1
|
Duffel MW, Lehmler HJ. Complex roles for sulfation in the toxicities of polychlorinated biphenyls. Crit Rev Toxicol 2024; 54:92-122. [PMID: 38363552 PMCID: PMC11067068 DOI: 10.1080/10408444.2024.2311270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 01/23/2024] [Indexed: 02/17/2024]
Abstract
Polychlorinated biphenyls (PCBs) are persistent organic toxicants derived from legacy pollution sources and their formation as inadvertent byproducts of some current manufacturing processes. Metabolism of PCBs is often a critical component in their toxicity, and relevant metabolic pathways usually include their initial oxidation to form hydroxylated polychlorinated biphenyls (OH-PCBs). Subsequent sulfation of OH-PCBs was originally thought to be primarily a means of detoxication; however, there is strong evidence that it may also contribute to toxicities associated with PCBs and OH-PCBs. These contributions include either the direct interaction of PCB sulfates with receptors or their serving as a localized precursor for OH-PCBs. The formation of PCB sulfates is catalyzed by cytosolic sulfotransferases, and, when transported into the serum, these metabolites may be retained, taken up by other tissues, and subjected to hydrolysis catalyzed by intracellular sulfatase(s) to regenerate OH-PCBs. Dynamic cycling between PCB sulfates and OH-PCBs may lead to further metabolic activation of the resulting OH-PCBs. Ultimate toxic endpoints of such processes may include endocrine disruption, neurotoxicities, and many others that are associated with exposures to PCBs and OH-PCBs. This review highlights the current understanding of the complex roles that PCB sulfates can have in the toxicities of PCBs and OH-PCBs and research on the varied mechanisms that control these roles.
Collapse
Affiliation(s)
- Michael W. Duffel
- Department of Pharmaceutical Sciences & Experimental Therapeutics, College of Pharmacy, The University of Iowa, Iowa City, Iowa, 52242, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa, 52242, United States
| |
Collapse
|
2
|
Zhang CY, Li X, Flor S, Ruiz P, Kruve A, Ludewig G, Lehmler HJ. Metabolism of 3-Chlorobiphenyl (PCB 2) in a Human-Relevant Cell Line: Evidence of Dechlorinated Metabolites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12460-12472. [PMID: 35994059 PMCID: PMC9573771 DOI: 10.1021/acs.est.2c03687] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Lower chlorinated polychlorinated biphenyls (LC-PCBs) and their metabolites make up a class of environmental pollutants implicated in a range of adverse outcomes in humans; however, the metabolism of LC-PCBs in human models has received little attention. Here we characterize the metabolism of PCB 2 (3-chlorobiphenyl), an environmentally relevant LC-PCB congener, in HepG2 cells with in silico prediction and nontarget high-resolution mass spectrometry. Twenty PCB 2 metabolites belonging to 13 metabolite classes, including five dechlorinated metabolite classes, were identified in the cell culture media from HepG2 cells exposed for 24 h to 10 μM or 3.6 nM PCB 2. The PCB 2 metabolite profiles differed from the monochlorinated metabolite profiles identified in samples from an earlier study with PCB 11 (3,3'-dichlorobiphenyl) under identical experimental conditions. A dechlorinated dihydroxylated metabolite was also detected in human liver microsomal incubations with monohydroxylated PCB 2 metabolites but not PCB 2. These findings demonstrate that the metabolism of LC-PCBs in human-relevant models involves the formation of dechlorination products. In addition, untargeted metabolomic analyses revealed an altered bile acid biosynthesis in HepG2 cells. Our results indicate the need to study the disposition and toxicity of complex PCB 2 metabolites, including novel dechlorinated metabolites, in human-relevant models.
Collapse
Affiliation(s)
- Chun-Yun Zhang
- Hubei
Key Laboratory of Regional Development and Environmental Response,
Faculty of Resources and Environmental Science, Hubei University, Wuhan 430062, China
- Department
of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Xueshu Li
- Department
of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Susanne Flor
- Department
of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Patricia Ruiz
- Office
of Innovation and Analytics, Simulation Science Section, Agency for Toxic Substances and Disease Registry, Atlanta, Georgia 30333, United States
| | - Anneli Kruve
- Department
of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius Väg 16, 10691 Stockholm, Sweden
| | - Gabriele Ludewig
- Department
of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Hans-Joachim Lehmler
- Department
of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa 52242, United States
- Phone: (319) 335-4981. Fax: (319) 335-4290.
| |
Collapse
|
3
|
Qiu Z, Xiao J, Zheng S, Huang W, Du T, Au WW, Wu K. Associations between functional polychlorinated biphenyls in adipose tissues and prognostic biomarkers of breast cancer patients. ENVIRONMENTAL RESEARCH 2020; 185:109441. [PMID: 32247153 DOI: 10.1016/j.envres.2020.109441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Exposure to polychlorinated biphenyls (PCBs) has been shown to influence expression of some biomarkers that are predictive/prognostic for breast cancer. Therefore, our study was conducted to further investigating associations of different functional PCBs in adipose tissue with breast cancer prognostic biomarkers. METHODS Two hundred and five breast cancer patients were recruited in Shantou, China. Breast adipose tissues were collected during their resection surgery and levels of 7 PCB congeners were analyzed by gas chromatography-mass spectrometry (GC-MS). The PCB congeners were divided into 4 groups according to structure-activity. Socio-demographic, clinical and pathological information were obtained from questionnaire and digital medical records. Odds ratios (ORs) for associations between prognostic biomarkers and PCB levels (tertile 3 [T3], tertile 2 [T2] vs. tertile 1) were estimated from logistic regression models. RESULTS Most PCB congeners were detectable, with a highest level (22.06 ng/g lipid) of PCB153. As for estrogenic PCBs, increased PCB52 exposure was positively associated with PR expression (ORT2 = 2.36, Ptrend = 0.054), but higher PCB101 level was negatively associated with HER-2 (ORT3 = 0.24, Ptrend = 0.029) and tumor size (OR = 0.43). Limited dioxin-like PCB138 exposure was positively associated with ER (ORT2 = 3.23, ORT3 = 3.77, Ptrend = 0.047) but negatively with Top-IIα expression (ORT2 = 0.35, ORT3 = 0.28, Ptrend = 0.080). Higher PCB153 (CYP inducer) level was negatively associated with ER (ORT2 = 0.32, ORT3 = 0.19, Ptrend = 0.038) but positively with Ki-67 expression (ORT2 = 1.43, ORT3 = 3.60, Ptrend = 0.055). Higher neurotoxic PCB28 was positively associated with HER-2 (ORT3 = 5.43, Ptrend = 0.006) and tumor size (OR = 2.37). Moreover, total PCBs exposure was positively associated with VEGF-C (ORT2 = 76.91, ORT3 = 97.96, Ptrend = 0.041) and tumor metastasis (OR = 2.25). CONCLUSIONS Different functional PCB congeners have different associations (both positive and negative) with breast cancer prognostic biomarkers, as well as tumor classification stage. Therefore, the development and aggressiveness of breast cancer may depend upon exposure to specific structure-activity of PCBs.
