1
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Leggett CS, Doll MA, Salazar-González RA, Habil MR, Trent JO, Hein DW. Identification and characterization of potent, selective, and efficacious inhibitors of human arylamine N-acetyltransferase 1. Arch Toxicol 2022; 96:511-524. [PMID: 34783865 PMCID: PMC8837702 DOI: 10.1007/s00204-021-03194-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 11/04/2021] [Indexed: 02/03/2023]
Abstract
Arylamine N-acetyltransferase 1 (NAT1) plays a pivotal role in the metabolism of carcinogens and is a drug target for cancer prevention and/or treatment. A protein-ligand virtual screening of 2 million chemicals was ranked for predicted binding affinity towards the inhibition of human NAT1. Sixty of the five hundred top-ranked compounds were tested experimentally for inhibition of recombinant human NAT1 and N-acetyltransferase 2 (NAT2). The most promising compound 9,10-dihydro-9,10-dioxo-1,2-anthracenediyl diethyl ester (compound 10) was found to be a potent and selective NAT1 inhibitor with an in vitro IC50 of 0.75 µM. Two structural analogs of this compound were selective but less potent for inhibition of NAT1 whereas a third structural analog 1,2-dihydroxyanthraquinone (a compound 10 hydrolysis product also known as Alizarin) showed comparable potency and efficacy for human NAT1 inhibition. Compound 10 inhibited N-acetylation of the arylamine carcinogen 4-aminobiphenyl (ABP) both in vitro and in DNA repair-deficient Chinese hamster ovary (CHO) cells in situ stably expressing human NAT1 and CYP1A1. Compound 10 and Alizarin effectively inhibited NAT1 in cryopreserved human hepatocytes whereas inhibition of NAT2 was not observed. Compound 10 caused concentration-dependent reductions in DNA adduct formation and DNA double-strand breaks following metabolism of aromatic amine carcinogens beta-naphthylamine and/or ABP in CHO cells. Compound 10 inhibited proliferation and invasion in human breast cancer cells and showed selectivity towards tumorigenic versus non-tumorigenic cells. In conclusion, our study identifies potent, selective, and efficacious inhibitors of human NAT1. Alizarin's ability to inhibit NAT1 could reduce breast cancer metastasis particularly to bone.
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Affiliation(s)
- Carmine S. Leggett
- Department of Pharmacology and Toxicology, University of
Louisville, Louisville, KY USA,UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA
| | - Mark A. Doll
- Department of Pharmacology and Toxicology, University of
Louisville, Louisville, KY USA,UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA
| | - Raúl A. Salazar-González
- Department of Pharmacology and Toxicology, University of
Louisville, Louisville, KY USA,UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA
| | - Mariam R. Habil
- Department of Pharmacology and Toxicology, University of
Louisville, Louisville, KY USA,UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA
| | - John O. Trent
- UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA,Department of Medicine, University of Louisville,
Louisville, KY USA
| | - David W. Hein
- Department of Pharmacology and Toxicology, University of
Louisville, Louisville, KY USA,UofL Health Brown Cancer Center, University of Louisville,
Louisville, KY USA,Department of Medicine, University of Louisville,
Louisville, KY USA,Corresponding author: David W. Hein, University of
Louisville Health Science Center, Kosair Charities Clinical and Translational
Research Building Room 303, 505 South Hancock Street, Louisville, KY USA
40202-1617. . Telephone:
502-852-6252
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2
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Huang X, Hou Y, Weng X, Pang W, Hou L, Liang Y, Wang Y, Du L, Wu T, Yao M, Wang J, Meng X. Diethyldithiocarbamate-copper complex (CuET) inhibits colorectal cancer progression via miR-16-5p and 15b-5p/ALDH1A3/PKM2 axis-mediated aerobic glycolysis pathway. Oncogenesis 2021; 10:4. [PMID: 33419984 PMCID: PMC7794448 DOI: 10.1038/s41389-020-00295-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023] Open
Abstract
Exploring novel anticancer drugs to optimize the efficacy may provide a benefit for the treatment of colorectal cancer (CRC). Disulfiram (DSF), as an antialcoholism drug, is metabolized into diethyldithiocarbamate-copper complex (CuET) in vivo, which has been reported to exert the anticancer effects on various tumors in preclinical studies. However, little is known about whether CuET plays an anti-cancer role in CRC. In this study, we found that CuET had a marked effect on suppressing CRC progression both in vitro and in vivo by reducing glucose metabolism. Mechanistically, using RNA-seq analysis, we identified ALDH1A3 as a target gene of CuET, which promoted cell viability and the capacity of clonal formation and inhibited apoptosis in CRC cells. MicroRNA (miR)-16-5p and 15b-5p were shown to synergistically regulate ALDH1A3, which was negatively correlated with both of them and inversely correlated with the survival of CRC patients. Notably, using co-immunoprecipitation followed with mass spectrometry assays, we identified PKM2 as a direct downstream effector of ALDH1A3 that stabilized PKM2 by reducing ubiquitination. Taken together, we disclose that CuET treatment plays an active role in inhibiting CRC progression via miR-16-5p and 15b-5p/ALDH1A3/PKM2 axis-mediated aerobic glycolysis pathway.
