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Walls KM, Joh JY, Martinez MM, Hong KU, Hein DW. Metabolic effects of heterocyclic amines on insulin‑induced AKT phosphorylation and gluconeogenic gene expression are modified by N -acetyltransferase 2 genetic polymorphism. Pharmacogenet Genomics 2025; 35:119-126. [PMID: 39878101 PMCID: PMC12043411 DOI: 10.1097/fpc.0000000000000559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2025]
Abstract
OBJECTIVE Heterocyclic amines (HCAs) are mutagens and carcinogens primarily generated when cooking meat at high temperatures or until well-done, and their major metabolic pathway includes hepatic N -hydroxylation via CYP1A2 followed by O -acetylation via N -acetyltransferase 2 (NAT2). NAT2 expresses a well-defined genetic polymorphism in humans resulting in rapid and slow acetylators. Recent epidemiological studies reported significant associations between dietary HCA exposure and insulin resistance and type II diabetes. METHODS We assessed the effect of some of the most common HCAs found in cooked meat, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, on insulin signaling and gluconeogenic gene expression in cryopreserved human hepatocytes characterized by their NAT2 genotype and phenotype to investigate the role of NAT2 genetic polymorphism in HCA-induced metabolic dysregulation. RESULTS HCA treatment significantly reduced insulin-induced protein kinase B phosphorylation and significantly increased expression of genes involved in gluconeogenesis ( G6PC , PCK1 , FOXO1 , and PPARA ) in cryopreserved human hepatocytes from rapid but not from slow acetylators. CONCLUSION The findings suggest that NAT2 genetic polymorphism modifies HCA-induced insulin resistance and gluconeogenic gene expression, implying that individuals with rapid acetylator phenotype may be at greater risk of dysregulated glucose homeostasis following exposure to HCAs.
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Affiliation(s)
- Kennedy M Walls
- Department of Pharmacology & Toxicology and Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky, USA
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Walls KM, Joh JY, Hong KU, Hein DW. Heterocyclic Amines Disrupt Lipid Homeostasis in Cryopreserved Human Hepatocytes. Cardiovasc Toxicol 2024; 24:747-756. [PMID: 38851663 PMCID: PMC11300155 DOI: 10.1007/s12012-024-09874-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 05/23/2024] [Indexed: 06/10/2024]
Abstract
Metabolic dysfunction associated-steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) is the liver manifestation of metabolic syndrome, which is characterized by insulin resistance, hyperglycemia, hypertension, dyslipidemia, and/or obesity. Environmental pollutant exposure has been recently identified as a risk factor for developing MASH. Heterocyclic amines (HCAs) are mutagens generated when cooking meat at high temperatures or until well-done. Recent epidemiological studies reported that dietary HCA exposure may be linked to insulin resistance and type II diabetes, and we recently reported that HCAs induce insulin resistance and glucose production in human hepatocytes. However, no previous studies have examined the effects of HCAs on hepatic lipid homeostasis. In the present study, we assessed the effects of two common HCAs, MeIQx (2-amino-3, 8-dimethylimidazo [4, 5-f] quinoxaline) and PhIP (2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine), on lipid homeostasis in cryopreserved human hepatocytes. Exposure to a single concentration of 25 μM MeIQx or PhIP in human hepatocytes led to dysregulation of lipid homeostasis, typified by significant increases in lipid droplets and triglycerides. PhIP significantly increased expression of lipid droplet-associated genes, PNPLA3 and HSD17B13, and both HCAs significantly increased PLIN2. Exposure to MeIQx or PhIP also significantly increased expression of several key genes involved in lipid synthesis, transport and metabolism, including FASN, DGAT2, CPT1A, SCD, and CD36. Furthermore, both MeIQx and PhIP significantly increased intracellular cholesterol and decreased expression of PON1 which is involved in cholesterol efflux. Taken together, these results suggest that HCAs dysregulate lipid production, metabolism, and storage. The current study demonstrates, for the first time, that HCA exposure may lead to fat accumulation in hepatocytes, which may contribute to hepatic insulin resistance and MASH.