Collapse
Affiliation(s)
- Zhaolong Qiu
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China
| | - Jiefeng Xiao
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China
| | - Shukai Zheng
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China
| | - Wenlong Huang
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China
| | - Taifeng Du
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China
| | - William W Au
- University of Medicine, Pharmacy, Science and Technology, Targu Mures, Romania
| | - Kusheng Wu
- Department of Preventive Medicine, Shantou University Medical College, Shantou, 515041, Guangdong Province, China.
| |
Collapse
|
4
|
Shu N, Hägglund P, Cai H, Hawkins CL, Davies MJ. Modification of Cys residues in human thioredoxin-1 by p-benzoquinone causes inhibition of its catalytic activity and activation of the ASK1/p38-MAPK signalling pathway. Redox Biol 2019; 29:101400. [PMID: 31926625 PMCID: PMC6926358 DOI: 10.1016/j.redox.2019.101400] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 01/27/2023] Open
Abstract
Quinones can modify biological molecules through both redox-cycling reactions that yield radicals (semiquinone, superoxide and hydroxyl) and via covalent adduction to nucleophiles (e.g. thiols and amines). Kinetic data indicate that Cys residues in GSH and proteins are major targets. In the studies reported here, the interactions of a prototypic quinone compound, p-benzoquinone (BQ), with the key redox protein, thioredoxin-1 (Trx1) were examined. BQ binds covalently with isolated Trx1 forming quinoprotein adducts, resulting in a concentration-dependent loss of enzyme activity and crosslink formation. Mass spectrometry peptide mass mapping data indicate that BQ forms adducts with all of the Trx1 Cys residues. Glutathione (GSH) reacts competitively with BQ, and thereby modulates the loss of activity and crosslink formation. Exposure of macrophage-like (J774A.1) cells to BQ results in a dose-dependent loss of Trx and thioredoxin reductase (TrxR) activities, quinoprotein formation, and a decrease in GSH levels without a concomitant increase in oxidized glutathione. GSH depletion aggravates the loss of Trx and TrxR activity. These data are consistent with adduction of GSH to BQ being a primary protective pathway. Reaction of BQ with Trx in cells resulted in the activation of apoptosis signal-regulating kinase 1 (ASK1), and p38 mitogen-activated protein kinase (MAPK) leading to apoptotic cell death. These data suggest that BQ reacts covalently with Cys residues in Trx, including at the active site, leading to enzyme inactivation and protein cross-linking. Modification of the Cys residues in Trx also results in activation of the ASK1/p38-MAPK signalling pathway and promotion of apoptotic cell death. Quinone (e.g. p-benzoquinone, BQ) toxicity is linked to Michael adduction reactions. Adduction of BQ to Cys residues in proteins are rapid (≤105 M−1 s−1) and selective. BQ reaction with Cys inactivates thioredoxin (Trx) and yields quinone- and disulfide-linked dimers. GSH reacts competitively with BQ and modulates damage, without GSSG formation. BQ activates ASK1 and p38 pathways and induced apoptosis in cells via Trx damage.
Collapse
Affiliation(s)
- Nan Shu
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Per Hägglund
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Huan Cai
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Clare L Hawkins
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark.
| |
Collapse
|
5
|
Li Y, Jongberg S, Andersen ML, Davies MJ, Lund MN. Quinone-induced protein modifications: Kinetic preference for reaction of 1,2-benzoquinones with thiol groups in proteins. Free Radic Biol Med 2016; 97:148-157. [PMID: 27212016 DOI: 10.1016/j.freeradbiomed.2016.05.019] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/11/2016] [Accepted: 05/18/2016] [Indexed: 12/23/2022]
Abstract
Oxidation of polyphenols to quinones serves as an antioxidative mechanism, but the resulting quinones may induce damage to proteins as they react through a Michael addition with nucleophilic groups, such as thiols and amines to give protein adducts. In this study, rate constants for the reaction of 4-methylbenzoquinone (4MBQ) with proteins, thiol and amine compounds were determined under pseudo first-order conditions by UV-vis stopped-flow spectrophotometry. The chemical structures of the adducts were identified by LC-ESI-MS/MS. Proteins with free thiols were rapidly modified by 4MBQ with apparent second order rate constants, k2 of (3.1±0.2)×10(4)M(-1)s(-1) for bovine serum albumin (BSA) and (4.8±0.2)×10(3)M(-1)s(-1) for human serum albumin at pH 7.0. These values are at least 12-fold greater than that for α-lactalbumin (4.0±0.2)×10(2)M(-1)s(-1), which does not contain any free thiols. Reaction of Cys-34 of BSA with N-ethylmaleimide reduced the thiol concentration by ~59%, which resulted in a decrease in k2 by a similar percentage, consistent with rapid adduction at Cys-34. Reaction of 4MBQ with amines (Gly, Nα-acetyl-l-Lys, Nε-acetyl-l-Lys and l-Lys) and the guanidine group of Nα-acetyl-l-Arg was at least 5×10(5) slower than with low-molecular-mass thiols (l-Cys, Nα-acetyl-l-Cys, glutathione). The thiol-quinone interactions formed colorless thiol-phenol products via an intermediate adduct, while the amine-quinone interactions generated colored amine-quinone products that require oxygen involvement. These data provide strong evidence for rapid modification of protein thiols by quinone species which may be of considerable significance for biological and food systems.
Collapse
Affiliation(s)
- Yuting Li
- School of Food Science and Technology, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510640, China; Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark; Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, China.
| | - Sisse Jongberg
- Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
| | - Mogens L Andersen
- Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
| | - Michael J Davies
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| | - Marianne N Lund
- Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark; Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.
| |
Collapse
|
6
|
Li M, Teesch LM, Murry DJ, Pope RM, Li Y, Robertson LW, Ludewig G. Cytochrome c adducts with PCB quinoid metabolites. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:2148-59. [PMID: 26062463 PMCID: PMC4676959 DOI: 10.1007/s11356-015-4801-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 05/27/2015] [Indexed: 04/15/2023]
Abstract
Polychlorinated biphenyls (PCBs) are a group of 209 individual congeners widely used as industrial chemicals. PCBs are found as by-products in dye and paint manufacture and are legacy, ubiquitous, and persistent as human and environmental contaminants. PCBs with fewer chlorine atoms may be metabolized to hydroxy- and dihydroxy-metabolites and further oxidized to quinoid metabolites both in vitro and in vivo. Specifically, quinoid metabolites may form adducts on nucleophilic sites within cells. We hypothesized that the PCB-quinones covalently bind to cytochrome c and, thereby, cause defects in the function of cytochrome c. In this study, synthetic PCB quinones, 2-(4'-chlorophenyl)-1,4-benzoquinone (PCB3-pQ), 4-4'-chlorophenyl)-1,2-benzoquinone (PCB3-oQ), 2-(3', 5'-dichlorophenyl)-1,4-benzoquinone, 2-(3',4', 5'-trichlorophenyl)-1,4-benzoquinone, and 2-(4'-chlorophenyl)-3,6-dichloro-1,4-benzoquinone, were incubated with cytochrome c, and adducts were detected by liquid chromatography-mass spectrometry (LC-MS) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was employed to separate the adducted proteins, while trypsin digestion and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied to identify the amino acid binding sites on cytochrome c. Conformation change of cytochrome c after binding with PCB3-pQ was investigated by SYBYL-X simulation and cytochrome c function was examined. We found that more than one molecule of PCB-quinone may bind to one molecule of cytochrome c. Lysine and glutamic acid were identified as the predominant binding sites. Software simulation showed conformation changes of adducted cytochrome c. Additionally, cross-linking of cytochrome c was observed on the SDS-PAGE gel. Cytochrome c was found to lose its function as electron acceptor after incubation with PCB quinones. These data provide evidence that the covalent binding of PCB quinone metabolites to cytochrome c may be included among the toxic effects of PCBs.