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Affiliation(s)
- Xin Huang
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Yichao Hou
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Xiaoling Weng
- Cancer Institute, Fudan University Shanghai Cancer Center, Fudan University, 200032, Shanghai, China
| | - Wenjing Pang
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Lidan Hou
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Yu Liang
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Yu Wang
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China
| | - Leilei Du
- Cancer Institute, Fudan University Shanghai Cancer Center, Fudan University, 200032, Shanghai, China
| | - Tianqi Wu
- Cancer Institute, Fudan University Shanghai Cancer Center, Fudan University, 200032, Shanghai, China
| | - Mengfei Yao
- Cancer Institute, Fudan University Shanghai Cancer Center, Fudan University, 200032, Shanghai, China
| | - Jianhua Wang
- Cancer Institute, Fudan University Shanghai Cancer Center, Fudan University, 200032, Shanghai, China.
| | - Xiangjun Meng
- Department of Gastroenterology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China.
- Digestive Disease Research and Clinical Translation Center, Shanghai Jiao Tong University, 200011, Shanghai, China.
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3
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Stepp MW, Doll MA, Carlisle SM, States JC, Hein DW. Genetic and small molecule inhibition of arylamine N-acetyltransferase 1 reduces anchorage-independent growth in human breast cancer cell line MDA-MB-231. Mol Carcinog 2018; 57:549-558. [PMID: 29315819 PMCID: PMC5832614 DOI: 10.1002/mc.22779] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/22/2017] [Accepted: 01/02/2018] [Indexed: 01/07/2023]
Abstract
Arylamine N-acetyltransferase 1 (NAT1) expression is reported to affect proliferation, invasiveness, and growth of cancer cells. MDA-MB-231 breast cancer cells were engineered such that NAT1 expression was elevated or suppressed, or treated with a small molecule inhibitor of NAT1. The MDA-MB-231 human breast cancer cell lines were engineered with a scrambled shRNA, a NAT1 specific shRNA or a NAT1 overexpression cassette stably integrated into a single flippase recognition target (FRT) site facilitating incorporation of these different genetic elements into the same genomic location. NAT1-specific shRNA reduced NAT1 activity in vitro by 39%, increased endogenous acetyl coenzyme A levels by 35%, and reduced anchorage-independent growth (sevenfold) without significant effects on cell morphology, growth rates, anchorage-dependent colony formation, or invasiveness compared to the scrambled shRNA cell line. Despite 12-fold overexpression of NAT1 activity in the NAT1 overexpression cassette transfected MDA-MB-231 cell line, doubling time, anchorage-dependent cell growth, anchorage-independent cell growth, and relative invasiveness were not changed significantly when compared to the scrambled shRNA cell line. A small molecule (5E)-[5-(4-hydroxy-3,5-diiodobenzylidene)-2-thioxo-1,3-thiazolidin-4-one (5-HDST) was 25-fold more selective towards the inhibition of recombinant human NAT1 than N-acetyltransferase 2. Incubation of MDA-MB-231 cell line with 5-HDST resulted in 60% reduction in NAT1 activity and significant decreases in cell growth, anchorage-dependent growth, and anchorage-independent growth. In summary, inhibition of NAT1 activity by either shRNA or 5-HDST reduced anchorage-independent growth in the MDA-MB-231 human breast cancer cell line. These findings suggest that human NAT1 could serve as a target for the prevention and/or treatment of breast cancer.