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Affiliation(s)
- Kennedy M Walls
- Department of Pharmacology and Toxicology and Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- Environmental Justice, Community Health and Environmental Review Division, US Environmental Protection Agency, Chicago, USA
| | - Jonathan Y Joh
- Department of Pharmacology and Toxicology and Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA
| | - Kyung U Hong
- Department of Pharmacology and Toxicology and Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA
- Department of Pharmaceutical and Administrative Sciences, Western New England University, Springfield, USA
| | - David W Hein
- Department of Pharmacology and Toxicology and Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, 40202, USA.
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Walls KM, Hong KU, Hein DW. Heterocyclic amines reduce insulin-induced AKT phosphorylation and induce gluconeogenic gene expression in human hepatocytes. Arch Toxicol 2023; 97:1613-1626. [PMID: 37005939 PMCID: PMC10192068 DOI: 10.1007/s00204-023-03488-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 03/21/2023] [Indexed: 04/04/2023]
Abstract
Heterocyclic amines (HCAs) are well-known for their mutagenic properties. One of the major routes of human exposure is through consumption of cooked meat, as certain cooking methods favor formation of HCAs. Recent epidemiological studies reported significant associations between dietary HCA exposure and insulin resistance and type II diabetes. However, no previous studies have examined if HCAs, independent of meat consumption, contributes to pathogenesis of insulin resistance or metabolic disease. In the present study, we have assessed the effect of three HCAs commonly found in cooked meat (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline [MeIQ], 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline [MeIQx], and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine [PhIP]) on insulin signaling and glucose production. HepG2 or cryopreserved human hepatocytes were treated with 0-50 μM of MeIQ, MeIQx, or PhIP for 3 days. Treatment of HepG2 cells and hepatocytes with MeIQ and MeIQx resulted in a significant reduction in insulin-induced AKT phosphorylation, suggesting that HCA exposure decreases hepatic insulin signaling. HCA treatment also led to significant increases in expression of gluconeogenic genes, G6PC and PCK1, in both HepG2 and cryopreserved human hepatocytes. Additionally, the level of phosphorylated FOXO1, a transcriptional regulator of gluconeogenesis, was significantly reduced by HCA treatment in hepatocytes. Importantly, HCA treatment of human hepatocytes led to increases in extracellular glucose level in the presence of gluconeogenic substrates, suggesting that HCAs induce hepatic glucose production. The current findings suggest that HCAs induce insulin resistance and promote hepatic glucose production in human hepatocytes. This implicates that exposure to HCAs may lead to the development of type II diabetes or metabolic syndrome.
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Affiliation(s)
- Kennedy M. Walls
- Department of Pharmacology & Toxicology and Brown Cancer Center,
University of Louisville School of Medicine, Louisville, KY. U.S.A
| | - Kyung U. Hong
- Department of Pharmacology & Toxicology and Brown Cancer Center,
University of Louisville School of Medicine, Louisville, KY. U.S.A
| | - David W. Hein
- Department of Pharmacology & Toxicology and Brown Cancer Center,
University of Louisville School of Medicine, Louisville, KY. U.S.A
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Hong KU, Doll MA, Lykoudi A, Salazar-González RA, Habil MR, Walls KM, Bakr AF, Ghare SS, Barve SS, Arteel GE, Hein DW. Acetylator Genotype-Dependent Dyslipidemia in Rats Congenic for N-Acetyltransferase 2. Toxicol Rep 2020; 7:1319-1330. [PMID: 33083237 PMCID: PMC7553889 DOI: 10.1016/j.toxrep.2020.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 01/10/2023] Open
Abstract
Recent reports suggest that arylamine N-acetyltransferases (NAT1 and/or NAT2) serve important roles in regulation of energy utility and insulin sensitivity. We investigated the interaction between diet (control vs. high-fat diet) and acetylator phenotype (rapid vs. slow) using previously established congenic rat lines (in F344 background) that exhibit rapid or slow Nat2 (orthologous to human NAT1) acetylator genotypes. Male and female rats of each genotype were fed control or high-fat (Western-style) diet for 26 weeks. We then examined diet- and acetylator genotype-dependent changes in body and liver weights, systemic glucose tolerance, insulin sensitivity, and plasma lipid profile. Male and female rats on the high fat diet weighed approximately 10% more than rats on the control diet and the percentage liver to body weight was consistently higher in rapid than slow acetylator rats. Rapid acetylator rats were more prone to develop dyslipidemia overall (i.e., higher triglyceride; higher LDL; and lower HDL), compared to slow acetylator rats. Total cholesterol (TC)-to-HDL ratios were significantly higher and HDL-to-LDL ratios were significantly lower in rapid acetylator rats. Our data suggest that rats with rapid systemic Nat2 (NAT1 in humans) genotype exhibited higher dyslipidemia conferring risk for metabolic syndrome and cardiovascular dysfunction.