Collapse
Affiliation(s)
- Miao Li
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA
| | - Lynn M Teesch
- High Resolution Mass Spectrometry Facility, The University of Iowa, Iowa City, IA, USA
| | - Daryl J Murry
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- College of Pharmacy, The University of Iowa, Iowa City, IA, USA
| | - R Marshal Pope
- Proteomics Facility, The University of Iowa, Iowa City, IA, USA
| | - Yalan Li
- Proteomics Facility, The University of Iowa, Iowa City, IA, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, Graduate College, The University of Iowa, Iowa City, IA, USA.
- Department of Occupational & Environmental Health, College of Public Health, The University of Iowa, 100 Oakdale Campus 214 IREH, Iowa City, IA, 52242-5000, USA.
| |
Collapse
|
7
|
Grimm FA, Hu D, Kania-Korwel I, Lehmler HJ, Ludewig G, Hornbuckle KC, Duffel MW, Bergman A, Robertson LW. Metabolism and metabolites of polychlorinated biphenyls. Crit Rev Toxicol 2015; 45:245-72. [PMID: 25629923 PMCID: PMC4383295 DOI: 10.3109/10408444.2014.999365] [Citation(s) in RCA: 282] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/11/2014] [Indexed: 11/13/2022]
Abstract
Abstract The metabolism of polychlorinated biphenyls (PCBs) is complex and has an impact on toxicity, and thereby on the assessment of PCB risks. A large number of reactive and stable metabolites are formed in the processes of biotransformation in biota in general, and in humans in particular. The aim of this document is to provide an overview of PCB metabolism, and to identify the metabolites of concern and their occurrence. Emphasis is given to mammalian metabolism of PCBs and their hydroxyl, methylsulfonyl, and sulfated metabolites, especially those that persist in human blood. Potential intracellular targets and health risks are also discussed.
Collapse
Affiliation(s)
- FA Grimm
- Interdisciplinary Graduate Program in Human Toxicology, Department of Pharmaceutical Sciences & Experimental Therapeutics, University of Iowa
| | - D Hu
- Department of Civil and Environmental Engineering, University of Iowa
| | - I Kania-Korwel
- Department of Occupational & Environmental Health, University of Iowa
| | - HJ Lehmler
- Interdisciplinary Graduate Program in Human Toxicology, Department of Occupational & Environmental Health, University of Iowa
| | - G Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, Department of Occupational & Environmental Health, University of Iowa
| | - KC Hornbuckle
- Interdisciplinary Graduate Program in Human Toxicology, Department of Civil and Environmental Engineering, University of Iowa
| | - MW Duffel
- Interdisciplinary Graduate Program in Human Toxicology, Department of Pharmaceutical Sciences & Experimental Therapeutics, University of Iowa
| | - A Bergman
- Swedish Toxicology Sciences Research Center (SWETOX), Forskargatan 20, SE-151 36 Södertälje, SWEDEN
| | - LW Robertson
- Interdisciplinary Graduate Program in Human Toxicology, Department of Occupational & Environmental Health, University of Iowa
| |
Collapse
|
8
|
Qin X, Lehmler HJ, Teesch LM, Robertson LW, Duffel MW. Chlorinated biphenyl quinones and phenyl-2,5-benzoquinone differentially modify the catalytic activity of human hydroxysteroid sulfotransferase hSULT2A1. Chem Res Toxicol 2013; 26:1474-85. [PMID: 24059442 DOI: 10.1021/tx400207q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Human hydroxysteroid sulfotransferase (hSULT2A1) catalyzes the sulfation of a broad range of environmental chemicals, drugs, and other xenobiotics in addition to endogenous compounds that include hydroxysteroids and bile acids. Polychlorinated biphenyls (PCBs) are persistent environmental contaminants, and oxidized metabolites of PCBs may play significant roles in the etiology of their adverse health effects. Quinones derived from the oxidative metabolism of PCBs (PCB-quinones) react with nucleophilic sites in proteins and also undergo redox cycling to generate reactive oxygen species. This, along with the sensitivity of hSULT2A1 to oxidative modification at cysteine residues, led us to hypothesize that electrophilic PCB-quinones react with hSULT2A1 to alter its catalytic function. Thus, we examined the effects of four phenylbenzoquinones on the ability of hSULT2A1 to catalyze the sulfation of the endogenous substrate, dehydroepiandrosterone (DHEA). The quinones studied were 2'-chlorophenyl-2,5-benzoquinone (2'-Cl-BQ), 4'-chlorophenyl-2,5-benzoquinone (4'-Cl-BQ), 4'-chlorophenyl-3,6-dichloro-2,5-benzoquinone (3,6,4'-triCl-BQ), and phenyl-2,5-benzoquinone (PBQ). At all concentrations examined, pretreatment of hSULT2A1 with the PCB-quinones decreased the catalytic activity of hSULT2A1. Pretreatment with low concentrations of PBQ, however, increased the catalytic activity of the enzyme, while higher concentrations inhibited catalysis. A decrease in substrate inhibition with DHEA was seen following preincubation of hSULT2A1 with all of the quinones. Proteolytic digestion of the enzyme followed by LC/MS analysis indicated PCB-quinone- and PBQ-adducts at Cys55 and Cys199, as well as oxidation products at methionines in the protein. Equilibrium binding experiments and molecular modeling suggested that changes due to these modifications may affect the nucleotide binding site and the entrance to the sulfuryl acceptor binding site of hSULT2A1.
Collapse
Affiliation(s)
- Xiaoyan Qin
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa , Iowa City, Iowa 52242, United States
| | | | | | | | | |
Collapse
|
9
|
Ludewig G, Robertson LW. Polychlorinated biphenyls (PCBs) as initiating agents in hepatocellular carcinoma. Cancer Lett 2013; 334:46-55. [PMID: 23211541 PMCID: PMC3648605 DOI: 10.1016/j.canlet.2012.11.041] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 11/20/2012] [Accepted: 11/25/2012] [Indexed: 12/11/2022]
Abstract
PCBs are carcinogens, but for many decades it was assumed that PCBs may not possess initiating activity. Initiation is a process that involves changes in the DNA sequence, often, but not exclusively produced through DNA adduction by a reactive compound or reactive oxygen species (ROS). DNA adducts can be detected by (32)P-postlabeling, a method that Dr. Ramesh Gupta co-developed and refined. Today these types of assays together with other mechanistic studies provide convincing evidence that specific PCB congeners can be biotransformed to genotoxic and therefore potentially initiating metabolites. This review will provide an overview of our current knowledge of PCBs' genotoxic potential and mechanism of action, emphasizing the contributions of Dr. Ramesh Gupta during his tenures at the Universities of Kentucky and Louisville.
