1
|
Bakulski KM, Blostein F, London SJ. Linking Prenatal Environmental Exposures to Lifetime Health with Epigenome-Wide Association Studies: State-of-the-Science Review and Future Recommendations. ENVIRONMENTAL HEALTH PERSPECTIVES 2023; 131:126001. [PMID: 38048101 PMCID: PMC10695268 DOI: 10.1289/ehp12956] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 10/06/2023] [Accepted: 10/16/2023] [Indexed: 12/05/2023]
Abstract
BACKGROUND The prenatal environment influences lifetime health; epigenetic mechanisms likely predominate. In 2016, the first international consortium paper on cigarette smoking during pregnancy and offspring DNA methylation identified extensive, reproducible exposure signals. This finding raised expectations for epigenome-wide association studies (EWAS) of other exposures. OBJECTIVE We review the current state-of-the-science for DNA methylation associations across prenatal exposures in humans and provide future recommendations. METHODS We reviewed 134 prenatal environmental EWAS of DNA methylation in newborns, focusing on 51 epidemiological studies with meta-analysis or replication testing. Exposures spanned cigarette smoking, alcohol consumption, air pollution, dietary factors, psychosocial stress, metals, other chemicals, and other exogenous factors. Of the reproducible DNA methylation signatures, we examined implementation as exposure biomarkers. RESULTS Only 19 (14%) of these prenatal EWAS were conducted in cohorts of 1,000 or more individuals, reflecting the still early stage of the field. To date, the largest perinatal EWAS sample size was 6,685 participants. For comparison, the most recent genome-wide association study for birth weight included more than 300,000 individuals. Replication, at some level, was successful with exposures to cigarette smoking, folate, dietary glycemic index, particulate matter with aerodynamic diameter < 10 μ m and < 2.5 μ m , nitrogen dioxide, mercury, cadmium, arsenic, electronic waste, PFAS, and DDT. Reproducible effects of a more limited set of prenatal exposures (smoking, folate) enabled robust methylation biomarker creation. DISCUSSION Current evidence demonstrates the scientific premise for reproducible DNA methylation exposure signatures. Better powered EWAS could identify signatures across many exposures and enable comprehensive biomarker development. Whether methylation biomarkers of exposures themselves cause health effects remains unclear. We expect that larger EWAS with enhanced coverage of epigenome and exposome, along with improved single-cell technologies and evolving methods for integrative multi-omics analyses and causal inference, will expand mechanistic understanding of causal links between environmental exposures, the epigenome, and health outcomes throughout the life course. https://doi.org/10.1289/EHP12956.
Collapse
Affiliation(s)
| | - Freida Blostein
- University of Michigan, Ann Arbor, Michigan, USA
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Stephanie J. London
- National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services, Research Triangle Park, North Carolina, USA
| |
Collapse
|
2
|
The selected epigenetic effects of phthalates: DBP, BBP and their metabolites: MBP, MBzP on human peripheral blood mononuclear cells (In Vitro). Toxicol In Vitro 2022; 82:105369. [PMID: 35487445 DOI: 10.1016/j.tiv.2022.105369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 03/27/2022] [Accepted: 04/21/2022] [Indexed: 11/21/2022]
Abstract
Phthalates are classified as non-genotoxic carcinogens. These compounds do not cause direct DNA damage but may induce indirect DNA lesions leading to cancer development. In the presented paper we have studied the effect of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), and their metabolites, such as mono-n-butyl phthalate (MBP) and monobenzyl phthalate (MBzP) on selected epigenetic parameters in human peripheral blood mononuclear cells (PBMCs). The cells were incubated with tested phthalates at 0.001, 0.01 and 0.1 μg/mL for 24 h. Next, global DNA methylation, methylation in the promoter regions of tumor suppressor genes (P16, TP53) and proto-oncogenes (BCL2, CCND1) were assessed as well as the expression profile of the indicated genes was analysed. The obtained results have revealed significant reduction of global DNA methylation level in PBMCs exposed to BBP, MBP and MBzP. Phthalates changed methylation pattern of the tested genes, decreased expression of P16 and TP53 genes and increased the expression of BCL2 and CCND1. In conclusion, our results have shown that the examined phthalates disturbed the processes of methylation and expression of tumor suppressor genes (P16, TP53) and protooncogenes (BCL2, CCND1) in human PBMCs.
Collapse
|
3
|
Childebayeva A, Goodrich JM, Chesterman N, Leon-Velarde F, Rivera-Ch M, Kiyamu M, Brutsaert TD, Bigham AW, Dolinoy DC. Blood lead levels in Peruvian adults are associated with proximity to mining and DNA methylation. ENVIRONMENT INTERNATIONAL 2021; 155:106587. [PMID: 33940396 PMCID: PMC9903334 DOI: 10.1016/j.envint.2021.106587] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 06/05/2023]
Abstract
BACKGROUND Inorganic lead (Pb) is common in the environment, and is toxic to neurological, renal, and cardiovascular systems. Pb exposure influences the epigenome with documented effects on DNA methylation (DNAm). We assessed the impact of low levels of Pb exposure on DNAm among non-miner individuals from two locations in Peru: Lima, the capital, and Cerro de Pasco, a highland mining town, to study the effects of Pb exposure on physiological outcomes and DNAm. METHODS Pb levels were measured in whole blood (n = 305). Blood leukocyte DNAm was determined for 90 DNA samples using the Illumina MethylationEPIC chip. An epigenome-wide association study was performed to assess the relationship between Pb and DNAm. RESULTS Individuals from Cerro de Pasco had higher Pb than individuals from Lima (p-value = 2.00E-16). Males had higher Pb than females (p-value = 2.36E-04). Pb was positively associated with hemoglobin (p-value = 8.60E-04). In Cerro de Pasco, blood Pb decreased with the distance from the mine (p-value = 0.04), and association with soil Pb was approaching significance (p-value = 0.08). We identified differentially methylated positions (DMPs) associated with genes SOX18, ZMIZ1, and KDM1A linked to neurological function. We also found 45 differentially methylated regions (DMRs), seven of which were associated with genes involved in metal ion binding and nine to neurological function and development. CONCLUSIONS Our results demonstrate that even low levels of Pb can have a significant impact on the body including changes to DNAm. We report associations between Pb and hemoglobin, Pb and distance from mining, and between blood and soil Pb. We also report associations between loci- and region-specific DNAm and Pb.
Collapse
Affiliation(s)
- Ainash Childebayeva
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA; Department of Archaeogenetics, Max Planck Institute for the Science of Human History, Jena 07745, Germany.
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nathan Chesterman
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA
| | - Fabiola Leon-Velarde
- Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Maria Rivera-Ch
- Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Melisa Kiyamu
- Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Tom D Brutsaert
- Department of Exercise Science, Syracuse University, Syracuse, NY 13244, USA
| | - Abigail W Bigham
- Department of Anthropology, University of California, Los Angeles, CA 90095, USA
| | - Dana C Dolinoy
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA; Department of Nutritional Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
4
|
Childebayeva A, Jones TR, Goodrich JM, Leon-Velarde F, Rivera-Chira M, Kiyamu M, Brutsaert TD, Dolinoy DC, Bigham AW. LINE-1 and EPAS1 DNA methylation associations with high-altitude exposure. Epigenetics 2019; 14:1-15. [PMID: 30574831 DOI: 10.1080/15592294.2018.1561117] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent discoveries indicate a genetic basis for high-altitude adaptation among human groups who have resided at high altitude for millennia, including Andeans, Tibetans, and Ethiopians. Yet, genetics alone does not explain the extent of variation in altitude-adaptive phenotypes. Current and past environments may also play a role, and one way to determine the effect of the environment is through the epigenome. To characterize if Andean adaptive responses to high altitude have an epigenetic component, we analyzed DNA methylation of the promoter region of EPAS1 and LINE-1 repetitive element among 572 Quechua individuals from high- (4,388 m) and low-altitude (0 m) in Peru. Participants recruited at high altitude had lower EPAS1 DNA methylation and higher LINE-1 methylation. Altitude of birth was associated with higher LINE-1 methylation, not with EPAS1 methylation. The number of years lived at high altitude was negatively associated with EPAS1 methylation and positively associated with LINE-1 methylation. We found four one-carbon metabolism SNPs (MTHFD1 rs2236225, TYMS rs502396, FOLH1 rs202676, GLDC rs10975681) that cumulatively explained 11.29% of the variation in average LINE-1 methylation. And identified an association between LINE-1 methylation and genome-wide SNP principal component 1 that distinguishes European from Indigenous American ancestry suggesting that European admixture decreases LINE-1 methylation. Our results indicate that both current and lifetime exposure to high-altitude hypoxia have an effect on EPAS1 and LINE-1 methylation among Andean Quechua, suggesting that epigenetic modifications may play a role in high-altitude adaptation.
