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Stacpoole PW. Clinical physiology and pharmacology of GSTZ1/MAAI. Biochem Pharmacol 2023; 217:115818. [PMID: 37742772 DOI: 10.1016/j.bcp.2023.115818] [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: 07/06/2023] [Revised: 09/05/2023] [Accepted: 09/21/2023] [Indexed: 09/26/2023]
Abstract
Herein I summarize the physiological chemistry and pharmacology of the bifunctional enzyme glutathione transferase zeta 1 (GSTZ1)/ maleylacetoacetate isomerase (MAAI) relevant to human physiology, drug metabolism and disease. MAAI is integral to the catabolism of the amino acids phenylalanine and tyrosine. Genetic or pharmacological inhibition of MAAI can be pathological in animals. However, to date, no clinical disease consequences are unequivocally attributable to inborn errors of this enzyme. MAAI is identical to the zeta 1 family isoform of GST, which biotransforms the investigational drug dichloroacetate (DCA) to the endogenous compound glyoxylate. DCA is a mechanism-based inhibitor of GSTZ1 that significantly reduces its rate of metabolism and increases accumulation of potentially harmful tyrosine intermediates and of the heme precursor δ-aminolevulinic acid (δ-ALA). GSTZ1 is most abundant in rodent and human liver, with its concentration several fold higher in cytoplasm than in mitochondria. Its activity and protein expression are dependent on the age of the host and the intracellular level of chloride ions. Gene association studies have linked GSTZ1 or its protein product to various physiological traits and pathologies. Haplotype variations in GSTZ1 influence the rate of DCA metabolism, enabling a genotyping strategy to allow potentially safe, precision-based drug dosing in clinical trials.
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Affiliation(s)
- Peter W Stacpoole
- Departments of Medicine and Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL 32601, USA.
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2
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Fan Z, Jiang H, Song X, Guo Y, Tian X. Glutathione S-transferase Omega 2 DD genotype is associated with an increased risk of sporadic amyotrophic lateral sclerosis in Chinese men. J Int Med Res 2021; 49:3000605211033219. [PMID: 34311603 PMCID: PMC8320566 DOI: 10.1177/03000605211033219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Objective To investigate whether GSTA1, GSTO2, and GSTZ1 are relevant to an increased risk of amyotrophic lateral sclerosis (ALS) in a Chinese population. Methods In this study, 143 sporadic ALS (sALS) patients (83 men, 60 women) and 210 age- and sex-matched healthy subjects were enrolled. Blood samples were collected by venipuncture. Genomic DNA was isolated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) according to the manufacturer’s instructions. The potential associations between ALS and GSTA1, GSTO2, and GSTZ1 polymorphisms were estimated using chi-squared analysis and unconditional logistic regression. Results The D allele and genotype frequencies of GSTO2 were increased in sALS patients compared with healthy subjects, indicating that the GSTO2 DD genotype was associated with an increased risk of sALS (odds ratio [OR] = 3.294, 95% confidence interval [CI] = 1.039–10.448). However, a significant association between the DD genotype and the risk of sALS was evident in men only (OR = 7.167, 95% CI = 1.381–37.202). Conclusion This study revealed that the D allele and genotype frequencies of GSTO2 were increased in sALS patients. The GSTO2 DD genotype was associated with an increased risk of sALS in men in a Chinese population.
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Affiliation(s)
- Zhiliang Fan
- Department of Neurology, 71213Second Hospital of Hebei Medical University, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,Hebei Province Key Laboratory of Neurology, Institute of Cardiocerebrovascular Disease, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,The Third Department of Neurology, Xingtai People's Hospital, Xingtai, Hebei, P.R. China
| | - Hong Jiang
- Department of Neurology, 71213Second Hospital of Hebei Medical University, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,Hebei Province Key Laboratory of Neurology, Institute of Cardiocerebrovascular Disease, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China
| | - Xueqin Song
- Department of Neurology, 71213Second Hospital of Hebei Medical University, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,Hebei Province Key Laboratory of Neurology, Institute of Cardiocerebrovascular Disease, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China
| | - Yansu Guo
- Department of Neurology, 71213Second Hospital of Hebei Medical University, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,Hebei Province Key Laboratory of Neurology, Institute of Cardiocerebrovascular Disease, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China
| | - Xinying Tian
- Department of Neurology, 71213Second Hospital of Hebei Medical University, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China.,Hebei Province Key Laboratory of Neurology, Institute of Cardiocerebrovascular Disease, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, P.R. China
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Chu MY, Huang HC, Li EM, Xu LY. CypA: A Potential Target of Tumor Radiotherapy and/or Chemotherapy. Curr Med Chem 2021; 28:3787-3802. [PMID: 33121398 DOI: 10.2174/0929867327666201029161055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/18/2020] [Accepted: 09/20/2020] [Indexed: 02/05/2023]
Abstract
Cyclophilin A (CypA) is a ubiquitous and highly conserved protein. CypA, the intracellular target protein for the immunosuppressant cyclosporine A (CsA), plays important cellular roles through peptidyl-prolyl cis-trans isomerase (PPIase). Increasing evidence shows that CypA is up-regulated in a variety of human cancers. In addition to being involved in the occurrence and development of multiple tumors, overexpression of CypA has also been shown to be strongly associated with malignant transformation. Surgery, chemotherapy and radiotherapy are the three main treatments for cancer. Chemotherapy and radiotherapy are often used as direct or adjuvant treatments for cancer. However, various side effects and resistance to both chemotherapy and radiotherapy bring great challenges to these two forms of treatment. According to recent reports, CypA can improve the chemosensitivity and/or radiosensitivity of cancers, possibly by affecting the expression of drug-resistant related proteins, cell cycle arrest and activation of the mitogen-activated protein kinase (MAPK) signaling pathways. In this review, we focus on the role of CypA in cancer, its impact on cancer chemotherapeutic and radiotherapy sensitivity, and the mechanism of action. It is suggested that CypA may be a novel potential therapeutic target for cancer chemotherapy and/or radiotherapy.
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Affiliation(s)
- Man-Yu Chu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, China
| | - He-Cheng Huang
- Department of Radiation Oncology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou, China
| | - En-Ming Li
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, China
| | - Li-Yan Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou, China
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Abstract
The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.
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Affiliation(s)
- Patrick E Hanna
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - M W Anders
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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Tian DD, Bennett SK, Coupland LA, Forwood K, Lwin Y, Pooryousef N, Tea I, Truong TT, Neeman T, Crispin P, D’Rozario J, Blackburn AC. GSTZ1 genotypes correlate with dichloroacetate pharmacokinetics and chronic side effects in multiple myeloma patients in a pilot phase 2 clinical trial. Pharmacol Res Perspect 2019; 7:e00526. [PMID: 31624634 PMCID: PMC6783648 DOI: 10.1002/prp2.526] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 08/08/2019] [Accepted: 08/29/2019] [Indexed: 12/16/2022] Open
Abstract
Dichloroacetate (DCA) is an investigational drug targeting the glycolytic hallmark of cancer by inhibiting pyruvate dehydrogenase kinases (PDK). It is metabolized by GSTZ1, which has common polymorphisms altering enzyme or promoter activity. GSTZ1 is also irreversibly inactivated by DCA. In the first clinical trial of DCA in a hematological malignancy, DiCAM (DiChloroAcetate in Myeloma), we have examined the relationship between DCA concentrations, GSTZ1 genotype, side effects, and patient response. DiCAM recruited seven myeloma patients in partial remission. DCA was administered orally for 3 months with a loading dose. Pharmacokinetics were performed on day 1 and 8. Trough and peak concentrations of DCA were measured monthly. GSTZ1 genotypes were correlated with drug concentrations, tolerability, and disease outcomes. One patient responded and two patients showed a partial response after one month of DCA treatment, which included the loading dose. The initial half-life of DCA was shorter in two patients, correlating with heterozygosity for GSTZ1*A genotype, a high enzyme activity variant. Over 3 months, one patient maintained DCA trough concentrations approximately threefold higher than other patients, which correlated with a low activity promoter genotype (-1002A, rs7160195) for GSTZ1. This patient displayed the strongest response, but also the strongest neuropathy. Overall, serum concentrations of DCA were sufficient to inhibit the constitutive target PDK2, but unlikely to inhibit targets induced in cancer. Promoter GSTZ1 polymorphisms may be important determinants of DCA concentrations and neuropathy during chronic treatment. Novel dosing regimens may be necessary to achieve effective DCA concentrations in most cancer patients while avoiding neuropathy.
