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Cox LA, Thompson WJ, Mundt KA. Interventional probability of causation (IPoC) with epidemiological and partial mechanistic evidence: benzene vs. formaldehyde and acute myeloid leukemia (AML). Crit Rev Toxicol 2024; 54:252-289. [PMID: 38753561 DOI: 10.1080/10408444.2024.2337435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 03/25/2024] [Indexed: 05/18/2024]
Abstract
INTRODUCTION Causal epidemiology for regulatory risk analysis seeks to evaluate how removing or reducing exposures would change disease occurrence rates. We define interventional probability of causation (IPoC) as the change in probability of a disease (or other harm) occurring over a lifetime or other specified time interval that would be caused by a specified change in exposure, as predicted by a fully specified causal model. We define the closely related concept of causal assigned share (CAS) as the predicted fraction of disease risk that would be removed or prevented by a specified reduction in exposure, holding other variables fixed. Traditional approaches used to evaluate the preventable risk implications of epidemiological associations, including population attributable fraction (PAF) and the Bradford Hill considerations, cannot reveal whether removing a risk factor would reduce disease incidence. We argue that modern formal causal models coupled with causal artificial intelligence (CAI) and realistically partial and imperfect knowledge of underlying disease mechanisms, show great promise for determining and quantifying IPoC and CAS for exposures and diseases of practical interest. METHODS We briefly review key CAI concepts and terms and then apply them to define IPoC and CAS. We present steps to quantify IPoC using a fully specified causal Bayesian network (BN) model. Useful bounds for quantitative IPoC and CAS calculations are derived for a two-stage clonal expansion (TSCE) model for carcinogenesis and illustrated by applying them to benzene and formaldehyde based on available epidemiological and partial mechanistic evidence. RESULTS Causal BN models for benzene and risk of acute myeloid leukemia (AML) incorporating mechanistic, toxicological and epidemiological findings show that prolonged high-intensity exposure to benzene can increase risk of AML (IPoC of up to 7e-5, CAS of up to 54%). By contrast, no causal pathway leading from formaldehyde exposure to increased risk of AML was identified, consistent with much previous mechanistic, toxicological and epidemiological evidence; therefore, the IPoC and CAS for formaldehyde-induced AML are likely to be zero. CONCLUSION We conclude that the IPoC approach can differentiate between likely and unlikely causal factors and can provide useful upper bounds for IPoC and CAS for some exposures and diseases of practical importance. For causal factors, IPoC can help to estimate the quantitative impacts on health risks of reducing exposures, even in situations where mechanistic evidence is realistically incomplete and individual-level exposure-response parameters are uncertain. This illustrates the strength that can be gained for causal inference by using causal models to generate testable hypotheses and then obtaining toxicological data to test the hypotheses implied by the models-and, where necessary, refine the models. This virtuous cycle provides additional insight into causal determinations that may not be available from weight-of-evidence considerations alone.
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Affiliation(s)
- Louis A Cox
- Cox Associates and University of Colorado, Denver, CO, USA
| | | | - Kenneth A Mundt
- Independent Consultants in Epidemiology, Amherst, MA, USA
- Adjunct Professor of Epidemiology, University of Massachusetts, Amherst, MA, USA
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Liu L, Liu Y, Zhou X, Xu Z, Zhang Y, Ji L, Hong C, Li C. Analyzing the metabolic fate of oral administration drugs: A review and state-of-the-art roadmap. Front Pharmacol 2022; 13:962718. [PMID: 36278150 PMCID: PMC9585159 DOI: 10.3389/fphar.2022.962718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
The key orally delivered drug metabolism processes are reviewed to aid the assessment of the current in vivo/vitro experimental systems applicability for evaluating drug metabolism and the interaction potential. Orally administration is the most commonly used state-of-the-art road for drug delivery due to its ease of administration, high patient compliance and cost-effectiveness. Roles of gut metabolic enzymes and microbiota in drug metabolism and absorption suggest that the gut is an important site for drug metabolism, while the liver has long been recognized as the principal organ responsible for drugs or other substances metabolism. In this contribution, we explore various experimental models from their development to the application for studying oral drugs metabolism of and summarized advantages and disadvantages. Undoubtedly, understanding the possible metabolic mechanism of drugs in vivo and evaluating the procedure with relevant models is of great significance for screening potential clinical drugs. With the increasing popularity and prevalence of orally delivered drugs, sophisticated experimental models with higher predictive capacity for the metabolism of oral drugs used in current preclinical studies will be needed. Collectively, the review seeks to provide a comprehensive roadmap for researchers in related fields.