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Affiliation(s)
- Marcus W Stepp
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky
| | - Mark A Doll
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky
| | - Samantha M Carlisle
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky
| | - J Christopher States
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky
| | - David W Hein
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky
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Xu X, Mathieu C, Berthelet J, Duval R, Bui LC, Busi F, Dupret JM, Rodrigues-Lima F. Human Arylamine N-Acetyltransferase 1 Is Inhibited by the Dithiocarbamate Pesticide Thiram. Mol Pharmacol 2017; 92:358-365. [DOI: 10.1124/mol.117.108662] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Identification of cancer chemopreventive isothiocyanates as direct inhibitors of the arylamine N-acetyltransferase-dependent acetylation and bioactivation of aromatic amine carcinogens. Oncotarget 2017; 7:8688-99. [PMID: 26840026 PMCID: PMC4890997 DOI: 10.18632/oncotarget.7086] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/15/2016] [Indexed: 11/25/2022] Open
Abstract
Aromatic amines (AAs) are chemicals of industrial, pharmacological and environmental relevance. Certain AAs, such as 4-aminobiphenyl (4-ABP), are human carcinogens that require enzymatic metabolic activation to reactive chemicals to form genotoxic DNA adducts. Arylamine N-acetyltransferases (NAT) are xenobiotic metabolizing enzymes (XME) that play a major role in this carcinogenic bioactivation process. Isothiocyanates (ITCs), including benzyl-ITC (BITC) and phenethyl-ITC (PEITC), are phytochemicals known to have chemopreventive activity against several aromatic carcinogens. In particular, ITCs have been shown to modify the bioactivation and subsequent mutagenicity of carcinogenic AA chemicals such as 4-ABP. However, the molecular and biochemical mechanisms by which these phytochemicals may modulate AA carcinogens bioactivation and AA-DNA damage remains poorly understood. This manuscript provides evidence indicating that ITCs can decrease the metabolic activation of carcinogenic AAs via the irreversible inhibition of NAT enzymes and subsequent alteration of the acetylation of AAs. We demonstrate that BITC and PEITC react with NAT1 and inhibit readily its acetyltransferase activity (ki = 200 M−1.s−1 and 66 M−1.s−1 for BITC and PEITC, respectively). Chemical labeling, docking approaches and substrate protection assays indicated that inhibition of the acetylation of AAs by NAT1 was due to the chemical modification of the enzyme active site cysteine. Moreover, analyses of AAs acetylation and DNA adducts in cells showed that BITC was able to modulate the endogenous acetylation and bioactivation of 4-ABP. In conclusion, we show that direct inhibition of NAT enzymes may be an important mechanism by which ITCs exert their chemopreventive activity towards AA chemicals.
