentiation in transgenic K6/ODC mouse skin. Toxicology 2007; 241:134-45. [DOI: 10.1016/j.tox.2007.08.094] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 08/23/2007] [Accepted: 08/27/2007] [Indexed: 11/24/2022]
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39
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Korashy HM, Brocks DR, El-Kadi AOS. Induction of the NAD(P)H:quinone oxidoreductase 1 by ketoconazole and itraconazole: a mechanism of cancer chemoprotection. Cancer Lett 2007; 258:135-43. [PMID: 17923278 DOI: 10.1016/j.canlet.2007.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 08/25/2007] [Accepted: 08/31/2007] [Indexed: 01/17/2023]
Abstract
Studies in many carcinogen-induced animal models and cell lines demonstrated that azole antifungal drugs are therapeutically effective against different types of cancer. Yet, the molecular mechanisms involved are still poorly understood. Therefore, we examined the ability of three structurally different antifungal drugs, ketoconazole (KTZ), itraconazole (ITZ), and fluconazole (FLZ) to induce the expression of NAD(P)H:quinone oxidoreductase 1 (Nqo1), an enzyme known to play an important role in xenobiotic and carcinogen detoxifications. We showed that KTZ and ITZ, but not FLZ, induced Nqo1 mRNA and enzymatic activity levels in a concentration- and time-dependent manner in wild-type but not aryl hydrocarbon receptor (AhR)-deficient Hepa 1c1c7 cells. Furthermore, KTZ and ITZ increased Nqo1 de novo RNA synthesis without significantly affecting the levels of existing RNA, suggesting a transcriptional mechanism is involved. This study provides the first evidence for the ability of KTZ and ITZ to induce the Nqo1 gene expression through an AhR-dependent mechanism.
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Affiliation(s)
- Hesham M Korashy
- Faculty of Pharmacy and Pharmaceutical Sciences, 3126 Dentistry/Pharmacy Centre, University of Alberta, Edmonton, Alberta, Canada
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40
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Korashy HM, El-Kadi AOS. Modulation of TCDD-mediated induction of cytochrome P450 1A1 by mercury, lead, and copper in human HepG2 cell line. Toxicol In Vitro 2007; 22:154-8. [PMID: 17889500 DOI: 10.1016/j.tiv.2007.08.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 08/01/2007] [Accepted: 08/02/2007] [Indexed: 11/20/2022]
Abstract
Co-contamination with complex mixtures of heavy metals and polycyclic aromatic hydrocarbons (PAHs) is a common environmental problem with multiple biological consequences. In this study, we tested in human hepatoma HepG2 cells the potential effects of three prominent environmental heavy metals, mercury (Hg(2+)), lead (Pb(2+)), and copper (Cu(2+)), on the induction of cytochrome P450 1A1 (CYP1A1) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most potent PAH. Our results show that TCDD in the absence and presence of heavy metals did not significantly affect HepG2 cell viability using MTT and LDH leakage assays. Exposure of HepG2 cells with either Hg(2+) or Pb(2+) significantly decreased, whereas Cu(2+) potentiated the CYP1A1 induction mediated by TCDD at the activity levels. In a manner similar to CYP1A1 activity, both Hg(2+) and Pb(2+) significantly down-regulated, while Cu(2+) up-regulated, the induction of CYP1A1 protein mediated by TCDD, suggesting that the modulations of CYP1A1 by heavy metals are mediated at least in part at the translational level. Based on these results, exposure to metal/PAH mixtures would differentially modulate PAHs-mediated carcinogenicity.
