1
|
Hartwig A, Arand M, Epe B, Guth S, Jahnke G, Lampen A, Martus HJ, Monien B, Rietjens IMCM, Schmitz-Spanke S, Schriever-Schwemmer G, Steinberg P, Eisenbrand G. Mode of action-based risk assessment of genotoxic carcinogens. Arch Toxicol 2020; 94:1787-1877. [PMID: 32542409 PMCID: PMC7303094 DOI: 10.1007/s00204-020-02733-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B1, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
Collapse
Affiliation(s)
- Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany.
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zurich, Switzerland
| | - Bernd Epe
- Institute of Pharmacy and Biochemistry, University of Mainz, 55099, Mainz, Germany
| | - Sabine Guth
- Department of Toxicology, IfADo-Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund, Ardeystr. 67, 44139, Dortmund, Germany
| | - Gunnar Jahnke
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Alfonso Lampen
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Hans-Jörg Martus
- Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Bernhard Monien
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Henkestr. 9-11, 91054, Erlangen, Germany
| | - Gerlinde Schriever-Schwemmer
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany
| | - Gerhard Eisenbrand
- Retired Senior Professor for Food Chemistry and Toxicology, Kühler Grund 48/1, 69126, Heidelberg, Germany.
| |
Collapse
|
2
|
Zhang J, Chan CK, Ham YH, Chan W. Identifying Cysteine, N-Acetylcysteine, and Glutathione Conjugates as Novel Metabolites of Aristolochic Acid I: Emergence of a New Detoxification Pathway. Chem Res Toxicol 2020; 33:1374-1381. [DOI: 10.1021/acs.chemrestox.9b00488] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jiayin Zhang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Chi-Kong Chan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Yat-Hing Ham
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Wan Chan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| |
Collapse
|
3
|
Sidorenko VS. Biotransformation and Toxicities of Aristolochic Acids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1241:139-166. [PMID: 32383120 DOI: 10.1007/978-3-030-41283-8_9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Environmental and iatrogenic exposures contribute significantly to human diseases, including cancer. The list of known human carcinogens has recently been extended by the addition of aristolochic acids (AAs). AAs occur primarily in Aristolochia herbs, which are used extensively in folk medicines, including Traditional Chinese Medicine. Ingestion of AAs results in chronic renal disease and cancer. Despite importation bans imposed by certain countries, herbal remedies containing AAs are readily available for purchase through the internet. With recent advancements in mass spectrometry, next generation sequencing, and the development of integrated organs-on-chips, our knowledge of cancers associated with AA exposure, and of the mechanisms involved in AA toxicities, has significantly improved. DNA adduction plays a central role in AA-induced cancers; however, significant gaps remain in our knowledge as to how cellular enzymes promote activation of AAs and how the reactive species selectively bind to DNA and kidney proteins. In this review, I describe pathways for AAs biotransformation, adduction, and mutagenesis, emphasizing novel methods and ideas contributing to our present understanding of AA toxicities in humans.
Collapse
Affiliation(s)
- Viktoriya S Sidorenko
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA.
| |
Collapse
|
4
|
Liu Y, Wang Q, Nie D, Zhang Y, Wang Z, Zhang Y. Novel Modified GLP-1 Derivatives with Prolonged Glucose-Lowering Ability In Vivo. Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-019-09991-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
5
|
Bellamri M, Wang Y, Yonemori K, White KK, Wilkens LR, Le Marchand L, Turesky RJ. Biomonitoring an albumin adduct of the cooked meat carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in humans. Carcinogenesis 2019; 39:1455-1462. [PMID: 30247550 DOI: 10.1093/carcin/bgy125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Accepted: 09/18/2018] [Indexed: 01/12/2023] Open
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is formed in cooked meats and may be linked to dietary-associated colorectal, prostate and mammary cancers. Genotoxic N-oxidized metabolites of PhIP react with the Cys34 of albumin (Alb) to form a sulfinamide adduct, a biomarker of the biologically effective dose. We examined the kinetics of PhIP-Alb adduct formation in plasma of volunteers on a 4-week semicontrolled diet of cooked meat containing known quantities of PhIP. The adduct was below the limit of detection (LOD) (10 femtograms PhIP/mg Alb) in most subjects before the meat feeding but increased by up to 560-fold at week 4 in subjects who ate meat containing 8.0 to 11.7 μg of PhIP per 150-200 g serving. In contrast, the adduct remained below the LOD in subjects who ingested 1.2 or 3.0 μg PhIP per serving. Correlations were not seen between PhIP-Alb adduct levels and PhIP intake levels (P = 0.76), the amount of PhIP accrued in hair (P = 0.13), the amounts of N-oxidized urinary metabolites of PhIP (P = 0.66) or caffeine CYP1A2 activity (P = 0.55), a key enzyme involved in the bioactivation of PhIP. The half-life of the PhIP-Alb adduct was <2 weeks, signifying that the adduct was not stable. PhIP-Alb adduct formation is direct evidence of bioactivation of PhIP in vivo. However, the PhIP hair biomarker is a longer lived and more sensitive biomarker to assess exposure to this potential human carcinogen.