Collapse
Affiliation(s)
- Gabriele Ludewig
- The University of Iowa, 100 Oakdale Campus, IREH, Iowa City, IA 52242-5000, United States.
| | - Larry W Robertson
- The University of Iowa, 100 Oakdale Campus, IREH, Iowa City, IA 52242-5000, United States
| |
Collapse
|
10
|
Dhakal K, He X, Lehmler HJ, Teesch LM, Duffel MW, Robertson LW. Identification of sulfated metabolites of 4-chlorobiphenyl (PCB3) in the serum and urine of male rats. Chem Res Toxicol 2012; 25:2796-804. [PMID: 23137097 DOI: 10.1021/tx300416v] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polychlorinated biphenyls (PCBs) are legacy pollutants that exert toxicities through various mechanisms. In recent years exposure to PCBs via inhalation has been recognized as a hazard. Those PCBs with lower numbers of chlorine atoms (LC-PCBs) are semivolatile and have been reported in urban air, as well as in the indoor air of older buildings. LC-PCBs are bioactivated to phenols and further to quinone electrophiles with genotoxic/carcinogenic potential. We hypothesized that phenolic LC-PCBs are subject to conjugation and excretion in the urine. PCB3, often present in high concentrations in air, is a prototypical congener for the study of the metabolism and toxicity of LC-PCBs. Our objective was to identify metabolites of PCB3 in urine that could be potentially employed in the estimation of exposure to LC-PCBs. Male Sprague-Dawley rats (150-175 g) were housed in metabolism cages and received a single intraperitoneal injection of 600 μmol/kg body weight of PCB3. Urine was collected every 4 h; rats were euthanized at 36 h; and serum was collected. LC/MS analysis of urine before and after incubation with β-glucuronidase and sulfatase showed that sulfate conjugates were in higher concentrations than glucuronide conjugates and free phenolic forms. At least two major metabolites and two minor metabolites were identified in urine that could be attributed to mercapturic acid metabolites of PCB3. Quantitation by authentic standards confirmed that approximately 3% of the dose was excreted in the urine as sulfates over 36 h, with peak excretion occurring at 10-20 h after exposure. The major metabolites were 4'PCB3sulfate, 3'PCB3 sulfate, 2'PCB3 sulfate, and presumably a catechol sulfate. The serum concentration of 4'PCB3 sulfate was 6.18 ± 2.16 μg/mL. This is the first report that sulfated metabolites of PCBs are formed in vivo. These findings suggest a prospective approach for exposure assessment of LC-PCBs by analysis of phase II metabolites in urine.
Collapse
Affiliation(s)
- Kiran Dhakal
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, Iowa 52242, United States
| | | | | | | | | | | |
Collapse
|
11
|
Liu J, Song E, Liu L, Ma X, Tian X, Dong H, Song Y. Polychlorinated biphenyl quinone metabolites lead to oxidative stress in HepG2 cells and the protective role of dihydrolipoic acid. Toxicol In Vitro 2012; 26:841-8. [DOI: 10.1016/j.tiv.2012.04.028] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 04/18/2012] [Accepted: 04/30/2012] [Indexed: 10/28/2022]
|
12
|
Recio-Vega R, Mendez-Henandez A, Gabriel APY, Jacobo-Avila A, Portales-Castanedo A, Hernandez-Gonzalez S, Gallegos-Arreola MP, Ocampo-Gomez G. Potentially estrogenic polychlorinated biphenyls congeners serum levels and its relation with lung cancer. J Appl Toxicol 2012; 33:906-14. [DOI: 10.1002/jat.2763] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/06/2012] [Accepted: 03/07/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Rogelio Recio-Vega
- Centro de Investigación Biomédica, Facultad de Medicina, Unidad Torreón; Universidad Autónoma de Coahuila; México
| | - Alejandra Mendez-Henandez
- Centro de Investigación Biomédica, Facultad de Medicina, Unidad Torreón; Universidad Autónoma de Coahuila; México
| | | | | | | | | | - Martha Patricia Gallegos-Arreola
- Molecular Genetics Laboratory, Division of Molecular Medicine; Centro de Investigación Biomédica de Occidente; Guadalajara; Jalisco; Mexico
| | - Guadalupe Ocampo-Gomez
- Centro de Investigación Biomédica, Facultad de Medicina, Unidad Torreón; Universidad Autónoma de Coahuila; México
| |
Collapse
|
13
|
Ambati J, Song Y, Rankin SE, Lehmler HJ. Density Functional Theory Study of Semiquinone Radical Anions of Polychlorinated Biphenyls in the Syn- and Anti-like Conformation. J Phys Chem A 2012; 116:1586-95. [DOI: 10.1021/jp2077193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jyothirmai Ambati
- Department
of Chemical and Materials
Engineering, University of Kentucky, Lexington,
Kentucky 40506-0046, United States
| | - Yang Song
- College of Pharmaceutical Sciences, Southwest University, Chong Qing, 400716, P.R. China
- Department of Occupational and
Environmental Health, The University of Iowa, UI Research Park, Iowa City, Iowa 52242-5000, United States
| | - Stephen E. Rankin
- Department
of Chemical and Materials
Engineering, University of Kentucky, Lexington,
Kentucky 40506-0046, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and
Environmental Health, The University of Iowa, UI Research Park, Iowa City, Iowa 52242-5000, United States
- Interdisciplinary Graduate Program
in Human Toxicology, The University of Iowa, Iowa City, Iowa 52242-5000, United States
| |
Collapse
|
14
|
Gurbani D, Kukshal V, Laubenthal J, Kumar A, Pandey A, Tripathi S, Arora A, Jain SK, Ramachandran R, Anderson D, Dhawan A. Mechanism of inhibition of the ATPase domain of human topoisomerase IIα by 1,4-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, and 9,10-phenanthroquinone. Toxicol Sci 2012; 126:372-90. [PMID: 22218491 DOI: 10.1093/toxsci/kfr345] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The inhibition of human topoisomerase IIα (Hu-TopoIIα), a major enzyme involved in maintaining DNA topology, repair, and chromosome condensation/decondensation results in loss of genomic integrity. In the present study, the inhibition of ATPase domain of Hu-TopoIIα as a possible mechanism of genotoxicity of 1,4-benzoquinone (BQ), hydroquinone (HQ), naphthoquinone (1,2-NQ and 1,4-NQ), and 9,10-phenanthroquinone (9,10-PQ) was investigated. In silico modeling predicted that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ could interact with Ser-148, Ser-149, Asn-150, and Asn-91 residues of the ATPase domain of Hu-TopoIIα. Biochemical inhibition assays with the purified ATPase domain of Hu-TopoIIα revealed that 1,4-BQ is the most potent inhibitor followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ. Ligand-binding studies using isothermal titration calorimetry revealed that 1,4-BQ, HQ, 1,4-NQ, 1,2-NQ, and 9,10-PQ enter into four sequentially binding site models inside the domain. 1,4-BQ exhibited the strongest binding, followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ, as revealed by their average K(d) values. The cellular fate of such inhibition was further evidenced by an increase in the number of Hu-TopoIIα-DNA cleavage complexes in the human lung epithelial cells (BEAS-2B) using trapped in agarose DNA immunostaining (TARDIS) assay, which utilizes antibody specific for Hu-TopoIIα. Furthermore, the increase in γ-H2A.X levels quantitated by flow cytometry and visualized by immunofluorescence microscopy illustrated that accumulation of DNA double-strand breaks inside the cells can be attributed to the inhibition of Hu-TopoIIα. These findings collectively suggest that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ inhibit the ATPase domain and potentially result in Hu-TopoIIα-mediated clastogenic and leukemogenic events.
Collapse
Affiliation(s)
- Deepak Gurbani
- Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Song Y, Ambati J, Parkin S, Rankin SE, Robertson LW, Lehmler HJ. Crystal structure and density functional theory studies of toxic quinone metabolites of polychlorinated biphenyls. CHEMOSPHERE 2011; 85:386-392. [PMID: 21824639 PMCID: PMC3206982 DOI: 10.1016/j.chemosphere.2011.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/29/2011] [Accepted: 07/06/2011] [Indexed: 05/31/2023]
Abstract
Lower chlorinated polychlorinated biphenyls (PCBs) are readily metabolized via hydroxylated metabolites to reactive PCB quinones. Although these PCB metabolites elicit biochemical changes by mechanisms involving cellular target molecules, such as the aryl hydrocarbon receptor, and toxicity by interacting with enzymes like topoisomerases, only few PCB quinones have been synthesized and their conformational properties investigated. Similar to the parent compounds, knowledge of the three-dimensional structure of PCB quinones may therefore be important to assess their fate and risk. To address this gap in our knowledge, the gas phase molecular structure of a series of PCB quinones was predicted using HF/3-21G, B3LYP/6-31G∗∗ and UB3LYP/6-311G∗∗ calculations and compared to the respective solid state structure. All three methods overestimated the Cl-C bond length, but otherwise provided a reasonable approximation of the solid state bond angles and bond lengths. Overall, the UB3LYP/6-311G∗∗ level of theory yielded the best approximation of the molecular structure of PCB quinones in the solid state. Chlorine addition at the ortho position of both rings was found to increase the dihedral angle of the resulting quinone compound, which may have important implications for their interaction with cellular targets and, thus, their toxicity.