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Affiliation(s)
- Dan Dan Tian
- ACRF Department of Cancer Biology and TherapeuticsThe John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | | | - Lucy A. Coupland
- ACRF Department of Cancer Biology and TherapeuticsThe John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Kathryn Forwood
- Department of HaematologyThe Canberra HospitalGarranACTAustralia
| | - Yadanar Lwin
- Department of HaematologyThe Canberra HospitalGarranACTAustralia
| | - Niloofar Pooryousef
- ACRF Department of Cancer Biology and TherapeuticsThe John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Illa Tea
- ACRF Department of Cancer Biology and TherapeuticsThe John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Thy T. Truong
- Joint Mass Spectrometry FacilityThe Australian National UniversityActonACTAustralia
| | - Teresa Neeman
- Statistical Consulting UnitThe Australian National UniversityActonACTAustralia
| | - Philip Crispin
- Department of HaematologyThe Canberra HospitalGarranACTAustralia
| | - James D’Rozario
- Department of HaematologyThe Canberra HospitalGarranACTAustralia
| | - Anneke C. Blackburn
- ACRF Department of Cancer Biology and TherapeuticsThe John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
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Zhou B, Yang P, Gong YJ, Zeng Q, Lu WQ, Miao XP. Effect modification of CPY2E1 and GSTZ1 genetic polymorphisms on associations between prenatal disinfection by-products exposure and birth outcomes. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 243:1126-1133. [PMID: 30253304 DOI: 10.1016/j.envpol.2018.09.083] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 07/23/2018] [Accepted: 09/17/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Prenatal disinfection by-products (DBPs) exposure is linked with adverse birth outcomes. Genetic susceptibility to DBP metabolism may modify the exposure-outcome associations. OBJECT To investigate whether CYP2E1 and GSTZ1 genetic polymorphisms modified the associations of prenatal DBP exposures with adverse birth outcomes. METHODS Two biomarkers of DBP exposures including trihalomethanes (THMs) in blood and trichloroacetic acid (TCAA) in urine were determined among 426 pregnant women from a Chinese cohort study. CYP2E1 (rs2031920, rs3813867, and rs915906) and GSTZ1 (rs7975) polymorphisms in cord blood were genotyped. Statistical interactions between prenatal DBP exposures and newborns CYP2E1 and GSTZ1 polymorphisms on birth outcomes (birth weight, birth length, and gestational age) were examined by multivariable linear regression with adjustment for potential confounders. RESULTS We found that newborns CYP2E1 genetic polymorphisms (rs2031920 and rs3813867) modified the associations of maternal blood THMs or urinary TCAA levels with birth outcomes. However, these interactions were nonsignificant after Bonferroni correction for multiple comparisons, except for the interaction between maternal blood BrTHMs [sum of dibromochloromethane (DBCM), bromodichloromethane (BDCM), and bromoform (TBM)] and newborns CYP2E1 gene rs2031920 polymorphisms on birth weight (P for interaction = 0.003). CONCLUSION Newborns genetic variations of CYP2E1 rs2031920 may modify the impacts of prenatal BrTHM exposure on birth weight. This finding needs to be further confirmed.
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Affiliation(s)
- Bin Zhou
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China
| | - Pan Yang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, AState Key Laboratory of Environmental Health (incubating), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China
| | - Ya-Jie Gong
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, AState Key Laboratory of Environmental Health (incubating), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China
| | - Qiang Zeng
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, AState Key Laboratory of Environmental Health (incubating), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China
| | - Wen-Qing Lu
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, AState Key Laboratory of Environmental Health (incubating), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China
| | - Xiao-Ping Miao
- Department of Epidemiology and Biostatistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, AState Key Laboratory of Environmental Health (incubating), Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China.
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Advances in drug metabolism and pharmacogenetics research in Australia. Pharmacol Res 2017; 116:7-19. [DOI: 10.1016/j.phrs.2016.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 01/04/2023]
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Yang H, Al-Hertani W, Cyr D, Laframboise R, Parizeault G, Wang SP, Rossignol F, Berthier MT, Giguère Y, Waters PJ, Mitchell GA. Hypersuccinylacetonaemia and normal liver function in maleylacetoacetate isomerase deficiency. J Med Genet 2016; 54:241-247. [PMID: 27876694 DOI: 10.1136/jmedgenet-2016-104289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/29/2016] [Accepted: 11/01/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND A high level of succinylacetone (SA) in blood is a sensitive, specific newborn screening marker for hepatorenal tyrosinemia type 1 (HT1, MIM 276700) caused by deficiency of fumarylacetoacetate hydrolase (FAH). Newborns with HT1 are usually clinically asymptomatic but show liver dysfunction with coagulation abnormalities (prolonged prothrombin time and/or high international normalised ratio). Early treatment with nitisinone (NTBC) plus dietary restriction of tyrosine and phenylalanine prevents the complications of severe liver disease and neurological crises. METHODS AND RESULTS Six newborns referred for hypersuccinylacetonaemia but who had normal coagulation testing on initial evaluation had sequence variants in the GSTZ1 gene, encoding maleylacetoacetate isomerase (MAAI), the enzyme preceding FAH in tyrosine degradation. Initial plasma SA levels ranged from 233 to 1282 nmol/L, greater than normal (<24 nmol/L) but less than the initial values of patients with HT1 (16 944-74 377 nmol/L, n=15). Four individuals were homozygous for c.449C>T (p.Ala150Val). One was compound heterozygous for c.259C>T (p.Arg87Ter) and an intronic sequence variant. In one, a single heterozygous GSTZ1 sequence variant was identified, c.295G>A (p.Val99Met). Bacterial expression of p.Ala150Val and p.Val99Met revealed low MAAI activity. The six individuals with mild hypersuccinylacetonaemia (MHSA) were not treated with diet or nitisinone. Their clinical course has been normal for up to 13 years. CONCLUSIONS MHSA can be caused by sequence variants in GSTZ1. Such individuals have thus far remained asymptomatic despite receiving no specific treatment.
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Affiliation(s)
- Hao Yang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada.,College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Walla Al-Hertani
- Departments of Medical Genetics and Paediatrics, Cumming School of Medicine, University of Calgary and Alberta Children's Hospital, Calgary, Alberta, Canada.,Department of Medical Genetics, Centre universitaire de Santé McGill (CUSM), Québec, Canada
| | - Denis Cyr
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Rachel Laframboise
- Service de Génétique médicale, Département de Pédiatrie, CHU de Québec-Centre hospitalier de l'Université Laval (CHUL), Québec City, Québec, Canada
| | - Guy Parizeault
- Département de Pédiatrie, Centre Hospitalier de la Sagamie, Sagamie, Québec, Canada
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Francis Rossignol
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Marie-Thérèse Berthier
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Yves Giguère
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Paula J Waters
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
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James MO, Jahn SC, Zhong G, Smeltz MG, Hu Z, Stacpoole PW. Therapeutic applications of dichloroacetate and the role of glutathione transferase zeta-1. Pharmacol Ther 2016; 170:166-180. [PMID: 27771434 DOI: 10.1016/j.pharmthera.2016.10.018] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dichloroacetate (DCA) has several therapeutic applications based on its pharmacological property of inhibiting pyruvate dehydrogenase kinase. DCA has been used to treat inherited mitochondrial disorders that result in lactic acidosis, as well as pulmonary hypertension and several different solid tumors, the latter through its ability to reverse the Warburg effect in cancer cells and restore aerobic glycolysis. The main clinically limiting toxicity is reversible peripheral neuropathy. Although administration of high doses to rodents can result in liver cancer, there is no evidence that DCA is a human carcinogen. In all studied species, including humans, DCA has the interesting property of inhibiting its own metabolism upon repeat dosing, resulting in alteration of its pharmacokinetics. The first step in DCA metabolism is conversion to glyoxylate catalyzed by glutathione transferase zeta 1 (GSTZ1), for which DCA is a mechanism-based inactivator. The rate of GSTZ1 inactivation by DCA is influenced by age, GSTZ1 haplotype and cellular concentrations of chloride. The effect of DCA on its own metabolism complicates the selection of an effective dose with minimal side effects.
