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Al-Owaisi A, Al-Sadi AM, Al-Sabahi JN, Sathish Babu SP, Al-Harrasi MMA, Hashil Al-Mahmooli I, Abdel-Jalil R, Velazhahan R. In vitro detoxification of aflatoxin B1 by aqueous extracts of medicinal herbs. ALL LIFE 2022. [DOI: 10.1080/26895293.2022.2049900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Arwa Al-Owaisi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Abdullah Mohammed Al-Sadi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Jamal Nasser Al-Sabahi
- Central Analytical Laboratory, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - S. P. Sathish Babu
- Central Analytical and Applied Research Unit, College of Science, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Majida Mohammed Ali Al-Harrasi
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Issa Hashil Al-Mahmooli
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Raid Abdel-Jalil
- Department of Chemistry, College of Science, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Rethinasamy Velazhahan
- Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
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2
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Aflatoxin contamination in food crops: causes, detection, and management: a review. FOOD PRODUCTION, PROCESSING AND NUTRITION 2021. [DOI: 10.1186/s43014-021-00064-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractMycotoxins are secondary metabolites produced by several fungal species and molds. Under favorable conditions like high temperature and moisture, they contaminate a large number of food commodities and regional crops during pre and post-harvesting. Aflatoxin is the main mycotoxin that harm animal and human health due to its carcinogenic nature. Aflatoxins are mainly released by Aspergillus flavus and Aspergillus parasiticus. AFB1 constitutes the most harmful type of aflatoxins and is a potent hepato-carcinogenic, mutagenic, teratogenic and it suppresses the immune system. To maintain food safety and to prevent aflatoxin contamination in food crops, combined approaches of using resistant varieties along with recommended farming practices should be followed. This review concentrates on various aspects of mycotoxin contamination in crops and recent methods to prevent or minimize the contamination.
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Aflatoxin B₁⁻Formamidopyrimidine DNA Adducts: Relationships between Structures, Free Energies, and Melting Temperatures. Molecules 2019; 24:molecules24010150. [PMID: 30609733 PMCID: PMC6337653 DOI: 10.3390/molecules24010150] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/21/2018] [Accepted: 12/26/2018] [Indexed: 12/02/2022] Open
Abstract
Thermal stabilities of DNA duplexes containing Gua (g), α- (a) or β-anomer of formamidopyrimidine-N7-9-hydroxy-aflatoxin B1 (b) differ markedly (Tm: a<g<b), but the underlying molecular origin of this experimentally observed phenomenon is yet to be identified and determined. Here, by employing explicit-solvent molecular dynamics simulations coupled with free-energy calculations using a combined linear-interaction-energy/linear-response-approximation approach, we explain the quantitative differences in Tm in terms of three structural features (bulkiness, order, and compactness) and three energetical contributions (non-polar, electrostatic, and preorganized-electrostatic), and thus advance the current understanding of the relationships between structures, free energies, and thermal stabilities of DNA double helices.
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4
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Li H, Guan K, Zuo Z, Wang F, Peng X, Fang J, Cui H, Zhou Y, Ouyang P, Su G, Chen Z. Effects of aflatoxin B 1 on the cell cycle distribution of splenocytes in chickens. J Toxicol Pathol 2019; 32:27-36. [PMID: 30739993 PMCID: PMC6361662 DOI: 10.1293/tox.2018-0015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 08/06/2018] [Indexed: 12/31/2022] Open
Abstract
The purpose of the present study was to evaluate effects of aflatoxin B1 (AFB1) on the cell cycle and proliferation of splenic cells in chickens. A total of 144 one-day-old Cobb male chickens were randomly divided into 2 equal groups of 72 each and were fed on diets as follows: a control diet and a 0.6 mg/kg AFB1 diet for 21 days. The AFB1 diet reduced body weight, absolute weight and relative weight of the spleen in broilers. Histopathological lesions in AFB1 groups were characterized as slight congestion in red pulp and lymphocytic depletion in white pulp. Compared with the control group, the expression levels of ataxia-telangiectasia mutated (ATM), cyclin E1, cyclin-dependent kinases 6 (CDK6), CDK2, p53, p21 and cyclin B3 mRNA were significantly increased, while the mRNA expression levels of cyclin D1, cdc2 (CDK1), p16, p15 were significantly decreased in the AFB1 groups. Significantly decreased proliferating cell nuclear antigen (PCNA) expression and arrested G0G1 phases of the cell cycle were also seen in the AFB1 groups. In conclusion, dietary AFB1 could induce cell cycle blockage at G0G1 phase and impair the immune function of the spleen. Cyclin D1/CDK6 complex, which inhibits the activin/nodal signaling pathway, might play a significant role in the cell cycle arrest induced by AFB1.
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Affiliation(s)
- Hang Li
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Ke Guan
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Zhicai Zuo
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Fengyuan Wang
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Xi Peng
- College of Life Sciences, China West Normal University, No.
1 Shida Road, Shunqing District, Nanchong, Sichuan 637002, P.R. China
| | - Jing Fang
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Hengmin Cui
- Key Laboratory of Animal Diseases and Environmental Hazards
of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R. China
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Yi Zhou
- Life science department, Sichuan Agricultural University, No.
211 Huimin Road, Wenjiang District, Ya’an, Sichuan 625014, P.R. China
| | - Ping Ouyang
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Gang Su
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
| | - Zhengli Chen
- College of Veterinary Medicine, Sichuan Agricultural
University, No. 211 Huimin Road, Wenjiang District, Chengdu, Sichuan 611130, P.R.
China
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5
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Li J, Huang J, Jin Y, Wu C, Shen D, Zhang S, Zhou R. Aflatoxin B 1 degradation by salt tolerant Tetragenococcus halophilus CGMCC 3792. Food Chem Toxicol 2018; 121:430-436. [PMID: 30165130 DOI: 10.1016/j.fct.2018.08.063] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/20/2018] [Accepted: 08/25/2018] [Indexed: 02/05/2023]
Abstract
This study explores aflatoxin B1 (AFB1) degradation by salt tolerant Tetragenococcus halophilus CGMCC 3792 (T. halophilus CGMCC 3792). Six non-toxic degradation products of AFB1 were identified by liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS), including m/z 243.06 (C14H10O4), 361.09 (C18H16O8), 229.09 (C14H12O3), 277.14 (C16H20O4), 217.12 (C14H16O2), 221.15 (C14H20O2). Two pathways were proposed based on molecular formulas and MS/MS spectra, and the final degradation product was m/z 221.15 (C14H20O2). The degradation ratio of active cell component (66%) and intracellular component (57%) was significantly higher than extracellular component (14%). AFB1 degradation ratio of intracellular component, initially at around 60%, was decreased to 32% after proteinase K treatment, and to 7% after heating, to 9% after proteinase K plus SDS treatment, and to 16% after TFA treatment. It suggests that the AFB1 removal mainly resulted from enzyme biodegradation. The degradation ratio was 92% in AFB1 polluted soy sauce mash. The high degradation ratio of AFB1 by T. halophilus CGMCC 3792 indicates its great potential for application in oriental fermentation condiment process.
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Affiliation(s)
- Jianlong Li
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China
| | - Jun Huang
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China
| | - Yao Jin
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China
| | - Chongde Wu
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China
| | - Dazhan Shen
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China
| | - Suyi Zhang
- National Engineering Research Center of Solid-State Manufacturing, Luzhou, 646000, China
| | - Rongqing Zhou
- College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu, 610065, China.