Collapse
Affiliation(s)
- Ainash Childebayeva
- a Department of Anthropology , University of Michigan , Ann Arbor , MI , USA.,b Department of Environmental Health Sciences , School of Public Health, University of Michigan , Ann Arbor , MI , USA
| | - Tamara R Jones
- b Department of Environmental Health Sciences , School of Public Health, University of Michigan , Ann Arbor , MI , USA
| | - Jaclyn M Goodrich
- b Department of Environmental Health Sciences , School of Public Health, University of Michigan , Ann Arbor , MI , USA
| | - Fabiola Leon-Velarde
- c Departamento de Ciencias Biológicas y Fisiológicas , Universidad Peruana Cayetano Heredia , Lima , Peru
| | - Maria Rivera-Chira
- c Departamento de Ciencias Biológicas y Fisiológicas , Universidad Peruana Cayetano Heredia , Lima , Peru
| | - Melisa Kiyamu
- c Departamento de Ciencias Biológicas y Fisiológicas , Universidad Peruana Cayetano Heredia , Lima , Peru
| | - Tom D Brutsaert
- d Department of Exercise Science , Syracuse University , Syracuse , NY , USA
| | - Dana C Dolinoy
- b Department of Environmental Health Sciences , School of Public Health, University of Michigan , Ann Arbor , MI , USA.,e Department of Nutritional Sciences , School of Public Health, University of Michigan , Ann Arbor , MI , USA
| | - Abigail W Bigham
- a Department of Anthropology , University of Michigan , Ann Arbor , MI , USA
| |
Collapse
|
5
|
Moggs J, Terranova R. Chromatin dynamics underlying latent responses to xenobiotics. Toxicol Res (Camb) 2018; 7:606-617. [PMID: 30090610 PMCID: PMC6062062 DOI: 10.1039/c7tx00317j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/26/2018] [Indexed: 11/21/2022] Open
Abstract
Pleiotropic xenobiotics can trigger dynamic alterations in mammalian chromatin structure and function but many of these are likely non-adverse and simply reflect short-term changes in DNA transactions underlying normal homeostatic, adaptive and protective cellular responses. However, it is plausible that a subset of xenobiotic-induced perturbations of somatic tissue or germline epigenomes result in delayed-onset and long-lasting adverse effects, in particular if they occur during critical stages of growth and development. These could include reprogramming, dedifferentiation, uncontrolled growth, and cumulative toxicity effects through molecular memory of prior xenobiotic exposures or altered susceptibility to subsequent xenobiotic exposures. Here we discuss the current evidence for epigenetic mechanisms underlying latent responses to xenobiotics, and the potential for identifying molecular epigenetic changes that are prodromal to overt morphologic or functional toxicity phenotypes.
Collapse
Affiliation(s)
- Jonathan Moggs
- Preclinical Safety , Translational Medicine , Novartis Institutes for BioMedical Research , Basel , Switzerland
| | - Rémi Terranova
- Preclinical Safety , Translational Medicine , Novartis Institutes for BioMedical Research , Basel , Switzerland
| |
Collapse
|
6
|
Corton JC, Peters JM, Klaunig JE. The PPARα-dependent rodent liver tumor response is not relevant to humans: addressing misconceptions. Arch Toxicol 2017; 92:83-119. [PMID: 29197930 DOI: 10.1007/s00204-017-2094-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/12/2017] [Indexed: 12/17/2022]
Abstract
A number of industrial chemicals and therapeutic agents cause liver tumors in rats and mice by activating the nuclear receptor peroxisome proliferator-activated receptor α (PPARα). The molecular and cellular events by which PPARα activators induce rodent hepatocarcinogenesis have been extensively studied elucidating a number of consistent mechanistic changes linked to the increased incidence of liver neoplasms. The weight of evidence relevant to the hypothesized mode of action (MOA) for PPARα activator-induced rodent hepatocarcinogenesis is summarized here. Chemical-specific and mechanistic data support concordance of temporal and dose-response relationships for the key events associated with many PPARα activators. The key events (KE) identified in the MOA are PPARα activation (KE1), alteration in cell growth pathways (KE2), perturbation of hepatocyte growth and survival (KE3), and selective clonal expansion of preneoplastic foci cells (KE4), which leads to the apical event-increases in hepatocellular adenomas and carcinomas (KE5). In addition, a number of concurrent molecular and cellular events have been classified as modulating factors, because they potentially alter the ability of PPARα activators to increase rodent liver cancer while not being key events themselves. These modulating factors include increases in oxidative stress and activation of NF-kB. PPARα activators are unlikely to induce liver tumors in humans due to biological differences in the response of KEs downstream of PPARα activation. This conclusion is based on minimal or no effects observed on cell growth pathways and hepatocellular proliferation in human primary hepatocytes and absence of alteration in growth pathways, hepatocyte proliferation, and tumors in the livers of species (hamsters, guinea pigs and cynomolgus monkeys) that are more appropriate human surrogates than mice and rats at overlapping dose levels. Despite this overwhelming body of evidence and almost universal acceptance of the PPARα MOA and lack of human relevance, several reviews have selectively focused on specific studies that, as discussed, contradict the consensus opinion and suggest uncertainty. In the present review, we systematically address these most germane suggested weaknesses of the PPARα MOA.
Collapse
Affiliation(s)
- J Christopher Corton
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Dr, MD-B105-03, Research Triangle Park, NC, 27711, USA.
| | - Jeffrey M Peters
- The Department of Veterinary and Biomedical Sciences and Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA, 16803, USA
| | - James E Klaunig
- Department of Environmental Health, Indiana University, Bloomington, IN, 47402, USA
| |
Collapse
|
7
|
|
8
|
Coskran TM, Jiang Z, Klaunig JE, Mager DL, Obert L, Robertson A, Tsinoremas N, Wang Z, Gosink M. Induction of endogenous retroelements as a potential mechanism for mouse-specific drug-induced carcinogenicity. PLoS One 2017; 12:e0176768. [PMID: 28472135 PMCID: PMC5417610 DOI: 10.1371/journal.pone.0176768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 04/17/2017] [Indexed: 11/23/2022] Open
Abstract
A number of chemical compounds have been shown to induce liver tumors in mice but not in other species. While several mechanisms for this species-specific tumorigenicity have been proposed, no definitive mechanism has been established. We examined the effects of the nongenotoxic rodent hepatic carcinogen, WY-14,643, in male mice from a high liver tumor susceptible strain (C3H/HeJ), and from a low tumor susceptible strain (C57BL/6). WY-14,643, a PPARα activator induced widespread increases in the expression of some endogenous retroelements, namely members of LTR and LINE elements in both strains. The expression of a number of known retroviral defense genes was also elevated. We also demonstrated that basal immune-mediated viral defense was elevated in C57BL/6 mice (the resistant strain) and that WY-14,643 further activated those immuno-defense processes. We propose that the previously reported >100X activity of retroelements in mice drives mouse-specific tumorigenicity. We also propose that C57BL/6's competent immune to retroviral activation allows it to remove cells before the activation of these elements can result in significant chromosomal insertions and mutation. Finally, we showed that WY-14,643 treatment induced gene signatures of DNA recombination in the sensitive C3H/HeJ strain.