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Affiliation(s)
- Kyung U. Hong
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Mark A. Doll
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Angeliki Lykoudi
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Raúl A. Salazar-González
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Mariam R. Habil
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Kennedy M. Walls
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Alaa F. Bakr
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Smita S. Ghare
- Departments of Medicine and Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Shirish S. Barve
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
- Departments of Medicine and Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Gavin E. Arteel
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
| | - David W. Hein
- Department of Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
- Departments of Medicine and Pharmacology & Toxicology, Center for Hepatobiology & Toxicology, University of Louisville School of Medicine, Louisville, KY, USA
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Syeda T, Foguth RM, Llewellyn E, Cannon JR. PhIP exposure in rodents produces neuropathology potentially relevant to Alzheimer's disease. Toxicology 2020; 437:152436. [PMID: 32169473 PMCID: PMC7218929 DOI: 10.1016/j.tox.2020.152436] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/01/2020] [Accepted: 03/09/2020] [Indexed: 12/31/2022]
Abstract
Alzheimer's disease (AD) is a public health crisis due to debilitating cognitive symptoms and lack of curative treatments, in the context of increasing prevalence. Thus, it is critical to identify modifiable risk factors. High levels of meat consumption may increase AD risk. Many toxins are formed during meat cooking such as heterocyclic aromatic amines (HAAs). Our prior studies have shown that HAAs produce dopaminergic neurotoxicity. Given the mechanistic and pathological overlap between AD and dopaminergic disorders we investigated whether exposure to 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), a prevalent dietary HAA formed during high-temperature meat cooking, may produce AD-relevant neurotoxicity. Here, C57BL/6 mice were treated with 100 or 200 mg/kg PhIP for 8 h or 75 mg/kg for 4 weeks and 16 weeks. PhIP exposure for 8 h produced oxidative damage, and AD-relevant alterations in hippocampal synaptic proteins, Amyloid-beta precursor protein (APP), and β-Site amyloid precursor protein cleaving enzyme 1 (BACE1). PhIP exposure for 4 weeks resulted in an increase in BACE1. PhIP exposure for 16 weeks resulted in increased hippocampal oxidative damage, APP, BACE1, Aβ aggregation, and tau phosphorylation. Quantification of intracellular nitrotyrosine revealed oxidative damage in cholinergic neurons after 8 h, 4 weeks and 16 weeks of PhIP exposure. Our study demonstrates that increase in oxidative damage, APP and BACE1 might be a possible mechanism by which PhIP promotes Aβ aggregation. Given many patients with AD or PD exhibit neuropathological overlap, our study suggests that HAA exposure should be further studied for roles in mediating pathogenic overlap.
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Affiliation(s)
- Tauqeerunnisa Syeda
- School of Health Sciences, Purdue University, West Lafayette, IN, 47907, United States; Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, IN, 47907, United States
| | - Rachel M Foguth
- School of Health Sciences, Purdue University, West Lafayette, IN, 47907, United States; Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, IN, 47907, United States
| | - Emily Llewellyn
- Summer Research Opportunities Program, Purdue, University, West Lafayette, IN, 47907, United States; Department of Biology, Utah Valley University, Orem, Utah, 84058, United States
| | - Jason R Cannon
- School of Health Sciences, Purdue University, West Lafayette, IN, 47907, United States; Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, IN, 47907, United States.
