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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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Zablon HA, VonHandorf A, Puga A. Mechanisms of chromate carcinogenesis by chromatin alterations. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 96:1-23. [PMID: 36858770 DOI: 10.1016/bs.apha.2022.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a dynamic environment, organisms must constantly mount an adaptive response to new environmental conditions in order to survive. Novel patterns of gene expression, driven by attendant changes in chromatin architecture, aid in adaptation and survival. Critical mechanisms in the control of gene transcription govern new spatiotemporal chromatin-chromatin interactions that make regulatory DNA elements accessible to the transcription factors that control the response. Consequently, agents that disrupt chromatin structure are likely to have a direct impact on the transcriptional programs of cells and organisms and to drive alterations in fundamental physiological processes. In this regard, hexavalent chromium (Cr(VI)) is of special interest because it interacts directly with cellular proteins, DNA, and other macromolecules, and is likely to upset cell functions that may cause generalized damage to the organism. Here, we will highlight chromium-mediated mechanisms that disrupt chromatin architecture and discuss how these mechanisms are integral to its carcinogenic properties. Emerging evidence indicates that Cr(VI) targets euchromatin, particularly in genomic locations flanking the binding sites of the essential transcription factors CTCF and AP1, and, in so doing, they disrupt nucleosomal architecture. Ultimately, the ensuing changes, if occurring in critical regulatory domains, may establish a new chromatin state, either toxic or adaptive, that will be governed by the corresponding gene transcription changes in key biological processes associated with that state.
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Affiliation(s)
- Hesbon A Zablon
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Andrew VonHandorf
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Alvaro Puga
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
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Wise JTF, Salazar-González RA, Walls KM, Doll MA, Habil MR, Hein DW. Hexavalent chromium increases the metabolism and genotoxicity of aromatic amine carcinogens 4-aminobiphenyl and β-naphthylamine in immortalized human lung epithelial cells. Toxicol Appl Pharmacol 2022; 449:116095. [PMID: 35662664 PMCID: PMC9382885 DOI: 10.1016/j.taap.2022.116095] [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: 03/23/2022] [Revised: 05/18/2022] [Accepted: 05/28/2022] [Indexed: 10/18/2022]
Abstract
Humans are exposed to carcinogenic chemicals via occupational and environmental exposures. Common chemicals of concern that can occur in exposures together are aromatic amines (e.g., 4-aminobiphenyl [4-ABP] and β-naphthylamine [BNA]) and hexavalent chromium (Cr[VI]). Arylamine N-acetyltransferases 1 and 2 (NAT1 and NAT2) are key to the metabolism of aromatic amines and their genotoxicity. The effects of Cr(VI) on the metabolism of aromatic amines remains unknown as well as how it may affect their ensuing toxicity. The objective of the research presented here is to investigate the effects of Cr(VI) on the metabolism and genotoxicity of 4-ABP and BNA in immortalized human lung epithelial cells (BEP2D) expressing NAT1 and NAT2. Exposure to Cr(VI) for 48 h increased NAT1 activity (linear regression analysis: P < 0.0001) as measured by N-acetylation of para-aminobenzoic acid (PABA) in BEP2D cells but not NAT2 N-acetylation of sulfamethazine, which are prototypic NAT1 and NAT2 substrates respectively. Cr(VI) also increased the N-acetylation of 4-ABP and BNA. In BEP2D cells the N-acetylation of 4-ABP (1-3 μM) exhibited a dose-dependent increase (linear regression analysis: P < 0.05) following co-incubation with 0-3 μM Cr(VI). In BEP2D cells, incubation with Cr(VI) caused dose-dependent increases (linear regression analysis: P < 0.01) in expression of CYP1A1 protein and catalytic activity. For genotoxicity, BEP2D cells were exposed to 4-ABP or BNA with/without Cr(VI) for 48 h. We observed dose-dependent increases (linear regression analysis: P < 0.01) in phospho-γH2AX protein expression for combined treatment of 4-ABP or BNA with Cr(VI). Further using a CYP1A1 inhibitor (α-naphthoflavone) and NAT1 siRNA, we found that CYP1A1 inhibition did not reduce the increased N-acetylation or genotoxicity of BNA by Cr(VI), while NAT1 inhibition did reduce increases in BNA N-acetylation and genotoxicity by Cr(VI). We conclude that during co-exposure of aromatic amines and Cr(VI) in human lung cells, Cr(VI) increased NAT1 activity contributing to increased 4-ABP and BNA genotoxicity.