Collapse
Affiliation(s)
- Yang Song
- Key Laboratory on Luminescence and Real-Time Analysis (Ministry of Education), College of Pharmaceutical Sciences, Southwest University, Chong Qing, 400716, P.R. China
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
| | - Jyothirmai Ambati
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Sean Parkin
- Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Stephen E. Rankin
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Larry W. Robertson
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
| |
Collapse
|
16
|
Tian Y, Ye S, Shi X, Jing L, Liang C, Xian Y. An electrochemical platform for acetylcholinesterase activity assay and inhibitors screening based on Michael addition reaction between thiocholine and catechol-terminated SAMs. Analyst 2011; 136:5084-90. [DOI: 10.1039/c1an15601b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
17
|
Xie W, Wang K, Robertson LW, Ludewig G. Investigation of mechanism(s) of DNA damage induced by 4-monochlorobiphenyl (PCB3) metabolites. ENVIRONMENT INTERNATIONAL 2010; 36:950-61. [PMID: 20129669 PMCID: PMC2888624 DOI: 10.1016/j.envint.2009.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 12/01/2009] [Accepted: 12/20/2009] [Indexed: 05/21/2023]
Abstract
4-Monochlorobiphenyl (PCB3) is readily converted by xenobiotic-metabolizing enzymes to dihydroxy-metabolites and quinones. The PCB3 hydroquinone (PCB3-HQ; 2-(4'-chlorophenyl)-1,4-hydroquinone) induces chromosome loss in Chinese Hamster V79 cells, whereas the para-quinone (PCB3-pQ; 2-(4'-chlorophenyl)-1,4-benzoquinone) very efficiently induces gene mutations and chromosome breaks. Apparently, each of these two metabolites, which are a redox pair, has a different spectrum of genotoxic effects due to different, metabolite-specific mechanisms. We hypothesized that the HQ requires enzymatic activation by peroxidases with the formation of reactive oxygen species (ROS) as the ultimate genotoxin, whereas the pQ reacts directly with nucleophilic sites in DNA and/or proteins. To examine this hypothesis, we employed two cell lines with different myeloperoxidase (MPO) activities, MPO-rich HL-60 and MPO-deficient Jurkat cells, and measured cytotoxicity, DNA damage (COMET assay), MPO activity, intracellular levels of reactive oxygen species (ROS) and intracellular free -SH groups (monochlorobimane assay, MCB) and free GSH contents (enzyme recycling method) after treatment with PCB3-HQ and PCB3-pQ. We also examined the modulation of these effects by normal/low temperature, pre-treatment with an MPO inhibitor (succinylacetone, SA), or GSH depletion. PCB3-p-Q increased intracellular ROS levels and induced DNA damage in both HL-60 and Jurkat cells at 37°C and 6°C, indicating a direct, MPO-independent mode of activity. It also strongly reduced intracellular free -SH groups and GSH levels in normal and GSH-depleted cells. Thus the ROS increase could be caused by reduced protection by GSH or non-enzymatic autoxidation of the resulting PCB3-HQ-GSH adduct. PCB3-HQ did not produce a significant reduction of intracellular GSH in HL-60 cells and reduced intracellular free -SH groups only at the highest concentration tested in GSH depleted cells. Moreover, PCB3-HQ induced DNA damage and ROS production only at 37 °C in HL-60 cells, not at 6 °C or in Jurkat cells at either temperature; no significant DNA damage and ROS production was observed in HL-60 cells at 37 °C if MPO activity was inhibited by SA. These studies show that the effects of PCB3-HQ are enzyme dependent, i.e. PCB3-HQ is oxidized by MPO in HL-60 cells with the generation of ROS and induction of DNA damage. However, this is not the case with the PCB3-pQ, which may produce DNA damage by the reactivity of the quinone with the DNA or nuclear proteins, or possibly by indirectly increasing intracellular ROS levels by GSH depletion. These different modes of action explain not only the different types of genotoxicity observed previously, but also suggest different organ specificity of these genotoxins.
Collapse
Affiliation(s)
- Wei Xie
- Department of Occupational and Environmental Health, College of Public Health, Iowa City, Iowa 52242, USA
| | - Kai Wang
- Department of Biostatistics University of Iowa, College of Public Health, Iowa City, Iowa 52242, USA
| | - Larry W. Robertson
- Department of Occupational and Environmental Health, College of Public Health, Iowa City, Iowa 52242, USA
| | - Gabriele Ludewig
- Department of Occupational and Environmental Health, College of Public Health, Iowa City, Iowa 52242, USA
| |
Collapse
|
18
|
Liu Y, Smart JT, Song Y, Lehmler HJ, Robertson LW, Duffel MW. Structure-activity relationships for hydroxylated polychlorinated biphenyls as substrates and inhibitors of rat sulfotransferases and modification of these relationships by changes in thiol status. Drug Metab Dispos 2009; 37:1065-72. [PMID: 19196841 PMCID: PMC2677757 DOI: 10.1124/dmd.108.026021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Accepted: 01/29/2009] [Indexed: 11/22/2022] Open
Abstract
Hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) are inhibitors and substrates for various human sulfotransferases (SULTs). Although the rat is often used in toxicological studies on PCBs, the interactions of OH-PCBs with rat SULTs are less well understood. In the present study, 15 OH-PCBs were investigated as potential substrates or inhibitors of purified recombinant rSULT1A1 and rSULT2A3, the major family 1 and family 2 SULTs present in rat liver, respectively. None of these OH-PCBs were substrates for rSULT2A3, 11 weakly inhibited rSULT2A3-catalyzed sulfation of dehydroepiandrosterone, and 4 had no effect on the reaction. With rSULT1A1, 4-OH-PCB 8, 4'-OH-PCB 3, 9, 12, 35, and 6'-OH-PCB 35 were substrates, whereas 4'-OH-PCB 6, 4-OH-PCB 14, 4'-OH-PCB 25, 4'-OH-PCB 33, 4-OH-PCB 34, 4-OH-PCB36, 4'-OH-PCB 36, 4'-OH-PCB 68, and 4-OH-PCB 78 inhibited the sulfation of 2-naphthol catalyzed by this enzyme. OH-PCBs with a 3,5-dichloro-4-hydroxy substitution were the most potent inhibitors of rSULT1A1, and the placement of chlorine atoms in the ortho- and meta-positions on either ring of para-OH-PCBs resulted in significant differences in activity as substrates and inhibitors. The specificity of rSULT1A1 for several inhibitory OH-PCBs was altered by pretreatment of the enzyme with oxidized glutathione (GSSG). Four OH-PCBs that were inhibitors of rSULT1A1 under reducing conditions became substrates after pretreatment of the enzyme with GSSG. This alteration in specificity of rSULT1A1 for certain OH-PCBs suggests that conditions of oxidative stress may significantly alter the sulfation of some OH-PCBs in the rat.