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Baldauf KJ, Salazar-González RA, Doll MA, Pierce WM, States JC, Hein DW. Role of Human N-Acetyltransferase 2 Genetic Polymorphism on Aromatic Amine Carcinogen-Induced DNA Damage and Mutagenicity in a Chinese Hamster Ovary Cell Mutation Assay. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:235-245. [PMID: 31490564 PMCID: PMC7017392 DOI: 10.1002/em.22331] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/27/2019] [Accepted: 08/30/2019] [Indexed: 05/10/2023]
Abstract
Carcinogenic aromatic amines such as 4-aminobiphenyl (ABP) and 2-aminofluorene (AF) require metabolic activation to form electrophilic intermediates that mutate DNA leading to carcinogenesis. Bioactivation of these carcinogens includes N-hydroxylation catalyzed by CYP1A2 followed by O-acetylation catalyzed by arylamine N-acetyltransferase 2 (NAT2). To better understand the role of NAT2 genetic polymorphism in ABP- and AF-induced mutagenesis and DNA damage, nucleotide excision repair-deficient (UV5) Chinese hamster ovary (CHO) cells were stably transfected with human CYP1A2 and either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles. ABP and AF both caused significantly (P < 0.001) greater mutagenesis measured at the hypoxanthine phosphoribosyl transferase (hprt) locus in the UV5/CYP1A2/NAT2*4 acetylator cell line compared to the UV5, UV5/CYP1A2, and UV5/CYP1A2/NAT2*5B cell lines. ABP- and AF-induced hprt mutant cDNAs were sequenced and over 80% of the single-base substitutions were at G:C base pairs. DNA damage also was quantified by γH2AX in-cell western assays and by identification and quantification of the two predominant DNA adducts, N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-ABP) and N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF) by liquid chromatography-mass spectrometry. DNA damage and adduct levels were dose-dependent, correlated highly with levels of hprt mutants, and were significantly (P < 0.0001) greater in the UV5/CYP1A2/NAT2*4 rapid acetylator cell line following treatment with ABP or AF as compared to all other cell lines. Our findings provide further clarity on the importance of O-acetylation in CHO mutagenesis assays for aromatic amines. They provide evidence that NAT2 genetic polymorphism modifies aromatic amine-induced DNA damage and mutagenesis that should be considered in human risk assessments following aromatic amine exposures. Environ. Mol. Mutagen. 61:235-245, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | | | | | | | - David W. Hein
- Correspondence to: David W. Hein, Kosair Charities CTR-Room 303, 505 South Hancock Street, Louisville, Kentucky 40202.
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Agim ZS, Cannon JR. Alterations in the nigrostriatal dopamine system after acute systemic PhIP exposure. Toxicol Lett 2018; 287:31-41. [PMID: 29378243 DOI: 10.1016/j.toxlet.2018.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/10/2018] [Accepted: 01/23/2018] [Indexed: 11/30/2022]
Abstract
Heterocyclic amines (HCAs) are primarily formed during cooking of meat at high temperature. HCAs have been extensively studied as mutagens and possible carcinogens. Emerging data suggest that HCAs are neurotoxic and may be relevant to Parkinson's disease (PD) etiology. However, the majority of HCAs have not been evaluated for in vivo neurotoxicity. Here, we investigated acute in vivo neurotoxicity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). PhIP is the most prevalent genotoxin in many types of meats. Adult, male Sprague-Dawley rats were subjected to acute, systemic PhIP at doses and time-points that have been extensively utilized in cancer studies (100 and 200 mg/kg for 8, 24 h) and evaluated for changes in dopaminergic, serotoninergic, GABAergic, and glutamatergic neurotransmission. PhIP exposure resulted in decreased striatal dopamine metabolite levels and dopamine turnover in the absence of changes to vesicular monoamine transporter 2 levels; other neurotransmitter systems were unaffected. Quantification of intracellular nitrotyrosine revealed higher levels of oxidative damage in dopaminergic neurons in the substantia nigra after PhIP exposure, while other neuronal populations were less sensitive. These changes occurred in the absence of an overt lesion to the nigrostriatal dopamine system. Collectively, our study suggests that acute PhIP treatment in vivo targets the nigrostriatal dopaminergic system and that PhIP should be further examined in chronic, low-dose studies for PD relevance.
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Affiliation(s)
- Zeynep Sena Agim
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, IN 47907, United States.
| | - Jason R Cannon
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, United States; Purdue Institute for Integrative Neurosciences, Purdue University, West Lafayette, IN 47907, United States.