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6
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Fedeles BI, Essigmann JM. Impact of DNA lesion repair, replication and formation on the mutational spectra of environmental carcinogens: Aflatoxin B 1 as a case study. DNA Repair (Amst) 2018; 71:12-22. [PMID: 30309820 DOI: 10.1016/j.dnarep.2018.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In a multicellular organism, somatic mutations represent a permanent record of the past chemical and biochemical perturbations experienced by a cell in its local microenvironment. Akin to a perpetual recording device, with every replication, genomic DNA accumulates mutations in patterns that reflect: i) the sequence context-dependent formation of DNA damage, due to environmental or endogenous reactive species, including spontaneous processes; ii) the activity of DNA repair pathways, which, depending on the type of lesion, can erase, ignore or exacerbate the mutagenic consequences of that DNA damage; and iii) the choice of replication machinery that synthesizes the nascent genomic copy. These three factors result in a richly contoured sequence context-dependent mutational spectrum that, from appearances, is distinct for most individual forms of DNA damage. Such a mutagenic legacy, if appropriately decoded, can reveal the local history of genome-altering events such as chemical or pathogen exposures, metabolic stress, and inflammation, which in turn can provide an indication of the underlying causes and mechanisms of genetic disease. Modern tools have positioned us to develop a deep mechanistic understanding of the cellular factors and pathways that modulate a mutational process and, in turn, provide opportunities for better diagnostic and prognostic biomarkers, better exposure risk assessment and even actionable therapeutic targets. The goal of this Perspective is to present a bottom-up, lesion-centric framework of mutagenesis that integrates the contributions of lesion replication, lesion repair and lesion formation to explain the complex mutational spectra that emerge in the genome following exposure to mutagens. The mutational spectra of the well-studied hepatocarcinogen aflatoxin B1 are showcased here as specific examples, but the implications are meant to be generalizable.
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Affiliation(s)
- Bogdan I Fedeles
- Departments of Biological Engineering, Chemistry and The Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - John M Essigmann
- Departments of Biological Engineering, Chemistry and The Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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7
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Malla S, Kadimisetty K, Jiang D, Choudhary D, Rusling JF. Pathways of Metabolite-Related Damage to a Synthetic p53 Gene Exon 7 Oligonucleotide Using Magnetic Enzyme Bioreactor Beads and LC-MS/MS Sequencing. Biochemistry 2018; 57:3883-3893. [PMID: 29750510 DOI: 10.1021/acs.biochem.8b00271] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Reactive metabolites of environmental chemicals and drugs can cause site specific damage to the p53 tumor suppressor gene in a major pathway for genotoxicity. We report here a high-throughput, cell-free, 96-well plate magnetic bead-enzyme system interfaced with LC-MS/MS sequencing for bioactivating test chemicals and identifying resulting adduction sites on genes. Bioactivated aflatoxin B1 was reacted with a 32 bp exon 7 fragment of the p53 gene using eight microsomal cytochrome (cyt) P450 enzymes from different organs coated on magnetic beads. All cyt P450s converted aflatoxin B1 to aflatoxin B1-8,9-epoxide that adducts guanine (G) in codon 249, with subsequent depurination to give abasic sites and then strand breaks. This is the first demonstration in a cell-free medium that the aflatoxin B1 metabolite selectively causes abasic site formation and strand breaks at codon 249 of the p53 probe, corresponding to the chemical pathway and mutations of p53 in human liver cells and tumors. Molecular modeling supports the view that binding of aflatoxin B1-8,9-epoxide to G in codon 249 precedes the SN2 adduction reaction. Among a range of metabolic enzymes characteristic of different organs, human liver microsomes and cyt P450 3A5 supersomes showed the highest bioactivation rate for p53 exon 7 damage. This method of identifying metabolite-related gene damage sites may facilitate predictions of organ specific cancers for test chemicals via correlations with mutation sites.
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Affiliation(s)
- Spundana Malla
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Karteek Kadimisetty
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Di Jiang
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - Dharamainder Choudhary
- Department of Surgery and Neag Cancer Center , UConn Health , Farmington , Connecticut 06032 , United States
| | - James F Rusling
- Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269 , United States.,Department of Surgery and Neag Cancer Center , UConn Health , Farmington , Connecticut 06032 , United States.,Institute of Material Science , University of Connecticut , Storrs , Connecticut 06269 , United States.,School of Chemistry , National University of Ireland at Galway , Galway , Ireland
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8
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Yokoyama Y, Sasaki Y, Terasaki N, Kawataki T, Takekawa K, Iwase Y, Shimizu T, Sanoh S, Ohta S. Comparison of Drug Metabolism and Its Related Hepatotoxic Effects in HepaRG, Cryopreserved Human Hepatocytes, and HepG2 Cell Cultures. Biol Pharm Bull 2018; 41:722-732. [DOI: 10.1248/bpb.b17-00913] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Yuichi Yokoyama
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
- Graduate School of Biomedical and Health Sciences, Hiroshima University
| | - Yoshifumi Sasaki
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Natsuko Terasaki
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Taku Kawataki
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Koji Takekawa
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Yumiko Iwase
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Toshinobu Shimizu
- Safety Research Laboratories, Sohyaku Innovative Research Division, Mitsubishi Tanabe Pharma Corporation
| | - Seigo Sanoh
- Graduate School of Biomedical and Health Sciences, Hiroshima University
| | - Shigeru Ohta
- Graduate School of Biomedical and Health Sciences, Hiroshima University
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Detoxification of Aflatoxin B₁ by Zygosaccharomyces rouxii with Solid State Fermentation in Peanut Meal. Toxins (Basel) 2017; 9:toxins9010042. [PMID: 28117705 PMCID: PMC5308274 DOI: 10.3390/toxins9010042] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 11/17/2022] Open
Abstract
Aflatoxins are highly carcinogenic, teratogenetic, and morbigenous secondary metabolites of Aspergillus flavus and A. parasiticus that can contaminate multiple staple foods, such as peanut, maize, and tree nuts. In this study, Zygosaccharomyces rouxii was screened out and identified from fermented soy paste—one kind of traditional Chinese food—to detoxify aflatoxin B1 (AFB1) by aerobic solid state fermentation in peanut meal. The optimal degradation condition was chosen from single factor experiment, and the most effective detoxification rate was about 97%. As for liquid fermentation, we tested the binding ability of Z. rouxii, and the highest binding rate reached was 74.3% (nonviable cells of Z. rouxii) in phosphate-buffered saline (PBS). Moreover, the biotransformation of AFB1 through fermentation of Z. rouxii in peanut meal was further verified by liquid chromatography/mass spectrometry (LC/MS). According to TIC scan, after fermentation by Z. rouxii, the AFB1 in peanut meal was prominently degraded to the lowering peaks of AFB1. Additionally, m/s statistics demonstrated that AFB1 may be degraded to some new products whose structural properties may be different from AFB1, or the degradation products may be dissolved in the aqueous phase rather than the organic phase. As far as we know, this is the first report indicating that the safe strain of Z. rouxii has the ability to detoxify AFB1.
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The mycotoxin zearalenone enhances cell proliferation, colony formation and promotes cell migration in the human colon carcinoma cell line HCT116. Toxicol Lett 2016; 254:1-7. [PMID: 27084041 DOI: 10.1016/j.toxlet.2016.04.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 04/08/2016] [Accepted: 04/11/2016] [Indexed: 02/08/2023]
Abstract
Zearalenone (ZEN) and Aflatoxin B1 (AFB1) are fungal secondary metabolites produced by Fusarium and Aspergillus genera, respectively. These mycotoxins are found world-wide as corn and wheat contaminants. AFB1 is probably the most toxic and carcinogenic mycotoxin. It has been demonstrated to be mutagenic, genotoxic, and hepatocarcinogenic. ZEN is a non-steroidal estrogenic mycotoxin that displays hepatotoxicity, immunotoxicity and genotoxicity. Its mutagenic and carcinogenic properties have so far remained controversial and questionable. Using the colon carcinoma cell line HCT116, we will show here that ZEN, at low concentrations, enhances cell proliferation, increases colony formation and fastens cell migration after wound healing. The highest effect of ZEN was observed at a concentration 10 times lower as compared to AFB1. Our findings suggest thus that this mycotoxin exhibits carcinogenesis-like properties in HCT116 cells.
