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Liu X, Song J, Yan X, Li P, Zhang J, Wang B, Si J, Chen Y. N-nitrosodimethylamine exposure to zebrafish embryos/larvae causes cardiac and spinal developmental toxicity. Comp Biochem Physiol C Toxicol Pharmacol 2024; 277:109823. [PMID: 38158031 DOI: 10.1016/j.cbpc.2023.109823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/27/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
N-nitrosodimethylamine (NDMA), one of the new nitrogen-containing disinfection by-products, is potentially cytotoxic, genotoxic, and carcinogenic. Its potential toxicological effects have attracted a wide range of attention, but the mechanism is still not sufficiently understood. To better understand the toxicological mechanisms of NDMA, zebrafish embryos were exposed to NDMA from 3 h post-fertilization (hpf) to 120hpf. Mortality and malformation were significantly increased, and hatching rate, heart rate, and swimming behavior were decreased in the exposure groups. The result indicated that NDMA exposure causes cardiac and spinal developmental toxicity. mRNA levels of genes involved in the apoptotic pathway, including p53, bax, and bcl-2 were significantly affected by NDMA exposure. Moreover, the genes associated with spinal and cardiac development (myh6, myh7, nkx2.5, eph, bmp2b, bmp4, bmp9, run2a, and run2b) were significantly downregulated after treatment with NDMA. Wnt and TGF-β signaling pathways, crucial for the development of diverse tissues and organs in the embryo and the establishment of the larval spine, were also significantly disturbed by NDMA treatment. In summary, the disinfection by-product, NDMA, exhibits spinal and cardiac developmental toxicity in zebrafish embryos, providing helpful information for comprehensive analyses and a better understanding the mechanism of its toxicity.
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Affiliation(s)
- Xiaoyi Liu
- College of Life Science, Lanzhou University, Lanzhou, China. https://twitter.com/@LanoLiu41230
| | - Jinge Song
- School of Stomatology, Lanzhou University, Lanzhou, China
| | - Xiaotao Yan
- Lanzhou Urban Water Supply (Group) Co., Ltd, Lanzhou, China
| | - Pingping Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jinhua Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Bin Wang
- Lanzhou Urban Water Supply (Group) Co., Ltd, Lanzhou, China
| | - Jing Si
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
| | - Yong Chen
- College of Life Science, Lanzhou University, Lanzhou, China.
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Carloni LE, Lochner S, Sterckx H, Van Daele T. Solid State Kinetics of Nitrosation Using Native Sources of Nitrite. J Pharm Sci 2023; 112:1324-1332. [PMID: 36828125 DOI: 10.1016/j.xphs.2023.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/01/2023] [Accepted: 02/16/2023] [Indexed: 02/24/2023]
Abstract
While many reactive species are known to cause N-nitrosation, trace nitrite (NO2-), which may be present in several excipients, is a source of nitrosating agents in pharmaceutical formulations. In this study we have found that the salt form of NO2- can influence the favored nitrosation conditions and final amount of nitrosamine being formed. Using native levels of NO2-, most likely present as ammonium nitrite (NH4NO2), in microcrystalline cellulose, we have determined the kinetics of nitrosamine formation in solid state with dimethylamine substrate present in metformin, used as model compound. It was found that the competing degradation of NH4NO2 into N2 and H2O limited the amount of nitrosamine formation to a great extent. Empirically modelling the kinetic data predicted reaching at maximum 1.6% conversion over a hypothetical 3-year shelf-life. These results also showed that using other sources of NO2- as spiking reagents, such as NaNO2, may lead to unrealistic worst-case situations when the main form of NO2- in the drug product (DP) under evaluation may be NH4NO2. As well, measuring NO2- in freshly manufactured excipients containing NO2- potentially as NH4NO2 may lead to biased high NO2- content, which is not representative of the actual amounts present at the time of DP manufacture.
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Affiliation(s)
- Laure-Elie Carloni
- Chemical and Pharmaceutical Development & Supply, Janssen Research & Development, Beerse, Belgium.
| | - Susanne Lochner
- Chemical and Pharmaceutical Development & Supply, Janssen Research & Development, Beerse, Belgium
| | - Hans Sterckx
- Chemical and Pharmaceutical Development & Supply, Janssen Research & Development, Beerse, Belgium
| | - Timothy Van Daele
- Chemical and Pharmaceutical Development & Supply, Janssen Research & Development, Beerse, Belgium
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Gao Z, Karfunkle M, Ye W, Marzan TA, Yang J, Lex T, Sommers C, Rodriguez JD, Han X, Florian J, Strauss DG, Keire DA. In Vitro Analysis of N-Nitrosodimethylamine (NDMA) Formation From Ranitidine Under Simulated Gastrointestinal Conditions. JAMA Netw Open 2021; 4:e2118253. [PMID: 34181009 PMCID: PMC8239951 DOI: 10.1001/jamanetworkopen.2021.18253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/21/2021] [Indexed: 12/24/2022] Open
Abstract
Importance A publication reported that N-nitrosodimethylamine (NDMA), a probable human carcinogen, was formed when ranitidine and nitrite were added to simulated gastric fluid. However, the nitrite concentrations used were greater than the range detected in acidic gastric fluid in prior clinical studies. Objective To characterize NDMA formation following the addition of ranitidine to simulated gastric fluid using combinations of fluid volume, pH levels, and nitrite concentrations, including physiologic levels. Design, Setting, and Participants One 150-mg ranitidine tablet was added to 50 or 250 mL of simulated gastric fluid with a range of nitrite concentrations from the upper range of physiologic (100 μmol/L) to higher concentrations (10 000 μmol/L) with a range of pH levels. NDMA amounts were assessed with a liquid chromatography-mass spectrometry method. Main Outcomes and Measures NDMA detected in simulated gastric fluid 2 hours after adding ranitidine. Results At a supraphysiologic nitrite concentration (ie, 10 000 μmol/L), the mean (SD) amount of NDMA detected in 50 mL simulated gastric fluid 2 hours after adding ranitidine increased from 222 (12) ng at pH 5 to 11 822 (434) ng at pH 1.2. Subsequent experiments with 50 mL of simulated gastric fluid at pH 1.2 with no added nitrite detected a mean (SD) of 22 (2) ng of NDMA, which is the background amount present in the ranitidine tablets. Similarly, at the upper range of physiologic nitrite (ie, 100 μmol/L) or at nitrite concentrations as much as 50-fold greater (1000 or 5000 μmol/L) only background mean (SD) amounts of NDMA were observed (21 [3] ng, 24 [2] ng, or 24 [3] ng, respectively). With 250 mL of simulated gastric fluid, no NDMA was detected at the upper physiologic range (100 μmol/L) or 10-fold physiologic (1000 μmol/L) nitrite concentrations, while NDMA was detected (mean [SD] level, 7353 [183] ng) at a 50-fold physiologic nitrite concentration (5000 μmol/L). Conclusions and Relevance In this in vitro study of ranitidine tablets added to simulated gastric fluid with different nitrite concentrations, ranitidine conversion to NDMA was not detected until nitrite was 5000 μmol/L, which is 50-fold greater than the upper range of physiologic gastric nitrite concentrations at acidic pH. These findings suggest that ranitidine is not converted to NDMA in gastric fluid at physiologic conditions.
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Affiliation(s)
- Zongming Gao
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Michael Karfunkle
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Wei Ye
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Tim Andres Marzan
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Jingyue Yang
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Timothy Lex
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Cynthia Sommers
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Jason D. Rodriguez
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
| | - Xiaomei Han
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Food and Drug Administration. Silver Spring, Maryland
| | - Jeffry Florian
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Food and Drug Administration. Silver Spring, Maryland
| | - David G. Strauss
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, Food and Drug Administration. Silver Spring, Maryland
| | - David A. Keire
- Division of Complex Drug Analysis and Division of Pharmaceutical Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, Food and Drug Administration, St Louis, Missouri
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Llorca M, Castellet-Rovira F, Farré MJ, Jaén-Gil A, Martínez-Alonso M, Rodríguez-Mozaz S, Sarrà M, Barceló D. Fungal biodegradation of the N-nitrosodimethylamine precursors venlafaxine and O-desmethylvenlafaxine in water. Environ Pollut 2019; 246:346-356. [PMID: 30577003 DOI: 10.1016/j.envpol.2018.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 11/04/2018] [Accepted: 12/04/2018] [Indexed: 06/09/2023]
Abstract
Antidepressant drugs such as Venlafaxine (VFX) and O-desmethylvenlafaxine (ODMVFX) are emerging contaminants that are commonly detected in aquatic environments, since conventional wastewater treatment plants are unable to completely remove them. They can be precursors of hazardous by-products, such as the carcinogenic N-nitrosodimethylamine (NDMA), generated upon water chlorination, as they contain the dimethylamino moiety, necessary for the formation of NDMA. In this study, the capability of three white rot fungi (Trametes versicolor, Ganoderma lucidum and Pleurotus ostreatus) to remove both antidepressants from water and to decrease NDMA formation potential was investigated. Furthermore, transformation by-products (TPs) generated along the treatment process were elucidated and also correlated with their NDMA formation potential. Very promising results were obtained for T. versicolor and G. lucidum, both being able to remove up to 100% of ODMVFX. In the case of VFX, which is very recalcitrant to conventional wastewater treatment, a 70% of removal was achieved by T. versicolor, along with a reduction in NDMA formation potential, thus decreasing the associated problems for human health and the environment. However, the NDMA formation potential remained practically constant during treatment with G. lucidum despite of the equally high VFX removal (70%). This difference was attributed to the generation of different TPs during both fungal treatments. For example, G. lucidum generated more ODMVFX, which actually has a higher NDMA formation potential than the parent compound itself.
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Affiliation(s)
- Marta Llorca
- Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003, Girona, Spain; Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain
| | - Francesc Castellet-Rovira
- Department of Chemical, Biological, and Environmental Engineering, Engineering School, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Catalonia, Spain
| | - María-José Farré
- Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003, Girona, Spain
| | - Adrián Jaén-Gil
- Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003, Girona, Spain
| | - Maira Martínez-Alonso
- Department of Genetics and Microbiology, Faculty of Biosciences, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Catalonia, Spain
| | - Sara Rodríguez-Mozaz
- Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003, Girona, Spain.
| | - Montserrat Sarrà
- Department of Chemical, Biological, and Environmental Engineering, Engineering School, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Catalonia, Spain
| | - Damià Barceló
- Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003, Girona, Spain; Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain
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5
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George J, Tsuchishima M, Tsutsumi M. Molecular mechanisms in the pathogenesis of N-nitrosodimethylamine induced hepatic fibrosis. Cell Death Dis 2019; 10:18. [PMID: 30622238 PMCID: PMC6325159 DOI: 10.1038/s41419-018-1272-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/03/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022]
Abstract
Hepatic fibrosis is marked by excessive synthesis and deposition of connective tissue proteins, especially interstitial collagens in the extracellular matrix of the liver. It is a result of an abnormal wound healing in response to chronic liver injury from various causes such as ethanol, viruses, toxins, drugs, or cholestasis. The chronic stimuli involved in the initiation of fibrosis leads to oxidative stress and generation of reactive oxygen species that serve as mediators of molecular events involved in the pathogenesis of hepatic fibrosis. These processes lead to cellular injury and initiate inflammatory responses releasing a variety of cytokines and growth factors that trigger activation and transformation of resting hepatic stellate cells into myofibroblast like cells, which in turn start excessive synthesis of connective tissue proteins, especially collagens. Uncontrolled and extensive fibrosis results in distortion of lobular architecture of the liver leading to nodular formation and cirrhosis. The perpetual injury and regeneration process could also results in genomic aberrations and mutations that lead to the development of hepatocellular carcinoma. This review covers most aspects of the molecular mechanisms involved in the pathogenesis of hepatic fibrosis with special emphasize on N-Nitrosodimethylamine (NDMA; Dimethylnitorsmaine, DMN) as the inducing agent.
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Affiliation(s)
- Joseph George
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY, 10029, USA.