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Teslenko I, Watson CJW, Xia Z, Chen G, Lazarus P. Characterization of Cytosolic Glutathione S-Transferases Involved in the Metabolism of the Aromatase Inhibitor, Exemestane. Drug Metab Dispos 2021; 49:1047-1055. [PMID: 34593616 PMCID: PMC11025106 DOI: 10.1124/dmd.121.000635] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/28/2021] [Indexed: 12/14/2022] Open
Abstract
Exemestane (EXE) is a hormonal therapy used to treat estrogen receptor-positive breast cancer by inhibiting the final step of estrogen biosynthesis catalyzed by the enzyme aromatase. Cysteine conjugates of EXE and its active metabolite 17β-dihydro-EXE (DHE) are the major metabolites found in both the urine and plasma of patients taking EXE. The initial step in cysteine conjugate formation is glutathione conjugation catalyzed by the glutathione S-transferase (GST) family of enzymes. The goal of the present study was to identify cytosolic hepatic GSTs active in the GST-mediated metabolism of EXE and 17β-DHE. Twelve recombinant cytosolic hepatic GSTs were screened for their activity against EXE and 17β-DHE, and glutathionylated EXE and 17β-DHE conjugates were detected by ultra-performance liquid chromatography tandem mass spectrometry. GST α (GSTA) isoform 1, GST μ (GSTM) isoform 3 and isoform 1 were active against EXE, whereas only GSTA1 exhibited activity against 17β-DHE. GSTM1 exhibited the highest affinity against EXE with a Michaelis-Menten constant (KM) value that was 3.8- and 7.1-fold lower than that observed for GSTA1 and GSTM3, respectively. Of the three GSTs, GSTM3 exhibited the highest intrinsic clearance against EXE (intrinsic clearance = 0.14 nl·min-1·mg-1). The KM values observed for human liver cytosol against EXE (46 μM) and 17β-DHE (77 μM) were similar to those observed for recombinant GSTA1 (53 and 30 μM, respectively). Western blot analysis revealed that GSTA1 and GSTM1 composed 4.3% and 0.57%, respectively, of total protein in human liver cytosol; GSTM3 was not detected. These data suggest that GSTA1 is the major hepatic cytosolic enzyme involved in the clearance of EXE and its major active metabolite, 17β-DHE. SIGNIFICANCE STATEMENT: Most previous studies related to the metabolism of the aromatase inhibitor exemestane (EXE) have focused mainly on phase I metabolic pathways and the glucuronidation phase II metabolic pathway. However, recent studies have indicated that glutathionylation is the major metabolic pathway for EXE. The present study is the first to characterize hepatic glutathione S-transferase (GST) activity against EXE and 17β-dihydro-EXE and to identify GST α 1 and GST μ 1 as the major cytosolic GSTs involved in the hepatic metabolism of EXE.
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Affiliation(s)
- Irina Teslenko
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Christy J W Watson
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Zuping Xia
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Gang Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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Ramírez‐Lopera V, Uribe‐Castro D, Bautista‐Amorocho H, Silva‐Sayago JA, Mateus‐Sánchez E, Ardila‐Barbosa WY, Pérez‐Cala TL. The effects of genetic polymorphisms on benzene-exposed workers: A systematic review. Health Sci Rep 2021; 4:e327. [PMID: 34295994 PMCID: PMC8284097 DOI: 10.1002/hsr2.327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/04/2021] [Accepted: 05/20/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND AND AIMS Benzene is a group I carcinogen, which has been associated with leukemia and myelodysplastic syndrome. Moreover, it has been proposed that polymorphisms in benzene metabolizing genes influence the outcomes of benzene exposure in the human body. This systematic review aims to elucidate the existent relationship between genetic polymorphisms and the risk of developing adverse health effects in benzene-exposed workers. METHODS Three databases were systematically searched until April 2020. The preferred reporting items for systematic reviews and meta-analyses method was used to select articles published between 2005 and 2020. Quality assessment and risk of bias were evaluated by the Newcastle-Ottawa scale. RESULTS After full-text evaluation, 36 articles remained out of 645 initially screened. The most studied health effects within the reviewed papers were chronic benzene poisoning, hematotoxicity, altered urinary biomarkers of exposure, micronucleus/chromosomal aberrations, and gene methylation. Furthermore, some polymorphisms on NQO1, GSTT1, GSTM1, MPO, and CYP2E1, among other genes, showed a statistically significant relationship with an increased risk of developing at least one of these effects on benzene-exposed workers. However, there was no consensus among the reviewed papers on which specific polymorphisms were the ones associated with the adverse health-related outcomes, except for the NQO1 rs1800566 and the GSTT1 null genotypes. Additionally, the smoking habit was identified as a confounder, demonstrating worse health outcomes in exposed workers that smoked. CONCLUSION Though there is a positive relationship between genetic polymorphisms and detrimental health outcomes for benzene-exposed workers, broader benzene-exposed cohorts that take into account the genetic diversity of the population are needed in order to determine which specific polymorphisms incur in health risks.