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Yu Z, Wang F, Liang N, Wang C, Peng X, Fang J, Cui H, Jameel Mughal M, Lai W. Effect of Selenium Supplementation on Apoptosis and Cell Cycle Blockage of Renal Cells in Broilers Fed a Diet Containing Aflatoxin B1. Biol Trace Elem Res 2015; 168:242-51. [PMID: 25931191 DOI: 10.1007/s12011-015-0344-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/13/2015] [Indexed: 12/11/2022]
Abstract
The aim of the study was to investigate the competency of selenium (Se) in counteracting the adverse effects of aflatoxin B1 (AFB1) on apoptosis, cell cycle, and proliferation of nephritic cells. Two hundred forty 1-day-old healthy male avian broilers were randomly divided into four groups and fed basal diet (control group), 0.3 mg/kg AFB1 diet (AFB1 group), 0.4 mg/kg Se diet (+Se group), and 0.3 mg/kg AFB1 + 0.4 mg/kg Se diet (AFB1 + Se group), respectively. Compared to the control group, the number of apoptotic renal cells and expressions of Bax and caspase-3 messenger RNA (mRNA) were significantly increased, while the expression of Bcl-2 was significantly decreased in the AFB1 and the +Se groups (p < 0.01). A significantly decreased proliferating cell nuclear antigen (PCNA) expression and arrested G0/G1 phases of the cell cycle were also seen in the AFB1 and the +Se groups when compared with those of the control group. Moreover, these parameters were restored to the control group levels in the AFB1 + Se group. These results suggested that sodium selenite supplied in the diet could effectively inhibit AFB1-induced apoptosis and cell cycle blockage in renal cells of broiler.
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Affiliation(s)
- Zhengqiang Yu
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Fengyuan Wang
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Na Liang
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Chuhan Wang
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Xi Peng
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China.
| | - Jing Fang
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Hengmin Cui
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Muhammad Jameel Mughal
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
| | - Weimin Lai
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Ya' an, 625014, Sichuan, People's Republic of China
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12
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Mahfouz ME. Ameliorative effect of curcumin on aflatoxin B1-induced changes in liver gene expression of Oreochromis niloticus. Mol Biol 2015. [DOI: 10.1134/s0026893315020089] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Guan LZ, Sun YP, Cai JS, Wu HD, Yu LZ, Zhang YL, Xi QY. The aflatoxin-detoxifizyme specific expression in mouse parotid gland. Transgenic Res 2015; 24:489-96. [PMID: 25603989 DOI: 10.1007/s11248-015-9863-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 01/06/2015] [Indexed: 11/28/2022]
Abstract
The aflatoxin-detoxifizyme (ADTZ) gene derived from Armillariella tabescens was cloned into parotid gland-specific expression vector (pPSPBGPneo) to construct the parotid gland-specific vector expressing ADTZ (pPSPBGPneo-ADTZ). Transgenic mice were generated by microinjection and identified by using PCR and Southern blotting analysis. PCR and Southern blotting analysis showed that total six transgenic mice carried the ADTZ gene were generated. RT-PCR analysis indicated that the expression of ADTZ mRNA could be detected only in parotid glands of the transgenic mice. The ADTZ activity in the saliva was found to be 3.72 ± 1.64 U/mL. After feeding a diet containing aflatoxin B1 (AFB1) for 14 days, the effect of ADTZ on serum biochemical indexes and AFB1 residues in serum and liver of mice were evaluated. The results showed that total protein and globulin contents in the test treatment (transgenic mice) produced ADTZ were significantly higher than that of the positive control, while alanine aminotransferase and aspartate aminotransferase activity in serum of the test treatment (transgenic mice) were remarkably lower compared to that of the positive control (P < 0.05). Moreover, AFB1 residues in serum and liver of the test treatment (transgenic mice) were significantly lower compared with that of the positive control (P < 0.05). These results in the study confirmed that ADTZ produced in transgenic mice could reduce, even eliminate the negative effects of AFB1 on mice.
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Affiliation(s)
- Li-zeng Guan
- Agriculture College, Yanbian University, Gongyuan Road, Yanji, 133000, China,
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14
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Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells. Methods Mol Biol 2014; 1105:419-37. [PMID: 24623245 DOI: 10.1007/978-1-62703-739-6_31] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In this chapter, we describe a gene-specific quantitative PCR (QPCR)-based assay for the measurement of DNA damage, using amplification of long DNA targets. This assay has been used extensively to measure the integrity of both nuclear and mitochondrial genomes exposed to different genotoxins and has proven to be particularly valuable in identifying reactive oxygen species-mediated mitochondrial DNA damage. QPCR can be used to quantify both the formation of DNA damage as well as the kinetics of damage removal. One of the main strengths of the assay is that it permits monitoring the integrity of mtDNA directly from total cellular DNA without the need for isolating mitochondria or a separate step of mitochondrial DNA purification. Here we discuss advantages and limitations of using QPCR to assay DNA damage in mammalian cells. In addition, we give a detailed protocol of the QPCR assay that helps facilitate its successful deployment in any molecular biology laboratory.
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Ceker S, Agar G, Alpsoy L, Nardemir G, Kizil HE. Antagonistic effects of Satureja hortensis essential oil against AFB, on human lymphocytes in vitro. CYTOL GENET+ 2014. [DOI: 10.3103/s0095452714050028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yang Q, Zhang S, Liu H, Wu J, Xu E, Peng B, Jiang Y. Oncogenic role of long noncoding RNA AF118081 in anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide-transformed 16HBE cells. Toxicol Lett 2014; 229:430-9. [PMID: 25050996 DOI: 10.1016/j.toxlet.2014.07.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 07/02/2014] [Accepted: 07/06/2014] [Indexed: 01/23/2023]
Abstract
Lung cancer is the leading cause of cancer deaths and remains an important public health problem worldwide. Long noncoding RNAs (lncRNAs) are newly identified regulators of tumorigenesis and tumor progression. However, the role of lncRNAs in lung cancer induced by environmental carcinogens remains largely unknown. In this study, an lncRNA microarray was used to compare the expression profiles of malignantly transformed 16HBE cells (16HBE-T) induced with anti-benzo[a]pyrene-trans-7,8-diol-9,10-epoxide (anti-BPDE) and normal 16HBE cells (16HBE-N). Using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR), lncRNA AF118081 was identified as the most significantly overexpressed lncRNA in 16HBE-T cells, lung cancer cells, and patient samples. Cell proliferation, colony formation, apoptosis, migration, and invasion were assayed in 16HBE-T cells following the knockdown of lncRNA AF118081 with small interfering RNA. AF118081 knockdown inhibited cell growth and tumor invasion. An in vivo (nude mouse) model was then used to assay tumor growth, and the downregulation of AF118081 clearly suppressed tumor growth, consistent with the results of the in vitro assays. Together, these findings identify a new oncogenic lncRNA, lncRNA AF118081, in malignantly transformed 16HBE cells. This enhances our understanding of lncRNAs as important regulatory elements in chemical carcinogenesis and potential targets of lung cancer therapies.
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Affiliation(s)
- Qiaoyuan Yang
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China
| | - Shaozhu Zhang
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China
| | - Huanying Liu
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China
| | - Jianjun Wu
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China
| | - Enwu Xu
- Department of Thoracic Surgery, General Hospital of Guangzhou Military Command of Chinese People's Liberation Army, Guangzhou 510010, PR China
| | - Baoying Peng
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China
| | - Yiguo Jiang
- Institute for Chemical Carcinogenesis, State Key Laboratory for Respiratory Diseases, Guangzhou Medical University, Guangzhou 510182, PR China.