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Affiliation(s)
- Margaret O James
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, United States.
| | - Stephan C Jahn
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Guo Zhong
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Marci G Smeltz
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Zhiwei Hu
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, United States
| | - Peter W Stacpoole
- Department of Medicine, University of Florida, Gainesville, FL 32610-0226, United States; Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, United States
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Font-Ribera L, Kogevinas M, Schmalz C, Zwiener C, Marco E, Grimalt JO, Liu J, Zhang X, Mitch W, Critelli R, Naccarati A, Heederik D, Spithoven J, Arjona L, de Bont J, Gracia-Lavedan E, Villanueva CM. Environmental and personal determinants of the uptake of disinfection by-products during swimming. ENVIRONMENTAL RESEARCH 2016; 149:206-215. [PMID: 27214136 DOI: 10.1016/j.envres.2016.05.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/20/2016] [Accepted: 05/09/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Trihalomethanes (THMs) in exhaled breath and trichloroacetic acid (TCAA) in urine are internal dose biomarkers of exposure to disinfection by-products (DBPs) in swimming pools. OBJECTIVE We assessed how these biomarkers reflect the levels of a battery of DBPs in pool water and trichloramine in air, and evaluated personal determinants. METHODS A total of 116 adults swam during 40min in a chlorinated indoor pool. We measured chloroform, bromodichloromethane, dibromochloromethane and bromoform in exhaled breath and TCAA in urine before and after swimming, trichloramine in air and several DBPs in water. Personal determinants included sex, age, body mass index (BMI), distance swum, energy expenditure, heart rate and 12 polymorphisms in GSTT1, GSTZ1 and CYP2E1 genes. RESULTS Median level of exhaled total THMs and creatinine adjusted urine TCAA increased from 0.5 to 14.4µg/m(3) and from 2.5 to 5.8µmol/mol after swimming, respectively. The increase in exhaled brominated THMs was correlated with brominated THMs, haloacetic acids, haloacetonitriles, haloketones, chloramines, total organic carbon and total organic halogen in water and trichloramine in air. Such correlations were not detected for exhaled chloroform, total THMs or urine TCAA. Exhaled THM increased more in men, urine TCAA increased more in women, and both were affected by exercise intensity. Genetic variants were associated with differential increases in exposure biomarkers. CONCLUSION Our findings suggest that, although affected by sex, physical activity and polymorphisms in key metabolizing enzymes, brominated THMs in exhaled breath could be used as a non-invasive DBP exposure biomarker in swimming pools with bromide-containing source waters. This warrants confirmation with new studies.
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Affiliation(s)
- Laia Font-Ribera
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain
| | - Manolis Kogevinas
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain
| | | | | | - Esther Marco
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain
| | - Joan O Grimalt
- Institute of Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain
| | - Jiaqi Liu
- Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - Xiangru Zhang
- Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - William Mitch
- Department of Civil and Environmental Engineering, Stanford University, Palo Alto, CA, USA
| | | | | | - Dick Heederik
- Institute for Risk Assessment Sciences (IRAS), Utrecht, The Netherlands
| | - Jack Spithoven
- Institute for Risk Assessment Sciences (IRAS), Utrecht, The Netherlands
| | - Lourdes Arjona
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain
| | - Jeroen de Bont
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain
| | - Esther Gracia-Lavedan
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain
| | - Cristina M Villanueva
- ISGlobal, Center for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
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James MO, Stacpoole PW. Pharmacogenetic considerations with dichloroacetate dosing. Pharmacogenomics 2016; 17:743-53. [PMID: 27143230 DOI: 10.2217/pgs-2015-0012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The investigational drug dichloroacetate (DCA) is a metabolic regulator that has been successfully used to treat acquired and congenital metabolic diseases and, recently, solid tumors. Its clinical use has revealed challenges in selecting appropriate doses. Chronic administration of DCA leads to inhibition of DCA metabolism and potential accumulation to levels that result in side effects. This is because conversion of DCA to glyoxylate is catalyzed by one enzyme, glutathione transferase zeta 1 (GSTZ1-1), which is inactivated by DCA. SNPs in the GSTZ1 gene result in expression of polymorphic variants of the enzyme that differ in activity and rates of inactivation by DCA under physiological conditions: these properties lead to considerable variation between people in the pharmacokinetics of DCA.
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Affiliation(s)
- Margaret O James
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610-0485, USA
| | - Peter W Stacpoole
- Department of Medicine, College of Medicine, University of Florida, Gainesville, FL 32610-0485, USA.,Department of Biochemistry & Molecular Biology, University of Florida, Gainesville, FL 32610-0485, USA
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Hrudey SE, Backer LC, Humpage AR, Krasner SW, Michaud DS, Moore LE, Singer PC, Stanford BD. Evaluating Evidence for Association of Human Bladder Cancer with Drinking-Water Chlorination Disinfection By-Products. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2015; 18:213-41. [PMID: 26309063 PMCID: PMC4642182 DOI: 10.1080/10937404.2015.1067661] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Exposure to chlorination disinfection by-products (CxDBPs) is prevalent in populations using chlorination-based methods to disinfect public water supplies. Multifaceted research has been directed for decades to identify, characterize, and understand the toxicology of these compounds, control and minimize their formation, and conduct epidemiologic studies related to exposure. Urinary bladder cancer has been the health risk most consistently associated with CxDBPs in epidemiologic studies. An international workshop was held to (1) discuss the qualitative strengths and limitations that inform the association between bladder cancer and CxDBPs in the context of possible causation, (2) identify knowledge gaps for this topic in relation to chlorine/chloramine-based disinfection practice(s) in the United States, and (3) assess the evidence for informing risk management. Epidemiological evidence linking exposures to CxDBPs in drinking water to human bladder cancer risk provides insight into causality. However, because of imprecise, inaccurate, or incomplete estimation of CxDBPs levels in epidemiologic studies, translation from hazard identification directly to risk management and regulatory policy for CxDBPs can be challenging. Quantitative risk estimates derived from toxicological risk assessment for CxDBPs currently cannot be reconciled with those from epidemiologic studies, notwithstanding the complexities involved, making regulatory interpretation difficult. Evidence presented here has both strengths and limitations that require additional studies to resolve and improve the understanding of exposure response relationships. Replication of epidemiologic findings in independent populations with further elaboration of exposure assessment is needed to strengthen the knowledge base needed to better inform effective regulatory approaches.
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Affiliation(s)
- Steve E. Hrudey
- Environmental and Analytical Toxicology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | | | | | - Stuart W. Krasner
- Metropolitan Water District of Southern California, Los Angeles, California, USA
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Cyclophilin A: a key player for human disease. Cell Death Dis 2013; 4:e888. [PMID: 24176846 PMCID: PMC3920964 DOI: 10.1038/cddis.2013.410] [Citation(s) in RCA: 296] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/10/2013] [Accepted: 09/11/2013] [Indexed: 01/23/2023]
Abstract
Cyclophilin A (CyPA) is a ubiquitously distributed protein belonging to the immunophilin family. CyPA has peptidyl prolyl cis-trans isomerase (PPIase) activity, which regulates protein folding and trafficking. Although CyPA was initially believed to function primarily as an intracellular protein, recent studies have revealed that it can be secreted by cells in response to inflammatory stimuli. Current research in animal models and humans has provided compelling evidences supporting the critical function of CyPA in several human diseases. This review discusses recently available data about CyPA in cardiovascular diseases, viral infections, neurodegeneration, cancer, rheumatoid arthritis, sepsis, asthma, periodontitis and aging. It is believed that further elucidations of the role of CyPA will provide a better understanding of the molecular mechanisms underlying these diseases and will help develop novel pharmacological therapies.