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Affiliation(s)
- James T F Wise
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Raúl A Salazar-González
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Kennedy M Walls
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Mark A Doll
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Mariam R Habil
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - David W Hein
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Louisville, KY 40202, USA.
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Mineral Micronutrients in Asthma. Nutrients 2021; 13:nu13114001. [PMID: 34836256 PMCID: PMC8625329 DOI: 10.3390/nu13114001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/07/2021] [Accepted: 11/08/2021] [Indexed: 01/01/2023] Open
Abstract
Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.
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VonHandorf A, Zablon HA, Puga A. Hexavalent chromium disrupts chromatin architecture. Semin Cancer Biol 2021; 76:54-60. [PMID: 34274487 PMCID: PMC8627925 DOI: 10.1016/j.semcancer.2021.07.009] [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: 05/28/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 12/21/2022]
Abstract
Accessibility of DNA elements and the orchestration of spatiotemporal chromatin-chromatin interactions are critical mechanisms in the regulation of gene transcription. Thus, in an ever-changing milieu, cells mount an adaptive response to environmental stimuli by modulating gene expression that is orchestrated by coordinated changes in chromatin architecture. Correspondingly, agents that alter chromatin structure directly impact transcriptional programs in cells. Heavy metals, including hexavalent chromium (Cr(VI)), are of special interest because of their ability to interact directly with cellular protein, DNA and other macromolecules, resulting in general damage or altered function. In this review we highlight the chromium-mediated mechanisms that promote disruption of chromatin architecture and how these processes are integral to its carcinogenic properties. Emerging evidence shows that Cr(VI) targets nucleosomal architecture in euchromatin, particularly in genomic locations flanking binding sites of the essential transcription factors CTCF and AP1. Ultimately, these changes contribute to an altered chromatin state in critical gene regulatory regions, which disrupts gene transcription in functionally relevant biological processes.
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Affiliation(s)
- Andrew VonHandorf
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, OH, 45267, USA
| | - Hesbon A Zablon
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, OH, 45267, USA
| | - Alvaro Puga
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, OH, 45267, USA.
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VonHandorf A, Zablon HA, Biesiada J, Zhang X, Medvedovic M, Puga A. Hexavalent chromium promotes differential binding of CTCF to its cognate sites in Euchromatin. Epigenetics 2021; 16:1361-1376. [PMID: 33319643 DOI: 10.1080/15592294.2020.1864168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hexavalent chromium compounds are well-established respiratory carcinogens to which humans are commonly exposed in industrial and occupational settings. In addition, natural and anthropogenic sources of these compounds contribute to the exposure of global populations through multiple routes, including dermal, ingestion and inhalation that elevate the risk of cancer by largely unresolved mechanisms. Cr(VI) has genotoxic properties that include ternary adduct formation with DNA, increases in DNA damage, mostly by double-strand break formation, and altered transcriptional responses. Our previous work using ATAC-seq showed that CTCF motifs were enriched in Cr(VI)-dependent differentially accessible chromatin, suggesting that CTCF, a key transcription factor responsible for the regulation of the transcriptome, might be a chromium target. To test this hypothesis, we investigated the effect of Cr(VI) treatment on the binding of CTCF to its cognate sites and ensuing changes in transcription-related histone modifications. Differentially bound CTCF sites were enriched by Cr(VI) treatment within transcription-related regions, specifically transcription start sites and upstream genic regions. Functional annotation of the affected genes highlighted biological processes previously associated with Cr(VI) exposure. Notably, we found that differentially bound CTCF sites proximal to the promoters of this subset of genes were frequently associated with the active histone marks H3K27ac, H3K4me3, and H3K36me3, in agreement with the concept that Cr(VI) targets CTCF in euchromatic regions of the genome. Our results support the conclusion that Cr(VI) treatment promotes the differential binding of CTCF to its cognate sites in genes near transcription-active boundaries, targeting these genes for dysregulation.