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de Carvalho FM, de Almeida Pereira T, Gonçalves PL, Jarske RD, Pereira FEL, Louro ID. Hepatocellular carcinoma and liver cirrhosis TP53 mutation analysis reflects a moderate dietary exposure to aflatoxins in Espírito Santo State, Brazil. Mol Biol Rep 2013; 40:4883-7. [PMID: 23649769 DOI: 10.1007/s11033-013-2587-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 04/29/2013] [Indexed: 01/27/2023]
Abstract
The close relationship between aflatoxins and 249ser TP53 gene mutation (AGG to AGT, Arg to Ser) in hepatocellular carcinoma (HCC) makes this mutation an indirect indicator of dietary contamination with this toxin. We have examined the prevalence of codon 249 TP53 mutation in 41 HCC and 74 liver cirrhosis (without HCC) cases diagnosed at the HUCAM University Hospital in Vitoria, Espírito Santo State, Brazil. DNA was extracted from paraffin sections and from plasma. The mutation was detected by DNA amplification, followed by restriction endonuclease digestion and confirmed by direct sequencing. DNA restriction showed 249ser mutation in 16 HCC and 13 liver cirrhosis, but sequencing confirmed mutations in only 6 HCC and 1 liver cirrhosis. In addition, sequencing revealed 4 patients with mutations at codon 250 (250ser and 250leu) in HCC cases. The prevalence of TP53 mutation was 10/41 (24.3%) in HCC and 1/74 (1.4%) in liver cirrhosis. No relationship between the presence of mutations and the etiology of HCC was observed. TP53 exon 7 mutations, which are related to aflatoxins exposure, were found at 14.6% (249ser), 7.3% (250leu) and 2.4% (250ser) in 41 cases of HCC and 1.4% in 74 liver cirrhosis (without HCC) cases, suggesting a moderate dietary exposure to aflatoxins in the Espírito Santo State, Brazil.
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Affiliation(s)
- Fernanda Magri de Carvalho
- Núcleo de Genética Humana e Molecular, Departamento de Ciências Biológicas, Centro de Ciências Humanas e Naturais, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468, Campus de Maruípe, Vitória, Espírito Santo, CEP 29040-090, Brazil
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Akçam M, Artan R, Yilmaz A, Ozdem S, Gelen T, Nazıroğlu M. Caffeic acid phenethyl ester modulates aflatoxin B1-induced hepatotoxicity in rats. Cell Biochem Funct 2013; 31:692-7. [DOI: 10.1002/cbf.2957] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/07/2012] [Accepted: 01/02/2013] [Indexed: 01/22/2023]
Affiliation(s)
- Mustafa Akçam
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Medical Faculty; Suleyman Demirel University; Isparta Turkey
| | - Reha Artan
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Medical Faculty; Akdeniz University; Antalya Turkey
| | - Aygen Yilmaz
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Medical Faculty; Akdeniz University; Antalya Turkey
| | - Sebahat Ozdem
- Department of Biochemistry, Medical Faculty; Akdeniz University; Antalya Turkey
| | - Tekinalp Gelen
- Department of Pathology, Medical Faculty; Akdeniz University; Antalya Turkey
| | - Mustafa Nazıroğlu
- Neuroscience Research Center; Suleyman Demirel University; Isparta Turkey
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Carvajal M. Transformación de la aflatoxina B1 de alimentos, en el cancerígeno humano, aducto AFB1-ADN. TIP REVISTA ESPECIALIZADA EN CIENCIAS QUÍMICO-BIOLÓGICAS 2013. [DOI: 10.1016/s1405-888x(13)72082-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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20
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Deabes MM, El-Soud NHA, El-Kassem LTA. In Vitro Inhibition of Growth and Aflatoxin B1 Production of Aspergillus Flavus Strain (ATCC 16872) by Various Medicinal Plant Essential Oils. ACTA ACUST UNITED AC 2012. [DOI: 10.3889/mjms.1857-5773.2011.0190] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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21
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Ayed-Boussema I, Pascussi JM, Maurel P, Bacha H, Hassen W. Effect of aflatoxin B1 on nuclear receptors PXR, CAR, and AhR and their target cytochromes P450 mRNA expression in primary cultures of human hepatocytes. Int J Toxicol 2011; 31:86-93. [PMID: 21994236 DOI: 10.1177/1091581811422453] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aflatoxin B1 (AFB1), one of the most common mycotoxins found in human foods and animal feed, is principally hepatotoxic and hepatocarcinogenic. The aim of the present study was to explore the effect of AFB1 on messenger RNA (mRNA) expression of pregnane X receptor (PXR), constitutive androstane receptor (CAR), and aryl hydrocarbon receptor (AhR) and some of their target cytochromes using primary cultures of human hepatocytes. Our results showed that AFB1, at noncytotoxic increasing concentrations, caused a significant upregulation of cytochrome P 2B6 (CYP2B6), CYP3A5, and to a lesser extent CYP3A4 and CYP2C9. Pregnane X receptor and CAR mRNA expression increased in the 3 treated livers. Aflatoxin B1 was found also to induce an overexpression of CYP1A1 and CYP1A2 genes accompanied by an increase in AhR mRNA expression. These findings suggest that AFB1 could activate PXR, CAR, and AhR; however, further investigations are needed to confirm nuclear receptor activation by AFB1.
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Affiliation(s)
- Imen Ayed-Boussema
- Laboratoire de Recherche sur les Substances Biologiquement Compatibles, (LRSBC), Rue Avicenne, 5019 Monastir, Tunisia
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Alpsoy L, Yalvac ME. Key roles of vitamins A, C, and E in aflatoxin B1-induced oxidative stress. VITAMINS AND HORMONES 2011; 86:287-305. [PMID: 21419276 DOI: 10.1016/b978-0-12-386960-9.00012-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Aflatoxins (Aspergillus flavus toxins) are one of the natural toxic molecules which are produced by a group of fungi called Aspergillus. Foods and drinks contaminated with aflatoxins cause global health and environmental problems. Today in many developing countries, these toxins are leading cause of some liver cancers and serious gastrointestinal problems. Aflatoxins, which are well known to be mutagenic, carcinogenic, hepatotoxic, and immunosuppressive, exert inhibitory effects on biological processes including DNA synthesis, DNA-dependent RNA synthesis, DNA repair, and protein synthesis. Aflatoxins B(1) (AFB(1)) is the most widespread oxidative agent of the aflatoxins. Numerous diverse compounds and extracts have been reported to reduce the aflatoxins induced oxidative stress in the body. Most of these inhibitors including phenylpropanoids, terpenoids, alkaloids, and vitamins are originally derived from plants. Among these, being essential biomolecules, vitamins are used as coenzymes in very significant biological reactions. They also function as nonenzymatic antioxidative agents protecting the cells from oxidative stress-induced toxicity and transformation. This chapter reviews the mechanism of AFB(1)-induced oxidative stress and focuses on the protective effects of vitamins A, C, and E on reducing this stress.
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Affiliation(s)
- Lokman Alpsoy
- Fatih University, Science and Art Faculty, Department of Biology, Buyukcekmece, Istanbul, Turkey
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Alpsoy L, Kotan E, Tatar A, Agar G. Protective effects of selenium against sister chromatid exchange induced by AFG 1 in human lymphocytes in vitro. Hum Exp Toxicol 2010; 30:515-9. [PMID: 20630912 DOI: 10.1177/0960327110377523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aflatoxins have been shown to be hepatotoxic, carcinogenic, mutagenic and teratogenic to different species of animals. Besides, at low concentrations, Selenium (Se(4+)) is antimutagenic and anticarcinogenic while it is toxic, mutagenic and carcinogenic at high concentrations. In this study, we aimed to evaluate the effect of Se(4+) against aflatoxin GAFG(1) (AFG(1)) on blood cultures in relation to induction of sister chromatid exchange (SCE). The results showed that at 0.4 and 0.8 parts per million (ppm) concentration of AFG(1), the frequency of SCE increased in cultured human lymphocytes. When different concentration of Se(4+) (0.08 and 8 ppm) were added to AFG(1), the frequencies of SCE decreased. Howewer, when 800 ppm concentration of Se(4+) together with 0.08 ppm AFG(1) were added to cell division inhibited in the cultures. Results suggested that Se(4+) could effectively inhibit AFG(1)-induced SCE. Besides, the protective role of Se(4+) against AFG(1)-induced SCE is probably related to its doses.