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Yu Y, Song J, Song Y, Guo X, Han Y, Wei J. Characterization of catalytic activity and structure of selenocysteine-containing hGSTZ1c-1c based on site-directed mutagenesis and computational analysis. IUBMB Life 2013; 65:163-70. [PMID: 23299908 DOI: 10.1002/iub.1128] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 12/06/2012] [Indexed: 11/06/2022]
Abstract
Human glutathione transferase zeta 1c-1c (hGSTZ1c-1c) is one of the glutathione transferase isoenzymes and considered to be a protein scaffold to imitate glutathione peroxidase (GPX) owing to the natural binding site of glutathione (GSH). In this report, several residues near GSH were mutated to selenocysteine (Sec) or cysteine (Cys) residues and the impacts of the substitutions on different activities were discussed. Mutations of Ser-14 or/and Ser-15 to Cys or Sec residues resulted in dramatic loss of catalytic activity of hGSTZ1c-1c with chlorofluoroacetic acid as substrate, which indicated the importance of the hydroxyl groups in Ser-14 and Ser-15. And subsequent study by molecular modeling suggested that Ser-15 was probably involved in catalysis, while Ser-14 may play a crucial role in binding and orientation of GSH and possibly had a synergistic effect with Ser-15 in catalysis. On the contrary, the result of converting Cys-16 to Ser indicated its trivial role in catalysis. The investigations of the selenocysteine-containing hGSTZ1c-1c (seleno-hGSTZ1c-1c) and the mutant S17C implied that the substitutions of multi-Sec for Cys residues at position 16, 137, and 205 could lead to subtle change in the structure of the protein molecule and concomitant change in catalytic activity as a direct result. This finding provides overwhelming evidence that the protein scaffold containing fewer cysteines should be chosen for imitating GPX using cysteine auxotrophic strain system to avoid unexpected structural changes.
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Affiliation(s)
- Yang Yu
- College of Pharmaceutical Science, Jilin University, Changchun, China
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Board PG, Menon D. Glutathione transferases, regulators of cellular metabolism and physiology. Biochim Biophys Acta Gen Subj 2012. [PMID: 23201197 DOI: 10.1016/j.bbagen.2012.11.019] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The cytosolic glutathione transferases (GSTs) comprise a super family of proteins that can be categorized into multiple classes with a mixture of highly specific and overlapping functions. SCOPE OF REVIEW The review covers the genetics, structure and function of the human cytosolic GSTs with particular attention to their emerging roles in cellular metabolism. MAJOR CONCLUSIONS All the catalytically active GSTs contribute to the glutathione conjugation or glutathione dependant-biotransformation of xenobiotics and many catalyze glutathione peroxidase or thiol transferase reactions. GSTs also catalyze glutathione dependent isomerization reactions required for the synthesis of several prostaglandins and steroid hormones and the catabolism of tyrosine. An increasing body of work has implicated several GSTs in the regulation of cell signaling pathways mediated by stress-activated kinases like Jun N-terminal kinase. In addition, some members of the cytosolic GST family have been shown to form ion channels in intracellular membranes and to modulate ryanodine receptor Ca(2+) channels in skeletal and cardiac muscle. GENERAL SIGNIFICANCE In addition to their well established roles in the conjugation and biotransformation of xenobiotics, GSTs have emerged as significant regulators of pathways determining cell proliferation and survival and as regulators of ryanodine receptors that are essential for muscle function. This article is part of a Special Issue entitled Cellular functions of glutathione.
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Affiliation(s)
- Philip G Board
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
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Li W, Gu Y, James MO, Hines RN, Simpson P, Langaee T, Stacpoole PW. Prenatal and postnatal expression of glutathione transferase ζ 1 in human liver and the roles of haplotype and subject age in determining activity with dichloroacetate. Drug Metab Dispos 2011; 40:232-9. [PMID: 22028318 DOI: 10.1124/dmd.111.041533] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Glutathione transferase ζ 1 (GSTZ1), also known as maleylacetoacetate isomerase, catalyzes the penultimate step of tyrosine catabolism and metabolizes several α-halocarboxylic acids, including dichloroacetic acid (DCA), an investigational drug used for lactic acidosis and, recently, solid tumors. Age-related differences have been suggested in DCA pharmacotoxicology, but no information is available on GSTZ1 ontogeny in humans. Here, we investigated the cytosolic GSTZ1 developmental expression pattern and the influence of haplotype on GSTZ1 activity with DCA by using human livers from donors between 10 weeks gestation and 74 years. GSTZ1 expression was very low in fetal livers (<2 pmol of GSTZ1/mg cytosol). The expression began to increase after birth in an age-dependent manner until age 7 years. GSTZ1 was then sustained at stable, yet variable, levels (median, 20.0 pmol/mg cytosol; range, 4.8-47.3 pmol/mg cytosol) until age 74 years. GSTZ1 activity with DCA was strongly associated with haplotype and expression level. Samples homozygous or heterozygous for GSTZ1A exhibited ∼3-fold higher DCA dechlorinating activity than samples carrying other alleles at a given level of expression. The correlations (r²) between activity and expression were 0.90 and 0.68, respectively, for GSTZ1A carriers (n = 11) and noncarriers (n = 61). GSTZ1 is expressed in mitochondria in addition to cytosol. The GSTZ1A allele exhibited similar effects in the mitochondrial fraction by conferring a higher activity with DCA. In summary, we report a neonatal onset and an age-related increase in GSTZ1 protein expression during human liver development. Haplotype influenced GSTZ1 activity with DCA but not protein expression.
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Affiliation(s)
- Wenjun Li
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA
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17
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Board PG, Anders MW. Glutathione transferase zeta: discovery, polymorphic variants, catalysis, inactivation, and properties of Gstz1-/- mice. Drug Metab Rev 2011; 43:215-25. [PMID: 21303221 DOI: 10.3109/03602532.2010.549132] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Glutathione transferase zeta (GSTZ1) is a member of the GST superfamily of proteins that catalyze the reaction of glutathione with endo- and xenobiotics. GSTZ1-1 was discovered by a bioinformatics strategy that searched the human-expressed sequence-tag database with a sequence that matched a putative plant GST. A sequence that was found was expressed and termed GSTZ1-1. In common with other GSTs, GSTZ1-1 showed some peroxidase activity, but lacked activity with most known GST substrates. GSTZ1-1 was also found to be identical with maleylacetoacetate isomerase, which catalyzes the penultimate step in the tyrosine-degradation pathway. Further studies showed that dichloroacetate (DCA) and a range of α-haloalkanoates and α,α-dihaloalkanoates were substrates. A subsequent search of the human-expressed sequence-tag database showed the presence of four polymorphic alleles: 1a, 1b, 1c, and 1d; GSTZ1c was the most common and was designated as the wild-type gene. DCA was shown to be a k(cat) inactivator of human, rat, and mouse GSTZ1-1; human GSTZ1-1 was more resistant to inactivation than mouse or rat GSTZ1-1. Proteomic analysis showed that hGSTZ1-1 was inactivated when Cys-16 was modified by glutathione and the carbon skeleton of DCA. The polymorphic variants of hGSTZ1-1 differ in their susceptibility to inactivation, with 1a-1a being more resistant to inactivation than the other variants. The targeted deletion of GSTZ1 yielded mice that were not phenotypically distinctive. Phenylalanine proved, however, to be toxic to Gstz1(-/-) mice, and these mice showed evidence of organ damage and leucopenia.