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Affiliation(s)
- Verónica Ramírez‐Lopera
- Bacterias & Cáncer Group, Microbiology and Parasitology, Faculty of MedicineUniversidad de AntioquiaMedellínColombia
| | - Daniel Uribe‐Castro
- Bacterias & Cáncer Group, Microbiology and Parasitology, Faculty of MedicineUniversidad de AntioquiaMedellínColombia
| | - Henry Bautista‐Amorocho
- Bacterias & Cáncer Group, Microbiology and Parasitology, Faculty of MedicineUniversidad de AntioquiaMedellínColombia
- Grupo de Investigación en Desarrollo Humano, Tejido Social e Innovaciones Tecnológicas—GIDTI, Programa Administración en Salud OcupacionalCentro Regional Bucaramanga, Corporación Universitaria Minuto de DiosBucaramangaColombia
| | - Jorge Alexander Silva‐Sayago
- Grupo de Investigación en Desarrollo Humano, Tejido Social e Innovaciones Tecnológicas—GIDTI, Programa Administración en Salud OcupacionalCentro Regional Bucaramanga, Corporación Universitaria Minuto de DiosBucaramangaColombia
| | - Enrique Mateus‐Sánchez
- Grupo de Investigación en Desarrollo Humano, Tejido Social e Innovaciones Tecnológicas—GIDTI, Programa de PsicologíaCentro Regional Bucaramanga, Corporación Universitaria Minuto de DiosBucaramangaColombia
| | - Wilman Yesid Ardila‐Barbosa
- Grupo de Investigación en Desarrollo Humano, Tejido Social e Innovaciones Tecnológicas—GIDTI, Programa Administración en Salud OcupacionalCentro Regional Bucaramanga, Corporación Universitaria Minuto de DiosBucaramangaColombia
| | - Tania Liseth Pérez‐Cala
- Bacterias & Cáncer Group, Microbiology and Parasitology, Faculty of MedicineUniversidad de AntioquiaMedellínColombia
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Ji B, Xiao LY, Ren JC, Zhang GH, Wang Y, Dong T, Li J, Zhang F, Xia ZL. Gene-Environment Interactions Between Environmental Response Genes Polymorphisms and Mitochondrial DNA Copy Numbers Among Benzene Workers. J Occup Environ Med 2021; 63:e408-e415. [PMID: 34184658 DOI: 10.1097/jom.0000000000002225] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To determine the effect of mitochondrial DNA copy number (mtDNAcn) as a biomarker of benzene exposure. METHODS A total of 294 benzene-exposed workers and 102 controls were recruited. Biomarkers of mtDNAcn, cytokinesis-block micronucleus (MN) frequency, and peripheral blood white blood cells (WBC) were detected. Eighteen polymorphism sites in DNA damage repair and metabolic genes were analyzed. RESULTS Benzene exposure increased mtDNAcn and indicated a dose-response relationship (P < 0.001). mtDNAcn was negatively correlated with WBC count and DNA methylation and positively correlated with MN frequency. The AG type in rs1695 interacted with benzene exposure to aggravate mtDNAcn (β = 0.006, 95% CI: 0, 0.012, P = 0.050). rs13181, rs1695, rs1800975, and GSTM1 null were associated with benzene-induced mtDNAcn. Rs1695 interacted with benzene to increase mitochondrial damage. CONCLUSIONS Benzene exposure increases mtDNAcn levels in benzene-exposed workers.