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Affiliation(s)
- Hesham M Korashy
- Faculty of Pharmacy and Pharmaceutical Sciences, 3126 Dentistry/Pharmacy Centre, University of Alberta, Edmonton, AB, Canada T6G 2N8
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Zhang L, Wu R, Dingle RWC, Gairola CG, Valentino J, Swanson HI. Cigarette smoke condensate and dioxin suppress culture shock induced senescence in normal human oral keratinocytes. Oral Oncol 2007; 43:693-700. [PMID: 17070097 PMCID: PMC1995564 DOI: 10.1016/j.oraloncology.2006.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 08/24/2006] [Accepted: 08/29/2006] [Indexed: 11/24/2022]
Abstract
The aryl hydrocarbon receptor is a ligand activated transcription factor which regulates biological responses to a variety of environmental pollutants, such as dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) and cigarette smoke. The purpose of this study was to determine whether cigarette smoke condensate (CSC) is capable of activating the AHR in normal human oral keratinocytes (NHOK) and inhibiting their ability to senesce. Towards this end, NHOK were isolated from human subjects and were cultured in the presence or absence of either TCDD or CSC. While neither TCDD nor CSC treatments altered the lifespan of NHOK in culture, both were capable of suppressing a culture induced premature senescence as indicated by their ability to decrease the mRNA and protein levels of the senescence markers p16(INK4a), p53 and p15(INK4b). A role of the AHR in mediating these events is indicated by the observations that the TCDD and CSC-induced decreases in p15(INK4b), p16(INK4a) and p53 expression was accompanied by a corresponding increase in the expression levels of the AHR target gene, CYP1A1. In addition, cotreatment with the AHR antagonist, 3'-methoxy-4'-nitroflavone (MNF) blocked the effects of TCDD and CSC on p53 and CYP1A1 expression. The findings of this study indicate that in NHOK, CSC is capable of altering a key cell fate decision, i.e., commitment to premature senescence, that is in part, dependent on the AHR. These results support the idea that progression of CSC-induced tumorigenesis may include an AHR-mediated inhibition of senescence that contributes to immortalization and agents that block the actions of the AHR may be effective components of novel cancer therapeutics.
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Affiliation(s)
- Li Zhang
- Department of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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42
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Lewińska D, Arkusz J, Stańczyk M, Palus J, Dziubałtowska E, Stepnik M. Comparison of the effects of arsenic and cadmium on benzo(a)pyrene-induced micronuclei in mouse bone-marrow. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 632:37-43. [PMID: 17561435 DOI: 10.1016/j.mrgentox.2007.04.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 03/26/2007] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
This study was undertaken to investigate the genotoxic interactions between the common environmental pollutants: arsenic (As), cadmium (Cd) and benzo(a)pyrene (BaP), which are known to be human carcinogens. C57BL/6J/Han mice were pre-treated with 100mg cadmium chloride (Cd(2+))/L or 50mg sodium arsenite (As(3+))/L in drinking water for 7 days and then given a single dose of 200mg BaP/kg bw by intra-peritoneal injection. A third group of mice did not receive the pre-treatment and was given BaP alone. Mice were sacrificed before or at 12, 24, 48 or 72h after BaP administration. Chromosome damage in bone-marrow cells was assessed by use of the micronucleus test. The study revealed that BaP induced a statistically significant increase in micronucleus (MN) frequency at 48h after administration. In animals exposed to Cd in drinking water no enhancement of genotoxicity was observed compared with the control group that was given tap water only. In Cd/BaP co-exposed animals, the MN frequency at respective time points did not differ from that for the animals exposed solely to BaP. A statistically higher MN frequency was found in bone marrow of animals exposed to As compared with controls that received tap water (0.92+/-0.29% versus 0.38+/-0.13%, respectively). This effect was even more pronounced after combined exposure to As and BaP. In the co-exposed animals, significantly elevated levels of MN were detected in samples examined at 12, 24 and 48h after BaP administration, compared with animals receiving BaP alone (1.14+/-0.31%, 1.26+/-0.3% and 2.02+/-0.45% versus 0.44+/-0.13%, 0.44+/-0.11% and 1.04+/-0.44%, respectively). These findings imply strong interactions between As and BaP, but not between Cd and BaP, in inducing DNA damage in polychromatic erythrocytes in mouse bone-marrow.