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Affiliation(s)
- Philip G Board
- Molecular Genetics Group, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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Cantor KP, Villanueva CM, Silverman DT, Figueroa JD, Real FX, Garcia-Closas M, Malats N, Chanock S, Yeager M, Tardon A, Garcia-Closas R, Serra C, Carrato A, Castaño-Vinyals G, Samanic C, Rothman N, Kogevinas M. Polymorphisms in GSTT1, GSTZ1, and CYP2E1, disinfection by-products, and risk of bladder cancer in Spain. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:1545-50. [PMID: 20675267 PMCID: PMC2974691 DOI: 10.1289/ehp.1002206] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 06/21/2010] [Accepted: 07/30/2010] [Indexed: 05/19/2023]
Abstract
BACKGROUND Bladder cancer has been linked with long-term exposure to disinfection by-products (DBPs) in drinking water. OBJECTIVES In this study we investigated the combined influence of DBP exposure and polymorphisms in glutathione S-transferase (GSTT1, GSTZ1) and cytochrome P450 (CYP2E1) genes in the metabolic pathways of selected by-products on bladder cancer in a hospital-based case-control study in Spain. METHODS Average exposures to trihalomethanes (THMs; a surrogate for DBPs) from 15 years of age were estimated for each subject based on residential history and information on municipal water sources among 680 cases and 714 controls. We estimated effects of THMs and GSTT1, GSTZ1, and CYP2E1 polymorphisms on bladder cancer using adjusted logistic regression models with and without interaction terms. RESULTS THM exposure was positively associated with bladder cancer: adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were 1.2 (0.8-1.8), 1.8 (1.1-2.9), and 1.8 (0.9-3.5) for THM quartiles 2, 3, and 4, respectively, relative to quartile 1. Associations between THMs and bladder cancer were stronger among subjects who were GSTT1 +/+ or +/- versus GSTT1 null (P(interaction) = 0.021), GSTZ1 rs1046428 CT/TT versus CC (P(interaction) = 0.018), or CYP2E1 rs2031920 CC versus CT/TT (P(interaction) = 0.035). Among the 195 cases and 192 controls with high-risk forms of GSTT1 and GSTZ1, the ORs for quartiles 2, 3, and 4 of THMs were 1.5 (0.7-3.5), 3.4 (1.4-8.2), and 5.9 (1.8-19.0), respectively. CONCLUSIONS Polymorphisms in key metabolizing enzymes modified DBP-associated bladder cancer risk. The consistency of these findings with experimental observations of GSTT1, GSTZ1, and CYP2E1 activity strengthens the hypothesis that DBPs cause bladder cancer and suggests possible mechanisms as well as the classes of compounds likely to be implicated.
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Affiliation(s)
- Kenneth P Cantor
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland 20892-7240, USA.
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19
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Wang J, Jiang J, Zhao Y, Gajalakshmi V, Kuriki K, Suzuki S, Nagaya T, Nakamura S, Akasaka S, Ishikawa H, Tokudome S. Genetic polymorphisms of glutathione S-transferase genes and susceptibility to colorectal cancer: a case-control study in an Indian population. Cancer Epidemiol 2010; 35:66-72. [PMID: 20688591 DOI: 10.1016/j.canep.2010.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 06/30/2010] [Accepted: 07/02/2010] [Indexed: 12/12/2022]
Abstract
BACKGROUND Susceptibility to sporadic colorectal cancer is multifactorial and arises from interactive combinations of allelic variants in low-penetrance genes and relevant environmental risk factors. Genetic polymorphisms in metabolic enzymes as gene susceptibility factors may modify colorectal cancer risk. We evaluated the risk of colorectal cancer associated with respective or combined glutathione S-transferase (GST) polymorphisms and assessed the interactions between genes and environmental factors in a case-control study in an Indian population. METHODS The study included 59 colon and 243 rectal cancer cases, and 291 cancer-free healthy controls. GST genotypes were detected by multiplex PCR-based and PCR-RFLP methods. The risk of cancer associated with GST polymorphisms was estimated by calculation of odds ratios (ORs) and confidence intervals (95% CIs) using unconditional logistic regression. RESULTS The GSTM1 null genotype was found to be associated with a significantly increased rectal cancer risk (OR=1.55; 95% CI, 1.05-2.30), while the GSTT1 null genotype with a greater risk of colon cancer (OR=2.15; 95% CI, 1.04-4.32). A substantial increase of both colon (OR=10.81; 95% CI, 1.11-107.22) and rectal (OR=4.80; 95% CI, 0.94-35.91) cancer risk was shown for the combination of GSTM1 null, GSTT1 null and GSTP1 105Val allele. The combined GSTM1 null and GSTP1 114Val allele also revealed an increased risk for either colon cancer (OR=4.69; 95% CI, 0.84-23.87) or rectal cancer (OR=5.68; 95% CI, 1.79-22.16). Furthermore, the combination of GSTM1 null, GSTT1 null and GSTP1 114Val allele was found in 2 rectal cancer cases. CONCLUSION Our results suggest that co-exist of GSTM1 null, GSTT1 null and the variant GSTP1 105Val or 114Val allele may be predisposing risk factors for colorectal cancer in Indian population.
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Affiliation(s)
- Jingwen Wang
- Department of Public Health, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
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Littler DR, Brown LJ, Breit SN, Perrakis A, Curmi PMG. Structure of human CLIC3 at 2 A resolution. Proteins 2010; 78:1594-600. [PMID: 20146363 DOI: 10.1002/prot.22675] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- D R Littler
- Department of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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Preliminary examination of polymorphisms of GSTM1, GSTT1, and GSTZ1 in relation to semen quality. Mutat Res 2010; 688:41-6. [PMID: 20214911 DOI: 10.1016/j.mrfmmm.2010.03.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 02/20/2010] [Accepted: 03/01/2010] [Indexed: 11/22/2022]
Abstract
BACKGROUND Environmental, lifestyle, and occupational exposures on semen quality have been investigated in epidemiological studies with inconsistent results. Genetic factors involved in toxicant activation and detoxification have been examined in relation to the risk of outcomes such as cancer, cardiovascular, and neurologic disorders. However, the effect of common genetic variants in the metabolism of toxicants on semen quality parameters has rarely been evaluated. In this analysis, we evaluated functional SNPs of three genes of the glutathione-S-transferase (GSTM1, GSTT1, GSTZ1) enzyme family. METHODS Participants were 228 presumed fertile men recruited as part of a community-based study. Semen outcome data from this study included total sperm count and concentration, sperm morphology, and sperm DNA integrity and chromatin maturity. DNA was obtained from 162 men from a mouth-rinse sample and genotyped for the presence of GSTT1-1 and GSTM1-1 null genotypes and the GSTZ1 SNPs at positions 94 (rs3177427) and 124 (rs3177429). We used multivariable linear regression to assess the relationship between each genotype and sperm outcomes. RESULTS Overall, our results did not reveal a consistent pattern between GSTM1 and GSTZ genotypes and increased occurrence of adverse sperm outcomes. However, the GSTT1 non-null genotype yielded the coefficients with the largest magnitude for sperm count and sperm concentration (beta=-0.528, 95% CI -1.238 to 0.199 and beta=-0.353, 95% CI -0.708 to 0.001, respectively), suggesting that it might be adverse. CONCLUSIONS These results indicate that common polymorphisms in GST genes do not negatively impact sperm parameters in healthy men with good semen quality. Contrary to expectations, the GSTT1 non-null genotype was associated with reduced sperm concentration and count in semen. Further study with a larger study size and inclusion of gene-exposure interactions is warranted.
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Stacpoole PW, Kurtz TL, Han Z, Langaee T. Role of dichloroacetate in the treatment of genetic mitochondrial diseases. Adv Drug Deliv Rev 2008; 60:1478-87. [PMID: 18647626 DOI: 10.1016/j.addr.2008.02.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 02/22/2008] [Indexed: 02/06/2023]
Abstract
Dichloroacetate (DCA) is an investigational drug for the treatment of genetic mitochondrial diseases. Its primary site of action is the pyruvate dehydrogenase (PDH) complex, which it stimulates by altering its phosphorylation state and stability. DCA is metabolized by and inhibits the bifunctional zeta-1 family isoform of glutathione transferase/maleylacetoacetate isomerase. Polymorphic variants of this enzyme differ in their kinetic properties toward DCA, thereby influencing its biotransformation and toxicity, both of which are also influenced by subject age. Results from open label studies and controlled clinical trials suggest chronic oral DCA is generally well-tolerated by young children and may be particularly effective in patients with PDH deficiency. Recent in vitro data indicate that a combined DCA and gene therapy approach may also hold promise for the treatment of this devastating condition.