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Affiliation(s)
- Lokman Alpsoy
- Department of Biology, Faculty of Science, Fatih University, Istanbul, Turkey
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24
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Besaratinia A, Kim SI, Hainaut P, Pfeifer GP. In vitro recapitulating of TP53 mutagenesis in hepatocellular carcinoma associated with dietary aflatoxin B1 exposure. Gastroenterology 2009; 137:1127-37, 1137.e1-5. [PMID: 19524575 PMCID: PMC2736365 DOI: 10.1053/j.gastro.2009.06.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 06/03/2009] [Accepted: 06/05/2009] [Indexed: 12/18/2022]
Abstract
BACKGROUND & AIMS Dietary exposure to aflatoxin B(1) (AFB(1)), in addition to other known factors, increases risk for human hepatocellular carcinoma (HCC). HCCs from AFB(1)-exposed individuals frequently have distinct TP53 mutations, such as G to T transversions in the second guanine of codon 249 (AGG to AGT), and a characteristic mutational spectrum predominated by G:C to T:A mutations. METHODS To recapitulate the distinctive features of TP53 mutations in AFB(1)-associated HCC, we investigated AFB(1)-induced DNA adduction in relation to mutagenesis in transgenic mouse fibroblasts exposed to AFB(1) in vitro. RESULTS Immunodotblot determination of DNA adducts in the overall genome of AFB(1)-exposed cells revealed the dose-dependant formation of persistent imidazole ring-opened AFB(1)-DNA adducts. DNA footprinting analysis of the cII transgene in AFB(1)-exposed cells verified the dose-dependent and sequence-specific formation of DNA adducts. The preferential formation of AFB(1)-induced DNA adducts along the cII transgene was almost exclusively localized to guanine-containing sequences encompassing CpG dinucleotides. Mutation analysis of the cII transgene in AFB(1)-exposed cells revealed a dose-dependent induction of cII mutant frequency (P < .001) and a unique induced mutational spectrum characterized by predominant induction of G:C to T:A transversions that occurred within CpG sequence contexts. Notably, codons 42 and 45 of the cII transgene, which have identical sequence contexts to that of codon 249 of human TP53, constituted 2 frequently mutated sites in AFB(1)-exposed cells that contained the G to T transversion signature mutation at their third base positions. CONCLUSIONS In this model system, AFB(1)-induced DNA adduction and mutagenesis recapitulate the unique mutational features of TP53 in AFB(1)-associated human HCC.
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Affiliation(s)
- Ahmad Besaratinia
- Department of Cancer Biology, Beckman Research Institute of the City of Hope National Medical Center, Duarte, California 91010, USA.
| | - Sang-in Kim
- Department of Cancer Biology, Beckman Research Institute of the City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Pierre Hainaut
- International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, Cedex 08, France
| | - Gerd P. Pfeifer
- Department of Cancer Biology, Beckman Research Institute of the City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA 91010, USA
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Nogueira JA, Ono-Nita SK, Nita ME, de Souza MMT, do Carmo EP, Mello ES, Scapulatempo C, Paranaguá-Vezozzo DC, Carrilho FJ, Alves VAF. 249 TP53 mutation has high prevalence and is correlated with larger and poorly differentiated HCC in Brazilian patients. BMC Cancer 2009; 9:204. [PMID: 19558663 PMCID: PMC2708192 DOI: 10.1186/1471-2407-9-204] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 06/26/2009] [Indexed: 12/12/2022] Open
Abstract
Background Ser-249 TP53 mutation (249Ser) is a molecular evidence for aflatoxin-related carcinogenesis in Hepatocellular Carcinoma (HCC) and it is frequent in some African and Asian regions, but it is unusual in Western countries. HBV has been claimed to add a synergic effect on genesis of this particular mutation with aflatoxin. The aim of this study was to investigate the frequency of 249Ser mutation in HCC from patients in Brazil. Methods We studied 74 HCC formalin fixed paraffin blocks samples of patients whom underwent surgical resection in Brazil. 249Ser mutation was analyzed by RFLP and DNA sequencing. HBV DNA presence was determined by Real-Time PCR. Results 249Ser mutation was found in 21/74 (28%) samples while HBV DNA was detected in 13/74 (16%). 249Ser mutation was detected in 21/74 samples by RFLP assay, of which 14 were confirmed by 249Ser mutant-specific PCR, and 12 by nucleic acid sequencing. All HCC cases with p53-249ser mutation displayed also wild-type p53 sequences. Poorly differentiated HCC was more likely to have 249Ser mutation (OR = 2.415, 95% CI = 1.001 – 5.824, p = 0.05). The mean size of 249Ser HCC tumor was 9.4 cm versus 5.5 cm on wild type HCC (p = 0.012). HBV DNA detection was not related to 249Ser mutation. Conclusion Our results indicate that 249Ser mutation is a HCC important factor of carcinogenesis in Brazil and it is associated to large and poorly differentiated tumors.
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Affiliation(s)
- Jeronimo A Nogueira
- Department of Gastroenterology, University of São Paulo School of Medicine, São Paulo, SP, Brazil.
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Alpsoy L, Agar G, Ikbal M. Protective role of vitamins A, C, and E against the genotoxic damage induced by aflatoxin B1 in cultured human lymphocytes. Toxicol Ind Health 2009; 25:183-8. [DOI: 10.1177/0748233709106068] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this study, we aimed to evaluate the effect of vitamins A, C, and E against aflatoxin B1 (AFB1) on blood cultures in relation to induction of sister chromatid exchange (SCE). The results indicated genotoxic and mutagenic damage in cultured human lymphocytes exposed to AFB1. The results showed that 5 μM concentration of AFB1 increased SCE. When vitamins A, C, and E were added to AFB1, the frequency of SCE decreased. These results suggest that vitamins A, C, and E could effectively inhibit AFB1-induced SCE, which may partially responsible for its mutagenic effect of AFB1. Besides, the protective effect of vitamins A, C, and E against AFB1 was increased in a dose-dependent manner (i.e., as the doses increased, their protective effects also increased). There was a significant decrease in the SCE frequency in AFB1-treated group compared with the groups receiving AFB1 and also vitamins A, C, and E. The most effective concentration was 100 microM vitamin C, and the lowest effective concentration was 0.5 microM vitamin A. Vitamin C has the most effective concentration of 100 μM, and vitamin A has the lowest effective concentration of 0.5 μM. The order of the decreasing effect of the SCE frequency of vitamins was as follows: vitamin C > vitamin E > vitamin A.
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Affiliation(s)
- L Alpsoy
- Faculty of Art and Science, Department of Biology, Fatih University, Istanbul, Turkey
| | - G Agar
- Faculty of Art and Science, Department of Biology, Atatürk University, Erzurum, Turkey
| | - M Ikbal
- Faculty of Medicine, Department of Medical Genetics, Karadeniz Technical University, Trabzon, Turkey
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Tak YK, Naoghare PK, Lee KH, Park SS, Song JM. Green fluorescent protein (GFP) as a direct biosensor for mutation detection: Elimination of false-negative errors in target gene expression. Anal Biochem 2008; 380:91-8. [DOI: 10.1016/j.ab.2008.05.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 05/08/2008] [Accepted: 05/18/2008] [Indexed: 11/16/2022]
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Paget V, Sichel F, Garon D, Lechevrel M. Aflatoxin B1-induced TP53 mutational pattern in normal human cells using the FASAY (Functional Analysis of Separated Alleles in Yeast). Mutat Res 2008; 656:55-61. [PMID: 18725321 DOI: 10.1016/j.mrgentox.2008.07.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 06/17/2008] [Accepted: 07/12/2008] [Indexed: 11/29/2022]
Abstract
Mutations in the TP53 gene are the most common alterations in human tumours. In hepatocellular carcinoma (HCC) related to exposure to aflatoxin B1, a specific G>T transversion in codon 249 is classically described as a hot spot. However, AFB1 is suspected to be a potent carcinogen in tissues other than the liver. By using the FASAY functional assay in yeast, the present study aimed at depicting the mutational pattern of TP53 in normal human fibroblasts after in vitro exposure to AFB1. Molecular analysis of mutants revealed that codon 245 was the main hot spot, whereas no mutations were found in codon 249. The locations of mutations within GG and GC/CG sequences are well in accordance with AFB1-adduct location data. In our assay with normal human fibroblasts, AFB1 mainly induced G>A transitions, followed by G>T and A>G mutations. This suggests that G>T transversions at codon 249 were likely the result of a selection bias in human HCC rather than a true fingerprint of AFB1 adducts. Indeed, a comparison of the mutation pattern with that found in human HCC excluding codon 249 reveals that the two spectra are quite similar. Furthermore, the similarity between our in vitro spectrum with that identified in AFB1-induced lung tumours in mice suggests that AFB1 may be a potent lung carcinogen in humans.