Collapse
Affiliation(s)
- Medjda Bellamri
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Yi Wang
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA.,Department of Medicinal Chemistry, Medical Science Building, University of Florida, Gainesville, FL, USA
| | - Kim Yonemori
- Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Kami K White
- Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Lynne R Wilkens
- Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Loïc Le Marchand
- Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI, USA
| | - Robert J Turesky
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| |
Collapse
|
6
|
Chen YS, Wang R, Dashwood WM, Löhr CV, Williams DE, Ho E, Mertens-Talcott S, Dashwood RH. A miRNA signature for an environmental heterocyclic amine defined by a multi-organ carcinogenicity bioassay in the rat. Arch Toxicol 2017; 91:3415-3425. [PMID: 28289824 PMCID: PMC5836314 DOI: 10.1007/s00204-017-1945-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 02/23/2017] [Indexed: 12/16/2022]
Abstract
Heterocyclic amines (HCAs) produced during high-temperature cooking have been studied extensively in terms of their genotoxic/genetic effects, but recent work has implicated epigenetic mechanisms involving non-coding RNAs. Colon tumors induced in the rat by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) have altered microRNA (miRNA) signatures linked to dysregulated pluripotency factors, such as c-Myc and Krüppel-like factor 4 (KLF4). We tested the hypothesis that dysregulated miRNAs from PhIP-induced colon tumors would provide a "PhIP signature" for use in other target organs obtained from a 1-year carcinogenicity bioassay in the rat. Downstream targets that were corroborated in the rat were then investigated in human cancer datasets. The results confirmed that multiple let-7 family members were downregulated in PhIP-induced skin, colon, lung, small intestine, and Zymbal's gland tumors, and were associated with c-myc and Hmga2 upregulation. PhIP signature miRNAs with the profile mir-21high/mir-126low/mir-29clow/mir-215low/mir-145low were linked to reduced Klf4 levels in rat tumors, and in human pan-cancer and colorectal cancer. It remains to be determined whether this PhIP signature has predictive value, given that more than 20 different genotoxic HCAs are present in the human diet, plus other agents that likely induce or repress many of the same miRNAs. Future studies should define more precisely the miRNA signatures of other HCAs, and their possible value for human risk assessment.
Collapse
Affiliation(s)
- Ying-Shiuan Chen
- Center for Epigenetics and Disease Prevention, Texas A&M University College of Medicine, 2121 W Holcombe Blvd., Houston, TX, 77030, USA
| | - Rong Wang
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Wan-Mohaiza Dashwood
- Center for Epigenetics and Disease Prevention, Texas A&M University College of Medicine, 2121 W Holcombe Blvd., Houston, TX, 77030, USA
| | - Christiane V Löhr
- College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - David E Williams
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Emily Ho
- Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
- College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA
| | - Susanne Mertens-Talcott
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Roderick H Dashwood
- Center for Epigenetics and Disease Prevention, Texas A&M University College of Medicine, 2121 W Holcombe Blvd., Houston, TX, 77030, USA.
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Department of Molecular and Cellular Medicine, Texas A&M College of Medicine, College Station, TX, USA.
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX, USA.
| |
Collapse
|
7
|
Wang Y, Villalta PW, Peng L, Dingley K, Malfatti MA, Turteltaub KW, Turesky RJ. Mass Spectrometric Characterization of an Acid-Labile Adduct Formed with 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and Albumin in Humans. Chem Res Toxicol 2017; 30:705-714. [PMID: 27984695 DOI: 10.1021/acs.chemrestox.6b00426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high-temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine, an electrophilic metabolite that forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized PhIP metabolites with human albumin in vitro primarily occurs at the Cys34 residue, to produce an acid-labile linked sulfinamide adduct. On the basis of these findings, we developed a sensitive ultraperformance liquid chromatography-mass spectrometry method to measure acid-labile albumin-PhIP adducts in human volunteers administered a dietary-relevant dose of 14C-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prev. 8, 507-512]. Mild acid treatment of albumin (0.1 N HCl, 37 °C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 °C for 18 h] released similar amounts of covalently bound PhIP, which was characterized by multistage scanning and quantified by Orbitrap mass spectrometry. The amount of [14C]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2-21.3% of the [14C]PhIP bound to albumin based on accelerator mass spectrometry measurements. 2-Amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine, a hydrolysis product of the Cys34 S-N linked sulfenamide adduct of PhIP, was not detected in either acid-treated or protease-treated samples. These findings suggest that a portion of the PhIP bound to albumin in vivo probably occurs as an acid-labile sulfinamide adduct formed at the Cys34 residue.