- Department of Hepatology, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan.
| | - Mutsumi Tsuchishima
- Department of Hepatology, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan
| | - Mikihiro Tsutsumi
- Department of Hepatology, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan
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6
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Liao E, Xu Y, Jiang Q, Xia W. Effects of inoculating autochthonous starter cultures on N-nitrosodimethylamine and its precursors formation during fermentation of Chinese traditional fermented fish. Food Chem 2018; 271:174-181. [PMID: 30236663 DOI: 10.1016/j.foodchem.2018.07.186] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 07/24/2018] [Accepted: 07/25/2018] [Indexed: 11/18/2022]
Abstract
This study investigated the effects of Lactobacillus plantarum 120, Saccharomyces cerevisiae 2018 and Staphylococcus xylosus 135 inoculation on N-nitrosodimethylamine (NDMA) and its precursors formation, and on microbiological characteristics of Chinese traditional fermented fish products (CTFPs). The results indicated that three strains could directly degrade NDMA in culture broth, and the highest degradation rate was observed in L. plantarum 120. The lactic acid bacteria counts in samples inoculated with L. plantarum 120 and mixed starter cultures were significantly (P < 0.05) higher than the others during the initial and middle fermentation stages (≤3 weeks). The final contents of total volatile base nitrogen, trimethylamine, dimethylamine, nitrite and NDMA in inoculated samples were significantly (P < 0.05) lower than those in spontaneous fermentation samples. According to these results, the inoculation with autochthonous starter cultures was a promising method to inhibit the NDMA and its precursors accumulation in CTFPs during fermentation process.
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Affiliation(s)
- E Liao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Yanshun Xu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Qixing Jiang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Wenshui Xia
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
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Abstract
The objective of this study was to assess reactivity of Minocycline (MNC) towards ozone and determine the effects of ozone dose, pH value, and water matrix on MNC degradation as well as to characterize N-Nitrosodimethylamine (NDMA) formation from MNC ozonation. The MNC initial concentration of the solution was set in the range of 2-20 mg/L to investigate NDMA formation during MNC ozonation. Four ozone doses (22.5, 37.2, 58.0, and 74.4 mg/min) were tested to study the effect of ozone dose. For the evaluation of effects of pH value, pH was adjusted from 5 to 9 in the presence of phosphate buffer. MNC ozonation experiments were also conducted in natural water to assess the influence of water matirx. The influence of the typical component of natural water was also investigated with the addition of HA and NaHCO3 solution. Results indicated that ozone was effective in MNC removal. Consequently, NDMA and dimethylamine (DMA) were generated from MNC oxidation. Increasing pH value enhanced MNC removal but led to greater NDMA generation. Water matrices, such as HCO3- and humic acid, affected MNC degradation. Conversely, more NDMA accumulated due to the inhibition of NDMA oxidation by oxidant consumption. Though ⋅OH can enhance MNC degradation, ozone molecules were heavily involved in NDMA production. Seven transformation products were identified. However, only DMA and the unidentified tertiary amine containing DMA group contributed to NDMA formation.
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Affiliation(s)
- Juan Lv
- a School of Environment and Architecture, University of Shanghai for Science and Technology , Shanghai , People's Republic of China
- b State Key Laboratory of Pollution Control and Resource Reuse , College of Environmental Science and Engineering, Tongji University , Shanghai , People's Republic of China
| | - Yong M Li
- b State Key Laboratory of Pollution Control and Resource Reuse , College of Environmental Science and Engineering, Tongji University , Shanghai , People's Republic of China
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Hatzinger PB, Lewis C, Webster TS. Biological treatment of N-nitrosodimethylamine (NDMA) and N-nitrodimethylamine (NTDMA) in a field-scale fluidized bed bioreactor. Water Res 2017; 126:361-371. [PMID: 28972939 DOI: 10.1016/j.watres.2017.09.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 09/15/2017] [Accepted: 09/22/2017] [Indexed: 06/07/2023]
Abstract
The ex situ treatment of N-nitrosodimethylamine (NDMA) and N-nitrodimethylamine (NTDMA) in groundwater was evaluated in a field-scale fluidized bed bioreactor (FBR). Both of these compounds, which originally entered groundwater at the test site from the use of liquid rocket propellant, are suspected human carcinogens. The objective of this research was to examine the application of a novel field-scale propane-fed fluidized bed bioreactor as an alternative to ultraviolet irradiation (UV) for treating NDMA and NTDMA to low part-per-trillion (ng/L) concentrations. Previous laboratory studies have shown that the bacterium Rhodococcus ruber ENV425 can biodegrade NDMA and NTDMA during growth on propane as a primary substrate and that the strain can effectively reduce NDMA concentrations in propane-fed bench-scale bioreactors of different design. R. ruber ENV425 was used as a seed culture for the FBR, which operated at a fluidization flow of ∼19 L-per-min (LPM) and received propane, oxygen, and inorganic nutrients in the feed. The reactor effectively treated ∼1 μg/L of influent NDMA to effluent concentrations of less than 10 ng/L at a hydraulic residence time (HRT) of only 10 min. At a 20 min HRT, the FBR reduced NDMA to <4.2 ng/L in the effluent, which was the discharge limit at the test site where the study was conducted. Similarly, NTDMA was consistently treated in the FBR from ∼0.5 μg/L to <10 ng/L at an HRT of 10 min or longer. Based on these removal rates, the average NDMA and NTDMA elimination capacities achieved were 2.1 mg NDMA treated/m3 of expanded bed/hr of operation and 1.1 mg NTDMA treated/m3 of expanded bed/hr of operation, respectively. The FBR system was highly resilient to upsets including power outages. Treatment of NDMA, but not NTDMA, was marginally affected when trace co-contaminants including trichloroethene (TCE) and trichlorofluoromethane (Freon 11) were initially added to feed groundwater, but performance recovered over a few weeks in the continued presence of these compounds. Strain ENV425 appeared to be replaced by native propanotrophs over time based on qPCR analysis, but contaminant treatment was not diminished. The results suggest that a FBR can be a viable alternative to UV treatment for removing NDMA from groundwater.
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Affiliation(s)
- Paul B Hatzinger
- Biotechnology Development and Applications Group, CB&I Federal Services, Lawrenceville, NJ, 08648, USA.
| | - Celeste Lewis
- Envirogen Technologies, Inc., Rancho Cucamonga, CA, 91730, USA
| | - Todd S Webster
- Envirogen Technologies, Inc., Rancho Cucamonga, CA, 91730, USA
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Ooka M, Takazawa H, Takeda S, Hirota K. Cytotoxic and genotoxic profiles of benzo[a]pyrene and N-nitrosodimethylamine demonstrated using DNA repair deficient DT40 cells with metabolic activation. Chemosphere 2016; 144:1901-1907. [PMID: 26547024 DOI: 10.1016/j.chemosphere.2015.10.085] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 10/19/2015] [Accepted: 10/21/2015] [Indexed: 06/05/2023]
Abstract
Benzo[a]pyrene and N-nitrosodimethylamine are major genotoxic compounds present in cigarette smoke, food and oil. To examine the type(s) of DNA damage induced by these compounds, we used a panel of DNA-repair-pathway-deficient mutants generated from chicken DT40 cells and achieved metabolic activation of the test compounds by including rat liver S9 mix. Consistent with expections, benzo[a]pyrene and N-nitrosodimethylamine require metabolicactivation to become genotoxic. The REV3(-/-) mutant cell line exhibited the highest sensitivity, in terms of increased cytotoxicity, to the both compounds after metabolic activation consistent with the known ability of these two compounds to induce DNA adducts. Strikingly, we found that the RAD54(-/-)/KU70(-/-) cell line, a mutant defective in the repair of double-strand breaks, is sensitive to benzo[a]pyrene, suggesting that this compound also induces strand breaks in these cells. In this study we combined a previously employed method, metabolic activation by S9 mix, with the use of a DNA-repair mutant panel, thereby broadening the range of compounds that can be screened for potential genotoxicity.
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Affiliation(s)
- Masato Ooka
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Hironori Takazawa
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan.
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Wang L, Li Y, He G. Degradation of typical N-nitrosodimethylamine (NDMA) precursors and its formation potential in anoxic-aerobic (AO) activated sludge system. J Environ Sci Health A Tox Hazard Subst Environ Eng 2014; 49:1727-1739. [PMID: 25320860 DOI: 10.1080/10934529.2014.951263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
N-nitrosodimethylamine (NDMA) is an emerging disinfection byproduct. Removal of its potential precursors is considered as an effective method to control NDMA. In this study, four typical NDMA precursors (dimethylamine (DMA), trimethylamine (TMA), dimethylformamide (DMFA) and dimethylaminobenzene (DMAB)) were selected, and their removal capacities by activated sludge were investigated. Batch experiments indicated that removal of NDMA precursors was better under aerobic condition than anoxic condition; and their specific degradation rates follow the order of DMA > TMA > DMFA > DMAB. In anoxic-aerobic (AO) activated sludge system, the optimal hydraulic retention time and sludge retention time were 10 h and 20 d, respectively, for the removal of both NDMA precursors (four selected NDMA precursors and NDMA formation potential (NDMA FP)) and nutrients. Our results also suggested that there was a positive correlation between NDMA FP and dissolved organic nitrogen (DON) in wastewater. The removal efficiency of NDMA FP was in the range of 46.8-72.5% in the four surveyed wastewater treatment plants except the one which adopted chemically enhanced primary process. The results revealed that the AO system had the advantage of removing NDMA FP. Our results are helpful for the knowledge of the removals of NDMA precursors during activated sludge treatment processes.
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Affiliation(s)
- Lin Wang
- a State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering , Tongji University , Shanghai , People's Republic of China
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Weidhaas J, Dupont RR. Aerobic biotransformation of N-nitrosodimethylamine and N-nitrodimethylamine in methane and benzene amended soil columns. J Contam Hydrol 2013; 150:45-53. [PMID: 23673086 DOI: 10.1016/j.jconhyd.2013.04.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
Aerobic biotransformation of N-nitrosodimethylamine (NDMA), an emerging contaminant of concern, and its structural analog N-nitrodimethylamine (DMN), was evaluated in benzene and methane amended groundwater passed through laboratory scale soil columns. Competitive inhibition models were used to model the kinetics for NDMA and DMN cometabolism accounting for the concurrent degradation of the growth and cometabolic substrates. Transformation capacities for NDMA and DMN with benzene (13 and 23μg (mgcells)(-1)) and methane (0.14 and 8.4μg (mgcells)(-1)) grown cultures, respectively are comparable to those presented in the literature, as were first order endogenous decay rates estimated to be 2.1×10(-2)±1.7×10(-3)d(-1) and 6.5×10(-1)±7.1×10(-1)d(-1) for the methane and benzene amended cultures, respectively. These studies highlight possible attenuation mechanisms and rates for NDMA and DMN biotransformation in aerobic aquifers undergoing active remediation, natural attenuation or managed aquifer recharge with treated wastewater (i.e., reclaimed water).
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Affiliation(s)
- Jennifer Weidhaas
- West Virginia University, Civil and Environmental Engineering, PO Box 6103, Morgantown, WV 26505, United States.
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Chowdhury G, Calcutt MW, Guengerich FP. Oxidation of N-Nitrosoalkylamines by human cytochrome P450 2A6: sequential oxidation to aldehydes and carboxylic acids and analysis of reaction steps. J Biol Chem 2010; 285:8031-44. [PMID: 20061389 PMCID: PMC2832954 DOI: 10.1074/jbc.m109.088039] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 12/26/2009] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 (P450) 2A6 activates nitrosamines, including N,N-dimethylnitrosamine (DMN) and N,N-diethylnitrosamine (DEN), to alkyl diazohydroxides (which are DNA-alkylating agents) and also aldehydes (HCHO from DMN and CH(3)CHO from DEN). The N-dealkylation of DMN had a high intrinsic kinetic deuterium isotope effect ((D)k(app) approximately 10), which was highly expressed in a variety of competitive and non-competitive experiments. The (D)k(app) for DEN was approximately 3 and not expressed in non-competitive experiments. DMN and DEN were also oxidized to HCO(2)H and CH(3)CO(2)H, respectively. In neither case was a lag observed, which was unexpected considering the k(cat) and K(m) parameters measured for oxidation of DMN and DEN to the aldehydes and for oxidation of the aldehydes to the carboxylic acids. Spectral analysis did not indicate strong affinity of the aldehydes for P450 2A6, but pulse-chase experiments showed only limited exchange with added (unlabeled) aldehydes in the oxidations of DMN and DEN to carboxylic acids. Substoichiometric kinetic bursts were observed in the pre-steady-state oxidations of DMN and DEN to aldehydes. A minimal kinetic model was developed that was consistent with all of the observed phenomena and involves a conformational change of P450 2A6 following substrate binding, equilibrium of the P450-substrate complex with a non-productive form, and oxidation of the aldehydes to carboxylic acids in a process that avoids relaxation of the conformation following the first oxidation (i.e. of DMN or DEN to an aldehyde).