Collapse
Affiliation(s)
- Timothy M. Coskran
- Drug Safety Research & Development, Pfizer Inc., Groton, Connecticut, United States of America
| | - Zhijie Jiang
- Department of Computer Science, University of Miami, Miami, Florida, United States of America
| | - James E. Klaunig
- Environmental Health, Indiana University, Bloomington, Indiana, United States of America
| | - Dixie L. Mager
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, British Columbia, Canada
| | - Leslie Obert
- GlaxoSmithKline plc, King of Prussia, Pennsylvania, United States of America
| | - Andrew Robertson
- Drug Safety Research & Development, Pfizer Inc., Groton, Connecticut, United States of America
| | - Nicholas Tsinoremas
- Department of Computer Science, University of Miami, Miami, Florida, United States of America
| | - Zemin Wang
- Environmental Health, Indiana University, Bloomington, Indiana, United States of America
| | - Mark Gosink
- Drug Safety Research & Development, Pfizer Inc., Groton, Connecticut, United States of America
| |
Collapse
|
9
|
Silva-Martínez GA, Rodríguez-Ríos D, Alvarado-Caudillo Y, Vaquero A, Esteller M, Carmona FJ, Moran S, Nielsen FC, Wickström-Lindholm M, Wrobel K, Wrobel K, Barbosa-Sabanero G, Zaina S, Lund G. Arachidonic and oleic acid exert distinct effects on the DNA methylome. Epigenetics 2016; 11:321-34. [PMID: 27088456 DOI: 10.1080/15592294.2016.1161873] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Abnormal fatty acid metabolism and availability are landmarks of metabolic diseases, which in turn are associated with aberrant DNA methylation profiles. To understand the role of fatty acids in disease epigenetics, we sought DNA methylation profiles specifically induced by arachidonic (AA) or oleic acid (OA) in cultured cells and compared those with published profiles of normal and diseased tissues. THP-1 monocytes were stimulated with AA or OA and analyzed using Infinium HumanMethylation450 BeadChip (Illumina) and Human Exon 1.0 ST array (Affymetrix). Data were corroborated in mouse embryonic fibroblasts. Comparisons with publicly available data were conducted by standard bioinformatics. AA and OA elicited a complex response marked by a general DNA hypermethylation and hypomethylation in the 1-200 μM range, respectively, with a maximal differential response at the 100 μM dose. The divergent response to AA and OA was prominent within the gene body of target genes, where it correlated positively with transcription. AA-induced DNA methylation profiles were similar to the corresponding profiles described for palmitic acid, atherosclerosis, diabetes, obesity, and autism, but relatively dissimilar from OA-induced profiles. Furthermore, human atherosclerosis grade-associated DNA methylation profiles were significantly enriched in AA-induced profiles. Biochemical evidence pointed to β-oxidation, PPAR-α, and sirtuin 1 as important mediators of AA-induced DNA methylation changes. In conclusion, AA and OA exert distinct effects on the DNA methylome. The observation that AA may contribute to shape the epigenome of important metabolic diseases, supports and expands current diet-based therapeutic and preventive efforts.
Collapse
Affiliation(s)
| | - Dalia Rodríguez-Ríos
- a Department of Genetic Engineering , CINVESTAV Irapuato Unit , Irapuato , Mexico
| | - Yolanda Alvarado-Caudillo
- b Department of Medical Sciences , Division of Health Sciences, León Campus, University of Guanajuato , Mexico
| | - Alejandro Vaquero
- c Laboratory of Chromatin Biology, Cancer Epigenetics and Biology Program (PEBC) , IDIBELL, L'Hospitalet de Llobregat , Barcelona , Catalonia , Spain
| | - Manel Esteller
- d Laboratory of Cancer Epigenetics, Cancer Epigenetics and Biology Program (PEBC) , IDIBELL, L'Hospitalet de Llobregat , Barcelona , Catalonia , Spain
| | - F Javier Carmona
- d Laboratory of Cancer Epigenetics, Cancer Epigenetics and Biology Program (PEBC) , IDIBELL, L'Hospitalet de Llobregat , Barcelona , Catalonia , Spain
| | - Sebastian Moran
- d Laboratory of Cancer Epigenetics, Cancer Epigenetics and Biology Program (PEBC) , IDIBELL, L'Hospitalet de Llobregat , Barcelona , Catalonia , Spain
| | - Finn C Nielsen
- e Center for Genomic Medicine, Rigshospitalet , University of Copenhagen , Copenhagen , Denmark
| | - Marie Wickström-Lindholm
- f Experimental Cardiovascular Research , Malmö University Hospital, Lund University , Malmö , Sweden
| | - Katarzyna Wrobel
- g Department of Chemistry, Division of Natural and Exact Sciences, Guanajuato Campus , University of Guanajuato , Mexico
| | - Kazimierz Wrobel
- g Department of Chemistry, Division of Natural and Exact Sciences, Guanajuato Campus , University of Guanajuato , Mexico
| | - Gloria Barbosa-Sabanero
- b Department of Medical Sciences , Division of Health Sciences, León Campus, University of Guanajuato , Mexico
| | - Silvio Zaina
- b Department of Medical Sciences , Division of Health Sciences, León Campus, University of Guanajuato , Mexico
| | - Gertrud Lund
- a Department of Genetic Engineering , CINVESTAV Irapuato Unit , Irapuato , Mexico
| |
Collapse
|
10
|
Acharyya N, Deb B, Chattopadhyay S, Maiti S. Arsenic-Induced Antioxidant Depletion, Oxidative DNA Breakage, and Tissue Damages are Prevented by the Combined Action of Folate and Vitamin B12. Biol Trace Elem Res 2015; 168:122-32. [PMID: 25850544 DOI: 10.1007/s12011-015-0324-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/24/2015] [Indexed: 02/07/2023]
Abstract
Arsenic is a grade I human carcinogen. It acts by disrupting one-carbon (1C) metabolism and cellular methyl (-CH3) pool. The -CH3 group helps in arsenic disposition and detoxification of the biological systems. Vitamin B12 and folate, the key promoters of 1C metabolism were tested recently (daily 0.07 and 4.0 μg, respectively/100 g b.w. of rat for 28 days) to evaluate their combined efficacy in the protection from mutagenic DNA-breakage and tissue damages. The selected tissues like intestine (first-pass site), liver (major xenobiotic metabolizer) and lung (major arsenic accumulator) were collected from arsenic-ingested (0.6 ppm/same schedule) female rats. The hemo-toxicity and liver and kidney functions were monitored. Our earlier studies on arsenic-exposed humans can correlate carcinogenesis with DNA damage. Here, we demonstrate that the supplementation of physiological/therapeutic dose of vitamin B12 and folate protected the rodents significantly from arsenic-induced DNA damage (DNA fragmentation and comet assay) and hepatic and renal tissue degeneration (histo-architecture, HE staining). The level of arsenic-induced free-radical products (TBARS and conjugated diene) was significantly declined by the restored actions of several antioxidants viz. urate, thiol, catalase, xanthine oxidase, lactoperoxidase, and superoxide dismutase in the tissues of vitamin-supplemented group. The alkaline phosphatase, transaminases, urea and creatinine (hepatic and kidney toxicity marker), and lactate dehydrogenase (tissue degeneration marker) were significantly impaired in the arsenic-fed group. But a significant protection was evident in the vitamin-supplemented group. In conclusion, the combined action of folate and B12 results in the restitution in the 1C metabolic pathway and cellular methyl pool. The cumulative outcome from the enhanced arsenic methylation and antioxidative capacity was protective against arsenic induced mutagenic DNA breakages and tissue damages.