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Affiliation(s)
- D Lewińska
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, 8 Sw. Teresy St, 91-348 Łódź, Poland
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Chang X, Fan Y, Karyala S, Schwemberger S, Tomlinson CR, Sartor MA, Puga A. Ligand-independent regulation of transforming growth factor beta1 expression and cell cycle progression by the aryl hydrocarbon receptor. Mol Cell Biol 2007; 27:6127-39. [PMID: 17606626 PMCID: PMC1952156 DOI: 10.1128/mcb.00323-07] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that mediates the toxic effects of its xenobiotic ligands and acts as an environmental checkpoint during the cell cycle. We expressed stably integrated, Tet-Off-regulated AHR variants in fibroblasts from AHR-null mice to further investigate the AHR role in cell cycle regulation. Ahr+/+ fibroblasts proliferated significantly faster than Ahr-/- fibroblasts did, and exposure to a prototypical AHR ligand or deletion of the ligand-binding domain did not change their proliferation rates, indicating that the AHR function in cell cycle was ligand independent. Growth-promoting genes, such as cyclin and cyclin-dependent kinase genes, were significantly down-regulated in Ahr-/- cells, whereas growth-arresting genes, such as the transforming growth factor beta1 (TGF-beta1) gene, extracellular matrix (ECM)-related genes, and cyclin-dependent kinase inhibitor genes, were up-regulated. Ahr-/- fibroblasts secreted significantly more TGF-beta1 into the culture medium than Ahr+/+ fibroblasts did, and Ahr-/- showed increased levels of activated Smad4 and TGF-beta1 mRNA. Inhibition of TGF-beta1 signaling by overexpression of Smad7 reversed the proliferative and gene expression phenotype of Ahr-/- fibroblasts. Changes in TGF-beta1 mRNA accumulation were due to stabilization resulting from decreased activity of TTP, the tristetraprolin RNA-binding protein responsible for mRNA destabilization through AU-rich motifs. These results show that the Ah receptor possesses interconnected intrinsic cellular functions, such as ECM formation, cell cycle control, and TGF-beta1 regulation, that are independent of activation by either exogenous or endogenous ligands and that may play a crucial role during tumorigenesis.
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Affiliation(s)
- Xiaoqing Chang
- Department of Environmental Health, University of Cincinnati Medical Center, and Shriners Hospital for Children, Cincinnati, OH 45267-0056, USA
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Shen S, Lee J, Sun X, Wang H, Weinfeld M, Le XC. Elevation of cellular BPDE uptake by human cells: a possible factor contributing to co-carcinogenicity by arsenite. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1832-7. [PMID: 17185271 PMCID: PMC1764144 DOI: 10.1289/ehp.9284] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
BACKGROUND Arsenite (iAsIII) can promote mutagenicity and carcinogenicity of other carcinogens. Considerable attention has focused on interference with DNA repair by inorganic arsenic, especially the nucleotide excision repair (NER) pathway, whereas less is known about the effect of arsenic on the induction of DNA damage by other agents. OBJECTIVES We examined how arsenic modulates DNA damage by other chemicals. METHODS We used an NER-deficient cell line to dissect DNA damage induction from DNA repair and to examine the effects of iAsIII on the formation of benzo[a]pyrene diol epoxide (BPDE)-DNA adducts. RESULTS We found that pretreatment with iAsIII at subtoxic concentrations (10 microM) led to enhanced formation of BPDE-DNA adducts. Reduced glutathione levels, glutathione S-transferase activity and chromatin accessibility were also measured after iAsIII treatment, but none of these factors appeared to account for the enhanced formation of DNA adducts. However, we found that pretreatment with iAsIII increased the cellular uptake of BPDE in a dose-dependent manner. CONCLUSIONS Our results suggest that iAsIII enhanced the formation of BPDE-DNA adducts by increasing the cellular uptake of BPDE. Therefore, the ability of arsenic to increase the bioavailability of other carcinogens may contribute to arsenic co-carcinogenicity.