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Affiliation(s)
- Goutam Chowdhury
- From the Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - M. Wade Calcutt
- From the Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - F. Peter Guengerich
- From the Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
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Fournier D, Hawari J, Halasz A, Streger SH, McClay KR, Masuda H, Hatzinger PB. Aerobic biodegradation of N-nitrosodimethylamine by the propanotroph Rhodococcus ruber ENV425. Appl Environ Microbiol 2009; 75:5088-93. [PMID: 19542346 PMCID: PMC2725486 DOI: 10.1128/aem.00418-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Accepted: 06/05/2009] [Indexed: 11/20/2022] Open
Abstract
The propanotroph Rhodococcus ruber ENV425 was observed to rapidly biodegrade N-nitrosodimethylamine (NDMA) after growth on propane, tryptic soy broth, or glucose. The key degradation intermediates were methylamine, nitric oxide, nitrite, nitrate, and formate. Small quantities of formaldehyde and dimethylamine were also detected. A denitrosation reaction, initiated by hydrogen atom abstraction from one of the two methyl groups, is hypothesized to result in the formation of n-methylformaldimine and nitric oxide, the former of which decomposes in water to methylamine and formaldehyde and the latter of which is then oxidized further to nitrite and then nitrate. Although the strain mineralized more than 60% of the carbon in [(14)C]NDMA to (14)CO(2), growth of strain ENV425 on NDMA as a sole carbon and energy source could not be confirmed. The bacterium was capable of utilizing NDMA, as well as the degradation intermediates methylamine and nitrate, as sources of nitrogen during growth on propane. In addition, ENV425 reduced environmentally relevant microgram/liter concentrations of NDMA to <2 ng/liter in batch cultures, suggesting that the bacterium may have applications for groundwater remediation.
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Affiliation(s)
- Diane Fournier
- Biotechnology Research Institute, Montreal, Quebec, Canada
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Hobbie KR, Deangelo AB, King LC, Winn RN, Law JM. Toward a molecular equivalent dose: use of the medaka model in comparative risk assessment. Comp Biochem Physiol C Toxicol Pharmacol 2009; 149:141-51. [PMID: 18722551 DOI: 10.1016/j.cbpc.2008.07.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Revised: 07/29/2008] [Accepted: 07/29/2008] [Indexed: 12/01/2022]
Abstract
Recent changes in the risk assessment landscape underscore the need to be able to compare the results of toxicity and dose-response testing between a growing list of animal models and, quite possibly, an array of in vitro screening assays. How do we compare test results for a given compound between vastly different species? For example, what dose level in the ambient water of a small fish model would be equivalent to 10 ppm of a given compound in the rat's drinking water? Where do we begin? To initially address these questions, and in order to compare dose-response tests in a standard rodent model with a fish model, we used the concept of molecular dose. Assays that quantify types of DNA damage that are directly relevant to carcinogenesis integrate the factors such as chemical exposure, uptake, distribution, metabolism, etc. that tend to vary so widely between different phyletic levels. We performed parallel exposures in F344 rats and Japanese medaka (Oryzias latipes) to the alkylating hepatocarcinogen, dimethylnitrosamine (DMN). In both models, we measured the DNA adducts 8-hydroxyguanine, N(7)-methylguanine and O(6)-methylguanine in the liver; mutation frequency using lambda cII transgenic medaka and lambda cII transgenic (Big Blue(R)) rats; and early morphological changes in the livers of both models using histopathology and immunohistochemistry. Pulse dose levels in fish were 0, 10, 25, 50, or 100 ppm DMN in the ambient water for 14 days. Since rats are reported to be especially sensitive to DMN, they received 0, 0.1, 1, 5, 10, or 25 ppm DMN in the drinking water for the same time period. While liver DNA adduct concentrations were similar in magnitude, mutant frequencies in the DMN-exposed medaka were up to 20 times higher than in the Big Blue rats. Future work with other compounds will generate a more complete picture of comparative dose response between different phyletic levels and will help guide risk assessors using "alternative" models.
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Affiliation(s)
- Kristen R Hobbie
- Comparative Biomedical Sciences Program and Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
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Glavin OA, Mikhailenko PM, Zaletok SP, Gulua L. Effects of green and black tea biocomposites on endogenous synthesis, metabolism and genotoxic effect of carcinogenic N-nitrosodimethylamine. Exp Oncol 2008; 30:306-314. [PMID: 19112429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
AIM To study the modifying effect of green and black tea biocomposites on endogenous synthesis and genotoxic action of the carcinogenic N-nitrosodimethylamine. METHODS Green and black tea biocomposites were administered to the white inbred rats in vivo. Amidopyrine and sodium nitrite were used as N-nitrosodimethylamine precursors and 4-methylpyrazol as an inhibitor of its metabolism. N-nitrosodimethylamine (blood, daily urine and reaction mixture), nitrites and nitrates (daily urine) levels were measured. Genotoxic action was tested by formation of DNA single-strand breaks in hepatocytes. RESULTS In in vitro system, biocomposites increased N-nitrosodimethylamine synthesis in neutral medium and decreased in acid conditions. In vivo, black tea biocomposite consumption resulted in enhanced background level of DNA single-strand breaks in rats hepatocytes and higher genotoxic effect upon administration of N-nitrosodimethylamine precursors. The levels of N-nitrosodimethylamine in blood and urine of experimental animals were increased after precursors' administration. In contrast, green tea biocomposite significantly decreased background level of DNA single-strand breaks. However, there was no protective action of this food supplement at the N-nitrosodimethylamine, precursors' administration. 4-methylpyrazol administration did not increase N-nitrosodimethylamine excretion in urine, while this effect was observed in control and black tea biocomposite groups. CONCLUSIONS The effects of green tea and black tea biocomposites on N-nitrosodimethylamine synthesis in in vitro system are unidirectional and depend on biocomposites' concentration and acidity of the medium. Long-term consumption of black tea biocomposite resulted in intensification of endogenous N-nitrosodimethylamine synthesis and increased damage of the hepatocytes' DNA. As to the green tea biocomposite, the obtained results allow us to suggest that this biocomposite enhanced N-nitrosodimethylamine metabolism.
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Affiliation(s)
- O A Glavin
- R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology NAS of Ukraine, Kiev 03022, Ukraine.
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Chung J, Ahn CH, Chen Z, Rittmann BE. Bio-reduction of N-nitrosodimethylamine (NDMA) using a hydrogen-based membrane biofilm reactor. Chemosphere 2008; 70:516-20. [PMID: 17720217 DOI: 10.1016/j.chemosphere.2007.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 07/12/2007] [Accepted: 07/13/2007] [Indexed: 05/16/2023]
Abstract
N-Nitrosodimethylamine (NDMA) is a disinfection by-product shown to be carcinogenic, mutagenic, and teratogenic. A feasible detoxification pathway for NDMA is a three-step bio-reduction that leads to ammonia and dimethylamine. This study examines the bio-reduction of NDMA in a H2-based membrane biofilm reactor (MBfR) that also is active in nitrate and sulfate reductions. In particular, the study investigates the effects of H2 availability and the relative loadings of NDMA, nitrate, and sulfate, which potentially are competing electron acceptors. The results demonstrate that NDMA was bio-reduced to a major extent (i.e., at least 96%) in a H2-based MBfR in which the electron-equivalent fluxes from H2 oxidation were dominated by nitrate and sulfate reductions. NDMA reduction kinetics responded to NDMA concentration, H2 pressure, and the presence of competing acceptors. The most important factor controlling NDMA-reduction kinetics was the H2 availability, controlled primarily by the H2 pressure, and secondarily by competition from nitrate reduction.
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Affiliation(s)
- Jinwook Chung
- R&D Center, Samsung Engineering Co. Ltd., 39-3 Sungbok-Dong, Yongin-Si, Gyeonggi-Do 449-844, Republic of Korea.
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Sharp JO, Sales CM, LeBlanc JC, Liu J, Wood TK, Eltis LD, Mohn WW, Alvarez-Cohen L. An inducible propane monooxygenase is responsible for N-nitrosodimethylamine degradation by Rhodococcus sp. strain RHA1. Appl Environ Microbiol 2007; 73:6930-8. [PMID: 17873074 PMCID: PMC2074979 DOI: 10.1128/aem.01697-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhodococci are common soil heterotrophs that possess diverse functional enzymatic activities with economic and ecological significance. In this study, the correlation between gene expression and biological removal of the water contaminant N-nitrosodimethylamine (NDMA) is explored. NDMA is a hydrophilic, potent carcinogen that has gained recent notoriety due to its environmental persistence and emergence as a widespread micropollutant in the subsurface environment. In this study, we demonstrate that Rhodococcus sp. strain RHA1 can constitutively degrade NDMA and that activity toward this compound is enhanced by approximately 500-fold after growth on propane. Transcriptomic analysis of RHA1 and reverse transcriptase quantitative PCR assays demonstrate that growth on propane elicits the upregulation of gene clusters associated with (i) the oxidation of propane and (ii) the oxidation of substituted benzenes. Deletion mutagenesis of prmA, the gene encoding the large hydroxylase component of propane monooxygenase, abolished both growth on propane and removal of NDMA. These results demonstrate that propane monooxygenase is responsible for NDMA degradation by RHA1 and explain the enhanced cometabolic degradation of NDMA in the presence of propane.
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Affiliation(s)
- Jonathan O Sharp
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, USA.
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Abstract
Dietary freeze-dried black raspberries (BRBs) inhibit N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the Fischer 344 rat esophagus. To determine the mechanistic basis of the anti-initiating effects of BRBs, NMBA metabolism was studied in esophageal explant cultures and in liver microsomes taken from rats fed with AIN-76A diet or AIN-76A diet containing 5% or 10% BRBs. Five percent and 10% dietary BRBs inhibited NMBA metabolism in explants (26% and 20%) and in microsomes (22% and 28%), but the inhibition was not dose dependent. To identify active inhibitory component(s) in BRBs, esophageal explants and liver microsomes from control rats were treated in vitro with an ethanol extract of BRBs or with individual components of BRBs [ellagic acid (EA) and two anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside)]. NMBA metabolism in explants was inhibited maximally by cyanidin-3-rutinoside (47%) followed by EA (33%), cyanidin-3-glucoside (23%), and the extract (11%). Similarly, in liver microsomes, the inhibition was maximal by cyanidin-3-rutinoside (47%) followed by EA (33%) and cyanidin-3-glucoside (32%). Phenylethylisothiocyanate (PEITC), a potent inhibitor of NMBA tumorigenesis in rat esophagus, was a stronger inhibitor of NMBA metabolism in vivo and in vitro than BRBs or their components. Dietary BRBs and PEITC induced glutathione S-transferase activity in the liver.
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Affiliation(s)
- Rashmeet K Reen
- Division of Hematology and Oncology, Department of Internal Medicine, The Ohio State University, Columbus 43210, USA.
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Fournier D, Hawari J, Streger SH, McClay K, Hatzinger PB. Biotransformation of N-nitrosodimethylamine by Pseudomonas mendocina KR1. Appl Environ Microbiol 2006; 72:6693-8. [PMID: 16950909 PMCID: PMC1610310 DOI: 10.1128/aem.01535-06] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 08/12/2006] [Indexed: 11/20/2022] Open
Abstract
N-Nitrosodimethylamine (NDMA) is a potent carcinogen and an emerging contaminant in groundwater and drinking water. The metabolism of NDMA in mammalian cells has been widely studied, but little information is available concerning the microbial transformation of this compound. The objective of this study was to elucidate the pathway(s) of NDMA biotransformation by Pseudomonas mendocina KR1, a strain that possesses toluene-4-monooxygenase (T4MO). P. mendocina KR1 was observed to initially oxidize NDMA to N-nitrodimethylamine (NTDMA), a novel metabolite. The use of 18O2 and H(2)18O revealed that the oxygen added to NDMA to produce NTDMA was derived from atmospheric O2. Experiments performed with a pseudomonad expressing cloned T4MO confirmed that T4MO catalyzes this initial reaction. The NTDMA produced by P. mendocina KR1 did not accumulate, but rather it was metabolized further to produce N-nitromethylamine (88 to 94% recovery) and a trace amount of formaldehyde (HCHO). Small quantities of methanol (CH3OH) were also detected when the strain was incubated with NDMA but not during incubation with either NTDMA or HCHO. The formation of methanol is hypothesized to occur via a second, minor pathway mediated by an initial alpha-hydroxylation of the nitrosamine. Strain KR1 did not grow on NDMA or mineralize significant quantities of the compound to carbon dioxide, suggesting that the degradation process is cometabolic.