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Fahrer J, Kaina B. Impact of DNA repair on the dose-response of colorectal cancer formation induced by dietary carcinogens. Food Chem Toxicol 2016; 106:583-594. [PMID: 27693244 DOI: 10.1016/j.fct.2016.09.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/10/2016] [Accepted: 09/27/2016] [Indexed: 12/30/2022]
Abstract
Colorectal cancer (CRC) is one of the most frequently diagnosed cancers, which is causally linked to dietary habits, notably the intake of processed and red meat. Processed and red meat contain dietary carcinogens, including heterocyclic aromatic amines (HCAs) and N-nitroso compounds (NOC). NOC are agents that induce various N-methylated DNA adducts and O6-methylguanine (O6-MeG), which are removed by base excision repair (BER) and O6-methylguanine-DNA methyltransferase (MGMT), respectively. HCAs such as the highly mutagenic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) cause bulky DNA adducts, which are removed from DNA by nucleotide excision repair (NER). Both O6-MeG and HCA-induced DNA adducts are linked to the occurrence of KRAS and APC mutations in colorectal tumors of rodents and humans, thereby driving CRC initiation and progression. In this review, we focus on DNA repair pathways removing DNA lesions induced by NOC and HCA and assess their role in protecting against mutagenicity and carcinogenicity in the large intestine. We further discuss the impact of DNA repair on the dose-response relationship in colorectal carcinogenesis in view of recent studies, demonstrating the existence of 'no effect' point of departures (PoDs), i.e. thresholds for genotoxicity and carcinogenicity. The available data support the threshold concept for NOC with DNA repair being causally involved.
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Affiliation(s)
- Jörg Fahrer
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
| | - Bernd Kaina
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
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Aarts JMMJG, Alink GM, Scherjon F, MacDonald K, Smith AC, Nijveen H, Roebroeks W. Fire Usage and Ancient Hominin Detoxification Genes: Protective Ancestral Variants Dominate While Additional Derived Risk Variants Appear in Modern Humans. PLoS One 2016; 11:e0161102. [PMID: 27655273 PMCID: PMC5031311 DOI: 10.1371/journal.pone.0161102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 07/29/2016] [Indexed: 11/19/2022] Open
Abstract
Studies of the defence capacity of ancient hominins against toxic substances may contribute importantly to the reconstruction of their niche, including their diets and use of fire. Fire usage implies frequent exposure to hazardous compounds from smoke and heated food, known to affect general health and fertility, probably resulting in genetic selection for improved detoxification. To investigate whether such genetic selection occurred, we investigated the alleles in Neanderthals, Denisovans and modern humans at gene polymorphisms well-known to be relevant from modern human epidemiological studies of habitual tobacco smoke exposure and mechanistic evidence. We compared these with the alleles in chimpanzees and gorillas. Neanderthal and Denisovan hominins predominantly possess gene variants conferring increased resistance to these toxic compounds. Surprisingly, we observed the same in chimpanzees and gorillas, implying that less efficient variants are derived and mainly evolved in modern humans. Less efficient variants are observable from the first early Upper Palaeolithic hunter-gatherers onwards. While not clarifying the deep history of fire use, our results highlight the long-term stability of the genes under consideration despite major changes in the hominin dietary niche. Specifically for detoxification gene variants characterised as deleterious by epidemiological studies, our results confirm the predominantly recent appearance reported for deleterious human gene variants, suggesting substantial impact of recent human population history, including pre-Holocene expansions.