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MESH Headings
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/chemistry
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/pharmacokinetics
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/pharmacology
- Arsenites/pharmacology
- Carcinogens/chemistry
- Carcinogens/pharmacokinetics
- Carcinogens/pharmacology
- Cell Line
- Cell Line, Transformed
- Chromatin/metabolism
- DNA Adducts/drug effects
- DNA Damage/drug effects
- DNA Repair/drug effects
- Glutathione/metabolism
- Humans
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Affiliation(s)
- Shengwen Shen
- Department of Public Health Sciences and Department of Laboratory Medicine and Pathology and
| | - Jane Lee
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Xuejun Sun
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Hailin Wang
- Department of Public Health Sciences and Department of Laboratory Medicine and Pathology and
| | - Michael Weinfeld
- Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - X. Chris Le
- Department of Public Health Sciences and Department of Laboratory Medicine and Pathology and
- Address correspondence to X.C. Le, Department of Public Health Sciences and Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, 10-102 Clinical Sciences Building, Edmonton, Alberta, Canada T6G 2G3. Telephone: (780) 492-6416. Fax: (780) 492-7800. E-mail:
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Korashy HM, El-Kadi AOS. The role of aryl hydrocarbon receptor in the pathogenesis of cardiovascular diseases. Drug Metab Rev 2006; 38:411-50. [PMID: 16877260 DOI: 10.1080/03602530600632063] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Numerous experimental and epidemiological studies have demonstrated that polycyclic aromatic hydrocarbons (PAHs), which are major constituents of cigarette tobacco tar, are strongly involved in the pathogenesis of the cardiovascular diseases (CVDs). Knowing that PAH-induced toxicities are mediated by the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR), which regulates the expression of a group of xenobiotic metabolizing enzymes (XMEs) such as CYP1A1, CYP1A2, CYP1B1, NQO1, and GSTA1, suggests a direct link between AhR-regulated XMEs and CVDs. Therefore, identifying the localization and expression of the AhR and its regulated XMEs in the cardiovascular system (CVS) is of major importance in understanding their physiological and pathological roles. Generally, it was believed that the levels of AhR-regulated XMEs are lower in the CVS than in the liver; however, it has been shown that similar or even higher levels of expression are demonstrated in the CVS in a tissue- and species-specific manner. Moreover, most, if not all, AhR-regulated XMEs are differentially expressed in most of the CVS, particularly in the endothelium cells, aorta, coronary arteries, and ventricles. Although the exact mechanisms of PAH-mediated cardiotoxicity are not fully understood, several mechanisms are proposed. Generally, induction of CYP1A1, CYP1A2, and CYP1B1 is considered cardiotoxic through generating reactive oxygen species (ROS), DNA adducts, and endogenous arachidonic acid metabolites. However the cardioprotective properties of NQO1 and GSTA1 are mainly attributed to the antioxidant effect by decreasing ROS and increasing the levels of endogenous antioxidants. This review provides a clear understanding of the role of AhR and its regulated XMEs in the pathogenesis of CVDs, in which imbalance in the expression of cardioprotective and cardiotoxic XMEs is the main determinant of PAH-mediated cardiotoxicity.