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Affiliation(s)
- Diane Fournier
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
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Mori Y, Tatematsu K, Koide A, Sugie S, Tanaka T, Mori H. Modification by curcumin of mutagenic activation of carcinogenic N-nitrosamines by extrahepatic cytochromes P-450 2B1 and 2E1 in rats. Cancer Sci 2006; 97:896-904. [PMID: 16805852 DOI: 10.1111/j.1349-7006.2006.00261.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
To elucidate the mechanism underlying suppression by curcumin of esophageal carcinogenesis induced by NMBA, we evaluated the CYP level and mutagenic activation of environmental carcinogens, by immunoblot analyses and Ames preincubation test, respectively, and bilirubin, 4-nitrophenol and testosterone UDPGT activities in F344 rats treated with curcumin and/or NMBA. No significant alterations in the hepatic levels of constitutive CYP proteins, mutagenic activation by liver S9 or hepatic UDPGT activities were produced by subcutaneous treatment with 0.5 mg/kg NMBA for 5 weeks and/or feeding of 0.05% and 0.2% curcumin for 6 weeks. In contrast, gavage of 0.2% curcumin decreased esophageal CYP2B1 and 2E1 by up to 60%, compared with vehicle control. Similarly, intragastric treatment with 270 mg/kg curcumin decreased esophageal and gastric CYP2B1 and CYP2E1, but not in lung, kidney or intestine. Conversely, large intestinal CYP2B1 was 2.8-fold higher in the treated rats than in control rats. Mutagenic activities of NOC, including NMBA, in the presence of esophagus and stomach S9 were markedly decreased in the treated rats, whereas those in the presence of large intestine S9 were 2.2-3.0-fold above control. These results show that modifying effects of curcumin on esophageal carcinogenesis can be attributed to a decrease in metabolic activation of NMBA by esophageal CYP2B1 during the initiation phase, without the contribution of metabolic activation and inactivation by liver. Further, the present findings suggest the potential of curcumin for modification of gastric and intestinal carcinogenesis initiated with NOC.
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Affiliation(s)
- Yukio Mori
- Institute of Biological Pharmacy, Gifu Pharmaceutical University, 6-1, Mitahora-higashi 5-chome, Gifu 502-8585, Japan.
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Jakszyn P, Bingham S, Pera G, Agudo A, Luben R, Welch A, Boeing H, Del Giudice G, Palli D, Saieva C, Krogh V, Sacerdote C, Tumino R, Panico S, Berglund G, Simán H, Hallmans G, Sanchez MJ, Larrañaga N, Barricarte A, Chirlaque MD, Quirós JR, Key TJ, Allen N, Lund E, Carneiro F, Linseisen J, Nagel G, Overvad K, Tjonneland A, Olsen A, Bueno-de-Mesquita HB, Ocké MO, Peeters PH, Numans ME, Clavel-Chapelon F, Trichopoulou A, Fenger C, Stenling R, Ferrari P, Jenab M, Norat T, Riboli E, Gonzalez CA. Endogenous versus exogenous exposure to N-nitroso compounds and gastric cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC-EURGAST) study. Carcinogenesis 2006; 27:1497-501. [PMID: 16571648 DOI: 10.1093/carcin/bgl019] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The risk of gastric cancer (GC) associated with dietary intake of nitrosodimethylamine (NDMA) and endogenous formation of nitroso compounds (NOCs) was investigated in the European Prospective Investigation into Cancer and Nutrition (EPIC). The study included 521,457 individuals and 314 incident cases of GC that had occurred after 6.6 average years of follow-up. An index of endogenous NOC (ENOC) formation was estimated using data of the iron content from meat intake and faecal apparent total NOC formation according to previous published studies. Antibodies to Helicobacter pylori and vitamin C levels were measured in a sub-sample of cases and matched controls included in a nested case-control within the cohort. Exposure to NDMA was < 1 microg on average compared with 93 mug on average from ENOC. There was no association between NDMA intake and GC risk (HR, 1.00; 95% CI, 0.7-1.43). ENOC was significantly associated with non-cardia cancer risk (HR, 1.42; 95% CI, 1.14-1.78 for an increase of 40 microg/day) but not with cardia cancer (HR, 0.96; 95% CI, 0.69-1.33). Although the number of not infected cases is low, our data suggest a possible interaction between ENOC and H.pylori infection (P for interaction = 0.09). Moreover, we observed an interaction between plasma vitamin C and ENOC (P < 0.02). ENOC formation may account for our previously reported association between red and processed meat consumption and gastric cancer risk.
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Affiliation(s)
- Paula Jakszyn
- Department of Epidemiology, Catalan Institute of Oncology, (ICO-IDIBELL) Barcelona, Spain.
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Sharan RN, Devi BJ, Humtsoe JO, Saikia JR, Kma L. Detection and quantification of poly-ADP-ribosylated cellular proteins of spleen and liver tissues of mice in vivo by slot and Western blot immunoprobing using polyclonal antibody against mouse ADP-ribose polymer. Mol Cell Biochem 2006; 278:213-21. [PMID: 16180107 DOI: 10.1007/s11010-005-7588-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Accepted: 05/19/2005] [Indexed: 11/29/2022]
Abstract
Poly-ADP-ribosylation (PAR) of cellular proteins has been shown to have decisive roles in diverse cellular functions including carcinogenesis. There are indications that metabolic level of poly-ADP-ribosylated cellular proteins might indicate carcinogenesis and, therefore, could be potentially used in cancer screening program. Keeping in mind the limitations of currently available assays of cellular PAR, a new assay is being reported that measures the metabolic level of poly-ADP-ribosylated cellular proteins. The ELISA based slot and Western blot immunoassay used polyclonal antibody against natural, heterogeneous ADP-ribose polymers. It could be successfully employed to qualitatively and quantitatively assay metabolic levels of poly-ADP-ribosylated proteins of spleen and liver tissues of normal mice or mice exposed to dimethylnitrosamine for up to 8 weeks; potentially PAR of cellular proteins could be assayed in any tissue or biopsy. Implications of the results in cancer screening program have been discussed.
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Affiliation(s)
- R N Sharan
- Radiation and Molecular Biology Unit, Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, India.
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Reen RK, Nines R, Stoner GD. Modulation of N-nitrosomethylbenzylamine metabolism by black raspberries in the esophagus and liver of Fischer 344 rats. Nutr Cancer 2006. [PMID: 16800772 DOI: 10.1207/s15327914nc54016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Dietary freeze-dried black raspberries (BRBs) inhibit N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the Fischer 344 rat esophagus. To determine the mechanistic basis of the anti-initiating effects of BRBs, NMBA metabolism was studied in esophageal explant cultures and in liver microsomes taken from rats fed with AIN-76A diet or AIN-76A diet containing 5% or 10% BRBs. Five percent and 10% dietary BRBs inhibited NMBA metabolism in explants (26% and 20%) and in microsomes (22% and 28%), but the inhibition was not dose dependent. To identify active inhibitory component(s) in BRBs, esophageal explants and liver microsomes from control rats were treated in vitro with an ethanol extract of BRBs or with individual components of BRBs [ellagic acid (EA) and two anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside)]. NMBA metabolism in explants was inhibited maximally by cyanidin-3-rutinoside (47%) followed by EA (33%), cyanidin-3-glucoside (23%), and the extract (11%). Similarly, in liver microsomes, the inhibition was maximal by cyanidin-3-rutinoside (47%) followed by EA (33%) and cyanidin-3-glucoside (32%). Phenylethylisothiocyanate (PEITC), a potent inhibitor of NMBA tumorigenesis in rat esophagus, was a stronger inhibitor of NMBA metabolism in vivo and in vitro than BRBs or their components. Dietary BRBs and PEITC induced glutathione S-transferase activity in the liver.
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Affiliation(s)
- Rashmeet K Reen
- Division of Hematology and Oncology, Department of Internal Medicine, The Ohio State University, Columbus 43210, USA.
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Mo CL, Li Y, Li Y. [Protective effects of bicyclol on alcohol-induced liver damage in mice]. Zhonghua Yi Xue Za Zhi 2005; 85:3409-13. [PMID: 16409862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
OBJECTIVE To study the protective effect of bicyclol on alcohol-induced liver injury in mice. METHODS Sixty male mice were randomly divided into 6 groups. Ten mice were fed with Lieber-Decarli liquid diet without alcohol and used as normal controls. Fifty mice were fed with Lieber-Decarli liquid diet containing 5% alcohol for four weeks so as to establish a model of alcohol-induced liver damage. Ten mice fed with Lieber-Decarli liquid diet containing 5% alcohol for four weeks were used as model group. Bicyclol in a dose of either 200 or 300 .kg(-1).d(-1) was given orally simultaneously with alcohol intake as prevention groups (10 mice in each group), and bicyclol in a dose of either 200 or 300 .kg(-1).d(-1) was given orally 2 weeks after the beginning of alcohol intake as treatment groups (10 mice in each group). Twenty-four hours after the last dose of bicyclol the mice were decapitated and then their blood samples and livers were taken. The serum alanine aminotransferase (ALT), cholesterol (CHOL), and high-density lipoprotein/low-density lipoprotein (HDL/LDL), and liver triglyceride (TG), N-nitrosodimethylamine demethylase (NDMA-DM), glutathione (GSH), glutathione S-transferase (GST), glutathione reductase (GR), and aldehyde dehydrogenase (ALDH) were determined by biochemical assays. The extent of liver damage was evaluated by histological examination. RESULTS Four weeks after alcohol intake the serum ALT and TG were 1.9 and 2.7 times those of the normal control group. The levels of liver TG of the bicyclol 200 kg(-1).d(-1) and 300 kg(-1).d(-1) treatment groups were significantly lower than that of the model group by 28% and 32% respectively (both P < 0.05). The levels of liver TG of the bicyclol 200 kg(-1).d(-1) and 300 kg(-1).d(-1) prevention groups were significantly lower than that of the model group by 32%, and 47% respectively (both P < 0.01). Pathological changes including steatosis and hepatocyte ballooning degeneration were found in the livers of the model group. The levels of liver GSH, GST, and GR in the model group decreased by 37%, 22%, and 19% in comparison with the normal control group. The levels of liver GSH and GST of the bicyclol prevention groups were normal, and the liver GR level was 1.2 times that of the normal control group. The liver NDMA-DM activity of the model group was 1.9 times that of the normal control group and was normal in the bicyclol prevention and treatment groups. The liver cytoplasmic ALDH level was 30% lower in the model group than in the normal control group (P < 0.05), and was 2.9 times in the bicyclol groups (P < 0.01). The serum cholesterol levels of the bicyclol groups were all significantly lower than that of the model group (all P < 0.01). The serum levels of HDL of the bicyclol prevention groups and treatment were all significantly lower than that in the model group (P < 0.01 or P < 0.05). CONCLUSION Bicyclol protects mice against alcohol-induced hepatotoxicity by reduction of hepatic steatosis and cellular damage, acceleration of alcohol and aldehyde elimination and anti-peroxidation.
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Affiliation(s)
- Cheng-lin Mo
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100050, China
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Lee J, Choi W, Yoon J. Photocatalytic degradation of N-nitrosodimethylamine: mechanism, product distribution, and TiO2 surface modification. Environ Sci Technol 2005; 39:6800-7. [PMID: 16190242 DOI: 10.1021/es0481777] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The photocatalytic degradation (PCD) reaction of N-nitrosodimethylamine (NDMA) in water was investigated using pure and surface-modified TiO2. The PCD products of NDMA were methylamine (MA), dimethylamine (DMA), nitrite, nitrate, and ammonium, and their distribution could be changed by modifying the surface of TiO2. The PCD reaction of NDMA seems to be initiated mostly by OH radicals, not valence band holes, because the addition of excess oxalates (hole scavengers) only moderately retarded the PCD rate. The presence of oxalate, however, enabled a new reductive transformation path in which the CO2-* radicals generated from the oxalate converted NDMA into DMA. In acidic suspensions of pure TiO2, the formation of MA was highly favored over DMA and NH3, whereas all degradation products (MA, DMA, and NH3) were generated at comparable concentrations at basic pH. It is suggested that there are three parallel paths depending on the position of the initial attack of OH radical on NDMA and the product distribution is closely related with which path is favored under a specific condition. DMA production is related to the OH radical attack on the nitrosyl nitrogen. Platinum deposition, silica loading, Nafion coating, and surface fluorination were tested to investigate the effects of TiO2 surface modification on the product distribution. The surface platinization of TiO2 had little effect on the PCD reaction of NDMA under air-equilibrated conditions but accelerated the PCD reaction under deaerated conditions. An enhanced PCD reaction of NDMA was achieved with the silica-loaded TiO2 and Nafion-coated TiO2, both of which favored the formation of DMA over MA. The PCD of NDMA on surface-fluorinated TiO2 was also highly enhanced but favored the formation of MA over the formation of DMA.