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Li T, Schultz I, Keys DA, Campbell JL, Fisher JW. Quantitative evaluation of dichloroacetic acid kinetics in human--a physiologically based pharmacokinetic modeling investigation. Toxicology 2007; 245:35-48. [PMID: 18242812 DOI: 10.1016/j.tox.2007.12.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 12/11/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022]
Abstract
Dichloroacetic acid is a common disinfection by-product in surface waters and is a probable minor metabolite of trichloroethylene. Dichloroacetic acid (DCA) liver carcinogenicity has been demonstrated in rodents but epidemiological evidence in humans is not available. High doses of DCA ( approximately 50mg/kg) are used clinically to treat metabolic acidosis. Biotransformation of DCA by glutathione transferase zeta (GSTzeta) in the liver is the major elimination pathway in humans. GSTzeta is also inactivated by DCA, leading to slower systemic clearance and nonlinear pharmacokinetics after multiple doses. A physiologically based pharmacokinetic (PBPK) model was developed to quantitatively describe DCA biotransformation and kinetics in humans administered DCA by intravenous infusion and oral ingestion. GSTzeta metabolism was described using a Michaelis-Menten equation coupled with rate constants to account for normal GSTzeta synthesis, degradation and irreversible covalent binding and inhibition by the glutathione-bound-DCA intermediate. With some departures between observation and model prediction, the human DCA PBPK model adequately predicted the DCA plasma kinetics over a 20,000-fold range in administered doses. Apparent inhibition of GSTzeta mediated metabolism of DCA was minimal for low doses of DCA (microg/kg day), but was significant for therapeutic doses of DCA. Plasma protein binding of DCA was assumed to be an important factor influencing the kinetics of low doses of DCA (microg/kg day). Polymorphisms of GSTzeta may help explain inter-individual variability in DCA plasma kinetics and warrants evaluation. In conclusion, using a previously published rodent DCA PBPK model (Keys, D.A., Schultz, I.R., Mahle, D.A., Fisher, J.W., 2004. A quantitative description of suicide inhibition of dichloroacetic acid in rats and mice. Toxicol. Sci. 82, 381-393) and this human DCA PBPK model, human equivalent doses (HEDs) were calculated for a 10% increase in mice hepatic liver cancer (2.1mg/kg day). The HEDs for the dosimetrics, area-under-the-concentration-curve (AUC) for total and free DCA in plasma, AUC of DCA in liver and amount of DCA metabolized per day were 0.02, 0.1, 0.1 and 1.0mg/kg day, respectively. Research on the mechanism of action of DCA and the relevance of mouse liver cancer is needed to better understand which dosimetric may be appropriate for extrapolation from animal studies to human.
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Affiliation(s)
- Ting Li
- University of Georgia, Department of Pharmaceutical and Biomedical Sciences, R.C. Wilson Pharmacy Building, Athens, GA 30602-2351, United States
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Board PG. The use of glutathione transferase-knockout mice as pharmacological and toxicological models. Expert Opin Drug Metab Toxicol 2007; 3:421-33. [PMID: 17539748 DOI: 10.1517/17425255.3.3.421] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
ADME/Tox studies are of increasing importance because of the necessity to eliminate poor drug candidates early in the development pipeline. The glutathione S-transferases (GSTs) are a family of phase II enzymes that have been shown to play a significant role in the disposition of a wide range of drugs and other xenobiotics. Several GST-knockout mice strains have been developed that can potentially be used in ADME/Tox studies. So far, mice have been generated with deficiencies of mGSTP1/2, mGSTA4-4, mGSTZ1-1, mGSTM1-1, mGSTO1-1 and mGSTS1-1, but studies of drug metabolism in these strains have been limited. As there are 21 recognised GST genes in mice there is potential for many more strains to be made. However, a review of the available data suggests that because of differences in the evolution of the GST gene family between rodents and humans, only some knockout strains can provide insights relevant to human drug metabolism. It is concluded that, of the strains generated so far, only those deficient in mGSTP1-1, mGSTA4-4, mGSTO1-1 and mGSTZ1-1 have direct human orthologues and can be considered as human models. In contrast, there may not be appropriate orthologues of some enzymes, such as hGSTM1-1, that are known to be of relevance in drug metabolism.
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Affiliation(s)
- Philip G Board
- Australian National University, Molecular Genetics Group, John Curtin School of Medical Research, PO Box 334, Canberra ACT 2601, Australia.
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Chen S, Zhang M, Ma H, Saiyin H, Shen S, Xi J, Wan B, Yu L. Oligo-microarray analysis reveals the role of cyclophilin A in drug resistance. Cancer Chemother Pharmacol 2007; 61:459-69. [PMID: 17520256 DOI: 10.1007/s00280-007-0491-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Accepted: 03/30/2007] [Indexed: 10/23/2022]
Abstract
Cyclophilin A (CYPA) belongs to peptidyl prolyl isomerases (PPIases), which catalyze the cis/trans isomerization of prolyl peptide bonds in cellular communication. CYPA has been implicated in several pathological processes, including cancer, inflammatory diseases, and HIV-1 infection. Up-regulation of CYPA has been found to be a common phenomenon in several tumor types, including in hepatocellular carcinoma (HCC). However, the role of CYPA in tumor cells remains unknown. We generated a stable SK-Hep1 cell line and studied the CYPA regulated genes at the transcriptome level. The microarray results reveal that CYPA can up-regulate the expression of many cytokine and drug resistance related genes. Furthermore, we showed that the elevated CYPA expression contributes to drug resistance. We postulate that the over-expression of CYPA in tumors may play a role in clinical resistance to chemotherapy.
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Affiliation(s)
- Shuai Chen
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China
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Caldwell JC, Keshava N. Key issues in the modes of action and effects of trichloroethylene metabolites for liver and kidney tumorigenesis. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1457-63. [PMID: 16966105 PMCID: PMC1570066 DOI: 10.1289/ehp.8692] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Trichloroethylene (TCE) exposure has been associated with increased risk of liver and kidney cancer in both laboratory animal and epidemiologic studies. The U.S. Environmental Protection Agency 2001 draft TCE risk assessment concluded that it is difficult to determine which TCE metabolites may be responsible for these effects, the key events involved in their modes of action (MOAs) , and the relevance of these MOAs to humans. In this article, which is part of a mini-monograph on key issues in the health risk assessment of TCE, we present a review of recently published scientific literature examining the effects of TCE metabolites in the context of the preceding questions. Studies of the TCE metabolites dichloroacetic acid (DCA) , trichloroacetic acid (TCA) , and chloral hydrate suggest that both DCA and TCA are involved in TCE-induced liver tumorigenesis and that many DCA effects are consistent with conditions that increase the risk of liver cancer in humans. Studies of S-(1,2-dichlorovinyl) -l-cysteine have revealed a number of different possible cell signaling effects that may be related to kidney tumorigenesis at lower concentrations than those leading to cytotoxicity. Recent studies of trichloroethanol exploring an alternative hypothesis for kidney tumorigenesis have failed to establish the formation of formate as a key event for TCE-induced kidney tumors. Overall, although MOAs and key events for TCE-induced liver and kidney tumors have yet to be definitively established, these results support the likelihood that toxicity is due to multiple metabolites through several MOAs, none of which appear to be irrelevant to humans.
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Affiliation(s)
- Jane C Caldwell
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA.