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Affiliation(s)
- Hesham M Korashy
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
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Korashy HM, El-Kadi AOS. The role of aryl hydrocarbon receptor and the reactive oxygen species in the modulation of glutathione transferase by heavy metals in murine hepatoma cell lines. Chem Biol Interact 2006; 162:237-48. [PMID: 16914127 DOI: 10.1016/j.cbi.2006.07.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2006] [Revised: 06/29/2006] [Accepted: 07/06/2006] [Indexed: 11/23/2022]
Abstract
Glutathione transferase (GST) is a phase II detoxifying enzyme that plays a protective mechanism against oxidizing substances and toxic contaminants. Among these contaminants, heavy metals and polycyclic and halogenated aromatic hydrocarbons (PHAHs) have been shown to exert their toxic effects through the modulation of detoxifying enzymes, including the GSTs. Recently, we showed that heavy metals particularly Hg2+, Pb2+, and Cu2+ modulate the expression of phase II detoxifying enzymes such as NAD(P)H:quinone oxidoreductase 1 and Gsta1 in a concentration- and time-dependent manner. However, the effect of heavy metals and their potential interactions with aryl hydrocarbon receptor (AhR) ligands, PHAHs, on total Gst activity is still unknown. In the current study, we have investigated the effects of Hg2+, Pb2+, and Cu2+ in the absence and presence of four AhR ligands on the total Gst activity and reactive oxygen species (ROS) production in wild-type and AhR-deficient Hepa 1c1c7 cells. Our results showed that Hg2+ and Cu2+, but not Pb2+, significantly induced Gst activity in wild-type cells, whereas all metals induced the Gst activity in AhR-deficient cells. The induction of Gst activity by heavy metals was strongly correlated with an increase in the ROS production in wild-type, but not in AhR-deficient cells. Co-administration of heavy metals with AhR ligands differentially modulated Gst activity, in that co-exposure to Hg2+ plus AhR ligands could be beneficial in protecting against cytotoxicity as demonstrated by the increase in Gst activity with a proportional decrease in ROS production. Whereas co-exposure to Cu2+ plus AhR ligands was more toxic in that a decrease in Gst activity and an increase in oxidative stress of the cell were observed. We concluded that heavy metals differentially modulate the Gst activity through oxidative stress- and AhR-mediated mechanisms.
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Affiliation(s)
- Hesham M Korashy
- Faculty of Pharmacy and Pharmaceutical Sciences, 3126 Dentistry/Pharmacy Centre, University of Alberta, Edmonton, Alta., Canada T6G 2N8
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Harper PA, Riddick DS, Okey AB. Regulating the regulator: Factors that control levels and activity of the aryl hydrocarbon receptor. Biochem Pharmacol 2006; 72:267-79. [PMID: 16488401 DOI: 10.1016/j.bcp.2006.01.007] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2005] [Revised: 01/12/2006] [Accepted: 01/12/2006] [Indexed: 11/17/2022]
Abstract
The aryl hydrocarbon receptor (AHR) participates in a wide range of critical cellular events in response to endogenous signals or xenobiotic chemicals. Hence, it is important that AHR levels and activity themselves be well controlled in target tissues. The AHR is essentially ubiquitous in its distribution in mammalian tissues. However, levels of the receptor vary widely across different tissues and among different cell types. AHR levels and activity are modulated by exposure to the receptor's own ligands and are influenced by other xenobiotic chemicals. Many different factors impinge on AHR levels and AHR activity. These factors may alter responsiveness of downstream pathways, thereby affecting normal physiologic functions as well as responses to toxic environmental chemicals such as dioxins. Our commentary appraises the current literature on factors that regulate AHR levels/activity and attempts to identify fruitful strategies towards discovery of key pathways by which AHR levels are modulated in response to endogenous signals and in response to xenobiotic chemicals. An extraordinarily large number of agents alter the level or activity of the AHR. We have not yet entered an age of enlightenment sufficient to achieve true understanding of the interplay of mechanisms that regulate AHR expression in space and in time.
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Affiliation(s)
- Patricia A Harper
- Program in Developmental Biology, The Hospital for Sick Children, Toronto, Ont., Canada
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Fischer JM, Robbins SB, Kannamkumarath SS, Al-Zoughool M, Stringer SL, Talaska G, Caruso JA, Stambrook PJ, Stringer JR. Exposure of mice to arsenic and/or benzo[a]pyrene does not increase the frequency of Aprt-deficient cells recovered from explanted skin of Aprt heterozygous mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2006; 47:334-44. [PMID: 16649189 DOI: 10.1002/em.20212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Exposure to inorganic arsenic in drinking water is linked to cancer in humans, but the mechanism of arsenic-induced cancer is not clear. Arsenic is not a powerful point mutagen, but can cause chromosome malsegregation and mitotic recombination, two events that can cause loss of tumor suppressor alleles and thereby contribute to the evolution of cancerous cells. To determine whether arsenic increases the frequency of allele loss due to either malsegregation or mitotic recombination in vivo, Aprt(+/-) hybrid mice were exposed to sodium arsenite (10 mg/L) in their drinking water for 10 weeks. To determine whether arsenic enhances the action of a known mutagen, half of the arsenic-treated mice were exposed to benzo[a]pyrene (BaP) for 8 weeks by skin painting (500 nmoles/week). Cells were taken from painted dorsal skin and cultured in the presence of 2,6-diaminopurine (DAP), to select colonies lacking adenosine phosphoribosyl transferase (Aprt) activity. The frequency of DAP-resistant (DAP(r)) colonies varied substantially within the treatment groups, but there was no significant difference between the groups. Analysis of DNA from DAP(r) colonies suggested that mitotic recombination contributed to the loss of wild-type Aprt allele. Whether arsenic or BaP enhanced or diminished the frequency of this process could not be deduced from these data.