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Affiliation(s)
- Vincent Paget
- GRECAN EA1772-IFR 146 ICORE, Université de Caen Basse-Normandie et Centre François Baclesse, Av. du Général Harris, 14076 Caen-cedex 05, France
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Nwagbara O, Darling-Reed SF, Tucker A, Harris C, Abazinge M, Thomas RD, Gragg RD. Induction of cell death, DNA strand breaks, and cell cycle arrest in DU145 human prostate carcinoma cell line by benzo[a]pyrene and benzo[a]pyrene-7,8-diol-9,10-epoxide. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2007; 4:10-4. [PMID: 17431309 PMCID: PMC3719953 DOI: 10.3390/ijerph2007010002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Accepted: 02/21/2007] [Indexed: 12/03/2022]
Abstract
Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon, is a major environmental pollutant. In this study, the effects of this carcinogen/mutagen and one of its metabolites, benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), on human prostate carcinoma cell line DU145, were examined. Cell viability, DNA damage, and cell cycle progression were evaluated as toxic end-points. We have shown that B[a]P and BPDE inhibited cell viability following 48 hr of exposure. Furthermore, comet assay analyses revealed that both B[a]P and BPDE induced DNA strand breaks in a concentration-dependent fashion. Flow cytometric analyses showed that about 70% of DU145 cells were arrested by B[a]P at the G1 phase, while about 76% were arrested at G1 phase by BPDE. These data reveal that B[a]P and BPDE are cytotoxic and genotoxic to DU145 prostate cancer cells.
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Affiliation(s)
- Onyinye Nwagbara
- Environmental Sciences Institute, Florida A&M University, Tallahassee, FL 32307, USA.
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Duran RM, Cary JW, Calvo AM. Production of cyclopiazonic acid, aflatrem, and aflatoxin by Aspergillus flavus is regulated by veA, a gene necessary for sclerotial formation. Appl Microbiol Biotechnol 2006; 73:1158-68. [PMID: 16988822 DOI: 10.1007/s00253-006-0581-5] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 07/10/2006] [Accepted: 07/10/2006] [Indexed: 11/26/2022]
Abstract
The plant pathogenic fungus Aspergillus flavus produces several types of mycotoxins. The most well known are the carcinogenic compounds called aflatoxins. In addition, A. flavus produces cyclopiazonic acid and aflatrem mycotoxins, contributing to the toxicity of A. flavus infected crops. Cyclopiazonic acid is a specific inhibitor of calcium-dependent ATPase in the sarcoplasmic reticulum that results in altered cellular Ca++ levels. Aflatrem is a potent tremorgenic mycotoxin known to lead to neurological disorders. Previously we showed that a gene called veA controls aflatoxin and sclerotial production in A. parasiticus. In this study in A. flavus, we show that the veA homolog in A. flavus not only is necessary for the production of aflatoxins B1 and B2 and sclerotia, but also regulates the synthesis of the mycotoxins cyclopiazonic acid and aflatrem. The A. flavus DeltaveA mutant was completely blocked in the production of aflatrem and showed greater than twofold decrease in cyclopiazonic acid production. The genes involved in the synthesis of cyclopiazonic acid are unknown; however, the aflatrem gene cluster has been characterized. Northern hybridization analysis showed that veA is required for expression of the A. flavus aflatrem genes atmC, atmG, and atmM. This is the first report of a regulatory gene governing the production of cyclopiazonic acid and aflatrem mycotoxins.
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MESH Headings
- Aflatoxins/biosynthesis
- Aspergillus flavus/cytology
- Aspergillus flavus/genetics
- Aspergillus flavus/metabolism
- Blotting, Northern
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- Gene Deletion
- Gene Expression Regulation, Fungal
- Genes, Fungal
- Genes, Regulator
- Indoles/metabolism
- Molecular Sequence Data
- Morphogenesis/genetics
- RNA, Fungal/analysis
- RNA, Fungal/genetics
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Sequence Analysis, DNA
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Affiliation(s)
- Rocio M Duran
- Department of Biological Sciences, Montgomery Hall, Northern Illinois University, De Kalb, IL 60115, USA
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Lee CM, Chen SY, Lee YCG, Huang CYF, Chen YMA. Benzo[a]pyrene and glycine N-methyltransferse Interactions: Gene expression profiles of the liver detoxification pathway. Toxicol Appl Pharmacol 2006; 214:126-35. [PMID: 16545412 DOI: 10.1016/j.taap.2005.12.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 11/22/2005] [Accepted: 12/06/2005] [Indexed: 11/15/2022]
Abstract
Benzo[a]pyrene (BaP) is one of many polycyclic aromatic hydrocarbons that have been identified as major risk factors for developing various cancers. We previously demonstrated that the liver cancer susceptibility gene glycine N-methyltransferase (GNMT) is capable of binding with BaP and protecting cells from BaP-7,8-diol 9,10-epoxide-DNA adduct formation. In this study, we used a cytotoxicity assay to demonstrate that the higher expression level of GNMT, the lower cytotoxicity occurred in the cells treated with BaP. In addition, a cDNA microarray containing 7,597 human genes was used to examine gene expression patterns in BaP-treated HepG2 (a liver cancer cell line that expresses very low levels of GNMT) and SCG2-1-1 (a stable HepG2 clone that expresses high levels of GNMT) cells. The results showed that among 6,018 readable HepG2 genes, 359 (6.0%) were up-regulated more than 1.5-fold and 768 (12.8%) were down-regulated. Overexpression of GNMT in SCG2-1-1 cells resulted in the down-regulation of genes related to the detoxification, kinase/phosphatase pathways, and oncogenes. Furthermore, real-time PCR was used to validate microarray data from 21 genes belonging to the detoxification pathway. Combining both microarray and real-time PCR data, the results showed that among 89 detoxification pathway genes analyzed, 22 (24.7%) were up-regulated and 6 (6.7%) were down-regulated in BaP-treated HepG2 cells, while in the BaP-treated SCG2-1-1 cells, 12 (13.5%) were up-regulated and 26 (29.2%) were down-regulated (P < 0.001). Therefore, GNMT sequesters BaP, diminishes BaP's effects to the liver detoxification pathway and prevents subsequent cytotoxicity.