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Affiliation(s)
- Jac M. M. J. G. Aarts
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, Wageningen, The Netherlands
- * E-mail:
| | - Gerrit M. Alink
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
- Division of Toxicology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands
| | - Fulco Scherjon
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
| | | | - Alison C. Smith
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
| | - Harm Nijveen
- Bioinformatics Group, Department of Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Wil Roebroeks
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
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Malfatti MA, Kuhn EA, Turteltaub KW, Vickers SM, Jensen EH, Strayer L, Anderson KE. Disposition of the Dietary Mutagen 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline in Healthy and Pancreatic Cancer Compromised Humans. Chem Res Toxicol 2016; 29:352-8. [PMID: 26918625 PMCID: PMC4831706 DOI: 10.1021/acs.chemrestox.5b00495] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pancreatic cancer is the fourth leading cause of cancer death in the U.S. Once diagnosed, prognosis is poor with a 5-year survival rate of less than 5%. Exposure to carcinogenic heterocyclic amines (HCAs) derived from cooked meat has been shown to be positively associated with pancreatic cancer risk. To evaluate the processes that determine the carcinogenic potential of HCAs for human pancreas, 14-carbon labeled 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), a putative human carcinogenic HCA found in well-done cooked meat, was administered at a dietary relevant dose to human volunteers diagnosed with pancreatic cancer undergoing partial pancreatectomy and healthy control volunteers. After (14)C-MeIQx exposure, blood and urine were collected for pharmacokinetic and metabolite analysis. MeIQx-DNA adducts levels were quantified by accelerator mass spectrometry from pancreatic tissue excised during surgery from the cancer patient group. Pharmacokinetic analysis of plasma revealed a rapid distribution of MeIQx with a plasma elimination half-life of approximately 3.5 h in 50% of the cancer patients and all of the control volunteers. In 2 of the 4 cancer patients, very low levels of MeIQx were detected in plasma and urine suggesting low absorption from the gut into the plasma. Urinary metabolite analysis revealed five MeIQx metabolites with 2-amino-3-methylimidazo[4,5-f]quinoxaline-8-carboxylic acid being the most abundant accounting for 25%-50% of the recovered 14-carbon/mL urine. There was no discernible difference in metabolite levels between the cancer patient volunteers and the control group. MeIQx-DNA adduct analysis of pancreas and duodenum tissue revealed adduct levels indistinguishable from background levels. Although other meat-derived HCA mutagens have been shown to bind DNA in pancreatic tissue, indicating that exposure to HCAs from cooked meat cannot be discounted as a risk factor for pancreatic cancer, the results from this current study show that exposure to a single dietary dose of MeIQx does not readily form measurable DNA adducts under the conditions of the experiment.
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Affiliation(s)
- Michael A Malfatti
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , 7000 East Avenue, L-452, Livermore, California 94550, United States
| | - Edward A Kuhn
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , 7000 East Avenue, L-452, Livermore, California 94550, United States
| | - Kenneth W Turteltaub
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , 7000 East Avenue, L-452, Livermore, California 94550, United States
| | - Selwyn M Vickers
- University of Alabama , 1720 2nd Avenue South, Birmingham, Alabama 35233, United States
| | - Eric H Jensen
- University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Lori Strayer
- University of Minnesota , Minneapolis, Minnesota 55455, United States
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Jain A, Samykutty A, Jackson C, Browning D, Bollag WB, Thangaraju M, Takahashi S, Singh SR. Curcumin inhibits PhIP induced cytotoxicity in breast epithelial cells through multiple molecular targets. Cancer Lett 2015; 365:122-31. [PMID: 26004342 DOI: 10.1016/j.canlet.2015.05.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/13/2015] [Accepted: 05/14/2015] [Indexed: 12/21/2022]
Abstract
Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), found in cooked meat, is a known food carcinogen that causes several types of cancer, including breast cancer, as PhIP metabolites produce DNA adduct and DNA strand breaks. Curcumin, obtained from the rhizome of Curcuma longa, has potent anticancer activity. To date, no study has examined the interaction of PhIP with curcumin in breast epithelial cells. The present study demonstrates the mechanisms by which curcumin inhibits PhIP-induced cytotoxicity in normal breast epithelial cells (MCF-10A). Curcumin significantly inhibited PhIP-induced DNA adduct formation and DNA double stand breaks with a concomitant decrease in reactive oxygen species (ROS) production. The expression of Nrf2, FOXO targets; DNA repair genes BRCA-1, H2AFX and PARP-1; and tumor suppressor P16 was studied to evaluate the influence on these core signaling pathways. PhIP induced the expression of various antioxidant and DNA repair genes. However, co-treatment with curcumin inhibited this expression. PhIP suppressed the expression of the tumor suppressor P16 gene, whereas curcumin co-treatment increased its expression. Caspase-3 and -9 were slightly suppressed by curcumin with a consequent inhibition of cell death. These results suggest that curcumin appears to be an effective anti-PhIP food additive likely acting through multiple molecular targets.