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Affiliation(s)
- Jaesang Lee
- School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790- 784, Korea
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Krul CAM, Zeilmaker MJ, Schothorst RC, Havenaar R. Intragastric formation and modulation of N-nitrosodimethylamine in a dynamic in vitro gastrointestinal model under human physiological conditions. Food Chem Toxicol 2004; 42:51-63. [PMID: 14630130 DOI: 10.1016/j.fct.2003.08.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Human exposure to carcinogenic N-alkylnitrosamines can occur exogenously via food consumption or endogenously by formation of these compounds through nitrosation of amine precursors. Information on the intragastric formation of NDMA from complex mixtures of precursors and inhibitors in humans is not available. In this study the formation of N-nitrosodimethylamine (NDMA) has been quantitatively analysed in a dynamic in vitro gastrointestinal model, in which gastric conditions can be modulated and closely simulates the physiological situation in humans. Substantial amounts of NDMA were produced when nitrite and dimethylamine or codfish were simultaneously introduced into the model. However, humans are gradually exposed to nitrite by the intake of nitrate-containing food. Nitrate secreted in saliva is converted to nitrite by oral bacteria. To mimic the human exposure to nitrite in a realistic way, nitrite was gradually added into the gastric compartment, simulating the swallowing of nitrite containing oral fluid after the intake of nitrate at the level of 0.1-10 times the ADI. Under these conditions, the cumulative amounts of NDMA formed were 2.3-422 microg NDMA and 1.8-42.7 microg NDMA at a rapid and slow gastric pH decrease, respectively. Beside codfish, various fish species and batches in combination with nitrite, simulating the intake of for times the ADI of nitrate, were investigated. Herring, pollack and plaice were also able to induce NDMA formation. Mackerel, salmon and pike perch did not result in increased NDMA formation. Furthermore, the effect of nitrosation modulators on NDMA formation was investigated. Thiocyanate (2 mM) increased NDMA formation, but the increase was not statistically significant. In contrast, orange jus and tea effectively, but not totally, reduced the amount of NDMA formed in the gastric compartment. These experiments show that (1). the dynamic in vitro gastrointestinal model is an appropriate tool for mechanistic studies on the intragastric formation of nitrosamines, and (2). that the results obtained with this model are helpful in evaluating human cancer risk for the combined intake of codfish-like fish species and nitrate-containing vegetables.
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Affiliation(s)
- Cyrille A M Krul
- TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands.
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Wilkening S, Stahl F, Bader A. Comparison of primary human hepatocytes and hepatoma cell line Hepg2 with regard to their biotransformation properties. Drug Metab Dispos 2003; 31:1035-42. [PMID: 12867492 DOI: 10.1124/dmd.31.8.1035] [Citation(s) in RCA: 564] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cultures of primary hepatocytes and hepatoma cell line HepG2 are frequently used in in vitro models for human biotransformation studies. In this study, we characterized and compared the capacity of these model systems to indicate the presence of different classes of promutagens. Genotoxic sensitivity, enzyme activity, and gene expression were monitored in response to treatment with food promutagens benzo[a]pyrene, dimethylnitrosamine (DMN), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). DNA damage could be detected reliably with the comet assay in primary human hepatocytes, which were maintained in sandwich culture. All three promutagens caused DNA damage in primary cells, but in HepG2 no genotoxic effects of DMN and PhIP could be detected. We supposed that the lack of specific enzymes accounts for their inability to process these promutagens. Therefore, we quantified the expression of a broad range of genes coding for drug-metabolizing enzymes with real-time reverse transcription-polymerase chain reaction. The genes code for cytochromes p450 and, in addition, for a series of important phase II enzymes. The expression level of these genes in human hepatocytes was similar to those previously reported for human liver samples. On the other hand, expression levels in HepG2 differed significantly from that in human. Activity and expression, especially of phase I enzymes, were demonstrated to be extremely low in HepG2 cells. Up-regulation of specific genes by test substances was similar in both cell types. In conclusion, human hepatocytes are the preferred model for biotransformation in human liver, whereas HepG2 cells may be useful to study regulation of drug-metabolizing enzymes.
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Affiliation(s)
- Stefan Wilkening
- German Research Centre for Biotechnology, Organ-und Gewebekultur, Braunschweig, Germany.
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Gopalakrishnan R, Gupta A, Carlton PS, Morse MA, Stoner GD. Functional role of cytochrome p-450 2a3 in N-nitrosomethylbenzylamine metabolism in rat esophagus. J Toxicol Environ Health A 2002; 65:1077-1091. [PMID: 12167220 DOI: 10.1080/152873902760125237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Previous in vitro studies demonstrated that the rat esophageal carcinogen N-nitrosomethylbenzylamine (NMBA) is metabolically activated by cytochrome P-450s (CYP) 2A3 and 2E1. However, the in vivo role of these P-450s in the metabolism of NMBA has not been fully evaluated. In this study, the effects of single and multiple doses of NMBA were investigated on CYP2A3 and CYP2E1 mRNA expression in the rat esophagus and lung. Seven- to 8-wk old male Fischer 344 rats were administered a single subcutaneous dose of NMBA at either 0.5 mg/kg or 2 mg/kg body weight, after which the rats were sacrificed at 1, 3, 6, 12, 24, 48, and 72 h. In the multiple-dose experiment, 2 groups of rats were dosed with 0.5 mg/kg body weight NMBA 3 times per week for 1 wk or 3 wk. The animals were sacrificed 24 h following the last treatment. Semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis demonstrated a reduction of CYP2A3 mRNA expression in lung and esophagus from NMBA-treated animals compared to dimethyl sulfoxide (DMSO)-treated vehicle controls. This reduction in CYP2A3 mRNA was significant at 48 h in the esophagus and at 24 and 48 h in the lung following a single dose of 2 mg/kg body weight NMBA. In contrast, CYP2E1 mRNA expression remained unchanged in rat lung following NMBA treatment and no consistent pattern of expression could be observed in the esophagus. In the multiple-dose study, a 32% and 25% reduction in esophageal CYP2A3 mRNA expression was observed at 1 and 3 wk, respectively. Similar reductions in CYP2A3 mRNA expression were also observed in the lung. Further, esophageal explants derived from animals pretreated with NMBA in vivo demonstrated a reduced ability to metabolize the carcinogen in vitro as compared to explants from vehicle control animals. Taken together, these data provide further support for a potential role of CYP2A3 in NMBA metabolism in the rat esophagus. Data suggest that CYP2A3 levels in the rat esophagus can be a determinant of its ability to metabolize this carcinogen in vivo.
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Affiliation(s)
- Rajaram Gopalakrishnan
- Department of Periodontics, Prevention, and Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, Michigan, USA
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Chung MJ, Lee SH, Sung NJ. Inhibitory effect of whole strawberries, garlic juice or kale juice on endogenous formation of N-nitrosodimethylamine in humans. Cancer Lett 2002; 182:1-10. [PMID: 12175517 DOI: 10.1016/s0304-3835(02)00076-9] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In vitro and in vivo experiments were performed on inhibition of nitrosation by strawberry, garlic, and kale extracts. Strawberry, garlic, and kale extracts inhibited nitrosation in vitro. However, garlic extract has a greater ability to inhibit the chemical nitrosation in vitro than strawberry and kale extracts. The garlic methanol-soluble fraction of the garlic extract was fractionated into G1-G4 fractions by Prep-LC. Fraction G1 inhibited N-nitrosodimethylamine (NDMA) formation by 84+/-1%. We studied the formation of the carcinogen NDMA in humans after administration of nitrate (400 mg/day) in combination with an amine-rich diet and its possible inhibition by administration of whole strawberries (300 g), garlic juice (200 g: 75 g garlic juice in drinking water), or kale juice (200 g) in 27 males and 13 females (ten healthy volunteers in each group) of age 24+/-3 years. Nitrate intake resulted in a significant rise in mean salivary nitrate and nitrite concentrations. Also, nitrate excretion in urine during the experimental day was significantly increased compared with the control days. When whole strawberries, garlic juice, or kale juice was provided immediately after an amine-rich diet with a nitrate, NDMA excretion was decreased by 70, 71, and 44%, respectively, compared with NDMA excretion after ingestion of an amine-rich diet with a nitrate. These results suggest that consumption of whole strawberries, garlic juice, or kale juice can reduce endogenous NDMA formation.
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Affiliation(s)
- Mi Ja Chung
- Department of Food and Nutrition, Gyeongsang National University, Jinju 660-701, South Korea
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Godoy W, Albano RM, Moraes EG, Pinho PRA, Nunes RA, Saito EH, Higa C, Filho IM, Kruel CDP, Schirmer CC, Gurski R, Lang MA, Pinto LFR. CYP2A6/2A7 and CYP2E1 expression in human oesophageal mucosa: regional and inter-individual variation in expression and relevance to nitrosamine metabolism. Carcinogenesis 2002; 23:611-6. [PMID: 11960914 DOI: 10.1093/carcin/23.4.611] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Oesophageal cancer is one of the most common and lethal malignancies in the world. Despite many efforts, treatment is still ineffective for most cases; thus, the development of preventive strategies is crucial for decreasing the burden presented by this disease. Environmental factors, particularly nitrosamines, are thought to be involved in the genesis of oesophageal tumours, and knowledge about the expression of enzymes capable of activating pre-carcinogens in human oesophagus is very important for the development of preventive measures. We analysed the expression of CYP1A1, CYP1A2, CYP2A6/2A7, CYP2E1 and CYP3A4 mRNA in oesophageal mucosa of 50 patients by semi-quantitative RT-PCR. In five patients, who suffered from squamous cell carcinoma, we measured Nnitrosodimethylamine and N-nitrosodiethylamine metabolism in normal and tumorous tissue. CYP2A6/2A7 mRNA was expressed in 61% and CYP2E1 mRNA in 96% of the patients, but in the latter a lower degree of inter-individual variation was observed. These enzymes were expressed either in the distal or middle portions of the oesophagus of 90% of the patients. CYP1A1, CYP1A2 and CYP3A4 mRNA expression was not detected in any portion of the oesophagus. Oesophageal microsomes activated N-nitrosodimethylamine with a low degree of inter-individual variation and microsomes prepared from the tumour of a patient who strongly expressed CYP2A6/2A7 mRNA activated N-nitrosodiethylamine. We conclude that the human oesophagus expresses CYP2A6/2A7 and CYP2E1 and can activate nitrosamines. Notably, the expression of these enzymes is preferentially localized to the most common sites where tumours arise.
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Affiliation(s)
- Wagner Godoy
- Departamento de Bioquímica, IBRAG, Universidade do Estado do Rio de Janeiro, RJ, Brazil
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Gómez MID, Valles E, Fanelli SL, de Layño AMAD, Castro GD, Castro JA. Alcohol induction of liver nuclear ethanol and N-nitrosodimethylamine metabolism to reactive metabolites. Teratog Carcinog Mutagen 2002; 22:139-45. [PMID: 11835291 DOI: 10.1002/tcm.10009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In previous studies from our laboratory we reported the presence in highly purified liver nuclei, free of contamination with other organelles, of an ethanol metabolizing system (NEMS) able to lead to acetaldehyde and 1-hydroxyethyl free radicals (1HEt). In the present study we tested whether this NEMS is inducible by chronic alcohol administration to rats and whether these nuclei also have increased ability to bioactivate N-nitrosodimethylamine (NDMA). Sprague Dawley male rats (125-150g) were fed with a nutritionally adequate liquid diet containing alcohol to provide 36% of total energy (standard Lieber-De Carli rat diet), for 28 days. Controls received an isocaloric diet without alcohol. Animals were sacrificed, livers were excised and microsomes and purified nuclear fractions were prepared. Both microsomes and nuclei from treated animals had significantly increased ability compared to controls, to biotransform ethanol to acetaldehyde using NADPH as cofactor under an air atmosphere. Both organelles also exhibited significantly increased capacity compared to controls, to bioactivate NDMA to formaldehyde and to reactive metabolites that bind covalently to proteins. Nuclear preparations from control animals were also able to metabolize NDMA to formaldehyde and reactive metabolites. Results indicate that liver nuclei may have a CYP2E1 able to bioactivate both NDMA and EtOH and that these processes are being induced by chronic alcohol drinking. The bioactivation of these xenobiotics to reactive metabolites in the neighborhood of nuclear proteins and DNA might have significant toxicological implications.