Collapse
Affiliation(s)
- Nirmallya Acharyya
- Department of Biochemistry, Cell and Molecular Therapeutics Laboratory, Oriental Institute of Science and TechnologyVidyasagar University, Midnapore, West Bengal, 721102, India
- Department of Biotechnology, Oriental Institute of Science and Technology, Vidyasagar University, Midnapore, West Bengal, 721102, India
- Department of Biomedical Laboratory Science and Management, (UGC Innovative Department), Vidyasagar University, Midnapore, West Bengal, 721102, India
| | - Bimal Deb
- Department of Biomedical Laboratory Science and Management, (UGC Innovative Department), Vidyasagar University, Midnapore, West Bengal, 721102, India
| | - Sandip Chattopadhyay
- Department of Biomedical Laboratory Science and Management, (UGC Innovative Department), Vidyasagar University, Midnapore, West Bengal, 721102, India
| | - Smarajit Maiti
- Department of Biochemistry, Cell and Molecular Therapeutics Laboratory, Oriental Institute of Science and TechnologyVidyasagar University, Midnapore, West Bengal, 721102, India.
- Department of Biotechnology, Oriental Institute of Science and Technology, Vidyasagar University, Midnapore, West Bengal, 721102, India.
- Epidemiology and Human Health Division, Agricure Biotech Research Society, Midnapore, 721101, India.
| |
Collapse
|
11
|
Romagnolo DF, Zempleni J, Selmin OI. Nuclear receptors and epigenetic regulation: opportunities for nutritional targeting and disease prevention. Adv Nutr 2014; 5:373-85. [PMID: 25022987 PMCID: PMC4085186 DOI: 10.3945/an.114.005868] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Posttranslational modifications of histones, alterations in the recruitment and functions of non-histone proteins, DNA methylation, and changes in expression of noncoding RNAs contribute to current models of epigenetic regulation. Nuclear receptors (NRs) are a group of transcription factors that, through ligand-binding, act as sensors to changes in nutritional, environmental, developmental, pathophysiologic, and endocrine conditions and drive adaptive responses via gene regulation. One mechanism through which NRs direct gene expression is the assembly of transcription complexes with cofactors and coregulators that possess chromatin-modifying properties. Chromatin modifications can be transient or become part of the cellular "memory" and contribute to genomic imprinting. Because many food components bind to NRs, they can ultimately influence transcription of genes associated with biologic processes, such as inflammation, proliferation, apoptosis, and hormonal response, and alter the susceptibility to chronic diseases (e.g., cancer, diabetes, obesity). The objective of this review is to highlight how NRs influence epigenetic regulation and the relevance of dietary compound-NR interactions in human nutrition and for disease prevention and treatment. Identifying gene targets of unliganded and bound NRs may assist in the development of epigenetic maps for food components and dietary patterns. Progress in these areas may lead to the formulation of disease-prevention models based on epigenetic control by individual or associations of food ligands of NRs.
Collapse
Affiliation(s)
- Donato F Romagnolo
- Department of Nutritional Sciences and University of Arizona Cancer Center, University of Arizona, Tucson, AZ; and
| | - Janos Zempleni
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE
| | - Ornella I Selmin
- Department of Nutritional Sciences and University of Arizona Cancer Center, University of Arizona, Tucson, AZ; and
| |
Collapse
|
12
|
Steegenga WT, Boekschoten MV, Lute C, Hooiveld GJ, de Groot PJ, Morris TJ, Teschendorff AE, Butcher LM, Beck S, Müller M. Genome-wide age-related changes in DNA methylation and gene expression in human PBMCs. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9648. [PMID: 24789080 PMCID: PMC4082572 DOI: 10.1007/s11357-014-9648-x] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 03/18/2014] [Indexed: 05/13/2023]
Abstract
Aging is a progressive process that results in the accumulation of intra- and extracellular alterations that in turn contribute to a reduction in health. Age-related changes in DNA methylation have been reported before and may be responsible for aging-induced changes in gene expression, although a causal relationship has yet to be shown. Using genome-wide assays, we analyzed age-induced changes in DNA methylation and their effect on gene expression with and without transient induction with the synthetic transcription modulating agent WY14,643. To demonstrate feasibility of the approach, we isolated peripheral blood mononucleated cells (PBMCs) from five young and five old healthy male volunteers and cultured them with or without WY14,643. Infinium 450K BeadChip and Affymetrix Human Gene 1.1 ST expression array analysis revealed significant differential methylation of at least 5 % (ΔYO > 5 %) at 10,625 CpG sites between young and old subjects, but only a subset of the associated genes were also differentially expressed. Age-related differential methylation of previously reported epigenetic biomarkers of aging including ELOVL2, FHL2, PENK, and KLF14 was confirmed in our study, but these genes did not display an age-related change in gene expression in PBMCs. Bioinformatic analysis revealed that differentially methylated genes that lack an age-related expression change predominantly represent genes involved in carcinogenesis and developmental processes, and expression of most of these genes were silenced in PBMCs. No changes in DNA methylation were found in genes displaying transiently induced changes in gene expression. In conclusion, aging-induced differential methylation often targets developmental genes and occurs mostly without change in gene expression.
Collapse
Affiliation(s)
- Wilma T Steegenga
- Division of Human Nutrition, Wageningen University, Bomenweg 2, Wageningen, 6703 HD, The Netherlands,
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Terasaki N, Goodier JL, Cheung LE, Wang YJ, Kajikawa M, Kazazian HH, Okada N. In vitro screening for compounds that enhance human L1 mobilization. PLoS One 2013; 8:e74629. [PMID: 24040300 PMCID: PMC3770661 DOI: 10.1371/journal.pone.0074629] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 08/05/2013] [Indexed: 12/31/2022] Open
Abstract
The Long interspersed element 1 (LINE1 or L1) retrotransposon constitutes 17% of the human genome. There are currently 80-100 human L1 elements that are thought to be active in any diploid human genome. These elements can mobilize into new locations of the genome, resulting in changes in genomic information. Active L1s are thus considered to be a type of endogenous mutagen, and L1 insertions can cause disease. Certain stresses, such as gamma radiation, oxidative stress, and treatment with some agents, can induce transcription and/or mobilization of retrotransposons. In this study, we used a reporter gene assay in HepG2 cells to screen compounds for the potential to enhance the transcription of human L1. We assessed 95 compounds including genotoxic agents, substances that induce cellular stress, and commercially available drugs. Treatment with 15 compounds increased the L1 promoter activity by >1.5-fold (p<0.05) after 6 or 24 hours of treatment. In particular, genotoxic agents (benzo[a]pyrene, camptothecin, cytochalasin D, merbarone, and vinblastine), PPARα agonists (bezafibrate and fenofibrate), and non-steroidal anti-inflammatory drugs (diflunisal, flufenamic acid, salicylamide, and sulindac) induced L1 promoter activity. To examine their effects on L1 retrotransposition, we developed a high-throughput real-time retrotransposition assay using a novel secreted Gaussia luciferase reporter cassette. Three compounds (etomoxir, WY-14643, and salicylamide) produced a significant enhancement in L1 retrotransposition. This is the first study to report the effects of a wide variety of compounds on L1 transcription and retrotransposition. These results suggest that certain chemical- and drug-induced stresses might have the potential to cause genomic mutations by inducing L1 mobilization. Thus, the risk of induced L1 transcription and retrotransposition should be considered during drug safety evaluation and environmental risk assessments of chemicals.