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Affiliation(s)
- Ashok Jain
- Department of Natural Sciences, Albany State University, Albany, Georgia 31705, USA.
| | - Abhilash Samykutty
- Department of Natural Sciences, Albany State University, Albany, Georgia 31705, USA
| | - Carissa Jackson
- Department of Natural Sciences, Albany State University, Albany, Georgia 31705, USA
| | - Darren Browning
- Cancer Center, Georgia Regents University, Augusta, Georgia 30912, USA
| | - Wendy B Bollag
- Department of Physiology, Georgia Regents University, Augusta, Georgia 30912, USA; Charlie Norwood VA Medical Center, Augusta, Georgia 30904, USA
| | | | - Satoru Takahashi
- Department of Experimental Pathology and Tumor Biology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Shree Ram Singh
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA.
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Arlt VM, Singh R, Stiborová M, Gamboa da Costa G, Frei E, Evans JD, Farmer PB, Wolf CR, Henderson CJ, Phillips DH. Effect of hepatic cytochrome P450 (P450) oxidoreductase deficiency on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine-DNA adduct formation in P450 reductase conditional null mice. Drug Metab Dispos 2011; 39:2169-73. [PMID: 21940903 DOI: 10.1124/dmd.111.041343] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), formed during the cooking of foods, induces colon cancer in rodents. PhIP is metabolically activated by cytochromes P450 (P450s). To evaluate the role of hepatic P450s in the bioactivation of PhIP, we used Reductase Conditional Null (RCN) mice, in which cytochrome P450 oxidoreductase (POR), the unique electron donor to P450s, can be specifically deleted in hepatocytes by pretreatment with 3-methylcholanthrene (3-MC), resulting in the loss of essentially all hepatic P450 function. RCN mice were treated orally with 50 mg/kg b.wt. PhIP daily for 5 days, with and without 3-MC pretreatment. PhIP-DNA adducts (i.e., N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine [dG-C8-PhIP]), measured by liquid chromatography-tandem mass spectrometry, were highest in colon (1362 adducts/10(8) deoxynucleosides), whereas adduct levels in liver were ∼3.5-fold lower. Whereas no differences in PhIP-DNA adduct levels were found in livers with active POR versus inactivated POR, adduct levels were on average ∼2-fold lower in extrahepatic tissues of mice lacking hepatic POR. Hepatic microsomes from RCN mice with or without 3-MC pretreatment were also incubated with PhIP and DNA in vitro. PhIP-DNA adduct formation was ∼8-fold lower with hepatic microsomes from POR-inactivated mice than with those with active POR. Most of the hepatic microsomal activation of PhIP in vitro was attributable to CYP1A. Our results show that PhIP-DNA adduct formation in colon involves hepatic N-oxidation, circulation of activated metabolites via the bloodstream to extrahepatic tissues, and further activation, resulting in the formation of dG-C8-PhIP. Besides hepatic P450s, PhIP may be metabolically activated mainly by a non-P450 pathway in liver.
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Affiliation(s)
- Volker M Arlt
- Section of Molecular Carcinogenesis, Institute of Cancer Research, Brookes Lawley Building, Sutton, Surrey SM2 5NG, UK.
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13
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Turesky RJ, Le Marchand L. Metabolism and biomarkers of heterocyclic aromatic amines in molecular epidemiology studies: lessons learned from aromatic amines. Chem Res Toxicol 2011; 24:1169-214. [PMID: 21688801 PMCID: PMC3156293 DOI: 10.1021/tx200135s] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct, and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels, and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs, and thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and emerging biomarkers of HAAs that may be implemented in molecular epidemiology studies are discussed.
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Affiliation(s)
- Robert J Turesky
- Division of Environmental Health Sciences, Wadsworth Center , Albany, New York 12201, United States.