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Affiliation(s)
- Buqiang Ji
- Department of Hematology, Linyi People's Hospital, 27 Jifang Road, Linyi, China (Ji, Xiao), School of Public Health, Xinxiang Medical University, 601 Jinsui Road, Xinxiang, China (Ren, Zhang, Wang, Dong, Li, Zhang), Department of Occupational Health and Toxicology, School of Public Health, Fudan University, 138 Yixueyuan Road, Shanghai, China (Xia)
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Hausman-Cohen SR, Hausman-Cohen LJ, Williams GE, Bilich CE. Genomics of Detoxification: How Genomics can be Used for Targeting Potential Intervention and Prevention Strategies Including Nutrition for Environmentally Acquired Illness. J Am Coll Nutr 2021; 39:94-102. [PMID: 32027241 DOI: 10.1080/07315724.2020.1713654] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Due to their genomic variants, some individuals are more highly affected by toxicants than others. Toxicant metabolizing and activating variants have been linked with a wide variety of health issues including an increased risk of miscarriages, birth defects, Alzheimer's, benzene toxicity, mercury toxicity and cancer. The study of genomics allows a clinician to identify pathways that are less effective and then gives the clinician the opportunity to counsel their patients about diet, supplements and lifestyle modifications that can improve the function of these pathways or compensate to some extent for their deficits. This article will review a few of these critical pathways relating to phase I and phase 2 detox such as GSTP1, GPX1, GSTT1 deletions, PON1 and some of the CYP 450 system as examples of how an individual's genomic vulnerabilities to toxicants can be addressed by upregulating or downregulating specific pathways via genomically targeted use of foods, supplements and lifestyle changes.
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Affiliation(s)
| | | | | | - Carol E Bilich
- Resilient Health Austin and IntellxxDNATM, Austin, Texas, USA
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Cytochrome P450 Can Epoxidize an Oxepin to a Reactive 2,3-Epoxyoxepin Intermediate: Potential Insights into Metabolic Ring-Opening of Benzene. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25194542. [PMID: 33023027 PMCID: PMC7582548 DOI: 10.3390/molecules25194542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 11/16/2022]
Abstract
Dimethyldioxirane epoxidizes 4,5-benzoxepin to form the reactive 2,3-epoxyoxepin intermediate followed by very rapid ring-opening to an o-xylylene that immediately isomerizes to the stable product 1H-2-benzopyran-1-carboxaldehyde. The present study demonstrates that separate incubations of 4,5-benzoxepin with three cytochrome P450 isoforms (2E1, 1A2, and 3A4) as well as pooled human liver microsomes (pHLM) also produce 1H-2-benzopyran-1-carboxaldehyde as the major product, likely via the 2,3-epoxyoxepin. The reaction of 4,5-benzoxepin with cerium (IV) ammonium nitrate (CAN) yields a dimeric oxidized molecule that is also a lesser product of the P450 oxidation of 4,5-benzoxepin. The observation that P450 enzymes epoxidize 4,5-benzoxepin suggests that the 2,3-epoxidation of oxepin is a major pathway for the ring-opening metabolism of benzene to muconaldehyde.