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6
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Mathieu C, Bui LC, Petit E, Haddad I, Agbulut O, Vinh J, Dupret JM, Rodrigues-Lima F. Molecular Mechanisms of Allosteric Inhibition of Brain Glycogen Phosphorylase by Neurotoxic Dithiocarbamate Chemicals. J Biol Chem 2016; 292:1603-1612. [PMID: 27965358 DOI: 10.1074/jbc.m116.766725] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/08/2016] [Indexed: 12/19/2022] Open
Abstract
Dithiocarbamates (DTCs) are important industrial chemicals used extensively as pesticides and in a variety of therapeutic applications. However, they have also been associated with neurotoxic effects and in particular with the development of Parkinson-like neuropathy. Although different pathways and enzymes (such as ubiquitin ligases or the proteasome) have been identified as potential targets of DTCs in the brain, the molecular mechanisms underlying their neurotoxicity remain poorly understood. There is increasing evidence that alteration of glycogen metabolism in the brain contributes to neurodegenerative processes. Interestingly, recent studies with N,N-diethyldithiocarbamate suggest that brain glycogen phosphorylase (bGP) and glycogen metabolism could be altered by DTCs. Here, we provide molecular and mechanistic evidence that bGP is a target of DTCs. To examine this system, we first tested thiram, a DTC pesticide known to display neurotoxic effects, observing that it can react rapidly with bGP and readily inhibits its glycogenolytic activity (kinact = 1.4 × 105 m-1 s-1). Using cysteine chemical labeling, mass spectrometry, and site-directed mutagenesis approaches, we show that thiram (and certain of its metabolites) alters the activity of bGP through the formation of an intramolecular disulfide bond (Cys318-Cys326), known to act as a redox switch that precludes the allosteric activation of bGP by AMP. Given the key role of glycogen metabolism in brain functions and neurodegeneration, impairment of the glycogenolytic activity of bGP by DTCs such as thiram may be a new mechanism by which certain DTCs exert their neurotoxic effects.
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Affiliation(s)
- Cécile Mathieu
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Linh-Chi Bui
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Emile Petit
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France
| | - Iman Haddad
- ESPCI ParisTech, Université Paris Sciences et Lettres, Laboratoire de Spectrométrie de Masse Biologique et Protéomique, CNRS USR, 3149 Paris, France
| | - Onnik Agbulut
- the Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris-Seine, UMR CNRS 8256, Biological Adaptation and Ageing, 75005 Paris, France
| | - Joelle Vinh
- ESPCI ParisTech, Université Paris Sciences et Lettres, Laboratoire de Spectrométrie de Masse Biologique et Protéomique, CNRS USR, 3149 Paris, France
| | - Jean-Marie Dupret
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France; UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France
| | - Fernando Rodrigues-Lima
- From the Université Paris Diderot, Sorbonne Paris Cité, Unité BFA, CNRS UMR 8251, 75013 Paris, France; UFR Sciences du Vivant, Université Paris Diderot, 75013 Paris, France.
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7
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Tiang JM, Butcher NJ, Minchin RF. Effects of human arylamine N-acetyltransferase I knockdown in triple-negative breast cancer cell lines. Cancer Med 2015; 4:565-74. [PMID: 25627111 PMCID: PMC4402071 DOI: 10.1002/cam4.415] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 12/23/2014] [Accepted: 12/26/2014] [Indexed: 12/21/2022] Open
Abstract
Expression of human arylamine N-acetyltransferase I (NAT1) has been associated with various cancer subtypes and inhibition of this enzyme with small molecule inhibitors or siRNA affects cell growth and survival. Here, we have investigated the role of NAT1 in the invasiveness of breast cancer cells both in vitro and in vivo. We knocked down NAT1 using a lentivirus-based shRNA approach and observed marked changes in cell morphology in the triple-negative breast cancer cell lines MDA-MB-231, MDA-MB-436, and BT-549. Most notable was a reduction in the number and size of the filopodia protrusions on the surface of the cells. The loss of filopodia could be rescued by the reintroduction of NAT1 into the knockdown cells. NAT1 expression was localized to the lamellipodia and extended into the filopodia protrusions. In vitro invasion through Geltrex was significantly inhibited in both the MDA cell lines but not in the BT-549 cells. The expression of Snail increased when NAT1 was knocked down, while other genes associated with mesenchymal to epithelial transition (vimentin, cytokeratin-18, and Twist) did not show any changes. By contrast, both N-cadherin and β-catenin were significantly reduced. When MDA-MB-231 cells expressing shRNA were injected in vivo into BALB/c nu/nu nude mice, a significant reduction in the number of colonies that formed in the lungs was observed. Taken together, the results show that NAT1 can alter the invasion and metastatic properties of some triple-negative breast cancer cells but not all. The study suggests that NAT1 may be a novel therapeutic target in a subset of breast cancers.