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Affiliation(s)
- Andrew VonHandorf
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Hesbon A Zablon
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Jacek Biesiada
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Xiang Zhang
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Mario Medvedovic
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Alvaro Puga
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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Zablon HA, VonHandorf A, Puga A. Chromium exposure disrupts chromatin architecture upsetting the mechanisms that regulate transcription. Exp Biol Med (Maywood) 2019; 244:752-757. [PMID: 30935235 PMCID: PMC6567585 DOI: 10.1177/1535370219839953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
IMPACT STATEMENT This mini-review highlights current evidence on the mechanisms through which hexavalent chromium (Cr(VI)) disrupts transcriptional regulation, an emerging area of interest and one of the central processes by which chromium induces carcinogenesis. Several studies have shown that Cr(VI) causes widespread DNA damage and disrupts epigenetic signatures, suggesting that chromatin may be a direct Cr(VI) target. The findings discussed here suggest that Cr(VI) disrupts transcriptional regulation by causing genomic architecture changes.
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Affiliation(s)
- Hesbon A Zablon
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Andrew VonHandorf
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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Chen P, Geng N, Zhou D, Zhu Y, Xu Y, Liu K, Liu Y, Liu J. The regulatory role of COX-2 in the interaction between Cr(VI)-induced endoplasmic reticulum stress and autophagy in DF-1 cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 170:112-119. [PMID: 30529609 DOI: 10.1016/j.ecoenv.2018.11.120] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 10/31/2018] [Accepted: 11/27/2018] [Indexed: 06/09/2023]
Abstract
Hexavalent chromium (Cr(VI)) is a common environmental pollutant. Exposure of Cr(VI) can lead to cell autophagy, but the preventive measures for diminishing Cr(VI)-induced autophagy need further study. COX-2 can be induced by several heavy metals and can lead to endoplasmic reticulum (ER) stress and autophagy; thus, COX-2, ER stress, and autophagy may be related. This study mainly investigated the role of COX-2 in the eIF2α-ATF4 pathway, which is a major pathway in cell autophagy. In this study, Cr(VI) was used as a xenobiotic to determine changes in the parameters of ER stress, autophagy, and COX-2 levels. At the same time, a clear contrast was obtained by assigning positive and negative controls of ER stress and autophagy. The results showed that during Cr(VI) invasion, the parameters of ER stress and autophagy (such as BiP, PERK, p62, LC3-II, and mTOR) were enhanced, similarly to the positive control of ER stress and/or the autophagy controls. Such enhancement is a protective mechanism for cell survival. Additionally, the COX-2 levels increased. Moreover, when COX-2 was inhibited, the PERK level remained high, whereas the LC3-II level decreased. This finding suggests that COX-2 specifically affects the interaction between ER stress and autophagy. Notably, this study reveals that Cr(VI) can induce ER stress and autophagy in DF-1 cells and that COX-2 plays an essential role in the interaction between ER stress and autophagy.
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Affiliation(s)
- Peng Chen
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, PR China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, 61 Daizong Street, Taian City, Shandong Province 271018, PR China
| | - Na Geng
- Research Center for Animal Disease Control Engineering Shandong Province, Shandong Agricultural University, Tai'an 271018, PR China
| | - Dong Zhou
- College of Veterinary Medicine, Northwest Agriculture and Forestry University, Yangling 712100, PR China
| | - Yiran Zhu
- Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, 61 Daizong Street, Taian City, Shandong Province 271018, PR China
| | - Yuliang Xu
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, PR China
| | - Kangping Liu
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, PR China
| | - Yongxia Liu
- Research Center for Animal Disease Control Engineering Shandong Province, Shandong Agricultural University, Tai'an 271018, PR China.
| | - Jianzhu Liu
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, PR China.