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Silvestre RT, Bravo M, Santiago F, Delmonico L, Scherrer L, Otero UB, Liehr T, Alves G, Chantre-Justino M, Ornellas MH. Hypermethylation in Gene Promoters Are Induced by Chronic Exposure to Benzene, Toluene, Ethylbenzene and Xylenes. Pak J Biol Sci 2020; 23:518-525. [PMID: 32363837 DOI: 10.3923/pjbs.2020.518.525] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVE Gas station attendants are occupationally exposed to benzene, toluene, ethylbenzene and xylene (BTEX) compounds and thus more susceptible to the biological effects of this mixture present in gasoline, especially due to the carcinogenicity of benzene. Furthermore, the harmful effects of BTEX exposure may be potentiated by genetic and epigenetic inactivation of critical genes. The objective was to evaluate such gene-BTEX interactions accessing the promoter methylation status of p14ARF, p16INK4A and GSTP1 in peripheral blood leukocyte samples. MATERIALS AND METHODS The 59 exposed and 68 unexposed participants from Rio de Janeiro, Brazil, were included. The promoter methylation status was accessed by methylation-specific PCR (MSP) and GSTP1 Ile105Val polymorphism was investigated by PCR-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS Both p14ARF and p16INK4A were significantly hypermethylated in exposed subjects compared to unexposed (p = 0.004 and p<0.001, respectively). Additionally, p16INK4A hypermethylation in the exposed group was correlated with chromosomal abnormalities (CAs) (p = 0.018), thus highlighting the influence of the gene-environment interactions on genome instability. Noteworthy, p16INK4A methylation was significantly associated with miscarriage among female attendants (p = 0.047), in which those who reported miscarriage exhibited hypermethylation in at least 2 of the 3 genes analyzed. The GSTP1 heterozygote genotype, which could affect the metabolism of benzene detoxification, was found in both groups but was more frequent in those occupationally exposed. No significant association was observed between GSTP1 genotypes and methylation status. CONCLUSION Together, these findings indicate that gas station attendants with the aforementioned epigenetic and genetic profiles may be at greater risk of occupational BTEX exposure-induced genome instability, which could require concerted efforts to establish more preventive actions and constant biomonitoring in gas station attendants.
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Chiarella P, Capone P, Carbonari D, Sisto R. A Predictive Model Assessing Genetic Susceptibility Risk at Workplace. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16112012. [PMID: 31195756 PMCID: PMC6603935 DOI: 10.3390/ijerph16112012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/30/2019] [Accepted: 06/03/2019] [Indexed: 01/08/2023]
Abstract
(1) Background: The study of susceptibility biomarkers in the immigrant workforce integrated into the social tissue of European host countries is always a challenge, due to high individual heterogeneity and the admixing of different ethnicities in the same workplace. These workers having distinct cultural backgrounds, beliefs, diets, and habits, as well as a poor knowledge of the foreign language, may feel reluctant to donate their biological specimens for the biomonitoring research studies. (2) Methods: A model predicting ethnicity-specific susceptibility based on principal component analysis has been conceived, using the genotype frequency of the investigated populations available in publicly accessible databases. (3) Results: Correlations among ethnicities and between ethnic and polymorphic genes have been found, and low/high-risk profiles have been identified as valuable susceptibility biomarkers. (4) Conclusions: In the absence of workers’ consent or access to blood genotyping, ethnicity represents a good indicator of the subject’s genotype. This model, associating ethnicity-specific genotype frequency with the susceptibility biomarkers involved in the metabolism of toxicants, may replace genotyping, ensuring the necessary safety and health conditions of workers assigned to hazardous jobs.
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Affiliation(s)
- Pieranna Chiarella
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL Research, Via Fontana Candida 1, 00078 Monteporzio Catone, Rome, Italy.
| | - Pasquale Capone
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL Research, Via Fontana Candida 1, 00078 Monteporzio Catone, Rome, Italy.
| | - Damiano Carbonari
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL Research, Via Fontana Candida 1, 00078 Monteporzio Catone, Rome, Italy.
| | - Renata Sisto
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL Research, Via Fontana Candida 1, 00078 Monteporzio Catone, Rome, Italy.
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Setsungnern A, Treesubsuntorn C, Thiravetyan P. Exogenous 24-epibrassinolide enhanced benzene detoxification in Chlorophytum comosum via overexpression and conjugation by glutathione. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 662:805-815. [PMID: 30708296 DOI: 10.1016/j.scitotenv.2019.01.258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
Benzene, a hydrophobic xenobiotic, induces cell damage in both humans and plants. Due to its volatilization, benzene is an airborne environmental problem. The potential of an exogenous bioactive brassinosteroid phytohormone to enhance benzene removal for phytoremediation was investigated. Chlorophytum comosum had higher brassinosteroids content under benzene stress. Plant treated with 24-epibrassinolide (EBR) removed significantly more gaseous benzene than untreated plants under both light and dark conditions at an initial benzene of 12.75 μmol in the systematic chambers (P < 0.05). Although benzene increased malondialdehyde in plant tissue, EBR-treated plants lowered this lipid peroxidation by enhancing their antioxidant content and increasing benzene detoxification-related genes expression, including ascorbic acid (AsA), homogentisate phytyltransferase (HPT), and glutathione synthethase (GS). This contributed to maintaining higher photosynthetic performances. Moreover, EBR-treated plants had higher gene expression of ferredoxin-NADP reductase (FNR) and glucose-6-phosphate 1-dehydrogenase (G6PDH), thus promoting NADPH biosynthesis to cope with benzene under light and dark conditions, respectively. Further, higher glutathione biosynthesis promoted more glutathione conjugate of benzene products including S-phenylcysteine (SPC) in EBR-treated plants. Hence, application of exogenous EBR as foliar spray provided for enhanced benzene detoxification via antioxidant content, benzene detoxification-related genes and benzene conjugation products with glutathione (GSH) and consequently greater gaseous benzene removal.