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Affiliation(s)
- M I Díaz Gómez
- Centro de Investigaciones Toxicológicas (CEITOX), CITEFA/CONICET, Buenos Aires, Argentina
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Frei E, Kuchenmeister F, Gliniorz R, Breuer A, Schmezer P. N-nitrososdimethylamine is activated in microsomes from hepatocytes to reactive metabolites which damage DNA of non-parenchymal cells in rat liver. Toxicol Lett 2001; 123:227-34. [PMID: 11641050 DOI: 10.1016/s0378-4274(01)00400-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The liver carcinogen N-nitrosodimethylamine (NDMA) has to be metabolically activated by specific cytochromes before it can react with cellular macromolecules (e.g. proteins or DNA). Although hepatocytes are believed to be responsible for this activation, the liver tumours originate mainly from non-parenchymal cells (NPC). To investigate their activation capacity we determined NDMA-demethylase activity in isolated microsomes from both liver cell types. The results demonstrate that only hepatocytes have activation capacity. Additional experiments were performed with hepatocytes and NPC using the single cell microgel electrophoresis assay (MGE). DNA damage appears in both cell types following in vivo exposure. Tested in vitro, however, the carcinogens induce DNA damages only in hepatocytes (the cells which activate these compounds). N-nitroso-hydroxymethyl-methylamine could be the responsible metabolite as it is stable enough to be transported from hepatocytes to NPC in an intact liver.
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Affiliation(s)
- E Frei
- German Cancer Research Center, Division of Molecular Toxicology, Heidelberg, Germany.
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Kresty LA, Morse MA, Morgan C, Carlton PS, Lu J, Gupta A, Blackwood M, Stoner GD. Chemoprevention of esophageal tumorigenesis by dietary administration of lyophilized black raspberries. Cancer Res 2001; 61:6112-9. [PMID: 11507061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Fruit and vegetable consumption has consistently been associated with decreased risk of a number of aerodigestive tract cancers, including esophageal cancer. We have taken a "food-based" chemopreventive approach to evaluate the inhibitory potential of lyophilized black raspberries (LBRs) against N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in the F344 rat, during initiation and postinitiation phases of carcinogenesis. Anti-initiation studies included a 30-week tumorigenicity bioassay, quantification of DNA adducts, and NMBA metabolism study. Feeding 5 and 10% LBRs, for 2 weeks prior to NMBA treatment (0.25 mg/kg, weekly for 15 weeks) and throughout a 30-week bioassay, significantly reduced tumor multiplicity (39 and 49%, respectively). In a short-term bioassay, 5 and 10% LBRs inhibited formation of the promutagenic adduct O(6)-methylguanine (O(6)-meGua) by 73 and 80%, respectively, after a single dose of NMBA at 0.25 mg/kg. Feeding 5% LBRs also significantly inhibited adduct formation (64%) after NMBA administration at 0.50 mg/kg. The postinitiation inhibitory potential of berries was evaluated in a second bioassay with sacrifices at 15, 25, and 35 weeks. Administration of LBRs began after NMBA treatment (0.25 mg/kg, three times per week for 5 weeks). LBRs inhibited tumor progression as evidenced by significant reductions in the formation of preneoplastic esophageal lesions, decreased tumor incidence and multiplicity, and reduced cellular proliferation. At 25 weeks, both 5 and 10% LBRs significantly reduced tumor incidence (54 and 46%, respectively), tumor multiplicity (62 and 43%, respectively), proliferation rates, and preneoplastic lesion development. Yet, at 35 weeks, only 5% LBRs significantly reduced tumor incidence and multiplicity, proliferation indices and preneoplastic lesion formation. In conclusion, dietary administration of LBRs inhibited events associated with both the initiation and promotion/progression stages of carcinogenesis, which is promising considering the limited number of chemopreventives with this potential.
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Affiliation(s)
- L A Kresty
- Division of Environmental Health Sciences, School of Public Health, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA
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Jabłoński J. [N-nitrosodimethylamine--toxicologic significance]. POSTEP HIG MED DOSW 2001; 55:317-37. [PMID: 11468977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
In this paper we have presented data on an environmental exposure to N-nitrosodimethylamine (NDMA) and factors which favour endogenous biosynthesis of this compound. The factors influencing metabolism and toxicity as well as health effect of exposure have been reported.
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Affiliation(s)
- J Jabłoński
- Zakład Toksykologii, Akademii Medycznej w Białymstoku.
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Gupta A, Nines R, Rodrigo KA, Aziz RA, Carlton PS, Gray DL, Steele VE, Morse MA, Stoner GD. Effects of dietary N-(4-hydroxyphenyl)retinamide on N-nitrosomethylbenzylamine metabolism and esophageal tumorigenesis in the Fischer 344 rat. J Natl Cancer Inst 2001; 93:990-8. [PMID: 11438564 DOI: 10.1093/jnci/93.13.990] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND 9-cis-Retinoic acid (9-cis-RA) and N-(4-hydroxyphenyl)retinamide (4-HPR) are effective chemopreventive agents against epithelial tumors in the oral cavity, breast, and prostate. We tested the inhibitory activity of these retinoids against N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the rat esophagus. METHODS Male Fischer 344 rats were randomly assigned to receive diets either lacking or containing 9-cis-RA or 4-HPR for 1 week before tumor initiation with NMBA and then for the duration of the study. NMBA metabolism, O(6)-methylguanine adduct formation, and cytochrome P450 messenger RNA (mRNA) expression in the esophagi of the rats were studied to investigate the mechanisms by which dietary 4-HPR affects tumorigenesis. All statistical tests were two-sided. RESULTS Dietary 4-HPR resulted in a dose-dependent and statistically significant enhancement (P<.05) of tumorigenesis in response to NMBA. In two different tumor bioassays, the mean tumor multiplicity for rats fed the highest concentration of dietary 4-HPR (0.8 g/kg diet) was increased by 5.9 tumors (95% confidence interval [CI] = 1.7 to 10.1 tumors) and 6.7 tumors (95% CI = 5.6 to 7.8 tumors) compared with the mean tumor multiplicity for rats that received the control diet lacking 4-HPR. Animals fed diets containing 9-cis-RA displayed no statistically significant increase in tumorigenesis. Compared with animals fed a diet lacking 4-HPR, animals fed 4-HPR had increased NMBA metabolism in esophageal explant cultures and had higher levels of O(6)-methylguanine DNA adducts and CYP2A3 mRNA in their esophagi. CONCLUSIONS Dietary 4-HPR enhances tumorigenesis in response to NMBA in the rat esophagus by increasing tumor initiation events. Dietary 4-HPR may exert paradoxical effects at some sites, such as the aerodigestive tract, by modulating the bioactivation of carcinogens in target tissues.
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Affiliation(s)
- A Gupta
- Division of Environmental Health Sciences, The Ohio State University School of Public Health and Comprehensive Cancer Center, The Ohio State University, Columbus 43210, USA
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Sheweita SA, Abu El-Maati MR, El-Shahat FG, Bazeed MA. Changes in the expression of cytochrome P450 2E1 and the activity of carcinogen-metabolizing enzymes in Schistosoma haematobium-infected human bladder tissues. Toxicology 2001; 162:43-52. [PMID: 11311457 DOI: 10.1016/s0300-483x(01)00357-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The bioactivation of N-nitrosamines and polycyclic aromatic hydrocarbons (PAHs) is mediated primarily by the mixed-function oxidase system, which includes dimethylnitrosamine N-demethylase I, arylhydrocarbon [benzo(a)pyerne] hydroxylase, cytochrome P450, cytochrome b(5), and ethoxycoumarin deethylase. Most of carcinogens and xenobiotics are conjugated and detoxified by phase II drug-metabolizing enzymes such as glutathione S-transferase. The present study showed the influence of Schistosoma haematobium on the activity of the above-mentioned enzymes in 13 schistosome-infected human bladder tissues compared with those of 15 schistosome-free samples. The contents of cytochrome P450 and cytochrome b(5) were increased in the bladder tissues by 48 and 69%, respectively. Moreover, the activities of dimethylnitrosamine N-demethylase I and arylhydrocarbon hydroxylase, ethoxycoumarin O-deethylase, ethoxyresourfin O-deethylase, and pentoxyresorufin O-pentoxyresorufin were increased by 75, 159, 49, 63 and 44%, respectively. The signal intensity for cytochrome P450 2E1 was greatly increased over the control. Also, the activity of glutathione S-transferase was increased by 89%. On the other hand, the activity of glutathione reductase and the level of reduced glutathione were decreased by 40 and 57%, respectively. Interestingly, the level of free radical, thiobarbituric acid reactive substance, was increased in the schistosome-infected human bladder tissues by 125%. The present study clearly demonstrated that S. haematobium changes the activity of carcinogen-metabolizing enzymes. We conclude that S. haematobium could enhance the carcinogenicity of polycyclic aromatic hydrocarbons (e.g. benzo(a)pyrene) and N-nitrosamines (e.g. dimethylnitrosamine) through induction of their corresponding bioactivating enzymes in human bladder tissues.
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Affiliation(s)
- S A Sheweita
- Department of Bioscience & Technology, Institute of Graduate Studies & Research, Alexandria University, 163 Horreya Ave., PO Box 832, Alexandria, Egypt.
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Lin H, Hollenberg PF. N-Nitrosodimethylamine-Mediated Formation of Oxidized and Methylated DNA Bases in a Cytochrome P450 2E1 Expressing Cell Line. Chem Res Toxicol 2001; 14:562-6. [PMID: 11368555 DOI: 10.1021/tx0001979] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The metabolic activation of N-nitrosodimethylamine (NDMA) to reactive metabolites is a critical step for the expression of its toxic and carcinogenic potential. We have previously reported that a P450 2E1 expressing cell line, GM2E1, can metabolize NDMA to toxic reactive metabolites and cause apoptotic cell death. To investigate whether DNA is a critical target for the reactive metabolites of NDMA, we measured the levels of DNA adducts in untreated and NDMA-treated GM2E1 cells. 8-Hydroxydeoxyguanosine (8-OHdG), a biomarker for oxidative DNA damage, was analyzed following enzymatic hydrolysis of DNA. 7-Methylguanine (7-mGua), the most suitable marker for the DNA adducts formed by methylating agents, was released by thermal depurination of DNA. The modified guanine adducts were separated by HPLC and quantified using electrochemical detection. The levels of 8-OHdG and 7-mGua in GM2E1 cells treated with NDMA increased up to approximately 4- and 100-fold over those in the untreated cells, respectively. The addition of ascorbic acid, an antioxidant, to the NDMA-treated cells resulted in a significant decrease in the cytotoxicity with a concomitant decrease in the levels of 8-OHdG, but not the levels of 7-mGua. Our results demonstrate that the metabolism of NDMA in GM2E1 cells causes both DNA methylation and oxidation and support the hypothesis that NDMA-mediated DNA damage may play an important role in its toxic effects.
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Affiliation(s)
- H Lin
- Department of Pharmacology, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109-0632, USA
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38
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Abstract
N-Nitrosodimethylamine is a procarcinogen that is activated by cytochrome P450 dependent N-nitrosodimethylamine N-demethylase to labile alpha-carbon hydroxylated products further resulting in active methylating agents. In vivo intraperitoneal administration of pyridine to rabbits significantly increased N-nitrosodimethylamine N-demethylase activity by 6.9- and 5.2-fold in liver and lung microsomes, respectively. Although, p-nitrophenol hydroxylase and aniline 4-hydroxylase activities were markedly enhanced by pyridine treatment in liver about 4.4- and 5.8-fold, respectively, no change was observed in the activities of these enzymes in lung microsomes. Pyridine treatment also elevated P450 contents of liver and lung by 2.04- and 1.4-fold, respectively. SDS-PAGE of pyridine-induced liver microsomes revealed a protein band of enhanced intensity having Mr of 51,000 migrating in the region of cytochrome P4502E1. The results obtained in this study demonstrated for the first time, a significant 5.2-fold induction of NDMA N-demethylase activity in the rabbit lung over the controls. Pyridine is readily absorbed by inhalation and is a constituent of tobacco and tobacco smoke. Thus induction of NDMA N-demethylase suggests that in the lung, as in the liver, pyridine may stimulate the metabolic activation of this nitrosamine significantly.