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Fang YY, Kashkarov U, Anders MW, Board PG. Polymorphisms in the human glutathione transferase zeta promoter. Pharmacogenet Genomics 2006; 16:307-13. [PMID: 16609361 DOI: 10.1097/01.fpc.0000205000.07054.b3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The zeta-class glutathione transferase GSTZ1-1 catalyses the glutathione-dependent isomerization of maleylacetoacetate to fumarylacetoacetate in the tyrosine catabolic pathway and the biotransformation of alpha-halo acids, including dichloroacetic acid (DCA). Genetic polymorphisms in the coding sequence of GSTZ1 result in significant changes in enzyme function, and deficiency of GSTZ1-1 in mice causes induction of a range of Phase-II enzymes. In this study, the potential for polymorphisms in regulatory sequences to alter gene transcription was investigated. METHODS A total of 10 single-nucleotide polymorphisms (SNP) were identified in African and Australian European subjects in a region extending 1.5-kb upstream of the GSTZ1 start of transcription. These SNPs formed at least 10 haplotypes and only two were shared between the two population samples. The effect of these SNPs on gene expression was evaluated by the transient expression of specific alleles fused to a luciferase reporter gene. RESULTS Of the 10 SNPs identified, only -1002 G>A and -289 C>T caused significant changes in promoter activity. The -1002 G>A SNP converts a v-Myb site to a S8 homeodomain (Prx2) site, and the -289 C>T SNP abolishes an Egr1 binding site. CONCLUSION These SNPs may alter GSTZ1 expression, which may alter the pharmacokinetics of DCA, which is used therapeutically for the treatment of lactic acidosis.
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Affiliation(s)
- Yu-Yan Fang
- Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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Schultz IR, Shangraw RE. Effect of short-term drinking water exposure to dichloroacetate on its pharmacokinetics and oral bioavailability in human volunteers: a stable isotope study. Toxicol Sci 2006; 92:42-50. [PMID: 16611621 DOI: 10.1093/toxsci/kfj193] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Dichloroacetic acid (DCAA) is a by-product of drinking water disinfection, is a known rodent hepatocarcinogen, and is also used therapeutically to treat a variety of metabolic disorders in humans. We measured DCAA bioavailability in 16 human volunteers (eight men, eight women) after simultaneous administration of oral and iv DCAA doses. Volunteers consumed DCAA-free bottled water for 2 weeks to wash out background effects of DCAA. Subsequently, each subject consumed (12)C-DCAA (2 mg/kg) dissolved in 500 ml water over a period of 3 min. Five minutes after the start of the (12)C-DCAA consumption, (13)C-labeled DCAA (0.3 mg/kg) was administered iv over 20 s and plasma (12)C/(13)C-DCAA concentrations measured at predetermined time points over 4 h. Volunteers subsequently consumed for 14 consecutive days DCAA 0.02 microg/kg/day dissolved in 500 ml water to simulate a low-level chronic DCAA intake. Afterward, the (12)C/(13)C-DCAA administrations were repeated. Study end points were calculation of AUC(0-->infinity), apparent volume of distribution (V(ss)), total body clearance (Cl(b)), plasma elimination half-life (t((1/2),beta)), oral absorption rate (K(a)), and oral bioavailability. Oral bioavailability was estimated from dose-adjusted AUC ratios and by using a compartmental pharmacokinetic model after simultaneous fitting of oral and iv DCAA concentration-time profiles. DCAA bioavailability had large interindividual variation, ranging from 27 to 100%. In the absence of prior DCAA intake, there were no significant differences (p > 0.05) in any pharmacokinetic parameters between male and female volunteers, although there was a trend that women absorbed DCAA more rapidly (increased K(a)), and cleared DCAA more slowly (decreased Cl(b)), than men. Only women were affected by previous 14-day DCAA exposure, which increased the AUC(0-->infinity) for both oral and iv DCAA doses (p < 0.04 and p < 0.014, respectively) with a corresponding decrease in the Cl(b).
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Affiliation(s)
- Irvin R Schultz
- Battelle Pacific NW Division, 1259 West Sequim Bay Road, Sequim, WA 98382, USA.
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29
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Abstract
The super family of glutathione S-transferases (GSTs) is composed of multiple isozymes with significant evidence of functional polymorphic variation. Over the last three decades, data from cancer studies have linked aberrant expression of GST isozymes with the development and expression of resistance to a variety of chemicals, including cancer drugs. This review addresses how differences in the human GST isozyme expression patterns influence cancer susceptibility, prognosis and treatment. In addition to the well-characterized catalytic activity, recent evidence has shown that certain GST isozymes can regulate mitogen-activated protein kinases or can facilitate the addition of glutathione to cysteine residues in target proteins (S-glutathionylation). These multiple functionalities have contributed to the recent efforts to target GSTs with novel small molecule therapeutics. Presently, at least two drugs are in late-stage clinical testing. The evolving functions of GST and their divergent expression patterns in individuals make them an attractive target for drug discovery.
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Affiliation(s)
- C C McIlwain
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA
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30
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Abstract
Zeta-class glutathione transferases (GSTZs) were recently discovered by a bioinformatics approach and the availability of human expressed sequence tag databases. Although GSTZ showed little activity with conventional GST substrates (1-chloro-2,4-dinitrobenzene; organic hydroperoxides), GSTZ was found to catalyze the oxygenation of dichloroacetic acid (DCA) to glyoxylic acid and the cis-trans isomerization of maleylacetoacetate to fumarylacetoacetate. Hence, GSTZ plays a critical role in the tyrosine degradation pathway and in alpha-haloacid metabolism. The GSTZ-catalyzed biotransformation of DCA is of particular interest, because DCA is used in the human clinical management of congenital lactic acidosis and because DCA is a common drinking water contaminant. Substrate selectivity studies showed that GSTZ catalyzes the glutathione-dependent biotransformation of a range of dihaloacetic acids along with fluoroacetic acid, 2-halopropanoic acids, and 2,2-dichloropropanoic acid. Human clinical studies showed that the elimination half-life of DCA increases with repeated doses of DCA; also, rats given DCA show low GSTZ activity with DCA as the substrate. DCA was found to be a mechanism-based inactivator of GSTZ, and proteomic studies showed that Cys-16 of human GSTZ1-1 is covalently modified by a reactive intermediate that contains glutathione and the carbon skeleton of DCA. Bioinformatics studies also showed the presence of at least four polymorphic variants of human GSTZ; these variants differ considerably in the rates of catalysis and in their susceptibility to inactivation by DCA. Finally, Gstz1(-/-) mouse strains have been developed; these mice fail to biotransform DCA or maleylacetone. Although the mice have no obvious phenotype, a high incidence of lethality is observed in young mice given phenylalanine in their drinking water. Gstz1(-/-) mice should prove useful in expanding the role of GSTZ in alpha-haloacid metabolism and in the tyrosine degradation pathway.
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Affiliation(s)
- Philip G Board
- Molecular Genetics Group, John Curtin School of Medical Research, Australian National University, CAnaberra, Australia
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Tetlow N, Robinson A, Mantle T, Board P. Polymorphism of human mu class glutathione transferases. ACTA ACUST UNITED AC 2004; 14:359-68. [PMID: 15247628 DOI: 10.1097/00008571-200406000-00005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES AND METHODS A combined database mining approach was used to detect polymorphisms in the mu class glutathione-S-transferase (GST) genes. Although a large number of potential polymorphisms were detected in the five genes that comprise the Mu class GSTs using sequence alignment programs and by searching single nucleotide polymorphism databases, the majority were not validated or detected in three major ethnic populations (African, Southern Chinese and Australian European). RESULTS Two new polymorphisms were detected and characterized in the GSTM3 gene. A rare pG147W substitution was detected only in the Southern Chinese subjects. A more common pV224I substitution was found in each of the ethnic groups studied, and significant differences in allele frequencies were observed between each group. These two polymorphisms can combine to form four distinct haplotypes (GSTM3A [p.G147;V224], GSTM3C [p.G147;I224], GSTM3D [p.W147;V224], GSTM3E [p.W147;I224]). The four isoforms were expressed in Escherichia coli and characterized enzymatically with several substrates including 1-chloro-2,4-dinitrobenzene (CDNB), cumene hydroperoxide and t-nonenal. GSTM3-3 containing the variant p.W147 residue tended to show diminished specific activity and catalytic efficiency with CDNB. In contrast, GSTM3-3 containing the variant p.I224 residue tended to show increased specific activity and catalytic efficiency with CDNB. Interactions between the different p.147 and p.224 residues were also observed, with the GSTM3C isoform exhibiting the greatest activity with each substrate, and GSTM3E the lowest. CONCLUSION These functional polymorphisms may play a significant role in modulating the ability of GSTM3-3 to metabolize substrates such as the chemotherapeutic agent 1,3-bis(2-chloroethyl)-1-nitrosourea.