Collapse
Affiliation(s)
- Yungang Liu
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA
| | | | | | | | | | | |
Collapse
|
19
|
Topoisomerase II inhibition involves characteristic chromosomal expression patterns. BMC Genomics 2008; 9:324. [PMID: 18611269 PMCID: PMC2488358 DOI: 10.1186/1471-2164-9-324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 07/08/2008] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The phenomenon of co-localization of transcriptionally upregulated genes showing similar expression levels is known across all eukaryotic genomes. We recently mapped the Aroclor 1254-regulated transcriptome back onto the genome and provided evidence for the statistically significant co-localization of regulated genes. They did, however, not always show similar expression levels, and many of the regulated genes were, in fact, repressed. RESULTS In this study, we were able to reproduce this observation with microarray data stemming from 1) human hepatocytes treated with the gyrase and potential topoisomerase II inhibitor trovafloxacin, 2) human hepatocytes treated with the topoisomerase II inhibitor doxorubicin and 3) mouse lymphoma cells treated with the topoisomerase II inhibitor etoposide. We found statistically significant co-localization of regulated gene pairs--induced and repressed--within the window size of 0-100 kbp. Notably, by using microarray data stemming from lung tissue of a mouse transgenic line overexpressing the transcription factor c-myc, which served as a negative control, we found regulated genes to be located with regard to each other nearly in the same way as genes distributed randomly all over the genome (0-100 kbp). CONCLUSION We suggest topoisomerase II inhibition by Aroclor 1254, trovafloxacin, doxorubicin, and etoposide to be responsible for significant co-localization of regulated genes through the inability of the stabilized enzyme complexes to religate DNA. Within the permanently opened chromatin domains, neighbored genes might be allowed to be regulated. Overexpression of c-myc, however, does not inhibit topoisomerase II activity. Consequently, the enzyme is able to perform its normal function of transiently breaking and rejoining the DNA double strand. As a result, exclusively target genes are regulated.
Collapse
|
20
|
Different effects of PCB101, PCB118, PCB138 and PCB153 alone or mixed in MCF-7 breast cancer cells. Food Chem Toxicol 2008; 46:2561-7. [DOI: 10.1016/j.fct.2008.04.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 04/07/2008] [Accepted: 04/08/2008] [Indexed: 11/20/2022]
|
21
|
Maddox C, Wang B, Kirby PA, Wang K, Ludewig G. Mutagenicity of 3-methylcholanthrene, pcb3, and 4-oh-pcb3 in the lung of transgenic bigblue rats. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:260-6. [PMID: 18438460 PMCID: PMC2346436 DOI: 10.1016/j.etap.2007.10.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Recent findings of high levels of predominantly lower chlorinated biphenyls in indoor and outdoor air open the question of possible health consequences. Lower chlorinated biphenyls are more readily metabolized to reactive and potentially harmful intermediates, acting as mutagens and cancer initiators. The goal of this study was to assess the mutagenicity of PCB3 in the lungs of rats. Male BigBlue® 334 Fisher transgenic rats, which carry the bacterial lacI gene as a target of mutagenicity, were given intraperitoneal injections of corn oil, 3-methylcholanthrene (3-MC, positive control), 4-monochlorobiphenyl (PCB3) or its metabolite 4-hydroxy-PCB3 (4-OH-PCB3) weekly for 4 weeks. Lungs tissue was harvested to determine mutant frequencies, mutation spectra, and pathological changes. 3-MC caused a 15-fold increase in mutant frequency and an increase in transversion type mutations; a very early occurrence of this type of mutation in lung tissue was previously identified in Ki-ras oncogenes of lung tumors from 3-MC exposed mice. The 2-fold increase in the mutant frequency after treatment with PCB3 and 4-OH-PCB3 was not statistically significant, but a shift in the mutation spectra, especially with PCB3, and an increase in mutations outside of the hotspot region for spontaneous mutations (bp 1-400), suggest that PCB3 and possibly 4-OH-PCB3 are mutagenic in the rat lung.
Collapse
Affiliation(s)
- Catherine Maddox
- Dept Occupational & Environmental Health, College of Public Health, The University of Iowa, Iowa City, IA, USA
| | | | | | | | | |
Collapse
|
22
|
Jacobus J, Flor S, Klingelhutz A, Robertson L, Ludewig G. 2-(4'-CHLOROPHENYL)-1,4-BENZOQUINONE INCREASES THE FREQUENCY OF MICRONUCLEI AND SHORTENS TELOMERES. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:267-272. [PMID: 18438462 PMCID: PMC2346440 DOI: 10.1016/j.etap.2007.10.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The toxicity of polychlorinated biphenyls (PCBs) has been attributed widely to receptor-mediated effects, buttressed by the popularity of the Toxic Equivalency Factor. We propose that a crucial toxic mechanism of lower-chlorinated PCBs is their enzymatic biotransformation to electrophiles, including quinoid metabolites, that bind intracellular sulfhydryl groups, such as those found in microtubulin and enzymes like telomerase. To test this hypothesis, we have examined micronuclei induction, cell cycle, and telomere shortening in cells in culture. Our findings show a large increase in micronuclei frequency and cell cycle perturbation in V79 cells, and a marked decrease in telomere length in HaCaT cells exposed to 2-(4'-chlorophenyl)-1,4-benzoquinone (PCB3pQ).
Collapse
Affiliation(s)
- J.A. Jacobus
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
| | - S. Flor
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
| | | | - L.W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
| | - G. Ludewig
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Address all correspondence to: Dr. Gabriele Ludewig, Department of Occupational & Environmental Health, College of Public Health, University of Iowa, 100 Oakdale Campus, #234 IREH, Iowa City, IA 52242-5000, Phone: 319/335-4650, Fax: 319/335-4290, e-mail:
| |
Collapse
|
23
|
Alonso M, Casado S, Miranda C, Tarazona JV, Navas JM, Herradón B. Decabromobiphenyl (PBB-209) activates the aryl hydrocarbon receptor while decachlorobiphenyl (PCB-209) is inactive: experimental evidence and computational rationalization of the different behavior of some halogenated biphenyls. Chem Res Toxicol 2008; 21:643-58. [PMID: 18311929 DOI: 10.1021/tx700362u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In rat H4IIE cells permanently transfected with a luciferase gene under the control of AhR, incubation with PBB-209 led to a statistically significant increase of luminescence. In this system, PCB-209 only caused a small induction of luciferase activity. In a fish cell line, only PBB-209 was able to provoke an induction of ethoxyresorufin- O-deethylase activity. Ligand binding to the AhR was studied by means of a cell-free in vitro system in which the activation of AhR is very unlikely to occur without ligand binding. None of the biphenyls studied provoked any activation of AhR in this system. To rationalize the results and to get insight into the molecular mechanism of activation of AhR by PBB-209 as compared with PCB-209, a comprehensive computational study was carried out on these congeners as well as on PCB-126 and PCB-169, two potent AhR activators through ligand binding. The calculations include (i) conformational analysis and dipole moments of each conformer, (ii) aromaticity indices, (iii) molecular electrostatic potentials, (iv) quadrupole moments, (v) electronic and reactivity descriptors, and (vi) dissociation energies of C-Cl and C-Br bonds in model aromatic compounds. It was found that some molecular features of PBB-209, such as the electrostatic potential (EP) and EP-derived descriptors (Politzer's parameters), indicate that PBB-209 is more similar to PCB-126 and PCB-169 than to PCB-209, which share quite similar geometries based on the substitution pattern. The similarity between PBB-209, PCB-126, and PCB-169 seems to hint that these three compounds can share, at least partially, similar mechanisms of activation of AhR. It is unquestionable that PCB-126 and PCB-169 directly bind AhR and PBB-209 does not. We hypothesize that there are several simultaneous mechanisms for activation of AhR, and the most active compounds act for more than one mechanism.