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Affiliation(s)
- Cheng-Ming Lee
- Division of Preventive Medicine, Institute of Public Health, National Yang-Ming University, Beitou District, Taipei 112, Taiwan
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Lee JK, Choi EH, Lee KG, Chun HS. Alleviation of aflatoxin B1-induced oxidative stress in HepG2 cells by volatile extract from Allii Fistulosi Bulbus. Life Sci 2005; 77:2896-910. [PMID: 15970298 DOI: 10.1016/j.lfs.2005.03.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Accepted: 03/03/2005] [Indexed: 10/25/2022]
Abstract
The volatile extract from Allii Fistulosi Bulbus (VEAF) was isolated by steam distillation under reduced pressure, followed by continuous liquid-liquid extraction, and its effects on aflatoxin B1 (AFB1)-induced oxidative stress were investigated in human hepatoma cells (HepG2). The main constituents of the VEAF, identified by gas chromatography/mass spectrometry, were 2-octyl-5-methyl-3(2H)-furanone, 2-hexyl-5-methyl-3(2H)-furanone, 2,5-dimethylthiophene, 3,5-diethyl-1,2,4-trithiolane and 3,4-dimethyl-2,5-dihydro-thiophene-2-one. VEAF significantly inhibited the formation of intracellular reactive oxygen species caused by AFB1 in a dose-dependent manner, concomitant with a significant decrease in the AFB1-induced cytotoxicity. VEAF pretreatment significantly reduced the levels of thiobarbituric acid reactive substances, an indicator of lipid peroxidation, whereas increased the level of reduced glutathione. The level of 8-hydroxy-2'-deoxyguanosine, a DNA oxidative stress marker, was also decreased by 49-59% with pretreatment of VEAF. With respect to the activity of AFB1 metabolizing enzymes, VEAF significantly increased the activity of glutathione S-transferase, and significantly decreased the cytochrome (CYP) P450 3A4 activity, but had a little effect on the CYP1As. These results suggest that VEAF may be selectively effective in alleviating the AFB1-induced oxidative stress, and lead to cytoprotection against AFB1 exposure.
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Affiliation(s)
- Joon-Kyoung Lee
- Food Function Research Division, Korea Food Research Institute, San 46-1, Backhyun, Bundang-gu, Sungnam, Kyonggi-do 463-746, South Korea
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Szkudelska K, Drzymała H, Szkudelski T, Bukowska K, Nogowski L. Lack of the effect of mycotoxins-aflatoxin B1 and ochratoxin A on some functions of rat adipocytes. Toxicol In Vitro 2005; 19:771-7. [PMID: 15963681 DOI: 10.1016/j.tiv.2005.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mycotoxins-aflatoxin B1 (AFB1) and ochratoxin A (OTA)-compounds which are strong carcinogenic, mutagenic and cytotoxic factors-are also known to evoke a decrease of food intake and body weight gains. The purpose of our study was to determine the direct influence of AFB1 and OTA incubated with isolated rat fat cells on the lipogenesis, lipolysis and leptin secretion. Adipocytes were isolated from the epididymal fat tissue by the collagenase digestion. Toxins used at concentrations 1, 10 and 100 microM were incubated for 90 min with adipocytes. Basal and insulin-stimulated lipogenesis-determined by the measure of [U-14C]glucose conversion to total lipids-was abated by AFB1 only at the highest concentration. At two lower ones, AFB1 did not affect the process. OTA at all used concentrations decreased insulin-stimulated lipogenesis but the effect was not dose-dependent. The lipolysis was determined by the measure of glycerol release from adipocytes. The basal lipolysis was unchanged by both toxins. The epinephrine-stimulated lipolysis was intensified by AFB1 only at the highest concentration, however, the process was not altered by OTA. The antilipolytic action of insulin was unaffected by both compounds (10 microM). To determine the influence of the tested toxins on leptin secretion, adipocytes were incubated for 120 min in the presence of glucose and insulin as stimulators of hormone secretion. AFB1 and OTA added to the incubation medium (1, 10 and 100 microM) had no significant influence on the leptin release. The results obtained in this experiment demonstrate that adipocytes are susceptible to the direct action of AFB1 and OTA. This susceptibility is, however, rather weak and is exhibited by a slight restriction of the lipogenesis (in the case of both toxins) and by a slight increase of the lipolysis (in the case of AFB1).
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Affiliation(s)
- K Szkudelska
- Department of Animal Physiology and Biochemistry, August Cieszkowski University of Agriculture, 60-637 Wołyńska 35, Poznań, Poland.
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Abstract
Aflatoxin B1 (AFB1) is a potent hepatocarcinogen. We have recently detected [via electron spin resonance (ESR) spectroscopy] free radicals in vivo in rat bile following AFB1 metabolism using the spin trapping [alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone (4-POBN)] technique. The aim of the present study was to identify the trapped free radical intermediates from the in vivo hepatic metabolism of AFB1. Rats were treated simultaneously with AFB1 (3 mg/kg i.p.) and the spin trapping agent 4-POBN (1 g/kg i.p.), and bile was collected over a period of 1 h at 20 min intervals. On-line high performance liquid chromatography (HPLC) coupled to ESR was used to identify an arachidonic acid-derived radical adduct of 4-POBN in rat bile, and a methyl adduct of 4-POBN from the reaction of hydroxyl radicals with carbon-13-labeled dimethyl sulfoxide ((13)C-DMSO). The effect of metabolic inhibitors, such as desferoxamine mesylate (DFO), an iron chelator, 2-dimethylaminoethyl-2,2-diphenylvalerate hydrochloride (SKF) 525A, a cytochrome P-450 inhibitor, and gadolinium chloride (GdCl(3)), a Kupffer cell inactivator, on in vivo aflatoxin-induced free radical formation were also studied. It was found that there was a significant decrease in radical formation as a result of DFO, SKF525A and GdCl(3) inhibition. Trapped 4-POBN radical adducts were also detected in rat bile following the in vivo metabolism of aflatoxin-M1, one of the hydroxylated metabolites of AFB1.
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Affiliation(s)
- Rheal A Towner
- Free Radical Biology and Aging Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.
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Abstract
The tumor suppressor gene p53 is commonly mutated with high frequencies at certain hot spots in human cancers. In liver cancers there is an especially high frequency of mutations at codon 249. To study the impact of carcinogen targeting and the role of cytosine methylation on the mutation spectrum, a common liver cancer carcinogen aflatoxin B1 (AFB1), was studied using the p53 cDNA template to examine mutation induction. Subsequent mutations were detected with a yeast p53 functional assay and identified by DNA sequencing. The results indicated that cytosine methylation enhances AFB1-induced guanine mutations at CpG sites. However, no mutations were detected at codon 249.
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Affiliation(s)
- Kin-Tak Chan
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), China
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Wang YC, Lee PJ, Shih CM, Chen HY, Lee CC, Chang YY, Hsu YT, Liang YJ, Wang LY, Han WH, Wang YC. Damage formation and repair efficiency in the p53 gene of cell lines and blood lymphocytes assayed by multiplex long quantitative polymerase chain reaction. Anal Biochem 2003; 319:206-15. [PMID: 12871714 DOI: 10.1016/s0003-2697(03)00330-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined ultraviolet (UV) irradiation and cisplatin treatment damage formation and repair efficiency in the p53 tumor suppressor gene of various cultured cell lines and lymphocytes using a nonradioactive multiplex long quantitative polymerase chain reaction (QPCR) assay, which amplified a 7-kb fragment of the target gene and a 500-bp fragment of the template control to successfully increase the sensitivity and reliability of the assay. The multiplex long QPCR detected a lesion frequency of 0.63 lesions/10kb/10J/m(2) in the p53 gene of fibroblast cells. In addition, the multiplex long QPCR assay detected pronounced differences in the repair of UV damage in the p53 gene among repair-proficient CRL-1475 cells and repair-deficient XP-A and XP-C cells. The multiplex long QPCR assay was also evaluated as a sensitive assay for the detection of DNA damage induced by cisplatin. The data indicated that the lesion frequency in the p53 gene was 1.27-1.75 times higher in the H23 cisplatin-sensitive cell than in the H1435 cisplatin-resistant cell at the IC(70) dose. After 8-h and 24-h repair periods, only 13 and 75% of cisplatin-induced damage had been removed in the H23 cells, whereas these values were 92 and 100% in the H1435 cells. In addition, our data indicate that multiplex long QPCR is a sensitive method for validly estimating repair in freshly isolated lymphocytes. The results suggest that the current protocol of the multiplex long QPCR method can be used to assess the damage formation and repair efficiency of various agents at biologically relevant doses and to allow a more precise determination of gene-specific repair in disease susceptibility and drug resistance in epidemiological studies.
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Affiliation(s)
- Yu-Chieh Wang
- Department of Biology, National Taiwan Normal University, Taipei, Taiwan, ROC.
