1
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Guttenplan JB, Chen KM, Sun YW, Shalaby NAE, Kosinska W, Desai D, Gowda K, Amin S, El-Bayoumy K. Effects of the Tobacco Carcinogens N'-Nitrosonornicotine and Dibenzo[ a, l]pyrene Individually and in Combination on DNA Damage in Human Oral Leukoplakia and on Mutagenicity and Mutation Profiles in lacI Mouse Tongue. Chem Res Toxicol 2019; 32:1893-1899. [PMID: 31433626 DOI: 10.1021/acs.chemrestox.9b00257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In previous studies, we showed that the topical application of dibenzo[a,l]pyrene (DB[a,l]P), also known as dibenzo[def,p]chrysene, to the oral cavity of mice induced oral squamous cell carcinoma. We also showed that dA and dG adducts likely account for most of the mutagenic activity of DB[a,l]P in the oral tissues in vivo. Here we report for the first time that the oral treatment of lacI mice with a combination of tobacco smoke carcinogens, DB[a,l]P and N'-nitrosonornicotine (NNN), induces a higher fraction of mutations than expected from a simple sum of their induced individual mutation fractions, and a change in the mutational profile compared with that expected from the sum of the individual agents. The mutational profile of the combination of agents resembled that of the P53 gene in human head and neck cancers more than that of either of the individual agents, in that the percentage of the major class of mutations (GC > AT transitions) is similar to that seen in the P53 gene. A preliminary study was performed to understand the origin of the unexpected mutagenesis observations by measuring specific DNA adducts produced by both NNN and DB[a,l]P in human oral leukoplakia cells. No significant differences in the expected and observed major adduct levels from either agent were observed between individual or combined treatments, suggesting that additional adducts are important in mutagenesis induced by the mixture. Taken together, the above observations support the use of this animal model not only to investigate tobacco smoke-induced oral cancer but also to study chemoprevention.
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Affiliation(s)
- Joseph B Guttenplan
- Department of Basic Science, College of Dentistry , New York University , New York , New York 10010 , United States.,Department of Environmental Medicine, School of Medicine , New York University , New York , New York 10019 , United States
| | | | | | - Nora A E Shalaby
- Department of Basic Science, College of Dentistry , New York University , New York , New York 10010 , United States
| | - Wieslawa Kosinska
- Department of Basic Science, College of Dentistry , New York University , New York , New York 10010 , United States
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2
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Burgos-Morón E, Pastor N, Orta ML, Jiménez-Alonso JJ, Vega-Holm M, Vega-Pérez JM, Iglesias-Guerra F, Mateos S, López-Lázaro M, Calderón-Montaño JM. Selective cytotoxic activity and DNA damage by an epoxyalkyl galactopyranoside. Drug Dev Res 2018; 79:426-436. [DOI: 10.1002/ddr.21483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/18/2018] [Accepted: 09/26/2018] [Indexed: 12/13/2022]
Affiliation(s)
| | - Nuria Pastor
- Department of Cell Biology, Faculty of Biology; University of Seville; Seville Spain
| | - Manuel Luis Orta
- Department of Cell Biology, Faculty of Biology; University of Seville; Seville Spain
| | | | - Margarita Vega-Holm
- Department of Organic and Medicinal Chemistry, Faculty of Pharmacy; University of Seville; Seville Spain
| | - José Manuel Vega-Pérez
- Department of Organic and Medicinal Chemistry, Faculty of Pharmacy; University of Seville; Seville Spain
| | - Fernando Iglesias-Guerra
- Department of Organic and Medicinal Chemistry, Faculty of Pharmacy; University of Seville; Seville Spain
| | - Santiago Mateos
- Department of Cell Biology, Faculty of Biology; University of Seville; Seville Spain
| | - Miguel López-Lázaro
- Department of Pharmacology, Faculty of Pharmacy; University of Seville; Seville Spain
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3
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Abstract
The eukaryotic global genomic nucleotide excision repair (GG-NER) pathway is the major mechanism that removes most bulky and some nonbulky lesions from cellular DNA. There is growing evidence that certain DNA lesions are repaired slowly or are entirely resistant to repair in cells, tissues, and in cell extract model assay systems. It is well established that the eukaryotic DNA lesion-sensing proteins do not detect the damaged nucleotide, but recognize the distortions/destabilizations in the native DNA structure caused by the damaged nucleotides. In this article, the nature of the structural features of certain bulky DNA lesions that render them resistant to NER, or cause them to be repaired slowly, is compared to that of those that are good-to-excellent NER substrates. Understanding the structural features that distinguish NER-resistant DNA lesions from good NER substrates may be useful for interpreting the biological significance of biomarkers of exposure of human populations to genotoxic environmental chemicals. NER-resistant lesions can survive to replication and cause mutations that can initiate cancer and other diseases. Furthermore, NER diminishes the efficacy of certain chemotherapeutic drugs, and the design of more potent pharmaceuticals that resist repair can be advanced through a better understanding of the structural properties of DNA lesions that engender repair-resistance.