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Affiliation(s)
- Jacky M Tiang
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland, 4072, Australia
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Mathieu C, Duval R, Xu X, Rodrigues-Lima F, Dupret JM. Effects of pesticide chemicals on the activity of metabolic enzymes: focus on thiocarbamates. Expert Opin Drug Metab Toxicol 2014; 11:81-94. [PMID: 25391334 DOI: 10.1517/17425255.2015.975691] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
INTRODUCTION Thiocarbamates are chemicals widely used as pesticides. Occupational exposure is associated with acute intoxication. Populations can be exposed through food and water. Moreover, certain thiocarbamates are used clinically. The widespread use of thiocarbamates raises many issues regarding their toxicological and pharmacological impact. AREAS COVERED Thiocarbamates and their metabolites can modify biological macromolecules functions, in particular enzymes, through modification of cysteine residues, chelation of metal ions or modulation of the oxidative stress. Loss of enzyme activity can lead to the disruption of metabolic pathways, and explain, at least in part, the effects of these pesticides. Additionally, their reactivity and ability to easily cross biological barrier confer them a great interest for development of clinical applications. EXPERT OPINION Many advances in the study of thiocarbamates metabolism and reactivity have led to a better knowledge of biological effects of these compounds. However, more data are needed on the determination of targets and specificity. Only few data concerning the exposure to a cocktail of pesticides/chemicals are available, raising the need to evaluate the toxic side effects of representative pesticides mixtures. Moreover, the dithiocarbamate Disulfiram has shown great potential in therapeutic applications and leads to the development of pharmacological thiocarbamates derivatives, highly specific to their target and easily distributed.
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Affiliation(s)
- Cécile Mathieu
- Paris Diderot University, Life Sciences , Paris , France
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D-penicillamine and other low molecular weight thiols: review of anticancer effects and related mechanisms. Cancer Lett 2013; 337:8-21. [PMID: 23727371 DOI: 10.1016/j.canlet.2013.05.027] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/21/2013] [Accepted: 05/22/2013] [Indexed: 01/13/2023]
Abstract
Low molecular weight thiols (LMWTs) like N-acetyl cysteine, D-penicillamine, captopril, Disulfiram and Amifostine, etc. have been used as chemo-preventive agents. Recent studies have reported cell growth inhibition and cytotoxicity in several different types of cancer cells following treatment with several LMWTs. Cytotoxic and cytostatic effects of LMWTs may involve interaction of the thiol group with cellular lipids, proteins, intermediates or enzymes. Some of the mechanisms that have been proposed include a p53 mediated apoptosis, thiyl radical induced DNA damage, membrane damage through lipid peroxidation, anti-angiogenic effects induced by inhibition of matrix metalloproteinase enzymes and angiostatin generation. LMWTs are strong chelators of transition metals like copper, nickel, zinc, iron and cobalt and may cause metal co-factor depletion resulting in cytotoxicity. Oxidation of thiol group can also generate cytotoxic reactive oxygen species (ROS).
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Dierolf D, Scheitza S, Bonifas J, Blömeke B. Cyanamide-mediated Inhibition of N-acetyltransferase 1. Toxicology 2012; 302:1-10. [PMID: 22835378 DOI: 10.1016/j.tox.2012.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 06/14/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
Abstract
Cyanamide has been used for decades for medical intentions in the treatment of alcoholism and for agricultural purposes as a plant growth regulator and bud-breaking agent. Its therapeutic effect is mediated by reversible inhibition of aldehyde dehydrogenase and it was reported to be metabolized in vivo mainly via coenzyme A dependent N-acetylation by N-acetyltransferases. Although described to be a substrate for N-acetyltransferases (NATs), cyanamide has a different molecular structure to arylamines and hydrazines, the preferred substrates for N-acetyltransferases. Therefore, a more detailed investigation of its interrelations with N-acetyltransferases was performed. We analyzed the impact of cyanamide on NAT1 activities of human monocytes (monocytic THP-1 cells) using the classical substrate p-aminobenzoic acid. We found that a 24h treatment with physiologically relevant concentrations of cyanamide decreased the NAT1 activity significantly. Based on this observation we performed additional experiments using recombinant human NAT1 and NAT2 to achieve further insights. In detail a significant dose- and time-dependent inhibition of NAT1 activity was observed for 100 and 1000μM cyanamide using recombinant human NAT1*4. However, cyanamide did not inhibit recombinant NAT2*4. Experiments testing cyanamide as substrate did not provide evidence that cyanamide is metabolized via coenzyme A dependent N-acetylation in vitro by human NAT1 or NAT2, THP-1 or human liver cytosol. Therefore we can conclude that the observed enzyme inhibition (around 50% and 25% after treatment with 0.5 and 0.25mM CA, respectively) is not based on substrate-dependent down-regulation of NAT1. Further mechanistic and kinetic studies indicated that cyanamide reacts with the active site cysteine residue of NAT1, leading to its rapid inhibition (significant inhibition after 30min and 2h for 1000 and 100μM CA, respectively). Addition of the reduction agent dithiothreitol (DTT) did not modify the effect, indicating that oxidative processes that can be reversed by 5mM DTT are not likely involved in the inhibition. Taken together our results show that cyanamide is able to inhibit NAT1 most likely via interaction with the active site cysteine residue. Thereby cyanamide might modulate NAT1 dependent detoxification and activation of arylamines.