Collapse
Affiliation(s)
| | | | - Lijuan Peng
- School of Food Science and Engineering, Wuhan Polytechnic University , ChangQing Garden, Hankou, Wuhan 430023, P. R. China
| | - Karen Dingley
- Biosciences and Biotechnology Division, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
| | - Michael A Malfatti
- Biosciences and Biotechnology Division, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
| | - K W Turteltaub
- Biosciences and Biotechnology Division, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
| | | |
Collapse
|
8
|
Sabbioni G, Turesky RJ. Biomonitoring Human Albumin Adducts: The Past, the Present, and the Future. Chem Res Toxicol 2017; 30:332-366. [PMID: 27989119 PMCID: PMC5241710 DOI: 10.1021/acs.chemrestox.6b00366] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Indexed: 12/21/2022]
Abstract
Serum albumin (Alb) is the most abundant protein in blood plasma. Alb reacts with many carcinogens and/or their electrophilic metabolites. Studies conducted over 20 years ago showed that Alb forms adducts with the human carcinogens aflatoxin B1 and benzene, which were successfully used as biomarkers in molecular epidemiology studies designed to address the role of these chemicals in cancer risk. Alb forms adducts with many therapeutic drugs or their reactive metabolites such as β-lactam antibiotics, acetylsalicylic acid, acetaminophen, nonsteroidal anti-inflammatory drugs, chemotherapeutic agents, and antiretroviral therapy drugs. The identification and characterization of the adduct structures formed with Alb have served to understand the generation of reactive metabolites and to predict idiosyncratic drug reactions and toxicities. The reaction of candidate drugs with Alb is now exploited as part of the battery of screening tools to assess the potential toxicities of drugs. The use of gas chromatography-mass spectrometry, liquid chromatography, or liquid chromatography-mass spectrometry (LC-MS) enabled the identification and quantification of multiple types of Alb xenobiotic adducts in animals and humans during the past three decades. In this perspective, we highlight the history of Alb as a target protein for adduction to environmental and dietary genotoxicants, pesticides, and herbicides, common classes of medicinal drugs, and endogenous electrophiles, and the emerging analytical mass spectrometry technologies to identify Alb-toxicant adducts in humans.
Collapse
Affiliation(s)
- Gabriele Sabbioni
- Institute of Environmental and Occupational Toxicology, CH-6780 Airolo, Switzerland
- Alpine Institute of Chemistry and Toxicology, CH-6718 Olivone, Switzerland
- Walther-Straub-Institut für Pharmakologie
und Toxikologie, Ludwig-Maximilians-Universität München, D-80336 München, Germany
| | - Robert J. Turesky
- Masonic Cancer Center and Department of
Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 Sixth Street SE, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
9
|
Nandhini T, Vaidyanathan V, Nair B. Effect of conformation of the arylamine-DNA adduct on the sensitivity of [Ru(phen)2(dppz)]2+ complex. INORG CHEM COMMUN 2016. [DOI: 10.1016/j.inoche.2016.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
10
|
Hughes T, Dang NL, Miller GP, Swamidass SJ. Modeling Reactivity to Biological Macromolecules with a Deep Multitask Network. ACS CENTRAL SCIENCE 2016; 2:529-37. [PMID: 27610414 PMCID: PMC4999971 DOI: 10.1021/acscentsci.6b00162] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Indexed: 05/14/2023]
Abstract
Most small-molecule drug candidates fail before entering the market, frequently because of unexpected toxicity. Often, toxicity is detected only late in drug development, because many types of toxicities, especially idiosyncratic adverse drug reactions (IADRs), are particularly hard to predict and detect. Moreover, drug-induced liver injury (DILI) is the most frequent reason drugs are withdrawn from the market and causes 50% of acute liver failure cases in the United States. A common mechanism often underlies many types of drug toxicities, including both DILI and IADRs. Drugs are bioactivated by drug-metabolizing enzymes into reactive metabolites, which then conjugate to sites in proteins or DNA to form adducts. DNA adducts are often mutagenic and may alter the reading and copying of genes and their regulatory elements, causing gene dysregulation and even triggering cancer. Similarly, protein adducts can disrupt their normal biological functions and induce harmful immune responses. Unfortunately, reactive metabolites are not reliably detected by experiments, and it is also expensive to test drug candidates for potential to form DNA or protein adducts during the early stages of drug development. In contrast, computational methods have the potential to quickly screen for covalent binding potential, thereby flagging problematic molecules and reducing the total number of necessary experiments. Here, we train a deep convolution neural network-the XenoSite reactivity model-using literature data to accurately predict both sites and probability of reactivity for molecules with glutathione, cyanide, protein, and DNA. On the site level, cross-validated predictions had area under the curve (AUC) performances of 89.8% for DNA and 94.4% for protein. Furthermore, the model separated molecules electrophilically reactive with DNA and protein from nonreactive molecules with cross-validated AUC performances of 78.7% and 79.8%, respectively. On both the site- and molecule-level, the model's performances significantly outperformed reactivity indices derived from quantum simulations that are reported in the literature. Moreover, we developed and applied a selectivity score to assess preferential reactions with the macromolecules as opposed to the common screening traps. For the entire data set of 2803 molecules, this approach yielded totals of 257 (9.2%) and 227 (8.1%) molecules predicted to be reactive only with DNA and protein, respectively, and hence those that would be missed by standard reactivity screening experiments. Site of reactivity data is an underutilized resource that can be used to not only predict if molecules are reactive, but also show where they might be modified to reduce toxicity while retaining efficacy. The XenoSite reactivity model is available at http://swami.wustl.edu/xenosite/p/reactivity.