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Affiliation(s)
- Arnon Setsungnern
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok 10150, Thailand
| | - Chairat Treesubsuntorn
- Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi, Bangkok 10150, Thailand
| | - Paitip Thiravetyan
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok 10150, Thailand.
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Luo S, Chen G, Truica CI, Baird CC, Xia Z, Lazarus P. Identification and Quantification of Novel Major Metabolites of the Steroidal Aromatase Inhibitor, Exemestane. Drug Metab Dispos 2018; 46:1867-1878. [PMID: 30257855 PMCID: PMC7333658 DOI: 10.1124/dmd.118.081166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 09/14/2018] [Indexed: 01/03/2023] Open
Abstract
Exemestane (EXE) is an aromatase inhibitor used for the prevention and treatment of estrogen receptor–positive breast cancer. Although the known major metabolic pathway for EXE is reduction to form the active 17β-dihydro-EXE (17β-DHE) and subsequent glucuronidation to 17β-hydroxy-EXE-17-O-β-D-glucuronide (17β-DHE-Gluc), previous studies have suggested that other major metabolites exist for exemestane. In the present study, a liquid chromatography–mass spectrometry (LC-MS) approach was used to acquire accurate mass data in MSE mode, in which precursor ion and fragment ion data were obtained simultaneously to screen novel phase II EXE metabolites in urine specimens from women taking EXE. Two major metabolites predicted to be cysteine conjugates of EXE and 17β-DHE by elemental composition were identified. The structures of the two metabolites were confirmed to be 6-methylcysteinylandrosta-1,4-diene-3,17-dione (6-EXE-cys) and 6-methylcysteinylandrosta-1,4-diene-17β-hydroxy-3-one (6-17β-DHE-cys) after comparison with their chemically synthesized counterparts. Both underwent biosynthesis in vitro in three stepwise enzymatic reactions, with the first involving glutathione conjugation. The cysteine conjugates of EXE and 17β-DHE were subsequently quantified by liquid chromatography–mass spectrometry in the urine and matched plasma samples of 132 subjects taking EXE. The combined 6-EXE-cys plus 6-17β-DHE-cys made up 77% of total EXE metabolites in urine (vs. 1.7%, 0.14%, and 21% for EXE, 17β-DHE, and 17β-DHE-Gluc, respectively) and 35% in plasma (vs. 17%, 12%, and 36% for EXE, 17β-DHE, and 17β-DHE-Gluc, respectively). Therefore, cysteine conjugates of EXE and 17β-DHE appear to be major metabolites of EXE in both urine and plasma.
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Affiliation(s)
- Shaman Luo
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
| | - Gang Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
| | - Cristina I Truica
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
| | - Cynthia C Baird
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
| | - Zuping Xia
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (S.L., G.C., Z.X., P.L.); Department of Medicine, Penn State University College of Medicine, Hershey, Pennsylvania (C.I.T., C.C.B.); and Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, Heilongjiang, China (S.L.)
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Ahmed HG, Alshmmari FD, Ginawi IA, Alshammari NG, Alshammari AMA, Alshuqayr MA, Alkhariji MT. Assessment of urothelial cells atypical changes among petroleum station workers in Saudi Arabia. EUR J INFLAMM 2017. [DOI: 10.1177/1721727x16689272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The aim of the present study was to assess atypical changes in urothelial cells among petroleum station workers. This is a case control study, investigating 300 participants by cytological methods. Of the 300 participants, 150 were cases (exposed to petroleum products) and 150 were controls (non-exposed). Full voided urine was obtained and was cytologically assessed. Cytological atypia was identified in nine (6%) out of the 150 cases and could not be identified in 141/150 (94%) of the cases, whereas, in the control group, cytological atypia was recognized in four (2.7%) of the 150 controls and could not be identified in 146/150 (97.3%). The risk associated with petroleum product exposure, the odds ratio (OR), and 95% confidence interval (CI) was 2.33 (0.7015–7.7378), P = 0.1673. Exposure of petroleum station workers to petroleum products increases the risk of urothelial atypical changes, which may progress to precancerous and cancerous changes.