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Affiliation(s)
- Jared M Fischer
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Ohio, USA
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Korashy HM, El-Kadi AOS. Regulatory mechanisms modulating the expression of cytochrome P450 1A1 gene by heavy metals. Toxicol Sci 2005; 88:39-51. [PMID: 16093525 DOI: 10.1093/toxsci/kfi282] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We recently demonstrated that heavy metals, Hg2+, Pb2+, and Cu2+ induced Cyp1a1 gene expression, yet the mechanisms involved remain unknown. To explore the molecular mechanisms involved in the modulation of Cyp1a1 by heavy metals, Hepa 1c1c7 cells were treated with the metals in the presence and absence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent Cyp1a1 inducer. Time-dependent effect study showed that all metals significantly induced the basal Cyp1a1 mRNA. This was apparent 3 h after treatment, and levels remained elevated for at least 24 h. At the inducible level, Hg2+ and Pb2+ further increased, while Cu2+ decreased, the TCDD-mediated induction of Cyp1a1 mRNA. The RNA synthesis inhibitor, actinomycin D, completely blocked the Cyp1a1 induction by heavy metals. The protein synthesis inhibitor, cycloheximide, and 26S proteasome inhibitor, carbobenzoxy-L-leucyl-L-leucyl-leucinal (MG-132), super-induced the metal-mediated induction of Cyp1a1 mRNA. In addition, all three metals induced aryl hydrocarbon receptor/xenobiotic-responsive element (AhR/XRE) binding, suggesting an AhR-dependent mechanism. Cyp1a1 mRNA and protein decay experiments showed that the three metals did not significantly affect the half-life of mRNA; however, they significantly decreased the degradation rate of its protein, implying a posttranslational regulation of the Cyp1a1 by the heavy metals. A significant decrease in TCDD-mediated induction of Cyp1a1 activity associated with an increase in HO-1 mRNA and a decrease in cellular heme content was observed after all metals treatment. This suggests that heme degradation plays a role in reducing Cyp1a1 activity. This is the first demonstration that heavy metals can directly induce Cyp1a1 gene expression in an AhR-dependent manner through transcriptional and posttranslational mechanisms.
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MESH Headings
- Animals
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/enzymology
- Carcinoma, Hepatocellular/genetics
- Cell Line, Tumor
- Cycloheximide/pharmacology
- Cytochrome P-450 CYP1A1/biosynthesis
- Cytochrome P-450 CYP1A1/genetics
- Dactinomycin/analogs & derivatives
- Dactinomycin/pharmacology
- Drug Interactions
- Enzyme Induction/drug effects
- Enzyme Induction/genetics
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Neoplastic/genetics
- Hepatocytes/drug effects
- Hepatocytes/enzymology
- Leupeptins/pharmacology
- Metals, Heavy/toxicity
- Mice
- Polychlorinated Dibenzodioxins/toxicity
- Protein Processing, Post-Translational/drug effects
- Protein Synthesis Inhibitors/pharmacology
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptors, Aryl Hydrocarbon/genetics
- Receptors, Aryl Hydrocarbon/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Response Elements/drug effects
- Response Elements/genetics
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Affiliation(s)
- Hesham M Korashy
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2N8
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