Collapse
Affiliation(s)
- Tyler
B. Hughes
- Department
of Pathology and Immunology, Washington
University School of Medicine, Campus
Box 8118, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
| | - Na Le Dang
- Department
of Pathology and Immunology, Washington
University School of Medicine, Campus
Box 8118, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
| | - Grover P. Miller
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - S. Joshua Swamidass
- Department
of Pathology and Immunology, Washington
University School of Medicine, Campus
Box 8118, 660 South Euclid Avenue, St. Louis, Missouri 63110, United States
- E-mail:
| |
Collapse
|
11
|
Sheng J, Wang Y, Turesky RJ, Kluetzman K, Zhang QY, Ding X. Novel Transgenic Mouse Model for Studying Human Serum Albumin as a Biomarker of Carcinogenic Exposure. Chem Res Toxicol 2016; 29:797-809. [PMID: 27028147 DOI: 10.1021/acs.chemrestox.5b00529] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Albumin is a commonly used serum protein for studying human exposure to xenobiotic compounds, including therapeutics and environmental pollutants. Often, the reactivity of albumin with xenobiotic compounds is studied ex vivo with human albumin or plasma/serum samples. Some studies have characterized the reactivity of albumin with chemicals in rodent models; however, differences between the orthologous peptide sequences of human and rodent albumins can result in the formation of different types of chemical-protein adducts with different interaction sites or peptide sequences. Our goal is to generate a human albumin transgenic mouse model that can be used to establish human protein biomarkers of exposure to hazardous xenobiotics for human risk assessment via animal studies. We have developed a human albumin transgenic mouse model and characterized the genotype and phenotype of the transgenic mice. The presence of the human albumin gene in the genome of the model mouse was confirmed by genomic PCR analysis, whereas liver-specific expression of the transgenic human albumin mRNA was validated by RT-PCR analysis. Further immunoblot and mass spectrometry analyses indicated that the transgenic human albumin protein is a full-length, mature protein, which is less abundant than the endogenous mouse albumin that coexists in the serum of the transgenic mouse. The transgenic protein was able to form ex vivo adducts with a genotoxic metabolite of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a procarcinogenic heterocyclic aromatic amine formed in cooked meat. This novel human albumin transgenic mouse model will facilitate the development and validation of albumin-carcinogen adducts as biomarkers of xenobiotic exposure and/or toxicity in humans.
Collapse
Affiliation(s)
- Jonathan Sheng
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Yi Wang
- Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Robert J Turesky
- Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Kerri Kluetzman
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Qing-Yu Zhang
- Wadsworth Center, New York State Department of Health , Albany, New York 12201, United States
| | - Xinxin Ding
- College of Nanoscale Science, SUNY Polytechnic Institute , Albany, New York 12203, United States
| |
Collapse
|
12
|
Cooper KM, Brennan SF, Woodside JV, Cantwell M, Guo X, Mooney M, Elliott CT, Cuskelly GJ. Acid-labile protein-adducted heterocyclic aromatic amines in human blood are not viable biomarkers of dietary exposure: A systematic study. Food Chem Toxicol 2016; 91:100-7. [PMID: 26993956 DOI: 10.1016/j.fct.2016.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/08/2016] [Accepted: 03/11/2016] [Indexed: 01/13/2023]
Abstract
Heterocyclic aromatic amines (HCA) are carcinogenic mutagens formed during cooking of protein-rich foods. HCA residues adducted to blood proteins have been postulated as biomarkers of HCA exposure. However, the viability of quantifying HCAs following hydrolytic release from adducts in vivo and correlation with dietary intake are unproven. To definitively assess the potential of labile HCA-protein adducts as biomarkers, a highly sensitive UPLC-MS/MS method was validated for four major HCAs: 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx). Limits of detection were 1-5 pg/ml plasma and recoveries 91-115%. Efficacy of hydrolysis was demonstrated by HCA-protein adducts synthesised in vitro. Plasma and 7-day food diaries were collected from 122 fasting adults consuming their habitual diets. Estimated HCA intakes ranged from 0 to 2.5 mg/day. An extensive range of hydrolysis conditions was examined for release of adducted HCAs in plasma. HCA was detected in only one sample (PhIP, 9.7 pg/ml), demonstrating conclusively for the first time that acid-labile HCA adducts do not reflect dietary HCA intake and are present at such low concentrations that they are not feasible biomarkers of exposure. Identification of biomarkers remains important. The search should concentrate on stabilised HCA-peptide markers and use of untargeted proteomic and metabolomic approaches.