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Affiliation(s)
| | - Fawaz D Alshmmari
- College of Applied Medical Science, University of Hail, Kingdome of Saudi Arabia
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Yuan JM, Murphy SE, Stepanov I, Wang R, Carmella SG, Nelson HH, Hatsukami D, Hecht SS. 2-Phenethyl Isothiocyanate, Glutathione S-transferase M1 and T1 Polymorphisms, and Detoxification of Volatile Organic Carcinogens and Toxicants in Tobacco Smoke. Cancer Prev Res (Phila) 2016; 9:598-606. [PMID: 27099270 PMCID: PMC4930697 DOI: 10.1158/1940-6207.capr-16-0032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/14/2016] [Indexed: 02/06/2023]
Abstract
Cigarette smoke contains relatively large quantities of volatile organic toxicants or carcinogens such as benzene, acrolein, and crotonaldehyde. Among their detoxification products are mercapturic acids formed from glutathione conjugation, catalyzed in part by glutathione S-transferases (GST). A randomized phase II clinical trial with a crossover design was conducted to evaluate the effect of 2-phenethyl isothiocyanate (PEITC), a natural product formed from gluconasturtiin in certain cruciferous vegetables, on the detoxification of benzene, acrolein, and crotonaldehyde in 82 cigarette smokers. Urinary mercapturic acids of benzene, acrolein, and crotonaldehyde at baseline and during treatment were quantified. Overall, oral PEITC supplementation increased the mercapturic acid formed from benzene by 24.6% (P = 0.002) and acrolein by 15.1% (P = 0.005), but had no effect on crotonaldehyde. A remarkably stronger effect was observed among subjects with the null genotype of both GSTM1 and GSTT1: in these individuals, PEITC increased the detoxification metabolite of benzene by 95.4% (P < 0.001), of acrolein by 32.7% (P = 0.034), and of crotonaldehyde by 29.8% (P = 0.006). In contrast, PEITC had no effect on these mercapturic acids in smokers possessing both genes. PEITC had no effect on the urinary oxidative stress biomarker 8-iso-prostaglandin F2α or the inflammation biomarker prostaglandin E2 metabolite. This trial demonstrates an important role of PEITC in detoxification of environmental carcinogens and toxicants which also occur in cigarette smoke. The selective effect of PEITC on detoxification in subjects lacking both GSTM1 and GSTT1 genes supports the epidemiologic findings of stronger protection by dietary isothiocyanates against the development of lung cancer in such individuals. Cancer Prev Res; 9(7); 598-606. ©2016 AACR.
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Affiliation(s)
- Jian-Min Yuan
- University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania. Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.
| | - Sharon E Murphy
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Department of Biochemistry, Molecular Biology and BioPhysics, University of Minnesota, Minneapolis, Minnesota
| | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Renwei Wang
- University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania
| | - Steven G Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Heather H Nelson
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota
| | - Dorothy Hatsukami
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
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Haiman CA, Patel YM, Stram DO, Carmella SG, Chen M, Wilkens LR, Le Marchand L, Hecht SS. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort. PLoS One 2016; 11:e0150641. [PMID: 26959369 PMCID: PMC4784986 DOI: 10.1371/journal.pone.0150641] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 02/16/2016] [Indexed: 12/17/2022] Open
Abstract
Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2-31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke.
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Affiliation(s)
- Christopher A. Haiman
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Yesha M. Patel
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Daniel O. Stram
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Steven G. Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
| | - Menglan Chen
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
| | - Lynne R. Wilkens
- Epidemiology Program, Cancer Research Center of Hawai’i, University of Hawai’i, Honolulu, HI, 96813, United States of America
| | - Loic Le Marchand
- Epidemiology Program, Cancer Research Center of Hawai’i, University of Hawai’i, Honolulu, HI, 96813, United States of America
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
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