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Chen P, Zhu Y, Wan H, Wang Y, Hao P, Cheng Z, Liu Y, Liu J. Effects of the Oral Administration of K 2Cr 2O 7 and Na 2SeO 3 on Ca, Mg, Mn, Fe, Cu, and Zn Contents in the Heart, Liver, Spleen, and Kidney of Chickens. Biol Trace Elem Res 2017; 180:285-296. [PMID: 28353138 DOI: 10.1007/s12011-017-0999-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 03/14/2017] [Indexed: 12/25/2022]
Abstract
This study aimed to investigate the effects of selenium on the ion profiles in the heart, liver, spleen, and kidney through the oral administration of hexavalent chromium. Approximately 22.14 mg/kg b.w. K2Cr2O7 was added to water to establish a chronic poisoning model. Different selenium levels (0.00, 0.31, 0.63, 1.25, 2.50, and 5.00 mg Na2SeO3/kg b.w.) around the safe dose were administered to the experimental group model. Ca, Mg, Mn, Fe, Cu, and Zn were detected in the organs through flame atomic absorption spectrometry after these organs were exposed to K2Cr2O7 and Na2SeO3 for 14, 28, and 42 days. Results showed that these elements exhibited various changes. Ca contents declined in the heart, liver, and spleen. Ca contents also decreased on the 28th day and increased on the 42nd day in the kidney. Mn contents declined in the heart and spleen but increased in the kidney. Mn contents also decreased on the 28th day and increased on the 42nd day in the liver. Cu contents declined in the heart and spleen. Cu contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Zn contents declined in the heart and spleen. Zn contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Fe contents decreased in the heart and liver. Fe contents increased on the 28th day and decreased on the 42nd day in the spleen and kidney. Mg contents did not significantly change in these organs. Appropriate selenium contents enhanced Mn and Zn contents, which were declined by chromium. Conversely, appropriate selenium contents reduced Ca, Fe, and Cu contents, which were increased by chromium. In conclusion, the exposure of chickens to K2Cr2O7 induced changes in different trace elements, and Na2SeO3 supplementation could alleviate this condition.
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Affiliation(s)
- Peng Chen
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Yiran Zhu
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Huiyu Wan
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Yang Wang
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Pan Hao
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Ziqiang Cheng
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Yongxia Liu
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China
| | - Jianzhu Liu
- College of Veterinary Medicine, Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, Shandong Province, 271018, China.
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Sánchez-Martín FJ, Fan Y, Carreira V, Ovesen JL, Vonhandorf A, Xia Y, Puga A. Long-term Coexposure to Hexavalent Chromium and B[a]P Causes Tissue-Specific Differential Biological Effects in Liver and Gastrointestinal Tract of Mice. Toxicol Sci 2015; 146:52-64. [PMID: 25820237 DOI: 10.1093/toxsci/kfv070] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Complex mixtures of environmental agents often cause mixture-specific health effects that cannot be accounted for by a single mechanism. To study the biological effects of exposure to a mixture of chromium-VI and benzo[a]pyrene (B[a]P), often found together in the environment, we exposed mice for 60 days to 0, 55, 550, or 5500 ppb Cr(VI) in drinking water followed by 90 days of coexposure to B[a]P at 0, 1.25, 12.5, or 125 mg/kg/day and examined liver and gastrointestinal (GI) tract for exposure effects. In the liver, the mixture caused more significant histopathology than expected from the sum of effects of the individual components, while in the GI tract, Cr(VI) alone caused significant enterocyte hypertrophy and increases in cell proliferation and DNA damage that were also observed in mice coexposed to B[a]P. Expression of genes involved in drug metabolism, tumor suppression, oxidative stress, and inflammation was altered in mixed exposures relative to control and to singly exposed mice. Drug metabolism and oxidative stress genes were upregulated and tumor suppressor and inflammation genes downregulated in the proximal GI tract, whereas most markers were upregulated in the distal GI tract and downregulated in the liver. Oral exposure to Cr(VI) and B[a]P mixtures appears to have tissue-specific differential consequences in liver and GI tract that cannot be predicted from the effects of each individual toxicant. Tissue specificity may be particularly critical in cases of extended exposure to mixtures of these agents, as may happen in the occupational setting or in areas where drinking water contains elevated levels of Cr(VI).