Collapse
Affiliation(s)
- Kevin M Cooper
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, United Kingdom.
| | - Sarah F Brennan
- Centre for Public Health, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast, BT12 6BA, United Kingdom
| | - Jayne V Woodside
- Centre for Public Health, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast, BT12 6BA, United Kingdom
| | - Marie Cantwell
- Centre for Public Health, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast, BT12 6BA, United Kingdom
| | - Xiaoxiao Guo
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, United Kingdom
| | - Mark Mooney
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, United Kingdom
| | - Christopher T Elliott
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, United Kingdom
| | - Geraldine J Cuskelly
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 18-30 Malone Road, Belfast, BT9 5BN, United Kingdom
| |
Collapse
|
13
|
Pathak KV, Bellamri M, Wang Y, Langouët S, Turesky RJ. 2-Amino-9H-pyrido[2,3-b]indole (AαC) Adducts and Thiol Oxidation of Serum Albumin as Potential Biomarkers of Tobacco Smoke. J Biol Chem 2015; 290:16304-18. [PMID: 25953894 PMCID: PMC4481229 DOI: 10.1074/jbc.m115.646539] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 05/05/2015] [Indexed: 12/30/2022] Open
Abstract
2-Amino-9H-pyrido[2,3-b]indole (AαC) is a carcinogenic heterocyclic aromatic amine formed during the combustion of tobacco. AαC undergoes bioactivation to form electrophilic N-oxidized metabolites that react with DNA to form adducts, which can lead to mutations. Many genotoxicants and toxic electrophiles react with human serum albumin (albumin); however, the chemistry of reactivity of AαC with proteins has not been studied. The genotoxic metabolites, 2-hydroxyamino-9H-pyrido[2,3-b]indole (HONH-AαC), 2-nitroso-9H-pyrido[2,3-b]indole (NO-AαC), N-acetyloxy-2-amino-9H-pyrido[2,3-b]indole (N-acetoxy-AαC), and their [(13)C6]AαC-labeled homologues were reacted with albumin. Sites of adduction of AαC to albumin were identified by data-dependent scanning and targeted bottom-up proteomics approaches employing ion trap and Orbitrap MS. AαC-albumin adducts were formed at Cys(34), Tyr(140), and Tyr(150) residues when albumin was reacted with HONH-AαC or NO-AαC. Sulfenamide, sulfinamide, and sulfonamide adduct formation occurred at Cys(34) (AαC-Cys(34)). N-Acetoxy-AαC also formed an adduct at Tyr(332). Albumin-AαC adducts were characterized in human plasma treated with N-oxidized metabolites of AαC and human hepatocytes exposed to AαC. High levels of N-(deoxyguanosin-8-yl)-AαC (dG-C8-AαC) DNA adducts were formed in hepatocytes. The Cys(34) was the sole amino acid of albumin to form adducts with AαC. Albumin also served as an antioxidant and scavenged reactive oxygen species generated by metabolites of AαC in hepatocytes; there was a strong decrease in reduced Cys(34), whereas the levels of Cys(34) sulfinic acid (Cys-SO2H), Cys(34)-sulfonic acid (Cys-SO3H), and Met(329) sulfoxide were greatly increased. Cys(34) adduction products and Cys-SO2H, Cys-SO3H, and Met(329) sulfoxide may be potential biomarkers to assess exposure and oxidative stress associated with AαC and other arylamine toxicants present in tobacco smoke.
Collapse
Affiliation(s)
- Khyatiben V Pathak
- From the Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 and
| | - Medjda Bellamri
- UMR INSERM 1085 IRSET, Rennes 1 University, UMS 3480 Biosit, F-35043 Rennes, France
| | - Yi Wang
- From the Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 and
| | - Sophie Langouët
- UMR INSERM 1085 IRSET, Rennes 1 University, UMS 3480 Biosit, F-35043 Rennes, France
| | - Robert J Turesky
- From the Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 and
| |
Collapse
|
14
|
Wang Y, Peng L, Bellamri M, Langouët S, Turesky RJ. Mass Spectrometric Characterization of Human Serum Albumin Adducts Formed with N-Oxidized Metabolites of 2-Amino-1-methylphenylimidazo[4,5-b]pyridine in Human Plasma and Hepatocytes. Chem Res Toxicol 2015; 28:1045-59. [PMID: 25815793 DOI: 10.1021/acs.chemrestox.5b00075] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogenic heterocyclic aromatic amine formed in cooked meats, is metabolically activated to electrophilic intermediates that form covalent adducts with DNA and protein. We previously identified an adduct of PhIP formed at the Cys(34) residue of human serum albumin following reaction of albumin with the genotoxic metabolite 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP). The major adducted peptide recovered from a tryptic/chymotryptic digest was identified as the missed-cleavage peptide LQQC*([SO2PhIP])PFEDHVK, a [cysteine-S-yl-PhIP]-S-dioxide linked adduct. In this investigation, we have characterized the albumin adduction products of N-sulfooxy-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-sulfooxy-PhIP), which is thought to be a major genotoxic metabolite of PhIP formed in vivo. Targeted and data-dependent scanning methods showed that N-sulfooxy-PhIP adducted to the Cys(34) of albumin in human plasma to form LQQC*([SO2PhIP])PFEDHVK at levels that were 8-10-fold greater than the adduct levels formed with N-(acetyloxy)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-acetoxy-PhIP) or HONH-PhIP. We also discovered that N-sulfooxy-PhIP forms an adduct at the sole tryptophan (Trp(214)) residue of albumin in the sequence AW*([PhIP])AVAR. However, stable adducts of PhIP with albumin were not detected in human hepatocytes. Instead, PhIP and 2-amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine (5-HO-PhIP), a solvolysis product of the proposed nitrenium ion of PhIP, were recovered during the proteolysis, suggesting a labile sulfenamide linkage had formed between an N-oxidized intermediate of PhIP and Cys(34) of albumin. A stable adduct was formed at the Tyr(411) residue of albumin in hepatocytes and identified as a deaminated product of PhIP, Y(*[desaminoPhIP])TK, where the 4-HO-tyrosine group bound to the C-2 imidazole atom of PhIP.