Collapse
Affiliation(s)
- Natsuko Terasaki
- Department of Biological Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
| | - John L. Goodier
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ling E. Cheung
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yue J. Wang
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Masaki Kajikawa
- Department of Biological Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
| | - Haig H. Kazazian
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Norihiro Okada
- Department of Biological Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
- * E-mail:
| |
Collapse
|
14
|
Wu HC, Wang Q, Yang HI, Tsai WY, Chen CJ, Santella RM. Global DNA methylation in a population with aflatoxin B1 exposure. Epigenetics 2013; 8:962-9. [PMID: 23867725 DOI: 10.4161/epi.25696] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We previously reported that global DNA hypomethylation, measured as Sat2 methylation in white blood cells (WBC), and aflatoxin B1 (AFB1) exposure were associated with increased hepatocellular carcinoma risk. In this study, we assessed the association between AFB1 exposure and global DNA methylation. We measured LINE-1 and Sat2 methylation in WBC DNA samples from 1140 cancer free participants of the Cancer Screening Program (CSP) cohort. Blood and urine samples were used to determine the level of AFB1-albumin (AFB1-Alb) adducts and urinary AFB1 metabolites. In continuous models, we found reverse associations of urinary AFB1 with LINE-1 and Sat2 methylation. The odds ratio (OR) per 1 unit decrease were 1.12 (95%CI = 1.03-1.22) for LINE-1 and 1.48 (95%CI = 1.10-2.00) for Sat2 methylation. When compared with subjects in the highest quartile of LINE-1, we found that individuals in the 2nd and 3rd quartiles were less likely to have detectable AFB1-Alb adducts, with ORs (95%CI) of 0.61 (0.40-0.93), 0.61 (0.40-.94), and 1.09 (0.69-1.72), respectively. The OR for detectable AFB1-Alb was 1.81 (95%CI = 1.15-2.85) for subjects in the lowest quartile of Sat2 methylation. The OR for detection of urinary AFB1 for those with LINE-1 methylation in the lowest quartile compared with those in the highest quartile was 1.87 (95%CI = 1.15-3.04). The corresponding OR was 1.75 (95%CI = 1.08-2.82) for subjects in the lowest quartile of Sat2 methylation. The association between AFB1 exposure and global DNA methylation may have implications for the epigenetic effect of AFB1 on hepatocellular carcinoma development and also suggests that changes in DNA methylation may represent an epigenetic biomarker of dietary AFB1 exposure.
Collapse
Affiliation(s)
- Hui-Chen Wu
- Department of Environmental Health Sciences; Mailman School of Public Health of Columbia University; New York, NY USA
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
BACKGROUND Arsenic exposure has been linked to epigenetic modifications such as DNA methylation in in-vitro and animal studies. This association has also been explored in highly exposed human populations, but studies among populations environmentally exposed to low arsenic levels are lacking. METHODS We evaluated the association between exposure to arsenic, measured in toenails, and blood DNA methylation in Alu and Long Interspersed Nucleotide Element-1 (LINE-1) repetitive elements in elderly men environmentally exposed to low levels of arsenic. We also explored potential effect modification by plasma folate, cobalamin (vitamin B12), and pyridoxine (vitamin B6). The study population was 581 participants from the Normative Aging Study in Boston, of whom 434, 140, and 7 had 1, 2, and 3 visits, respectively, between 1999-2002 and 2006-2007. We used mixed-effects models and included interaction terms to assess potential effect modification by nutritional factors. RESULTS There was a trend of increasing Alu and decreasing LINE-1 DNA methylation as arsenic exposure increased. In subjects with plasma folate below the median (<14.1 ng/mL), arsenic was positively associated with Alu DNA methylation (β = 0.08 [95% confidence interval = 0.03 to 0.13] for one interquartile range [0.06 μg/g] increase in arsenic), whereas a negative association was observed in subjects with plasma folate above the median (β = -0.08 [-0.17 to 0.01]). CONCLUSIONS We found an association between arsenic exposure and DNA methylation in Alu repetitive elements that varied by folate level. This suggests a potential role for nutritional factors in arsenic toxicity.
Collapse
|
16
|
Caldwell JC. DEHP: Genotoxicity and potential carcinogenic mechanisms—A review. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:82-157. [DOI: 10.1016/j.mrrev.2012.03.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/22/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
|
17
|
Pogribny IP, Beland FA. DNA methylome alterations in chemical carcinogenesis. Cancer Lett 2012; 334:39-45. [PMID: 23010082 DOI: 10.1016/j.canlet.2012.09.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/28/2012] [Accepted: 09/14/2012] [Indexed: 01/30/2023]
Abstract
Carcinogenesis, a complex multifactorial process of the transformation of normal cells into malignant cells, is characterized by many biologically significant and interdependent alterations triggered by the mutational and/or non-mutational (i.e., epigenetic) events. One of these events, specific to all types of cancer, is alterations in DNA methylation. This review summarizes the current knowledge of the role of DNA methylation changes induced by various genotoxic chemicals (carcinogenic agents that interact with DNA) and non-genotoxic carcinogens (chemicals causing tumor by mechanisms other than directly damaging DNA) in the lung, colorectal, liver, and hematologic carcinogenesis. It also emphasizes the potential role for epigenetic changes to serve as markers for carcinogen exposure and carcinogen risk assessment.
Collapse
Affiliation(s)
- Igor P Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
| | - Frederick A Beland
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
| |
Collapse
|
18
|
Koturbash I, Simpson NE, Beland FA, Pogribny IP. Alterations in histone H4 lysine 20 methylation: implications for cancer detection and prevention. Antioxid Redox Signal 2012; 17:365-74. [PMID: 22035019 DOI: 10.1089/ars.2011.4370] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
SIGNIFICANCE Cancer development and progression are associated with numerous genetic, epigenetic, and metabolic changes. RECENT ADVANCES A number of epigenetic aberrations have been characterized in cancer, including DNA methylation and various histone modification changes. One of the most unique and enigmatic epigenetic marks that is noticeably altered in several major human cancers is methylation of histone H4 lysine 20; however, there is insufficient knowledge of the underlying molecular mechanisms associated with this abberation. CRITICAL ISSUES This review presents current evidence of the role of histone H4 lysine 20 methylation in normal and cancer cells and during tumorigenesis induced by genotoxic and nongenotoxic carcinogens. Additionally, it describes molecular mechanisms that may cause this alteration and highlights the significance of this epigenetic mark as an early indicator of carcinogenesis. FUTURE DIRECTIONS Accumulating evidence suggests that dietary components may be significant regulators of the cellular epigenome, including histone methylation, by providing and maintaining the adequate levels of S-adenosyl-L-methionine, flavin adenine dinucleotide, α-ketoglutarate, and iron. Future research should elucidate the potential for modifying cellular metabolism through dietary intervention for timely regulation of the epigenome as means for the prevention of cancer development.
Collapse
Affiliation(s)
- Igor Koturbash
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
| | | | | | | |
Collapse
|
19
|
Koturbash I, Scherhag A, Sorrentino J, Sexton K, Bodnar W, Tryndyak V, Latendresse JR, Swenberg JA, Beland FA, Pogribny IP, Rusyn I. Epigenetic alterations in liver of C57BL/6J mice after short-term inhalational exposure to 1,3-butadiene. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:635-40. [PMID: 21147608 PMCID: PMC3094413 DOI: 10.1289/ehp.1002910] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 12/13/2010] [Indexed: 05/25/2023]
Abstract
BACKGROUND 1,3-Butadiene (BD) is a high-volume industrial chemical and a known human carcinogen. The main mode of BD carcinogenicity is thought to involve formation of genotoxic epoxides. OBJECTIVES In this study we tested the hypothesis that BD may be epigenotoxic (i.e., cause changes in DNA and histone methylation) and explored the possible molecular mechanisms for the epigenetic changes. METHODS AND RESULTS We administered BD (6.25 and 625 ppm) to C57BL/6J male mice by inhalation for 2 weeks (6 hr/day, 5 days a week) and then examined liver tissue from these mice for signs of toxicity using histopathology and gene expression analyses. We observed no changes in mice exposed to 6.25 ppm BD, but glycogen depletion and dysregulation of hepatotoxicity biomarker genes were observed in mice exposed to 625 ppm BD. We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation. In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3-9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks. Although the epigenetic effects were most pronounced in the 625-ppm exposure group, some effects were evident in mice exposed to 6.25 ppm BD. CONCLUSIONS This study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity.