Collapse
Affiliation(s)
- Mercedes Alonso
- Instituto de Química Orgánica General, CSIC, Juan de la Cierva 3, E-28006 Madrid, Spain
| | | | | | | | | | | |
Collapse
|
24
|
Ludewig G, Lehmann L, Esch H, Robertson LW. Metabolic Activation of PCBs to Carcinogens in Vivo - A Review. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:241-6. [PMID: 18452002 PMCID: PMC2364599 DOI: 10.1016/j.etap.2007.10.029] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many higher-chlorinated biphenyls, persistent and predominant in foods, are active as promoters in hepatocarcinogenesis. Lower-chlorinated biphenyls, predominating in indoor and outdoor air, are more readily metabolized and therefore shorter lived, 'episodic' contaminants. Thus inhalation of such lower chlorinated biphenyls may expose humans to reactive, possibly genotoxic/carcinogenic intermediates. Lower chlorinated biphenyls may be metabolized via arene-oxides to mono- and dihydroxylated intermediates and further to (semi)quinones, highly reactive intermediates. Covalently bound lower chlorinated biphenyls have been detected in rodent tissues in vivo. We recently showed using the modified Solt-Farber foci assay that several mono- to tetrachlorinated biphenyls have initiating activity in the livers of rats. In a follow-up study of PCB3 (4-chlorobiphenyl) metabolites only one monohydroxy- and one quinoid- metabolite showed initiating activity, indicating that the metabolic activation of PCB3 proceeds via hydroxylation and oxidation to the 3,4-quinone, the ultimate carcinogen. Since cancer initiation is based on genotoxic event(s), we hypothesized that PCB3 and/or its metabolite(s) are mutagenic in rat liver in vivo. To investigate this, BigBlue® rats, transgenic for the lacI reporter gene, were exposed to PCB3 and 4-hydroxy-PCB3 (4-HO-PCB3). In male rats the mutant frequency (MF) of lac I in the liver was significantly elevated and the mutation spectrum differed significantly from the control. 4-HO-PCB3 caused a non-significant (p = 0.115) doubling of the MF compared to the control. These studies prove that lower halogenated biphenyls may be metabolically activated in vivo to genotoxic and initiating intermediates.
Collapse
Affiliation(s)
- Gabriele Ludewig
- Department of Occupational & Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, USA
- Address all correspondence to: Dr. Gabriele Ludewig, Department of Occupational & Environmental Health, College of Public Health, University of Iowa, 100 Oakdale Campus, #234 IREH, Iowa City, IA 52242-5000, Phone: 319/335-4650, Fax: 319/335-4290, e-mail:
| | | | | | - Larry W. Robertson
- Department of Occupational & Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
25
|
Pacsial-Ong EJ, McCarley RL, Wang W, Strongin RM. Electrochemical detection of glutathione using redox indicators. Anal Chem 2007; 78:7577-81. [PMID: 17073429 PMCID: PMC2662349 DOI: 10.1021/ac061451q] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nucleophilic addition of the aminothiols homocysteine (HCY), cysteine (CYS), and glutathione (GSH) to the electrogenerated quinone of fluorone black (1) via the ECE mechanism is reported. It is demonstrated that 1selectively reacts with GSH to form the bis-GSH adduct, 1-(GSH)(2), while only the monothiol adducts were generated in the presence of HCY and CYS (1-HCY and 1-CYS, respectively). The more anodic E(pa) of 1-(GSH)2 relative to 1 and 1-GSH (DeltaE(pa) approximately +0.14) is the voltammetric signature that allows the discrimination of GSH from HCY and CYS. It is also shown that the presence of structurally similar aminothiols-HCY and CYS-posed no interference to the signature voltammetric response of 1-(GSH)2.
Collapse
Affiliation(s)
| | - Robin L. McCarley
- Corresponding author. Telephone: +1-225-578-3239. Fax: +1-225-578-3458. E-mail:
| | | | | |
Collapse
|
26
|
Sadeghi-Aliabadi H, Chan K, Lehmler HJ, Robertson LW, O'Brien PJ. Molecular cytotoxic mechanisms of catecholic polychlorinated biphenyl metabolites in isolated rat hepatocytes. Chem Biol Interact 2007; 167:184-92. [PMID: 17408604 DOI: 10.1016/j.cbi.2007.02.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 02/13/2007] [Accepted: 02/15/2007] [Indexed: 11/21/2022]
Abstract
Polychlorinated biphenyl (PCB) and PCB metabolites are highly lipophilic and accumulate easily in the lipid bilayer and fat deposits of the body. The molecular cytotoxic mechanisms of these metabolites are still not understood. The aim of the present study was to compare the cytotoxicity and toxicological properties of six dihydroxylated metabolites using isolated rat hepatocytes. All of the metabolites were more cytotoxic than 4-chlorobiphenyl (4-ClBP) and less cytotoxic than phenyl hydroquinone (PHQ). The order of cytotoxic effectiveness of catecholic metabolites expressed as LC(50) (2h) was 3',4'-diCl-2,3-diOH-biphenyl>PHQ>4'-Cl-2,5-diOH-biphenyl, 4'-Cl-2,3-diOH-biphenyl>2',5'-diCl-3,4-diOH-biphenyl>2',3'-diCl-3,4-diOH-biphenyl>3',4'-diCl-3,4-diOH-biphenyl>4'Cl-3,4-diOH-biphenyl>4'-Cl-biphenyl; showing that the positions of hydroxyl and chlorine groups were important for their hepatotoxicity and that the two 2,3-diOH congeners were the most cytotoxic. Cytotoxicity for 3,4-diOH metabolites correlated with the number and position of chlorine atoms with the more chlorine atoms being more cytotoxic. The cytotoxic order of metabolites with two chlorine atoms being 2',5'>2',3'>3',4'. Borneol, an uridine diphosphate glucuronosyltransferases (UGT) inhibitor, increased the cytotoxicity of all tested metabolites; suggesting that glucuronidation was a major mechanism of elimination of these compounds. On the other hand entacapone, a catechol-O-methyl transferase (COMT) inhibitor, only increased the cytotoxicity of 3',4'-diCl-3,4-diOH-biphenyl, 3',4'-diCl-2,3-diOH-biphenyl and 4'-Cl-2,3-diOH-biphenyl. Hepatocyte GSH was depleted (oxidized and conjugated) by these metabolites before cytotoxicity ensued in a similar order of effectiveness to their cytotoxicity with PHQ being the most effective. Hepatocyte mitochondrial membrane potential also decreased before cytotoxicity ensued with a similar order of effectiveness as their cytotoxicity. These results suggest that catecholic cytotoxicity can be attributed to mitochondrial toxicity and oxidative stress. Semiquinone or benzoquinone species were also important in the cytotoxicity of catecholic metabolites.