Collapse
Affiliation(s)
- Yi Wang
- †Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiology Research Building, University of Minnesota, 2231 6th Street, Minneapolis, Minnesota 55455, United States
| | - Lijuan Peng
- ‡School of Chemical and Environmental Engineering, Wuhan Polytechnic University, ChangQing Garden, Hankou, Wuhan 430023, P. R. China
| | - Medjda Bellamri
- §Institut National de la Santé et de la Recherche Médicale (Inserm), U.1085, Institut de Recherche Santé Environnement et Travail (IRSET), Université de Rennes 1, UMS 3480 Biosit, F-35043 Rennes, France.,∥ANSES Laboratoire de Fougères, La Haute Marche-Javené, BP 90203, 350302 Fougères, France
| | - Sophie Langouët
- §Institut National de la Santé et de la Recherche Médicale (Inserm), U.1085, Institut de Recherche Santé Environnement et Travail (IRSET), Université de Rennes 1, UMS 3480 Biosit, F-35043 Rennes, France
| | - Robert J Turesky
- †Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiology Research Building, University of Minnesota, 2231 6th Street, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
15
|
LeBlanc A, Shiao TC, Roy R, Sleno L. Absolute Quantitation of NAPQI-Modified Rat Serum Albumin by LC–MS/MS: Monitoring Acetaminophen Covalent Binding in Vivo. Chem Res Toxicol 2014; 27:1632-9. [DOI: 10.1021/tx500284g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- André LeBlanc
- Pharmaqam, Chemistry Department, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal, Québec H3C 3P8, Canada
| | - Tze Chieh Shiao
- Pharmaqam, Chemistry Department, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal, Québec H3C 3P8, Canada
| | - René Roy
- Pharmaqam, Chemistry Department, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal, Québec H3C 3P8, Canada
| | - Lekha Sleno
- Pharmaqam, Chemistry Department, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal, Québec H3C 3P8, Canada
| |
Collapse
|
16
|
Peng L, Turesky RJ. Optimizing proteolytic digestion conditions for the analysis of serum albumin adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a potential human carcinogen formed in cooked meat. J Proteomics 2014; 103:267-78. [PMID: 24698664 DOI: 10.1016/j.jprot.2014.03.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/08/2014] [Accepted: 03/21/2014] [Indexed: 01/05/2023]
Abstract
UNLABELLED Heterocyclic aromatic amines (HAAs) are carcinogens formed during the cooking of meats or arise in tobacco smoke. The genotoxic N-oxidized metabolites of HAAs bind to Cys residues of proteins to form arylsulfinamide adducts. However, these adducts are unstable and undergo hydrolysis during enzymatic digestion, and thus have been precluded as biomarkers of exposure to HAAs. Arylsulfinamide adducts of HAAs can undergo oxidation to form stable arylsulfonamide linkages, which are chemically stable and amenable for analysis. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogen present in cooked meat. We established a quantitative MS-based method to measure the sulfinamide adduct of PhIP formed at the cysteine(34) (Cys(34)) residue of human serum albumin (SA), following chemical oxidation of PhIP-modified SA with m-chloroperoxybenzoic acid. Different enzyme systems (trypsin; chymotrypsin; trypsin/chymotrypsin; proteinase K; pronase E; and pronase E/leucine aminopeptidase/prolidase) were evaluated for their proficiency of digestion of SA modified with PhIP. The strongest signal was observed for the L(31)QQC*PFEDHVK(41) peptide, by ultraperformance liquid chromatography and ion trap MS. A limit of quantification value was 0.3fmol of LQQC*PFEDHVK per μg SA, or 2.5 adducts per 10(5) SA molecules, when assaying 0.75μg of SA. BIOLOGICAL SIGNIFICANCE This article describes a mass spectrometric based method to characterize and measure human serum albumin (SA) adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogenic heterocyclic aromatic amine formed in cooked meats and tobacco smoke. PhIP undergoes metabolic activation to form reactive N-oxidized intermediates that bind to DNA and proteins. N-oxidized PhIP metabolites bind to the Cys(34) residue of SA to form a sulfinamide linkage. However, the linkage undergoes hydrolysis during proteolysis, precluding the employment of this adduct as a biomarker in human studies. We have shown that the sulfinamide linkage undergoes oxidation to form the [cysteine-S-yl-PhIP]-S-dioxide, a sulfonamide linked adduct which is stable toward proteolysis. The specificity and efficiency of several different proteases toward the digestion of the SA-Cys(34)-PhIP adduct were examined. The combination of trypsin and chymotrypsin produced the single-missed cleaved peptide LQQC*PFEDHVK in high yield. Moreover, denaturation and chemical reduction of the internal Cys disulfide bonds of SA were not required for the recovery of LQQC*PFEDHVK. The novel chemistry and proteomic approaches developed in this study may be applied to monitor biologically reactive N-oxidized intermediates of arylamines through their adduction products formed at nucleophilic Cys residues of proteins.