Collapse
Affiliation(s)
- Igor Koturbash
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Anne Scherhag
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
- Technical University of Kaiserslautern, Kaiserslautern, Rheinland-Pfalz, Germany
| | - Jessica Sorrentino
- Curriculum in Toxicology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kenneth Sexton
- Department of Environmental Sciences and Engineering, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Wanda Bodnar
- Department of Environmental Sciences and Engineering, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Volodymyr Tryndyak
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - John R. Latendresse
- Toxicologic Pathology Associates, National Center for Toxicological Research, Jefferson, Arkansas, USA
| | - James A. Swenberg
- Curriculum in Toxicology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Environmental Sciences and Engineering, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| | - Frederick A. Beland
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Igor P. Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA
| | - Ivan Rusyn
- Curriculum in Toxicology, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Environmental Sciences and Engineering, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
| |
Collapse
|
20
|
Koturbash I, Beland FA, Pogribny IP. Role of epigenetic events in chemical carcinogenesis—a justification for incorporating epigenetic evaluations in cancer risk assessment. Toxicol Mech Methods 2011; 21:289-97. [DOI: 10.3109/15376516.2011.557881] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
21
|
Bradford BU, Lock EF, Kosyk O, Kim S, Uehara T, Harbourt D, DeSimone M, Threadgill DW, Tryndyak V, Pogribny IP, Bleyle L, Koop DR, Rusyn I. Interstrain differences in the liver effects of trichloroethylene in a multistrain panel of inbred mice. Toxicol Sci 2011; 120:206-17. [PMID: 21135412 PMCID: PMC3044200 DOI: 10.1093/toxsci/kfq362] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 11/17/2010] [Indexed: 12/11/2022] Open
Abstract
Trichloroethylene (TCE) is a widely used industrial chemical and a common environmental contaminant. It is a well-known carcinogen in rodents and a probable carcinogen in humans. Studies utilizing panels of mouse inbred strains afford a unique opportunity to understand both metabolic and genetic basis for differences in responses to TCE. We tested the hypothesis that strain- and liver-specific toxic effects of TCE are genetically controlled and that the mechanisms of toxicity and susceptibility can be uncovered by exploring responses to TCE using a diverse panel of inbred mouse strains. TCE (2100 mg/kg) or corn oil vehicle was administered by gavage to 6- to 8-week-old male mice of 15 mouse strains. Serum and liver were collected at 2, 8, and 24 h postdosing and were analyzed for TCE metabolites, hepatocellular injury, and gene expression of liver. TCE metabolism, as evident from the levels of individual oxidative and conjugative metabolites, varied considerably between strains. TCE treatment-specific effect on the liver transcriptome was strongly dependent on genetic background. Peroxisome proliferator-activated receptor-mediated molecular networks, consisting of the metabolism genes known to be induced by TCE, represent some of the most pronounced molecular effects of TCE treatment in mouse liver that are dependent on genetic background. Conversely, cell death, liver necrosis, and immune-mediated response pathways, which are altered by TCE treatment in liver, are largely genetic background independent. These studies provide better understanding of the mechanisms of TCE-induced toxicity anchored on metabolism and genotype-phenotype correlations that may define susceptibility or resistance.
Collapse
Affiliation(s)
| | - Eric F. Lock
- Department of Statistics and Operations Research, and
| | - Oksana Kosyk
- Department of Environmental Sciences and Engineering
| | - Sungkyoon Kim
- Department of Environmental Sciences and Engineering
| | - Takeki Uehara
- Department of Environmental Sciences and Engineering
| | - David Harbourt
- Department of Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Michelle DeSimone
- Department of Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - David W. Threadgill
- Department of Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
| | | | - Igor P. Pogribny
- National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Lisa Bleyle
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239
| | - Dennis R. Koop
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239
| | - Ivan Rusyn
- Department of Environmental Sciences and Engineering
- Department of Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27599
| |
Collapse
|
22
|
Lei J, Hasegawa H, Matsumoto T, Yasukawa M. Peroxisome proliferator-activated receptor α and γ agonists together with TGF-β convert human CD4+CD25- T cells into functional Foxp3+ regulatory T cells. THE JOURNAL OF IMMUNOLOGY 2010; 185:7186-98. [PMID: 21057085 DOI: 10.4049/jimmunol.1001437] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human peripheral CD4(+)CD25(-) T cells can be induced to express Foxp3 when activated in vitro by TCR stimulation with TGF-β and IL-2. However, these TGF-β-induced Foxp3(+) regulatory T cells (iTregs) lack a regulatory phenotype. From libraries of nuclear receptor ligands and bioactive lipids, we screened three peroxisome proliferator-activated receptor (PPAR)α (bezafibrate, GW7647, and 5,8,11,14-eicosatetraynoic acid) and two PPARγ agonists (ciglitazone and 15-deoxy-Δ-(12,14)-PG J(2)) as molecules that increased Foxp3 expression in human iTregs significantly compared with that in DMSO-treated iTregs (control). These PPARα and PPARγ agonist-treated iTregs maintained a high level of Foxp3 expression and had suppressive properties. There were no significant differences in the suppressive properties of iTregs treated with the three PPARα and two PPARγ agonists, and all of the treated iTregs increased demethylation levels of the Foxp3 promoter and intronic conserved noncoding sequence 3 regions. Furthermore, PPARα and PPARγ agonists, together with TGF-β, more strongly inhibited the expression of all three DNA methyltransferases (DNMTs) (DNMT1, DNMT3a, and DNMT3b) in activated CD4(+) T cells. These results demonstrate that PPARα and PPARγ agonists together with TGF-β elicit Foxp3 DNA demethylation through potent downregulation of DNMTs and induce potent and stable Foxp3 expression, resulting in the generation of functional iTregs. Moreover, trichostatin A and retinoic acid enhanced the generation of iTregs synergistically with PPARα and PPARγ agonists.
Collapse
Affiliation(s)
- Jin Lei
- Department of Bioregulatory Medicine, Ehime University Graduate School of Medicine, Ehime, Japan
| | | | | | | |
Collapse
|
23
|
Wright RO, Schwartz J, Wright RJ, Bollati V, Tarantini L, Park SK, Hu H, Sparrow D, Vokonas P, Baccarelli A. Biomarkers of lead exposure and DNA methylation within retrotransposons. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:790-5. [PMID: 20064768 PMCID: PMC2898855 DOI: 10.1289/ehp.0901429] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 01/11/2010] [Indexed: 05/02/2023]
Abstract
BACKGROUND DNA methylation is an epigenetic mark that regulates gene expression. Changes in DNA methylation within white blood cells may result from cumulative exposure to environmental metals such as lead. Bone lead, a marker of cumulative exposure, may therefore better predict DNA methylation than does blood lead. OBJECTIVE In this study we compared associations between lead biomarkers and DNA methylation. METHODS We measured global methylation in participants of the Normative Aging Study (all men) who had archived DNA samples. We measured patella and tibia lead levels by K-X-Ray fluorescence and blood lead by atomic absorption spectrophotometry. DNA samples from blood were used to determine global methylation averages within CpG islands of long interspersed nuclear elements-1 (LINE-1) and Alu retrotransposons. A mixed-effects model using repeated measures of Alu or LINE-1 as the dependent variable and blood/bone lead (tibia or patella in separate models) as the primary exposure marker was fit to the data. RESULTS Overall mean global methylation (+/- SD) was 26.3 +/- 1.0 as measured by Alu and 76.8 +/- 1.9 as measured by LINE-1. In the mixed-effects model, patella lead levels were inversely associated with LINE-1 (beta = -0.25; p < 0.01) but not Alu (beta = -0.03; p = 0.4). Tibia lead and blood lead did not predict global methylation for either Alu or LINE-1. CONCLUSION Patella lead levels predicted reduced global DNA methylation within LINE-1 elements. The association between lead exposure and LINE-1 DNA methylation may have implications for the mechanisms of action of lead on health outcomes, and also suggests that changes in DNA methylation may represent a biomarker of past lead exposure.