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Affiliation(s)
- Dorothea Dierolf
- Department of Environmental Toxicology, University of Trier, Universitätsring 15, 54296 Trier, Germany
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Bonamassa B, Ma Y, Liu D. Glucocorticoid receptor-mediated transcriptional regulation of N-acetyltransferase 1 gene through distal promoter. AAPS JOURNAL 2012; 14:581-90. [PMID: 22644701 DOI: 10.1208/s12248-012-9370-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 05/09/2012] [Indexed: 11/30/2022]
Abstract
Human arylamine N-acetyltransferase 1, (HUMAN)NAT1, is a phase II xenobiotic-metabolizing enzyme that plays an important role in drug and carcinogen biotransformation and cancer development. Its gene expression has been shown to be regulated by environmental factors. The purpose of the current study is to determine the involvement of nuclear receptors in transcriptional regulation of (HUMAN)NAT1 gene. We show that among the nuclear receptors examined, including the glucocorticoid receptor, retinoid acid receptor-related orphan receptor alpha, constitutive androstane receptor, pregnane X receptor, aryl hydrocarbon receptor, and retinoic acid receptor, the glucocorticoid receptor plays a dominant role in regulating (HUMAN)NAT1 gene expression through distal promoter (P3). The involvement of the glucocorticoid receptor in transcription regulation of (HUMAN)NAT1 gene expression was demonstrated by dexamethasone treatment, reporter assay using plasmid-containing 3 kbp of 5'-end region of promoter 3, and treatment of anti-glucocorticoid RU486 in primary culture of human hepatocytes and transfected HepG2 cells. In addition, translation inhibition did not affect dexamethasone-induced gene expression through P3, suggesting that dexamethasone effect is directly mediated by glucocorticoid receptor activation. Furthermore, deletion analysis revealed the presence of multiple responsive elements within the 3 kbp fragment of P3. Transfection assays in mice using hydrodynamics-based procedure and reporter gene assay in a mouse cell line revealed that glucocorticoid-induced NAT gene expression is species dependent. Dexamethasone treatment of transfected mice and mouse cell line decreased (MOUSE)Nat2 gene expression, (HUMAN)NAT1 homologue. These results suggest that glucocorticoids serve as a modulator for (HUMAN)NAT1 gene expression via the P3-containing 5'-flanking region.
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Affiliation(s)
- Barbara Bonamassa
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pennsylvania 15261, USA
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Arylamine N-Acetyltransferases – from Drug Metabolism and Pharmacogenetics to Identification of Novel Targets for Pharmacological Intervention. CURRENT CONCEPTS IN DRUG METABOLISM AND TOXICOLOGY 2012; 63:169-205. [DOI: 10.1016/b978-0-12-398339-8.00005-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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13
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Butcher NJ, Minchin RF. Arylamine N-Acetyltransferase 1: A Novel Drug Target in Cancer Development. Pharmacol Rev 2011; 64:147-65. [DOI: 10.1124/pr.110.004275] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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