Collapse
Affiliation(s)
- Lijuan Peng
- School of Chemical and Environmental Engineering, Wuhan Polytechnic University, ChangQing Garden, Hankou, Wuhan 430023, PR China; Division of Environmental Health Sciences,Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
| | - Robert J Turesky
- Division of Environmental Health Sciences,Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA; Masonic Cancer Center and Department of Medicinal Chemistry, Cancer and Cardiology Research Building, University of Minnesota, 2231 6th Street, Minneapolis, MN 55455, USA.
| |
Collapse
|
17
|
Bruschi M, Candiano G, Santucci L, Ghiggeri GM. Oxidized albumin. The long way of a protein of uncertain function. Biochim Biophys Acta Gen Subj 2013; 1830:5473-9. [PMID: 23618696 DOI: 10.1016/j.bbagen.2013.04.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/11/2013] [Accepted: 04/15/2013] [Indexed: 12/12/2022]
Abstract
BACKGROUND Proteins are extremely reactive to oxidants and should represent a potential target of instable reactive oxygen. This may represent a problem for plasma proteins since they may be directly modified in vivo in a compartment where antioxidant enzymatic systems are scarcely represented. On the other hand, it is possible that some plasma components have evolved over time to guarantee protection, in which case they can be considered as anti-oxidants. SCOPE OF REVIEW To present and discuss main studies which addressed the role of albumin in plasma antioxidant activity mainly utilizing in vitro models of oxidation. To present some advances on structural features of oxidized albumin deriving from studies carried out on in vitro models as well as albumin purified in vivo from patients affected by clinical conditions characterized by oxidative stress. MAJOR CONCLUSIONS There are different interaction with HOCl and chloramines. In the former case, HOCl produces an extensive alteration of (238)Trp and (162)Tyr, (425)Tyr, (47)Tyr, while thiol groups are only partially involved. Chloramines are extremely reactive with the unique free SH group of albumin ((34)Cys) with the formation of sulfenic and sulfinic acid as intermediates and sulfonic acid as end-product. Oxidized albumin has a modified electrical charge for the addition of an acidic residue and presents α-helix and random coil reorganization with subtle changes in domain orientation. GENERAL SIGNIFICANCE Albumin, is the major antioxidants in plasma with a concentration (0.8mM) higher than other antioxidants by an exponential factor. Functional and protective roles in the presence of oxidative stress must be defined. This article is part of a Special Issue entitled Serum Albumin.
Collapse
Affiliation(s)
- Maurizio Bruschi
- Laboratory on Pathophysiology of Uremia, Istituto Giannina Gaslini, Genoa, Italy
| | | | | | | |
Collapse
|
18
|
Zhou X, Jin X, Sun G, Wu X. A Sensitive and Selective Fluorescent Probe for Cysteine Based on a New Response-Assisted Electrostatic Attraction Strategy: The Role of Spatial Charge Configuration. Chemistry 2013; 19:7817-24. [DOI: 10.1002/chem.201300078] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/11/2013] [Indexed: 12/22/2022]
|
19
|
Peng L, Turesky RJ. Capturing labile sulfenamide and sulfinamide serum albumin adducts of carcinogenic arylamines by chemical oxidation. Anal Chem 2012; 85:1065-72. [PMID: 23240913 DOI: 10.1021/ac3028273] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aromatic amines and heterocyclic aromatic amines (HAAs) are a class of structurally related carcinogens that are formed during the combustion of tobacco or during the high temperature cooking of meats. These procarcinogens undergo metabolic activation by N-oxidation of the exocyclic amine group to produce N-hydroxylated metabolites, which are critical intermediates implicated in toxicity and DNA damage. The arylhydroxylamines and their oxidized arylnitroso derivatives can also react with cysteine (Cys) residues of glutathione or proteins to form, respectively, sulfenamide and sulfinamide adducts. However, sulfur-nitrogen linked adducted proteins are often difficult to detect because they are unstable and undergo hydrolysis during proteolytic digestion. Synthetic N-oxidized intermediates of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogenic HAA produced in cooked meats, and 4-aminobiphenyl, a carcinogenic aromatic amine present in tobacco smoke, were reacted with human serum albumin (SA) and formed labile sulfenamide or sulfinamide adducts at the Cys(34) residue. Oxidation of the carcinogen-modified SA with m-chloroperoxybenzoic acid (m-CPBA) produced the arylsulfonamide adducts, which were stable to heat and the chemical reduction conditions employed to denature SA. The sulfonamide adducts of PhIP and 4-ABP were identified, by liquid chromatography/mass spectrometry, in proteolytic digests of denatured SA. Thus, selective oxidation of arylamine-modified SA produces stable arylsulfonamide-SA adducts, which may serve as biomarkers of these tobacco and dietary carcinogens.