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Affiliation(s)
- Natasha Tetlow
- Molecular Genetics Group, Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, Canberra ACT 2601, Australia
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Livingston RJ, von Niederhausern A, Jegga AG, Crawford DC, Carlson CS, Rieder MJ, Gowrisankar S, Aronow BJ, Weiss RB, Nickerson DA. Pattern of sequence variation across 213 environmental response genes. Genome Res 2004; 14:1821-31. [PMID: 15364900 PMCID: PMC524406 DOI: 10.1101/gr.2730004] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
To promote the clinical and epidemiological studies that improve our understanding of human genetic susceptibility to environmental exposure, the Environmental Genome Project (EGP) has scanned 213 environmental response genes involved in DNA repair, cell cycle regulation, apoptosis, and metabolism for single nucleotide polymorphisms (SNPs). Many of these genes have been implicated by loss-of-function mutations associated with severe diseases attributable to decreased protection of genomic integrity. Therefore, the hypothesis for these studies is that individuals with functionally significant polymorphisms within these genes may be particularly susceptible to genotoxic environmental agents. On average, 20.4 kb of baseline genomic sequence or 86% of each gene, including a substantial amount of introns, all exons, and 1.3 kb upstream and downstream, were scanned for variations in the 90 samples of the Polymorphism Discovery Resource panel. The average nucleotide diversity across the 4.2 MB of these 213 genes is 6.7 x 10(-4), or one SNP every 1500 bp, when two random chromosomes are compared. The average candidate environmental response gene contains 26 PHASE inferred haplotypes, 34 common SNPs, 6.2 coding SNPs (cSNPs), and 2.5 nonsynonymous cSNPs. SIFT and Polyphen analysis of 541 nonsynonymous cSNPs identified 57 potentially deleterious SNPs. An additional eight polymorphisms predict altered protein translation. Because these genes represent 1% of all known human genes, extrapolation from these data predicts the total genomic set of cSNPs, nonsynonymous cSNPs, and potentially deleterious nonsynonymous cSNPs. The implications for the use of these data in direct and indirect association studies of environmentally induced diseases are discussed.
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Affiliation(s)
- Robert J Livingston
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195-7730, USA
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Lim CEL, Matthaei KI, Blackburn AC, Davis RP, Dahlstrom JE, Koina ME, Anders MW, Board PG. Mice deficient in glutathione transferase zeta/maleylacetoacetate isomerase exhibit a range of pathological changes and elevated expression of alpha, mu, and pi class glutathione transferases. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:679-93. [PMID: 15277241 PMCID: PMC1618558 DOI: 10.1016/s0002-9440(10)63332-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Glutathione transferase zeta (GSTZ1-1) is the major enzyme that catalyzes the metabolism of alpha-halo acids such as dichloroacetic acid, a carcinogenic contaminant of chlorinated water. GSTZ1-1 is identical with maleylacetoacetate isomerase, which catalyzes the penultimate step in the catabolic pathways for phenylalanine and tyrosine. In this study we have deleted the Gstz1 gene in BALB/c mice and characterized their phenotype. Gstz1(-/-) mice do not have demonstrable activity with maleylacetone and alpha-halo acid substrates, and other GSTs do not compensate for the loss of this enzyme. When fed a standard diet, the GSTZ1-1-deficient mice showed enlarged liver and kidneys as well as splenic atrophy. Light and electron microscopic examination revealed multifocal hepatitis and ultrastructural changes in the kidney. The addition of 3% (w/v) phenylalanine to the drinking water was lethal for young mice (<28 days old) and caused liver necrosis, macrovesicular steatosis, splenic atrophy, and a significant loss of circulating leukocytes in older surviving mice. GSTZ1-1-deficient mice showed constitutive induction of alpha, mu, and pi class GSTs as well as NAD(P)H:quinone oxidoreductase 1. The overall response is consistent with the chronic accumulation of a toxic metabolite(s). We detected the accumulation of succinylacetone in the serum of deficient mice but cannot exclude the possibility that maleylacetoacetate and maleylacetone may also accumulate.
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Affiliation(s)
- Cindy E L Lim
- John Curtin School of Medical Research, PO Box 334, Canberra ACT 2601, Australia
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Ricci G, Turella P, De Maria F, Antonini G, Nardocci L, Board PG, Parker MW, Carbonelli MG, Federici G, Caccuri AM. Binding and kinetic mechanisms of the Zeta class glutathione transferase. J Biol Chem 2004; 279:33336-42. [PMID: 15173170 DOI: 10.1074/jbc.m404631200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Zeta class of glutathione transferases (GSTs) has only recently been discovered and hence has been poorly characterized. Here we investigate the substrate binding and kinetic mechanisms of the human Zeta class GSTZ1c-1c by means of pre-steady state and steady-state experiments and site-directed mutagenesis. Binding of GSH occurs at a very low rate compared with that observed for the more recently evolved GSTs (Alpha, Mu, and Pi classes). Moreover, the single step binding mechanism observed in this enzyme is reminiscent of that found for the Theta class enzyme, whereas the Alpha, Mu, and Pi classes have adopted a multistep binding mechanism. Replacement of Cys16 with Ala increases the rate of GSH release from the active site causing a 10-fold decrease of affinity toward GSH. Cys16 also plays a crucial role in co-substrate binding; the mutant enzyme is unable to bind the carcinogenic substrate dichloroacetic acid in the absence of GSH. However, both substrate binding and GSH activation are not rate-limiting in catalysis. A peculiarity of the hGSTZ1c-1c is the half-site activation of bound GSH. This suggests a primitive monomer-monomer interaction that, in the recently diverged GSTP1-1, gives rise to a sophisticated cooperative mechanism that preserves the catalytic efficiency of this GST under stress conditions.
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Affiliation(s)
- Giorgio Ricci
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy
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Cai M, Xun L. Organization and regulation of pentachlorophenol-degrading genes in Sphingobium chlorophenolicum ATCC 39723. J Bacteriol 2002; 184:4672-80. [PMID: 12169590 PMCID: PMC135293 DOI: 10.1128/jb.184.17.4672-4680.2002] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The first three enzymes of the pentachlorophenol (PCP) degradation pathway in Sphingobium chlorophenolicum (formerly Sphingomonas chlorophenolica) ATCC 39723 have been characterized, and the corresponding genes, pcpA, pcpB, and pcpC, have been individually cloned and sequenced. To search for new genes involved in PCP degradation and map the physical locations of the pcp genes, a 24-kb fragment containing pcpA and pcpC was completely sequenced. A putative LysR-type transcriptional regulator gene, pcpM, and a maleylacetate reductase gene, pcpE, were identified upstream of pcpA. pcpE was found to play a role in PCP degradation. pcpB was not found on the 24-kb fragment. The four gene products PcpB, PcpC, PcpA, and PcpE were responsible for the metabolism of PCP to 3-oxoadipate in ATCC 39723, and inactivational mutation of each gene disrupted the degradation pathway. The organization of the pcp genes is unusual because the four PCP-degrading genes, pcpA, pcpB, pcpC, and pcpE, were found to be located at four discrete locations. Two hypothetical LysR-type regulator genes, pcpM and pcpR, have been identified; pcpM was not required, but pcpR was essential for the induction of pcpB, pcpA, and pcpE. The coinducers of PcpR were PCP and other polychlorinated phenols. The expression of pcpC was constitutive. Thus, the organization and regulation of the genes involved in PCP degradation to 3-oxoadipate were documented.
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Affiliation(s)
- Mian Cai
- School of Molecular Biosciences, Washington State University, Science Hall 301, Pullman, WA 99164-4233, USA
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