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Affiliation(s)
- E Arinç
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
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Diwan BA, Ramakrishna G, Anderson LM, Ramljak D. Overexpression of Grb2 in inflammatory lesions and preneoplastic foci and tumors induced by N-nitrosodimethylamine in Helicobacter hepaticus-infected and -noninfected A/J mice. Toxicol Pathol 2000; 28:548-54. [PMID: 10930041 DOI: 10.1177/019262330002800407] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Growth factors bind to membrane receptor tyrosine kinases, resulting in autophosphorylation and subsequent binding to proteins with SH2 domains, including growth factor receptor-bound protein 2 (Grb2). Grb2 bridges receptors to tyrosine kinase substrates such as SHC and SOS, which in turn facilitate the activation of downstream signaling pathways, including Ras and mitogen-activated protein kinase (MAPK). Overexpression of Grb2 has been demonstrated in several types of neoplasia but has not been investigated in liver tumorigenesis. Here we investigated Grb2 expression in liver lesions in N-nitrosodimethylamine (NDMA)-treated Helicobacter hepaticus-infected and -noninfected A/J mice at 1 year of age. Previously, we reported (6) that infection promotes the development of these NDMA-initiated tumors. In controls, Grb2 immunostaining was absent from normal hepatic tissues, whereas the inflammatory lesions in infected livers were positive for cytoplasmic Grb2 in both hepatocytes and infiltrating leukocytes. All preneoplastic foci (7 of 7), 15 of 27 adenomas, and 3 of 7 carcinomas were positive for Grb2 by immunostaining in both infected and noninfected NDMA-initiated livers. Involvement of Grb2 was confirmed by immunoblotting of similarly infected mice at 9 to 18 months of age, showing a 2.5- to 3.3-fold increase in Grb2 protein in infected livers (p < 0.05 compared with uninfected controls) as well as in preneoplastic foci, adenomas, and carcinomas. These livers also showed a 2.5- to 2.8-fold increase in total Ras protein. The results suggest that upregulation of Grb2 is an early event in liver carcinogenesis, whether caused by the bacterial infection or by NDMA. Concomitant upregulation of Ras p21 would ensure transmission of amplified signal from growth factors via Grb2.
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Affiliation(s)
- B A Diwan
- Intramural Research Support Program, SAIC Frederick, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland 21702-1201, USA.
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40
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Reed JR, Kraft MD, Hollenberg PF. Rat liver cytosol catalyzes a reaction involving activated N-nitrosodimethylamine and a carbohydrate from the pentose phosphate pathway. Chem Res Toxicol 2000; 13:126-33. [PMID: 10688537 DOI: 10.1021/tx990151j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-Nitrosodimethylamine is a liver toxin and mutagen following activation by cytochrome P450. The role of the cytosol in N-nitrosodimethylamine metabolism is not well understood. The effect of cytosol on N-nitrosodimethylamine metabolism was investigated using microsomes and cytosol from rat liver in in vitro reactions with N-nitrosodimethylamine and an NADPH generating system. Studies in which [(14)C]-N-nitrosodimethylamine and calf thymus DNA were used indicated that the addition of cytosol to the microsomal reaction mixture resulted in >200% enhancement of the radioactivity associated with DNA after the DNA was isolated from the reaction mixture by phenol extraction followed by ethanol precipitation. This stimulatory effect was associated with a cytosolic protein and was found to be dependent on both the microsomes and the carbohydrate used in the glucose-6-phosphate dehydrogenase system for the generation of NADPH. The carbohydrate requirement was found to be specific for intermediates of the pentose phosphate pathway, and maximum stimulation occurred with ribulose 5-phosphate. Most of the counts from [(14)C]-N-nitrosodimethylamine which were isolated with DNA after the addition of cytosol to reaction mixtures were not covalently bound to the DNA. HPLC analysis identified four radiolabeled metabolites derived from [(14)C]-N-nitrosodimethylamine following the in vitro incubations. One of the four products was formed only when both cytosol and ribulose 5-phosphate were added to the enzymatic incubations. This product also formed from [(14)C]-alpha-acetoxy nitrosodimethylamine in the absence of microsomes, only when cytosol and ribulose 5-phosphate were added to the reaction mixtures. Thus, these data demonstrate that an enzyme in the cytosol catalyzes a reaction involving a metabolite of N-nitrosodimethylamine (which is formed following cytochrome P450-mediated activation) and a carbohydrate related to the pentose phosphate pathway. A similar reaction also occurs with N-diethylnitrosamine but not with N-dipropylnitrosamine or N-dibutylnitrosamine.
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Affiliation(s)
- J R Reed
- Department of Pharmacology, Medical Science Research Building III, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109-0632, USA
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41
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Smerdova LN, Kishko TO, Glavin AA, Rubenchik BL, Dmitrenko NP. [Effect of exogenous and endogenous nitrosation factors on formation of N-nitrosodimethylamine in rats depending on the status of purine catabolism]. Ukr Biokhim Zh (1999) 2000; 72:82-8. [PMID: 10979564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Nitrogen dioxide's rats' inhalations with injections per os of pyrazole, amidopyrine and sodium nitrite lead to considerable increasing of endogenic N-nitrosodimethylamine formation, which had been determined by system gas chromatograph-thermal energetic analyser. This increasing essentially didn't depend on the rats' immunisation by vaccine BCG, which leads to the intensification of NO synthesis by peritoneal macrophages and others manifestations of their metabolic activation: increasing of creatine kinase and adenosine desaminase activities. It hadn't been brought to light the obvious dependent between changes of xanthine oxidase and xanthine dehydrogenase activities in the liver and blood serum and intensification of lipids peroxidation and also the amount of N-nitrosodimethylamine in the rats in the conditions of endogenic and exogenic nitrosation factors' influence.
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Affiliation(s)
- L N Smerdova
- L.I. Medved Institute of Ecohygiene and Toxicology, Kyiv
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von Weymarn LB, Felicia ND, Ding X, Murphy SE. N-Nitrosobenzylmethylamine hydroxylation and coumarin 7-hydroxylation: catalysis by rat esophageal microsomes and cytochrome P450 2A3 and 2A6 enzymes. Chem Res Toxicol 1999; 12:1254-61. [PMID: 10604876 DOI: 10.1021/tx990128y] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
N-Nitrosobenzylmethylamine (NBzMA) is a potent and selective esophageal carcinogen in the rat and may be a causative agent for human esophageal cancer. This nitrosamine, like most, must be metabolically activated to exert its carcinogenic potential. NBzMA may be metabolized by P450-catalyzed methyl or methylene hydroxylation; the latter is believed to be the activation pathway. The sensitivity of the esophagus to NBzMA-induced tumorigenesis is believed to be due, at least in part, to the presence of efficient P450 catalysts in this tissue. However, while it was reported almost 20 years ago that the rat esophagus catalyzes the methylene hydroxylation of NBzMA, the P450 that catalyzes this reaction has yet to be identified. We report here that human P450 2A6 and the closely related extrahepatic rat enzyme P450 2A3 both efficiently catalyze NBzMA methylene hydroxylation, characterized as benzaldehyde formation. The catalytic efficiency of P450 2A3 in this reaction was 3-fold greater than that of P450 2A6, 7.6 (K(m) = 0.63 +/- 0.18 microM and the V(max) = 4.8 nmol min(-)(1) nmol of P450(-)(1)) versus 2.3 (K(m) = 6.7 +/- 2.9 microM and the V(max) = 15.7 nmol min(-)(1) nmol of P450(-)(1)), respectively. Both enzymes catalyzed methylene hydroxylation at least 4-fold more efficiently than methyl hydroxylation. In addition, P450 2A6, but not P450 2A3, catalyzed benzyl ring hydroxylation, generating N-(p-hydroxybenzyl)methylamine. The identity of this metabolite was confirmed by synthesis of a standard and LC/MS and LC/MS/MS analysis. P450 2A6 is an efficient coumarin 7-hydroxylase, and we report here that P450 2A3 is an equally good catalyst of this reaction (K(m) = 1. 7 +/- 0.41 microM and V(max) = 1.7 +/- 0.08 nmol min(-)(1) nmol of P450(-)(1)). Rat esophageal microsomes (REM), like P450 2A3, were efficient catalysts of NBzMA methylene hydroxylation. However, in contrast to P450 2A3, the major product of this reaction was the product of benzaldehyde oxidation, benzoic acid. Antibody to the closely related mouse P450, 2A5, did not inhibit REM-catalyzed NBzMA metabolism, and most importantly, REM did not catalyze the 7-hydroxylation of coumarin. Therefore, P450 2A3 does not appear to be the P450 in the rat esophagus responsible for catalyzing the methylene hydroxylation of NBzMA.
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Affiliation(s)
- L B von Weymarn
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Cancer Center, Minneapolis, Minnesota 55455, USA
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Vermeer IT, Moonen EJ, Dallinga JW, Kleinjans JC, van Maanen JM. Effect of ascorbic acid and green tea on endogenous formation of N-nitrosodimethylamine and N-nitrosopiperidine in humans. Mutat Res 1999; 428:353-61. [PMID: 10518007 DOI: 10.1016/s1383-5742(99)00061-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Many constituents present in the human diet may inhibit endogenous formation of N-nitroso compounds (NOC). Studies with human volunteers showed inhibiting effects of intake of ascorbic acid and green tea consumption on nitrosation using the N-nitrosoproline test. The aim of the present study was to evaluate the effects of ascorbic acid and green tea on urinary excretion of carcinogenic N-nitrosodimethylamine (NDMA) and N-nitrosopiperidine (NPIP) in humans. Twenty-five healthy female volunteers consumed a fish meal rich in amines as nitrosatable precursors in combination with intake of nitrate-containing drinking water at the Acceptable Daily Intake level during 7 consecutive days. During 1 week before and after nitrate intake a diet low in nitrate was consumed. Using the same protocol, the effect of two different doses of ascorbic acid (250 mg and 1 g/day) and two different doses of green tea (2 g and 4 g/day) on formation of NDMA and NPIP was studied. Mean nitrate excretion in urine significantly increased from control (76+/-24) to 167+/-25 mg/24 h. Intake of nitrate and fish resulted in a significant increase in mean urinary excretion of NDMA compared with the control weeks: 871+/-430 and 640+/-277 ng/24 h during days 1-3 and 4-7, respectively, compared with 385+/-196 ng/24 h (p<0.0002). Excretion of NPIP in urine was not related to nitrate intake and composition of the diet. Intake of 250 mg and 1 g of ascorbic acid per day resulted in a significant decrease in urinary NDMA excretion during days 4-7 (p=0.0001), but not during days 1-3. Also, consumption of four cups of green tea per day (2 g) significantly decreased excretion of NDMA during days 4-7 (p=0.0035), but not during days 1-3. Surprisingly, consumption of eight cups of green tea per day (4 g) significantly increased NDMA excretion during days 4-7 (p=0.0001), again not during days 1-3. This increase is probably a result of catalytic effects of tea polyphenols on nitrosation, or of another, yet unknown, mechanism. These results suggest that intake of ascorbic acid and moderate consumption of green tea can reduce endogenous NDMA formation.
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Affiliation(s)
- I T Vermeer
- Department of Health Risk Analysis and Toxicology, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, Netherlands.
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Lin HL, Parsels LA, Maybaum J, Hollenberg PF. N-Nitrosodimethylamine-mediated cytotoxicity in a cell line expressing P450 2E1: evidence for apoptotic cell death. Toxicol Appl Pharmacol 1999; 157:117-24. [PMID: 10366544 DOI: 10.1006/taap.1999.8651] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
N-Nitrosodimethylamine (NDMA) is an acute hepatotoxin and potent carcinogen. The metabolic activation of NDMA to reactive metabolites is a critical step for the expression of its toxic and carcinogenic potential. We have previously demonstrated a strong correlation between methylation of cellular macromolecules and NDMA-mediated cytotoxicity, and we have demonstrated that reactive oxygen species may partially contribute to the toxic effects in P450 2E1-expressing cells. The mode of cell death in NDMA-treated monolayer cultures exhibited the following characteristics: (i) condensation of nuclear chromatin as demonstrated by using Hoechst 33258 staining, (ii) DNA fragmentation as detected by combining pulsed field and conventional agarose gel electrophoresis, and (iii) DNA double strand breaks determined by using the in situ terminal deoxynucleotidyl transferase assay and flow cytometric analysis. These results indicate that reactive metabolites of NDMA trigger activation of the signal pathway for apoptotic cell death in these P450-expressing cells. The NDMA-mediated cell death was partially prevented by the endonuclease inhibitor, aurintricarboxylic acid, as well as the caspase inhibitors, acetyl-Asp-Glu-Val-Asp-CHO and acetyl-Tyr-Val-Ala-Asp-CHO. The cell cycle distribution was altered in NDMA-treated cells resulting in an increase in the G2/M phase and a decrease in the G1 phase. Our results suggest that DNA degradation, the inability to complete DNA repair, the biochemical events associated with G2/M arrest, and the process of apoptotic death all result from P450 2E1-catalyzed metabolism of NDMA.