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Singh R, Arlt VM, Henderson CJ, Phillips DH, Farmer PB, Gamboa da Costa G. Detection and quantitation of N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine adducts in DNA using online column-switching liquid chromatography tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:2155-62. [PMID: 20598652 PMCID: PMC2923026 DOI: 10.1016/j.jchromb.2010.06.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/03/2010] [Accepted: 06/03/2010] [Indexed: 10/19/2022]
Abstract
The heterocyclic aromatic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is formed by the grilled cooking of certain foods such as meats, poultry and fish. PhIP has been shown to induce tumours in the colon, prostate and mammary glands of rats and is regarded as a potential human dietary carcinogen. PhIP is metabolically activated via cytochrome P450 mediated oxidation to an N-hydroxylamino-PhIP intermediate that is subsequently converted to an ester by N-acetyltransferases or sulfotransferases and undergoes heterolytic cleavage to produce a PhIP-nitrenium ion, which reacts with DNA to form the N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP-C8-dG) adduct. Thus far, the detection and quantification of PhIP-DNA adducts has relied to a large extent on (32)P-postlabelling methodologies. In order to expand the array of available techniques for the detection and improved quantification of PhIP-C8-dG adducts in DNA we have developed an online column-switching liquid chromatography (LC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) selected reaction monitoring (SRM) method incorporating an isotopically [(13)C(10)]-labelled PhIP-C8-dG internal standard for the analysis of DNA enzymatically hydrolysed to 2'-deoxynucleosides. A dose-dependent increase was observed for PhIP-C8-dG adducts when salmon testis DNA was reacted with N-acetoxy-PhIP. Analysis of DNA samples isolated from colon tissue of mice treated by oral gavage daily for 5 days with 50 mg/kg body weight of PhIP resulted in the detection of an average level of 14.8+/-3.7 PhIP-C8-dG adducts per 10(6) 2'-deoxynucleosides. The method required 50 microg of hydrolysed animal DNA on column and the limit of detection for PhIP-C8-dG was 2.5 fmol (1.5 PhIP-C8-dG adducts per 10(8) 2'-deoxynucleosides). In summary, the LC-ESI-MS/MS SRM method provides for the rapid automation of the sample clean up and a reduction in matrix components that would otherwise interfere with the mass spectrometric analysis, with sufficient sensitivity and precision to analyse DNA adducts in animals exposed to PhIP.
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Affiliation(s)
- Rajinder Singh
- Cancer Biomarkers and Prevention Group, Biocentre, Department of Cancer Studies and Molecular Medicine, University of Leicester, University Road, Leicester LE1 7RH, UK.
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Metry KJ, Neale JR, Doll MA, Howarth AL, States JC, McGregor WG, Pierce WM, Hein DW. Effect of rapid human N-acetyltransferase 2 haplotype on DNA damage and mutagenesis induced by 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx). Mutat Res 2009; 684:66-73. [PMID: 20004212 DOI: 10.1016/j.mrfmmm.2009.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 12/01/2009] [Accepted: 12/02/2009] [Indexed: 01/01/2023]
Abstract
Heterocyclic amines such as 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) are dietary carcinogens generated when meats are cooked well-done. Bioactivation includes N-hydroxylation catalyzed by cytochrome P4501A2 (CYP1A2) followed by O-acetylation catalyzed by N-acetyltransferase 2 (NAT2). Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human CYP1A2 and either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles were treated with IQ or MeIQx to examine the effect of NAT2 genetic polymorphism on IQ- or MeIQx-induced DNA adducts and mutagenesis. MeIQx and IQ both induced decreases in cell survival and significantly (p<0.001) greater number of endogenous hypoxanthine phosphoribosyl transferase (hprt) mutants in the CYP1A2/NAT2*4 than the CYP1A2/NAT2*5B cell line. IQ- and MeIQx-induced hprt mutant cDNAs were sequenced and over 85% of the mutations were single-base substitutions with the remainder exon deletions likely caused by splice-site mutations. For the single-base substitutions, over 85% were at G:C base pairs. Deoxyguanosine (dG)-C8-IQ and dG-C8-MeIQx adducts were significantly (p<0.001) greater in the CYP1A2/NAT2*4 than the CYP1A2/NAT2*5B cell line. DNA adduct levels correlated very highly with hprt mutants for both IQ and MeIQx. These results suggest substantially increased risk for IQ- and MeIQx-induced DNA damage and mutagenesis in rapid NAT2 acetylators.
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Affiliation(s)
- Kristin J Metry
- Department of Pharmacology & Toxicology, James Graham Brown Cancer Center and Center for Environmental Genomics and Integrative Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA
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