Collapse
Affiliation(s)
- Robert O. Wright
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Department of Pediatrics, Children’s Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA
| | - Joel Schwartz
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Rosalind J. Wright
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- The Channing Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Address correspondence to R.O. Wright, Department of Environmental Health, Harvard School of Public Health, Landmark Center, Third Floor East, 401 Park Dr., Boston, MA 02215 USA. Telephone: (617) 384-8870. Fax: (617) 384-8994. E-mail:
| | - Valentina Bollati
- Laboratory of Environmental Epigenetics, Department of Occupational and Environmental Health, IRCCS Maggiore Policlinico Hospital, Mangiagalli e Regina Elena Foundation and Università degli Studi di Milano, Milan, Italy
| | - Letizia Tarantini
- Laboratory of Environmental Epigenetics, Department of Occupational and Environmental Health, IRCCS Maggiore Policlinico Hospital, Mangiagalli e Regina Elena Foundation and Università degli Studi di Milano, Milan, Italy
| | - Sung Kyun Park
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Howard Hu
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - David Sparrow
- VA Normative Aging Study, VA Boston Healthcare System and Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Pantel Vokonas
- VA Normative Aging Study, VA Boston Healthcare System and Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Andrea Baccarelli
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
- Laboratory of Environmental Epigenetics, Department of Occupational and Environmental Health, IRCCS Maggiore Policlinico Hospital, Mangiagalli e Regina Elena Foundation and Università degli Studi di Milano, Milan, Italy
| |
Collapse
|
24
|
Kostka G, Urbanek-Olejnik K, Wiadrowska B. Di-butyl phthalate-induced hypomethylation of the c-myc gene in rat liver. Toxicol Ind Health 2010; 26:407-16. [PMID: 20504828 DOI: 10.1177/0748233710369124] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Peroxisome proliferators (PPs)-induced DNA hypomethylation has been proposed as a mechanism of their toxicity, including carcinogenic action. The effect of di-butyl phthalate (DBP), a known peroxisome proliferators, on the methylation level of the c-myc promoter region in rat liver was studied. Changes in the methylation status of the c-myc gene were correlated with changes in DNA synthesis, DNA methyltransferase (DNMTs) activity and liver weight. Male Wistar rats received DBP in one, three or fourteen daily oral doses of 1800 mg/kg body weight (b.w.) x day(-1) (this dose is close to the dose that increases the numbers of peroxisomes in male Wistar rats). We have demonstrated that DBP decreased the methylation of the c-myc gene. Cytosine hypomethylation in the analyzed CpG sites of the c-myc gene promoter occurred during the whole period of study, although after 14 doses of DBP the difference from control was only on the borderline of significance (p = 0.066). An increase in DNA synthesis was only observed after 24 hours of treatment with DBP, and it preceded liver growth. We hypothesize that DBP-induced demethylation of the c-myc gene was an active mechanism, not associated with DNMTs activity and DNA replication.
Collapse
Affiliation(s)
- Grazyna Kostka
- Department of Environmental Toxicology, National Institute of Public Health-National Institute of Hygiene, Chocimska, Warsaw, Poland.
| | | | | |
Collapse
|
25
|
Rebollo R, Horard B, Hubert B, Vieira C. Jumping genes and epigenetics: Towards new species. Gene 2010; 454:1-7. [DOI: 10.1016/j.gene.2010.01.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 01/06/2010] [Accepted: 01/19/2010] [Indexed: 01/13/2023]
|
26
|
Asano J, Kudo T, Shimizu T, Fan Y, Nanashima N, Yamana D, Miura T, Yamada T, Tsuchida S. Histone acetylation and steroid receptor coactivator expression during clofibrate-induced rat hepatocarcinogenesis. Cancer Sci 2010; 101:869-75. [PMID: 20132223 PMCID: PMC11158118 DOI: 10.1111/j.1349-7006.2009.01460.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Peroxisome proliferators (PPs), non-genotoxic rodent carcinogens, cause the induction of the peroxisomal fatty acid beta-oxidation system, including bifunctional enzyme (BE) and 3-ketoacyl-CoA thiolase (TH), in the liver. GST M1 gene is polymorphic in Sprague-Dawley rats, NC- and KS-type. The KS-type rats showed enhanced susceptibility to ethyl-alpha-chlorophenoxyisobutyrate (clofibrate, CF), one of the PPs. The degree of BE induction was higher in the KS-type and preneoplastic foci developed after 6-8 weeks of treatment, whereas no foci developed in the NC-type. In the preset study, factors involved in different BE inducibility were investigated. There were no differences in hepatic peroxisome proliferator-activated receptor (PPAR) alpha levels between them. Among various coactivators for PPARalpha, only steroid receptor coactivator (SRC)-3 level was higher in the KS-type. To investigate the association between PPARalpha and SRC-3 or other proteins, nuclear extracts from CF-treated livers were applied to a PPARalpha column. In the KS-type, 110, 72, and 42 kDa proteins were bound and these were identified as SRC-3, BE, and TH, respectively. EMSA supported the binding of these proteins to PPARalpha associated to the BE enhancer in CF-treated KS-type, but not in the NC-type. Histone H3 acetylation was increased 11-fold in the KS-type by CF treatment but not in the NC-type. As BE and TH are responsible for acetyl-CoA production and SRC-3 possesses a histone acetyltransferase activity, these results suggest that enhanced BE induction in the KS-type livers is due to acetylation-mediated transcriptional activation and epigenetic mechanisms might be involved in CF-induced rat hepatocarcinogenesis.
Collapse
Affiliation(s)
- Jumpei Asano
- Department of Biochemistry and Genome Biology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Guyton KZ, Chiu WA, Bateson TF, Jinot J, Scott CS, Brown RC, Caldwell JC. A reexamination of the PPAR-alpha activation mode of action as a basis for assessing human cancer risks of environmental contaminants. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:1664-72. [PMID: 20049115 PMCID: PMC2801168 DOI: 10.1289/ehp.0900758] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 05/14/2009] [Indexed: 05/17/2023]
Abstract
BACKGROUND Diverse environmental contaminants, including the plasticizer di(2-ethylhexyl)phthalate (DEHP), are hepatocarcinogenic peroxisome proliferators in rodents. Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) activation and its sequelae have been proposed to constitute a mode of action (MOA) for hepatocarcinogenesis by such agents as a sole causative factor. Further, based on a hypothesized lower sensitivity of humans to this MOA, prior reviews have concluded that rodent hepatocarcinogenesis by PPAR-alpha agonists is irrelevant to human carcinogenic risk. DATA SYNTHESIS Herein, we review recent studies that experimentally challenge the PPAR-alpha activation MOA hypothesis, providing evidence that DEHP is hepatocarcinogenic in PPAR-alpha-null mice and that the MOA but not hepatocarcinogenesis is evoked by PPAR-alpha activation in a transgenic mouse model. We further examine whether relative potency for PPAR-alpha activation or other steps in the MOA correlates with tumorigenic potency. In addition, for most PPAR-alpha agonists of environmental concern, available data are insufficient to characterize relative human sensitivity to this rodent MOA or to induction of hepatocarcinogenesis. CONCLUSIONS Our review and analyses raise questions about the hypothesized PPAR-alpha activation MOA as a sole explanation for rodent hepatocarcinogenesis by PPAR-alpha agonists and therefore its utility as a primary basis for assessing human carcinogenic risk from the diverse compounds that activate PPAR-alpha. These findings have broad implications for how MOA hypotheses are developed, tested, and applied in human health risk assessment. We discuss alternatives to the current approaches to these key aspects of mechanistic data evaluation.