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Affiliation(s)
- H L Lin
- Department of Pharmacology, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan, 48109-0632, USA
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45
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Gopalakrishnan R, Morse MA, Lu J, Weghorst CM, Sabourin CL, Stoner GD, Murphy SE. Expression of cytochrome P450 2A3 in rat esophagus: relevance to N-nitrosobenzylmethylamine. Carcinogenesis 1999; 20:885-91. [PMID: 10334207 DOI: 10.1093/carcin/20.5.885] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
N-nitrosobenzylmethylamine (NBzMA) must be metabolically activated to exert its carcinogenic potential and is a potent inducer of tumors in the rat esophagus. The activation is believed to occur in the esophagus. Although the pathways of NBzMA metabolism are well studied, the principal cytochrome P450 enzyme(s) (P450) responsible for catalyzing its activation is unknown. Several preliminary studies have suggested that this enzyme may belong to the P450 2A family. We report here that P450 2A3 expressed in a baculovirus system metabolizes NBzMA, predominantly by methylene hydroxylation. To determine whether or not P450 2A3 is present in the rat esophagus, the relative level of P450 2A3 mRNA was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The mRNA levels of P450 2A3 were compared with the levels of P450 2A1 and 2A2 mRNA in the esophagus, liver, lung and nasal mucosa. P450 2A3 mRNA was detected in rat nasal mucosa, lung and esophagus, but not in liver, whereas P450 2A1 and 2A2 mRNAs were detected only in the liver. To determine the relative expression of P450 2A3 in each tissue, quantitative RT-PCR with PCR-MIMICS used as internal standards was performed. The expression level in the nasal mucosa was by far the greatest. The expression in the lung and esophagus was 60- and 1600-fold less, respectively. Using antibodies to P450 2A4/5 and P450 2A10/11 a 50 kDa immunoreactive protein was detected in all three tissues by western blot analysis. This is consistent with the expression of P450 2A3 in these tissues. However, the amount of protein detected in the nasal mucosa was much greater than that in the esophagus or lung. The expression of P450 2A protein was similar in the lung and esophagus. The rate of coumarin 7-hydroxylation in cultured rat esophagus was very low. This is a reaction efficiently catalyzed by P450 2A5, 2A6 and 2A10. In summary, our results clearly demonstrate the presence of P450 2A3 protein and mRNA in the esophagus, but the amounts are low and may not be sufficient to account for NBzMA activation in this tissue.
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Affiliation(s)
- R Gopalakrishnan
- Department of Pathology, College of Medicine and Public Health, The Ohio State University, Columbus 43210, USA
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46
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Schulze J. Presystemic intestinal metabolism of N-nitrosodimethylamine in mouse intestine. Cancer Detect Prev 1999; 23:107-15. [PMID: 10101591 DOI: 10.1046/j.1525-1500.1999.09913.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
N-Nitrosodimethylamine (NDMA), a common food contaminant, is a potent liver carcinogen in rodents. A high presystemic intestinal metabolism has been shown for several nitrosamines including environmentally important compounds. We determined the metabolism of 1 micron [14C]-NDMA in isolated perfused mouse intestinal segments. We found NDMA to be equally distributed between the absorbed fluid and the perfusate. During a 2-h perfusion period, 0.13% of the radioactivity was converted to CO2. The formation of CO2 was decreased by pretreatment with diallylsulfide or addition of SKF 525A, and slightly increased by phenobarbital. Hydrophilic metabolites were found in the absorbate (0.9%) and perfusate (3.8%) of untreated mice. The amount of metabolites in the absorbate was increased by treatment with acetone or phenobarbital (8-fold), but not after starvation, with formaldehyde being present only in phenobarbital-treated animals. Treatment with diallylsulfide or addition of SKF 525A reduced the amount of metabolites in acetone-treated animals to control values. In conclusion, intestinal turnover does not significantly reduce the body burden of orally ingested NDMA and thus is not a first-line defense against this carcinogenic nitrosamine. NDMA metabolism has been attributed to the presence of cytochrome P450IIE1, which has not been detected in the intestine of untreated animals. The low turnover of NDMA, the induction by acetone and phenobarbital treatment, and the inhibition by diallylsulfide suggest the presence of low amounts of this or related cytochrome P450 isozyme(s) in mouse intestine.
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Affiliation(s)
- J Schulze
- Walther-Straub Institute of Pharmacology and Toxicology, Ludwig Maximilians Universität München, Germany
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47
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Abstract
Acarbose reduces the absorption of monosaccharides derived from dietary carbohydrates, which play an important role in the metabolism and toxicity of some chemical compounds. We studied the effects of acarbose on the hepatotoxicity of carbon tetrachloride (CCl4) and acetaminophen (AP) in rats, both of which exert their toxic effects through bioactivation associated with cytochrome P450 2E1 (CYP2E1). Male Sprague-Dawley rats were kept on a daily ration (20 g) of powdered chow diet containing 0, 20, 40, or 80 mg/100 g of acarbose, with drinking water containing 0% or 10% of ethanol (vol/vol). Three weeks later, the rats were either killed for an in vitro metabolism study or challenged with 0.50 g/kg CCl4 orally or 0. 75 g/kg AP intraperitoneally. The ethanol increased the hepatic microsomal CYP2E1 level and the rate of dimethylnitrosamine (DMN) demethylation. The 40- or 80-mg/100 g acarbose diet, which alone increased the CYP2E1 level and the rate of DMN demethylation, augmented the enzyme induction by ethanol. The 40- or 80-mg/100 g acarbose diet alone potentiated CCl4 and AP hepatotoxicity, as evidenced by significantly increased levels of both alanine transaminase (ALT) and aspartate transaminase (AST) in the plasma of rats pretreated with acarbose. Ethanol alone also potentiated the toxicity of both chemicals. When the 40- or 80-mg/100 g acarbose diet was combined with ethanol, the ethanol-induced potentiation of CCl4 and AP hepatotoxicity was augmented. Our study demonstrated that high doses of acarbose, alone or in combination with ethanol, can potentiate CCl4 and AP hepatotoxicity in rats by inducing hepatic CYP2E1.
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Affiliation(s)
- P Y Wang
- Department of Environmental Health, Medical University of Yamanashi, Tamaho, Yamanashi, Japan
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Stoner GD, Adams C, Kresty LA, Amin SG, Desai D, Hecht SS, Murphy SE, Morse MA. Inhibition of N'-nitrosonornicotine-induced esophageal tumorigenesis by 3-phenylpropyl isothiocyanate. Carcinogenesis 1998; 19:2139-43. [PMID: 9886569 DOI: 10.1093/carcin/19.12.2139] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The ability of dietary isothiocyanates to inhibit the esophageal metabolism of N'-nitrosonornicotine (NNN) was examined in F344 rats. Following feeding of benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC), 3-phenylpropyl isothiocyanate (PPITC), 4-phenylbutyl isothiocyanate (PBITC) or 6-phenylhexyl isothiocyanate for 2 weeks, rats were killed and the esophagi were incubated in vitro with [5-3H]NNN. While dietary BITC, PEITC and PBITC all decreased NNN metabolism, dietary PPITC had the greatest effect, yielding inhibition ranging from 55 to 91% of the control production of various NNN metabolites. To determine the chemopreventive efficacy of PPITC on NNN-induced esophageal tumorigenesis, rats were fed AIN-76A diets containing 0, 1.0 or 2.5 micromol/g PPITC and were given untreated drinking water or drinking water containing 5 p.p.m. NNN. After 87 weeks, the experiment was terminated and the esophageal tumors were counted. Rats that were given untreated drinking water developed no tumors. Rats that were given 5 p.p.m. NNN and unadulterated AIN-76A diet had an esophageal tumor incidence of 71% and a multiplicity of 1.57 tumors/animal. The two dietary concentrations of PPITC reduced the incidence and multiplicity of NNN-induced esophageal tumors by >95%. These results demonstrate the remarkable chemopreventive efficacy of PPITC in the NNN-induced esophageal tumor model.
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Affiliation(s)
- G D Stoner
- Division of Environmental Health Sciences, The Ohio State University School of Public Health and The Ohio State University Comprehensive Cancer Center, Ohio State University, CHRI, Columbus 43210, USA.
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49
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Abstract
The objective of this study was to measure the rate of demethylation of nitrosodimethylamine in vivo in the rat and determine its value to assess CYP2E1 activity in intact animals. Nitrosodimethylamine labeled with 14C on both methyl groups was administered to rats and exhaled 14CO2 was collected during 2-3 h. The nitrosodimethylamine breath test was increased by inducers of CYP2E1, such as ethanol (+139%) and 4-methylpyrazole (+115%), and decreased by the inhibitor diallyl sulfide (-53%). In addition, the nitrosodimethylamine breath test was not changed significantly by inducers specific for other cytochrome P450 such as beta-naphthoflavone, dexamethasone, and phenobarbital. The specificity of the induction by 4-methylpyrazole and of the inhibition by diallyl sulfide for CYP2E1 was determined using the [14C]caffeine (CYP1A2), [14C]aminopyrine (CYP2C11), and [14C]erythromycin (CYP3A2) breath tests. 4-Methylpyrazole treatment caused a small increase of the caffeine (+33%) and aminopyrine (+9%) breath tests and no change of the erythromycin breath test. Diallyl sulfide treatment led to a small decrease of the caffeine breath test (-33%) and of the aminopyrine breath test (-13%) but a 23% increase of the erythromycin breath test. It is concluded that the [14C]nitrosodimethylamine breath test is useful to assess CYP2E1 activity in vivo in the rat.
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Affiliation(s)
- M C Bastien
- Centre hospitalier de l'Université de Montréal and Département de pharmacologie, Faculté de médecine, Université de Montréal, Québec, Canada
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50
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Smith TJ, Liao A, Wang LD, Yang GY, Starcic S, Philbert MA, Yang CS. Characterization of xenobiotic-metabolizing enzymes and nitrosamine metabolism in the human esophagus. Carcinogenesis 1998; 19:667-72. [PMID: 9600353 DOI: 10.1093/carcin/19.4.667] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Esophageal cancer has been associated with tobacco smoking, and nitrosamines are possible causative agents for this cancer. The present study investigated the metabolism of the tobacco carcinogens N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and N-nitrosodimethylamine (NDMA), as well as the presence of xenobiotic-metabolizing enzymes in human esophageal tissues from individuals in the United States and Huixian, Henan Province, China (a high-risk area for esophageal cancer). All esophageal microsomal samples activated NNN and the metabolic rate was 2-fold higher in the esophageal samples from China than the USA. All microsomal samples activated NDMA. However, most of the microsomal samples did not activate NNK. Troleandomycin (an inhibitor of cytochrome P450 3A) decreased the formation of NNN-derived keto acid by 20-26% in the esophageal microsomes. The activities for NADPH: cytochrome c reductase, ethoxycoumarin O-deethylase, NAD(P)H: quinone oxidoreductase and glutathione S-transferase were present in the esophageal samples. Coumarin 7-hydroxylase (a representative activity for P450 2A6) activity was not detected in the esophageal microsomal samples. The activities for nitrosamine metabolism and xenobiotic-metabolizing enzymes were decreased (by 30-50%) in the squamous cell carcinomas compared with their corresponding non-cancerous mucosa. The presence of activation and detoxification enzymes in the esophagus may play an important role in determining the susceptibility of the esophagus to the carcinogenic effect of nitrosamines. Our results suggest that P450s 3A4 and 2E1 are involved in the activation of NNN and NDMA, respectively, in the human esophagus.
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Affiliation(s)
- T J Smith
- Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, NJ 08855, USA.
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