Collapse
Affiliation(s)
- Hojjat Sadeghi-Aliabadi
- Department of Medicinal Chemistry, School of Pharmacy, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | | | | | | |
Collapse
|
27
|
Bender RP, Ham AJL, Osheroff N. Quinone-induced enhancement of DNA cleavage by human topoisomerase IIalpha: adduction of cysteine residues 392 and 405. Biochemistry 2007; 46:2856-64. [PMID: 17298034 PMCID: PMC2896225 DOI: 10.1021/bi062017l] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several quinone-based metabolites of drugs and environmental toxins are potent topoisomerase II poisons. These compounds act by adducting the protein and appear to increase levels of enzyme-DNA cleavage complexes by at least two potentially independent mechanisms. Treatment of topoisomerase IIalpha with quinones inhibits DNA religation and blocks the N-terminal gate of the protein by cross-linking its two protomer subunits. It is not known whether these two effects result from adduction of quinone to the same amino acid residue(s) in topoisomerase IIalpha or whether they are mediated by modification of separate residues. Therefore, this study identified amino acid residues in human topoisomerase IIalpha that are modified by quinones and determined their role in the actions of these compounds as topoisomerase II poisons. Four cysteine residues were identified by mass spectrometry as sites of quinone adduction: Cys170, Cys392, Cys405, and Cys455. Mutations (Cys --> Ala) were individually generated at each position. Only mutations at Cys392 or Cys405 reduced sensitivity ( approximately 50% resistance) to benzoquinone. Top2alphaC392A and top2alphaC405A displayed faster rates ( approximately 2-fold) of DNA religation than wild-type topoisomerase IIalpha in the presence of the quinone. In contrast, as determined by DNA binding, protein clamp closing, and protomer cross-linking experiments, mutations at Cys392 and Cys405 did not affect the ability of benzoquinone to block the N-terminal gate of topoisomerase IIalpha. These findings indicate that adduction of Cys392 and Cys405 is important for the actions of quinones against the enzyme and increases levels of cleavage complexes primarily by inhibiting DNA religation.
Collapse
Affiliation(s)
| | | | - Neil Osheroff
- To whom correspondence should be addressed. Tel: 615-322-4338. Fax: 615-343-1166.
| |
Collapse
|
28
|
Stronati A, Manicardi GC, Cecati M, Bordicchia M, Ferrante L, Spanò M, Toft G, Bonde JP, Jönsson BAG, Rignell-Hydbom A, Rylander L, Giwercman A, Pedersen HS, Bonefeld-Jørgensen EC, Ludwicki JK, Lesovoy V, Sakkas D, Bizzaro D. Relationships between sperm DNA fragmentation, sperm apoptotic markers and serum levels of CB-153 and p,p′-DDE in European and Inuit populations. Reproduction 2006; 132:949-58. [PMID: 17127755 DOI: 10.1530/rep.1.01034] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Persistent organochlorine pollutants (POPs) are suspected to interfere with hormone activity and the normal homeostasis of spermatogenesis. We investigated the relationships between sperm DNA fragmentation, apoptotic markers identified on ejaculated spermatozoa and POP levels in the blood of 652 adult males (200 Inuits from Greenland, 166 Swedish, 134 Polish and 152 Ukrainian). Serum levels of 2, 2′, 4, 4′, 5, 5′-hexachlorobiphenyl (CB-153), as a proxy of the total POP burden, and of 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p′-DDE), as a proxy of the total DDT exposure were determined. Sperm DNA fragmentation was measured by using the TUNEL assay, whereas immunofluorescence methods were utilized for detecting pro-apoptotic (Fas) and anti-apoptotic (Bcl-xL) markers. Both TUNEL assay and apoptotic markers were statistically differed across the four populations. No correlation between neither sperm DNA fragmentation nor apoptotic sperm parameters and the large variations in POPs exposure was observed for the separate study groups. However, considering the European populations taken together, we showed that both %TUNEL positivity and Bcl-xL were related to CB-153 serum levels, whereas our study failed to demonstrate any relations between DDE and %TUNEL positivity and apoptotic sperm biomarkers (Fas and Bcl-xL) in any region or overall regions. These results suggest that CB-153 and related chemicals might alter sperm DNA integrity and Bcl-xL levels in European adult males, but not in the highly exposed Inuit men. Additional issues (genetic background, lifestyle habits and characterization of total xeno-hormonal activities) need to be investigated in order to fully assess the population variations observed.
Collapse
Affiliation(s)
- A Stronati
- Institute of Biology and Genetics, Marche Polytechnic University, Ancona, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Bittner S. When quinones meet amino acids: chemical, physical and biological consequences. Amino Acids 2006; 30:205-24. [PMID: 16601927 DOI: 10.1007/s00726-005-0298-2] [Citation(s) in RCA: 227] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 10/24/2005] [Indexed: 10/24/2022]
Abstract
Quinones and amino acids are usually compartmentally separated in living systems, however there are several junctions in which they meet, react and influence. It occurs mainly in wounded, cut or crushed plant material during harvest, ensiling or disintegrating cells. Diffusing polyphenols are oxidized by polyphenol oxidases (PPOs) to quinonic compounds, which associate reversibly or irreversibly with amino acids and proteins. The reaction takes place with the free nucleophilic functional groups such as sulfhydryl, amine, amide, indole and imidazole substituents. It results in imine formation, in 1,4-Michael addition via nitrogen or sulphur and in Strecker degradation forming aldehydes. The formation and activity of quinone-amino acids conjugates influences the colour, taste, and aroma of foods. Physical and physiological phenomena such as browning of foods, discoloration of plants during processing, alteration of solubility and digestibility, formation of humic substances, germicidal activity, cytotoxicity and more occur when quinones from disintegrating cells meet amino acids. The mechanisms of toxicity and the pathways by which PCBs may be activated and act as a cancer initiator include oxidation to the corresponding quinones and reaction with amino acids or peptides. Sclerotization of insect cuticle is a biochemical process involving also the reaction between quinones and amino acid derivatives.
Collapse
Affiliation(s)
- S Bittner
- Department of Chemistry, Ben Gurion University of the Negev, Beer Sheva, Israel.
| |
Collapse
|
30
|
Spanò M, Toft G, Hagmar L, Eleuteri P, Rescia M, Rignell-Hydbom A, Tyrkiel E, Zvyezday V, Bonde JP. Exposure to PCB and p, p′-DDE in European and Inuit populations: impact on human sperm chromatin integrity. Hum Reprod 2005; 20:3488-99. [PMID: 16223788 DOI: 10.1093/humrep/dei297] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Persistent organochlorine pollutants (POP), such as polychlorinated biphenyls (PCB) and dichlorodiphenyldichloroethylene (p, p'-DDE), are widely found in the environment and considered potential endocrine-disrupting compounds (EDC). Their impact on male fertility is still unknown. METHODS To explore the hypothesis that POP is associated with altered sperm chromatin integrity, a cross-sectional study involving 707 adult males (193 Inuits from Greenland, 178 Swedish fishermen, 141 men from Warsaw, Poland, and 195 men from Kharkiv, Ukraine) was carried out. Serum levels of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153), as a proxy of the total PCB burden, and of p,p'-DDE were determined. Sperm chromatin structure assay (SCSA) was used to assess sperm DNA/chromatin integrity. RESULTS We found a strong and monotonically increasing DNA fragmentation index with increasing serum levels of CB-153 among European but not Inuit men, reaching a 60% higher average level in the highest exposure group. No significant associations were found between SCSA-derived parameters and p, p'-DDE serum concentrations. CONCLUSION These results suggest that human dietary PCB exposure might have a negative impact on the sperm chromatin integrity of adult males but additional issues, including differences in the genetic background and lifestyle habits, still need to be elucidated.
Collapse
Affiliation(s)
- M Spanò
- Section of Toxicology and Biomedical Sciences, BIOTEC-MED, ENEA Casaccia, 00060 Rome, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|