Collapse
Affiliation(s)
- Kathryn Z. Guyton
- Address correspondence to K.Z. Guyton, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Mail Code: 8623P, Washington, DC 20460 USA. Telephone: (703) 347-8562. Fax: (703) 347-8692. E-mail:
| | | | | | | | | | | | | |
Collapse
|
28
|
Pogribny IP, Tryndyak VP, Bagnyukova TV, Melnyk S, Montgomery B, Ross SA, Latendresse JR, Rusyn I, Beland FA. Hepatic epigenetic phenotype predetermines individual susceptibility to hepatic steatosis in mice fed a lipogenic methyl-deficient diet. J Hepatol 2009; 51:176-86. [PMID: 19450891 PMCID: PMC2773516 DOI: 10.1016/j.jhep.2009.03.021] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 02/15/2009] [Accepted: 03/02/2009] [Indexed: 12/11/2022]
Abstract
BACKGROUND/AIMS The importance of epigenetic changes in etiology and pathogenesis of disease has been increasingly recognized. However, the role of epigenetic alterations in the genesis of hepatic steatosis and cause of individual susceptibilities to this pathological state are largely unknown. METHODS Male inbred C57BL/6J and DBA/2J mice were fed a lipogenic methyl-deficient diet (MDD) that causes liver injury similar to human non-alcoholic steatohepatitis (NASH) for 6, 12, or 18 weeks, and the status of global and repetitive elements cytosine methylation, histone modifications, and expression of proteins responsible for those epigenetic modifications in livers was determined. RESULTS The development of hepatic steatosis in inbred C57BL/6J and DBA/2J mice was accompanied by prominent epigenetic abnormalities. This was evidenced by pronounced loss of genomic and repetitive sequences cytosine methylation, especially at major and minor satellites, accompanied by increased levels of repeat-associated transcripts, aberrant histone modifications, and alterations in expression of the maintenance DNA methyltransferase 1 (DNMT1) and de novo DNMT3A proteins in the livers of both mouse strains. However, the DBA/2J mice, which were characterized by an initially lower degree of methylation of repetitive elements and lower extent of histone H3 lysine 9 (H3K9) and H3 lysine 27 (H3K27) trimethylation in the normal livers, as compared to those in the C57BL/6J mice, developed more prominent NASH-specific pathomorphological changes. CONCLUSIONS These results mechanistically link epigenetic alterations to the pathogenesis of hepatic steatosis and strongly suggest that differences in the cellular epigenetic status may be a predetermining factor to individual susceptibilities to hepatic steatosis.
Collapse
Affiliation(s)
- Igor P. Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| | - Volodymyr P. Tryndyak
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| | - Tetyana V. Bagnyukova
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| | - Stepan Melnyk
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Beverly Montgomery
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| | - Sharon A. Ross
- Division of Cancer Prevention, National Cancer Institute, Bethesda, MD 20892
| | - John R. Latendresse
- Toxicologic Pathology Associates, National Center for Toxicological Research, Jefferson, AR 72079
| | - Ivan Rusyn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599
| | - Frederick A. Beland
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| |
Collapse
|
29
|
Bibliography. Current world literature. Nutrition and metabolism. Curr Opin Lipidol 2009; 20:63-72. [PMID: 19106709 DOI: 10.1097/mol.0b013e32832402a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
30
|
Marlowe J, Teo SS, Chibout SD, Pognan F, Moggs J. Mapping the epigenome--impact for toxicology. EXS 2009; 99:259-88. [PMID: 19157065 DOI: 10.1007/978-3-7643-8336-7_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recent advances in technological approaches for mapping and characterizing the epigenome are generating a wealth of new opportunities for exploring the relationship between epigenetic modifications, human disease and the therapeutic potential of pharmaceutical drugs. While the best examples for xenobiotic-induced epigenetic perturbations come from the field of non-genotoxic carcinogenesis, there is growing evidence for the relevance of epigenetic mechanisms associated with a wide range of disease areas and drug targets. The application of epigenomic profiling technologies to drug safety sciences has great potential for providing novel insights into the molecular basis of long-lasting cellular perturbations including increased susceptibility to disease and/or toxicity, memory of prior immune stimulation and/or drug exposure, and transgenerational effects.
Collapse
Affiliation(s)
- Jennifer Marlowe
- Novartis Pharma AG, Investigative Toxicology, Preclinical Safety, Basel, Switzerland.
| | | | | | | | | |
Collapse
|
31
|
Isabel Panadero M, González MDC, Herrera E, Bocos C. Modulación del PPARα por agentes farmacológicos y naturales y sus implicaciones metabólicas. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS 2008. [DOI: 10.1016/s0214-9168(08)75789-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
32
|
Roberts R. Receptor-mediated toxicity: PPARα. Toxicol Lett 2008. [DOI: 10.1016/j.toxlet.2008.06.852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
33
|
Pogribny IP, Tryndyak VP, Boureiko A, Melnyk S, Bagnyukova TV, Montgomery B, Rusyn I. Mechanisms of peroxisome proliferator-induced DNA hypomethylation in rat liver. Mutat Res 2008; 644:17-23. [PMID: 18639561 DOI: 10.1016/j.mrfmmm.2008.06.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 06/11/2008] [Accepted: 06/19/2008] [Indexed: 01/05/2023]
Abstract
Genomic hypomethylation is a consistent finding in both human and animal tumors and mounting experimental evidence suggests a key role for epigenetic events in tumorigenesis. Furthermore, it has been suggested that early changes in DNA methylation and histone modifications may serve as sensitive predictive markers in animal testing for carcinogenic potency of environmental agents. Alterations in metabolism of methyl donors, disturbances in activity and/or expression of DNA methyltransferases, and presence of DNA single-strand breaks could contribute to the loss of cytosine methylation during carcinogenesis; however, the precise mechanisms of genomic hypomethylation induced by chemical carcinogens remain largely unknown. This study examined the mechanism of DNA hypomethylation during hepatocarcinogenesis induced by peroxisome proliferators WY-14,643 (4-chloro-6-(2,3-xylidino)-pyrimidynylthioacetic acid) and DEHP (di-(2-ethylhexyl)phthalate), agents acting through non-genotoxic mode of action. In the liver of male Fisher 344 rats exposed to WY-14,643 (0.1% (w/w), 5 months), the level of genomic hypomethylation increased by approximately 2-fold, as compared to age-matched controls, while in the DEHP group (1.2% (w/w), 5 months) DNA methylation did not change. Global DNA hypomethylation in livers from WY-14,643 group was accompanied by the accumulation of DNA single-strand breaks, increased cell proliferation, and diminished expression of DNA methyltransferase 1, while the metabolism of methyl donors was not affected. In contrast, none of these parameters changed significantly in rats fed DEHP. Since WY-14,643 is much more potent carcinogen than DEHP, we conclude that the extent of loss of DNA methylation may be related to the carcinogenic potential of the chemical agent, and that accumulation of DNA single-strand breaks coupled to the increase in cell proliferation and altered DNA methyltransferase expression may explain genomic hypomethylation during peroxisome proliferator-induced carcinogenesis.
Collapse
Affiliation(s)
- Igor P Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.
| | | | | | | | | | | | | |
Collapse
|
34
|
Pogribny IP, Rusyn I, Beland FA. Epigenetic aspects of genotoxic and non-genotoxic hepatocarcinogenesis: studies in rodents. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:9-15. [PMID: 17879298 PMCID: PMC2705440 DOI: 10.1002/em.20342] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Hepatocellular carcinoma, which is one of the most prevalent life-threatening human cancers, is showing an increased incidence worldwide. Recent evidence indicates that the development of hepatocellular carcinoma is associated with not only genetic alterations, but also with profound epigenetic changes. This review summarizes the current knowledge about epigenetic alterations during rodent hepatocarcinogenesis, considers the similarities and differences in epigenetic effects of genotoxic and non-genotoxic rodent liver carcinogens, and discusses the possible role of these effects in the causality of liver tumor development.
Collapse
Affiliation(s)
- Igor P Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
| | | | | |
Collapse
|