Collapse
Affiliation(s)
- Lijuan Peng
- Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health, Albany, New York 12201, USA
| | | |
Collapse
|
20
|
Peng L, Dasari S, Tabb DL, Turesky RJ. Mapping serum albumin adducts of the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by data-dependent tandem mass spectrometry. Chem Res Toxicol 2012; 25:2179-93. [PMID: 22827630 DOI: 10.1021/tx300253j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic aromatic amine that is formed during the cooking of meats. PhIP is a potential human carcinogen: it undergoes metabolic activation to form electrophilic metabolites that bind to DNA and proteins, including serum albumin (SA). The structures of PhIP-SA adducts formed in vivo are unknown and require elucidation before PhIP protein adducts can be implemented as biomarkers in human studies. We previously examined the reaction of genotoxic N-oxidized metabolites of PhIP with human SA in vitro and identified covalent adducts formed at cysteine³⁴ (Cys³⁴); however, other adduction products were thought to occur. We have now identified adducts of PhIP formed at multiple sites of SA reacted with isotopic mixtures of electrophilic metabolites of PhIP and 2-amino-1-methyl-6-[²H₅]-phenylimidazo[4,5-b]pyridine ([²H₅]-PhIP). The metabolites used for study were 2-nitro-1-methyl-6-phenylimidazo[4,5-b]pyridine (NO₂-PhIP), 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP), or N-acetyloxy-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-acetoxy-PhIP). Following proteolytic digestion, PhIP-adducted peptides were separated by ultra performance liquid chromatography and characterized by ion trap mass spectrometry, employing isotopic data-dependent scanning. Analysis of the tryptic or tryptic/chymotryptic digests of SA modified with NO₂-PhIP revealed that adduction occurred at Cys³⁴, Lys¹⁹⁵, Lys¹⁹⁹, Lys³⁵¹, Lys⁵⁴¹, Tyr¹³⁸, Tyr¹⁵⁰, Tyr⁴⁰¹, and Tyr⁴¹¹, whereas the only site of HONH-PhIP adduction was detected at Cys³⁴. N-Acetoxy-PhIP, a penultimate metabolite of PhIP that reacts with DNA to form covalent adducts, did not appear to form stable adducts with SA; instead, PhIP and 2-amino-1-methyl-6-(5-hydroxy)-phenylimidazo[4,5-b]pyridine, an aqueous reaction product of the proposed nitrenium ion of PhIP, were recovered during the proteolysis of N-acetoxy-PhIP-modified SA. Some of these SA adduction products of PhIP may be implemented in molecular epidemiology studies to assess the role of well-done cooked meat, PhIP, and the risk of cancer.
Collapse
Affiliation(s)
- Lijuan Peng
- Division of Environmental Health Sciences, Wadsworth Center, New York State Department of Health , Albany, New York 12201, USA
| | | | | | | |
Collapse
|
21
|
Wang K, Guengerich FP. Bioactivation of fluorinated 2-aryl-benzothiazole antitumor molecules by human cytochrome P450s 1A1 and 2W1 and deactivation by cytochrome P450 2S1. Chem Res Toxicol 2012; 25:1740-51. [PMID: 22734839 DOI: 10.1021/tx3001994] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Both 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) and 5-fluoro-2-(3,4-dimethoxyphenyl)-benzothiazole (GW 610) contain the benzothiazole pharmacophore and possess potent and selective in vitro antitumor properties. Prior studies suggested the involvement of cytochrome P450 (P450) 1A1 and 2W1-mediated bioactivation in the antitumor activities and P450 2S1-mediated deactivation of 5F 203 and GW 610. In the present study, the biotransformation pathways of 5F 203 and GW 610 by P450s 1A1, 2W1, and 2S1 were investigated, and the catalytic parameters of P450 1A1- and 2W1-catalyzed oxidation were determined in steady-state kinetic studies. The oxidations of 5F 203 catalyzed by P450s 1A1 and 2W1 yielded different products, and the formation of a hydroxylamine was observed for the first time in the latter process. Liquid chromatography-mass spectrometry (LC-MS) analysis with the synthetic hydroxylamine and also a P450 2W1/5F 203 incubation mixture indicated the formation of dGuo adduct via a putative nitrenium intermediate. P450 2W1-catalyzed oxidation of GW 610 was 5-fold more efficient than the P450 1A1-catalyzed reaction. GW 610 underwent a two-step oxidation process catalyzed by P450 1A1 or 2W1: a regiospecific O-demethylation and a further hydroxylation. Glutathione (GSH) conjugates of 5F 203 and GW 610, presumably through a quninoneimine and a 1,2-quinone intermediate, respectively, were detected. These results demonstrate that human P450s 1A1 and 2W1 mediate 5F 203 and GW 610 bioactivation to reactive intermediates and lead to GSH conjugates and a dGuo adduct, which may account for the antitumor activities of 5F 203 and GW 610 and also be involved in cell toxicity. P450 2S1 can catalyze the reduction of the hydroxylamine to the amine 5F 203 under anaerobic conditions and, to a lesser extent, under aerobic conditions, thus attenuating the anticancer activity.
Collapse
Affiliation(s)
- Kai Wang
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University, School of Medicine, 638 Robinson Research Building, 2200 Pierce Avenue, Nashville, TN 37232-0146, USA
| | | |
Collapse
|