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Wani MA, El-Mahdy MA, Hamada FM, Wani G, Zhu Q, Wang QE, Wani AA. Efficient repair of bulky anti-BPDE DNA adducts from non-transcribed DNA strand requires functional p53 but not p21(waf1/cip1) and pRb. Mutat Res 2002; 505:13-25. [PMID: 12175902 DOI: 10.1016/s0027-5107(02)00107-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Wild-type p53 protein is known to regulate the global genomic repair (GGR), removing bulky chemical DNA adducts as well as cyclobutane pyrimidine dimers from the genome overall and from non-transcribed strands (NTS) in DNA. To investigate the role of cellular factor(s) relevant to p53 regulated DNA repair processes, we examined the repair kinetics of chemical carcinogen, anti-benzo[a]pyrene-diol epoxide (anti-BPDE), induced bulky DNA adducts in normal human mammary epithelial cells (HMECs) and HMEC transformed by human papillomavirus (HPV)-16E6 or -16E7 oncoproteins, which, respectively targets p53 or pRb proteins for degradation. The results show that the removal of anti-BPDE DNA adducts from the genome overall and NTS by GGR was significantly reduced in HPV-16E6 protein expressing cells as compared to that in normal and HPV-16E7 protein expressing cells, indicating the role of p53 and not pRb in nucleotide excision repair (NER). We further determined the potential effects of the p53-regulated p21(waf1/cip1) gene product in NER in human colon carcinoma, HCT116 cells expressing wild-type p53 but different p21(waf1/cip1) genotypes (p21+/+, p21+/-, p21-/-). The results donot show a discernible difference in the removal of anti-BPDE DNA adducts from the genome overall and the transcribed strand (TS) and NTS irrespective of the presence or absence of p21(waf1/cip1) expression. Based on these results, we suggest that: (i) the wild-type p53 function but not p21(waf1/cip1) expression is necessary for GGR of chemical induced bulky DNA adducts; (ii) the Rb gene product does not play a significant role in NER; and (iii) the modulation of NER by p53 may be independent of its function in the regulation of cell cycle arrest upon chemically induced DNA damage.
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Affiliation(s)
- Manzoor A Wani
- Department of Radiology, The Ohio State University, Columbus 43210, USA
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Smela ME, Hamm ML, Henderson PT, Harris CM, Harris TM, Essigmann JM. The aflatoxin B(1) formamidopyrimidine adduct plays a major role in causing the types of mutations observed in human hepatocellular carcinoma. Proc Natl Acad Sci U S A 2002; 99:6655-60. [PMID: 12011430 PMCID: PMC124458 DOI: 10.1073/pnas.102167699] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A G to T mutation has been observed at the third position of codon 249 of the p53 tumor-suppressor gene in over 50% of the hepatocellular carcinoma cases associated with high exposure to aflatoxin B(1) (AFB(1)). Hypotheses have been put forth that AFB(1), in concert with hepatitis B virus (HBV), may play a role in the formation of, and/or the selection for, this mutation. The primary DNA adduct of AFB(1) is 8,9-dihydro-8-(N(7)-guanyl)-9-hydroxyaflatoxin B(1) (AFB(1)-N7-Gua), which is converted naturally to two secondary lesions, an apurinic site and an AFB(1)-formamidopyrimidine (AFB(1)-FAPY) adduct. AFB(1)-FAPY is detected at near maximal levels in rat DNA days to weeks after AFB(1) exposure, underscoring its high persistence in vivo. The present study reveals two striking properties of this DNA adduct: (i) AFB(1)-FAPY was found to cause a G to T mutation frequency in Escherichia coli approximately 6 times higher than that of AFB(1)-N7-Gua, and (ii) one proposed rotamer of AFB(1)-FAPY is a block to replication, even when the efficient bypass polymerase MucAB is used by the cell. Taken together, these characteristics make the FAPY adduct the prime candidate for both the genotoxicity of aflatoxin, because mammalian cells also have similar bypass mechanisms for combating DNA damage, and the mutagenicity that ultimately may lead to liver cancer.
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Affiliation(s)
- Maryann E Smela
- Biological Engineering Division and Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 56, Room 669, Cambridge, MA 02139, USA
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Smela ME, Currier SS, Bailey EA, Essigmann JM. The chemistry and biology of aflatoxin B(1): from mutational spectrometry to carcinogenesis. Carcinogenesis 2001; 22:535-45. [PMID: 11285186 DOI: 10.1093/carcin/22.4.535] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dietary exposure to aflatoxin B(1) (AFB(1)) is associated with an increased incidence of hepatocellular carcinoma (HCC), especially in populations in which exposure to hepatitis B virus (HBV) is a common occurrence. Most HCC samples from people living where HBV is prevalent have one striking mutational hotspot: a GC-->TA transversion at the third position of codon 249 of the p53 gene. In this review, the chemical reaction of an electrophilic derivative of aflatoxin with specific DNA sequences is examined, along with the types of mutations caused by AFB(1) and the sequence context dependence of those mutations. An attempt is made to assign the source of these mutations to specific chemical forms of AFB(1)-DNA damage. In addition, epidemiological and experimental data are examined regarding the synergistic effects of AFB(1) and HBV on HCC formation and the predominance of one hotspot GC-->TA transversion in the p53 gene of affected individuals.
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Affiliation(s)
- M E Smela
- Department of Chemistry and Division of Bioengineering and Environmental Health Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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40
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Abstract
Mutations of the p53 tumor suppressor gene are found in about 50% of all human cancers. The p53 mutation spectra in these cancers are providing clues to the etiology and molecular pathogenesis of cancer. Recent studies indicate that the p53 protein is involved in several vital cellular functions, such as gene transcription, DNA synthesis and repair, cell cycle arrest, senescence and programmed cell death. Mutations in the p53 gene can abrogate these functions and may contribute to genomic instability and progression to cancer. Characteristic p53 mutation spectra have been associated with dietary aflatoxin B(1) (AFB(1)) exposure and hepatocellular carcinoma (HCC); sunlight exposure and skin cancer; and cigarette smoking and lung cancer. The mutation spectrum also reveals those p53 mutants that provide cells with a selective clonal expansion advantage during the multistep process of carcinogenesis. Although a number of different exogenous carcinogens have been shown to selectively target p53, pieces of evidence supporting the endogenous insult of p53 are accumulating. Furthermore, analysis of a characteristic p53 mutation load in nontumorous human tissue can indicate previous carcinogen exposure and may identify individuals at an increased cancer risk.
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Affiliation(s)
- S P Hussain
- Laboratory of Human Carcinogenesis, Building 37, Room 2C05, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Yoon JH, Lee CS. Mapping of altromycin B-DNA adduct at nucleotide resolution in the human genomic DNA by ligation-mediated PCR. Mol Cells 2000; 10:71-5. [PMID: 10774750 DOI: 10.1007/s10059-000-0071-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The ligation-mediated PCR was used to map DNA alkylation sites induced by altromycin B at nucleotide resolution in genomic DNA purified from cultured human colon carcinoma. Altromycin B, one of the pluramycin group of antitumor antibiotics, is characterized as intercalator with the added ability to alkylate N7 guanine. DNA adducts formed in genomic DNA were cleaved into DNA strand breaks by hot piperidine treatment, and fragments containing ligatable breaks were then amplified in a single-sided, ligation-mediated PCR. The alkylation sites observed in exon 9 of the p53 gene revealed that the most high reactivity sites for altromycin B were found to be N7 of guanine in a 5'-AG* sequence. Determination of the DNA alkylation sites in naked radiolabeled plasmid DNA also showed that altromycin B preferred N7 of guanine in a 5'-AG* sequence. Thus, it can be concluded that the sequence selective DNA adduct formation induced by the intercalating alkylator, altromycin B, in genomic DNA is similar to that observed in naked plasmid DNA.
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Affiliation(s)
- J H Yoon
- Department of Biochemistry, College of Natural Sciences, Yeungnam University, Kyongsan, Korea
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