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Affiliation(s)
- Francisco Javier Sánchez-Martín
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Yunxia Fan
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Vinicius Carreira
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Jerald L Ovesen
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Andrew Vonhandorf
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Ying Xia
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
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Abstract
Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.
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Affiliation(s)
- Peter A. Lay
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
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12
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Cytogenomics of hexavalent chromium (Cr 6+) exposed cells: a comprehensive review. Indian J Med Res 2014; 139:349-70. [PMID: 24820829 PMCID: PMC4069729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The altered cellular gene expression profile is being hypothesized as the possible molecular basis navigating the onset or progress of various morbidities. This hypothesis has been evaluated here in respect of Cr 6+ induced toxicity. Several studies using gene microarray show selective and strategic dysregulations of cellular genes and pathways induced by Cr 6+. Relevant literature has been reviewed to unravel these changes in different test systems after exposure to Cr 6+ and also to elucidate association if any, of the altered cytogenomics with Cr 6+ induced toxicity or carcinogenicity. The aim was to verify the hypothesis for critical role of altered cytogenomics in onset of Cr 6+ induced biological/clinical effects by identifying genes modulated commonly by the toxicant irrespective of test system or test concentrations/doses, and by scrutinizing their importance in regulation of the flow of mechanistically linked events crucial for resultant morbidities. Their probability as biomarkers to monitor the toxicant induced biological changes is speculative. The modulated genes have been found to cluster under the pathways that manage onset of oxidative stress, DNA damage, apoptosis, cell-cycle regulation, cytoskeleton, morphological changes, energy metabolism, biosynthesis, oncogenes, bioenergetics, and immune system critical for toxicity. In these studies, the identity of genes has been found to differ remarkably; albeit the trend of pathways' dysregulation has been found to remain similar. We conclude that the intensity of dysregulation of genes or pathways involved in mechanistic events forms a sub-threshold or threshold level depending upon the dose and type (including speciation) of the toxicant, duration of exposure, type of target cells, and niche microenvironment of cells, and the intensity of sub-threshold or threshold level of the altered cytogenomics paves way in toxicant exposed cells eventually either to opt for reversal to differentiation and growth, or to result in toxicity like dedifferentiation and apoptosis, respectively.
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Wang TC, Song YS, Yu SF, Zhang J, Wang H, Gu YE, Chen T, Jia G. Association of folate deficiency and selected tumor marker concentrations in long-term hexavalent chromium exposed population. Int J Hyg Environ Health 2014; 217:88-94. [DOI: 10.1016/j.ijheh.2013.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 03/23/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
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Golubnitschaja O, Yeghiazaryan K. Opinion controversy to chromium picolinate therapy's safety and efficacy: ignoring 'anecdotes' of case reports or recognising individual risks and new guidelines urgency to introduce innovation by predictive diagnostics? EPMA J 2012; 3:11. [PMID: 23039227 PMCID: PMC3515400 DOI: 10.1186/1878-5085-3-11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 08/17/2012] [Indexed: 01/13/2023]
Abstract
Due to the important physiologic function of trivalent chromium in glucose/insulin homeostasis, some commercial organisations promote Cr3+ supplements in maintaining proper carbohydrate and lipid metabolism; regulation of reducing carbohydrate carvings and appetite; prevention of insulin resistance and glucose intolerance; regulation of body composition, including reducing fat mass and increasing lean body mass; optimal body building for athletes; losing weight; treatment of atypical depression as an antidepressant; and prevention of obesity and type 2 diabetes mellitus. On one hand, case reports are commented as 'nonevidence-based anecdotes'. On the other hand, a number of independent studies warn against adverse health outcomes assigned to chromium picolinate (CrPic) dietary application. This review analyses opinion controversies, demonstrates highly individual reactions towards CrPic dietary supplements and highlights risks when the dietary supplements are used freely as therapeutic agents, without application of advanced diagnostic tools to predict individual outcomes.
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Affiliation(s)
- Olga Golubnitschaja
- Department of Radiology, Rheinische Friedrich-Wilhelms-University of Bonn, Sigmund-Freud-Str, 25, Bonn, 53105, Germany.
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