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Affiliation(s)
- Nicholas E. Geacintov
- Chemistry and Biology Departments, New York University, New York, New York 10003-5180, United States
| | - Suse Broyde
- Chemistry and Biology Departments, New York University, New York, New York 10003-5180, United States
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4
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El-Bayoumy K, Chen KM, Zhang SM, Sun YW, Amin S, Stoner G, Guttenplan JB. Carcinogenesis of the Oral Cavity: Environmental Causes and Potential Prevention by Black Raspberry. Chem Res Toxicol 2016; 30:126-144. [DOI: 10.1021/acs.chemrestox.6b00306] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | | | - Shang-Min Zhang
- Department
of Pathology, Yale University, Yale School of Medicine, New Haven, Connecticut 06510, United States
| | | | | | - Gary Stoner
- Department
of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Joseph B. Guttenplan
- Department
of Basic Science, and Department of Environmental Medicine, New York University College of Dentistry and New York University School of Medicine, New York, New York 10010, United States
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5
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Siddens LK, Bunde KL, Harper TA, McQuistan TJ, Löhr CV, Bramer LM, Waters KM, Tilton SC, Krueger SK, Williams DE, Baird WM. Cytochrome P450 1b1 in polycyclic aromatic hydrocarbon (PAH)-induced skin carcinogenesis: Tumorigenicity of individual PAHs and coal-tar extract, DNA adduction and expression of select genes in the Cyp1b1 knockout mouse. Toxicol Appl Pharmacol 2015; 287:149-160. [PMID: 26049101 DOI: 10.1016/j.taap.2015.05.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 05/12/2015] [Accepted: 05/29/2015] [Indexed: 01/05/2023]
Abstract
FVB/N mice wild-type, heterozygous or null for Cyp 1b1 were used in a two-stage skin tumor study comparing PAH, benzo[a]pyrene (BaP), dibenzo[def,p]chrysene (DBC), and coal tar extract (CTE, SRM 1597a). Following 20 weeks of promotion with TPA the Cyp 1b1 null mice, initiated with DBC, exhibited reductions in incidence, multiplicity, and progression. None of these effects were observed with BaP or CTE. The mechanism of Cyp 1b1-dependent alteration of DBC skin carcinogenesis was further investigated by determining expression of select genes in skin from DBC-treated mice 2, 4 and 8h post-initiation. A significant reduction in levels of Cyp 1a1, Nqo1 at 8h and Akr 1c14 mRNA was observed in Cyp 1b1 null (but not wt or het) mice, whereas no impact was observed in Gst a1, Nqo 1 at 2 and 4h or Akr 1c19 at any time point. Cyp 1b1 mRNA was not elevated by DBC. The major covalent DNA adducts, dibenzo[def,p]chrysene-(±)-11,12-dihydrodiol-cis and trans-13,14-epoxide-deoxyadenosine (DBCDE-dA) were quantified by UHPLC-MS/MS 8h post-initiation. Loss of Cyp1 b1 expression reduced DBCDE-dA adducts in the skin but not to a statistically significant degree. The ratio of cis- to trans-DBCDE-dA adducts was higher in the skin than other target tissues such as the spleen, lung and liver (oral dosing). These results document that Cyp 1b1 plays a significant role in bioactivation and carcinogenesis of DBC in a two-stage mouse skin tumor model and that loss of Cyp 1b1 has little impact on tumor response with BaP or CTE as initiators.
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Affiliation(s)
- Lisbeth K Siddens
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA
| | - Kristi L Bunde
- College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Tod A Harper
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA; Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA
| | - Tammie J McQuistan
- Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA; Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA
| | - Christiane V Löhr
- Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA; College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Lisa M Bramer
- Applied Statistics and Computational Modeling, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Katrina M Waters
- Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA; Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Susan C Tilton
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA
| | - Sharon K Krueger
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA; Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA
| | - David E Williams
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA; Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA; Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA.
| | - William M Baird
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA; Superfund Research Center, Oregon State University, Corvallis, OR 97331, USA; Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA
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6
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Zhang SM, Chen KM, Sun YW, Aliaga C, Lin JM, Sharma AK, Amin S, El-Bayoumy K. Simultaneous detection of deoxyadenosine and deoxyguanosine adducts in the tongue and other oral tissues of mice treated with Dibenzo[a,l]pyrene. Chem Res Toxicol 2014; 27:1199-206. [PMID: 24911113 PMCID: PMC4106691 DOI: 10.1021/tx5001078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We
were the first to demonstrate that direct application of the
environmental pollutant and tobacco smoke constituent dibenzo[a,l]pyrene (DB[a,l]P) into the oral cavity of mice induced squamous cell
carcinoma (SCC) in oral tissues but not in the tongue; however, the
mechanisms that can account for the varied carcinogenicity remain
to be determined. Furthermore, we also showed that not only dA adducts,
but also dG adducts can account for the mutagenic activity of DB[a,l]P in the oral tissues in vivo. In this study, we initially focused on DB[a,l]P-induced genotoxic effects in both oral and tongue tissues.
Therefore, to fully assess the contribution of these DNA adducts in
the initiation stage of carcinogenesis induced by DB[a,l]P, an LC-MS/MS method to simultaneously detect
and quantify DB[a,l]PDE-dG and -dA
adducts was developed. Mice were orally administered with DB[a,l]P (24 nmole, 3 times per week for 5
weeks) or its fjord region diol epoxide, (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DB[a,l]PDE, 12 nmole, single application); animals were sacrificed
at 2, 7, 14, and 28 days after the last dose of carcinogen administration.
Oral and tongue tissues were obtained and DNA were isolated followed
by enzymatic hydrolysis. Following the development of an isotope dilution
LC-MS/MS method, we successfully detected (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N2-dG, as well as (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N6-dA in oral and tongue
tissues of mice treated with DB[a,l]P. Levels of (−)-anti-trans-DB[a,l]PDE-N6-dA were
≥2 folds higher than (−)-anti-cis-DB[a,l]PDE-N6-dA adduct and those of dG adducts in the oral tissues and tongue
at all time points selected after the cessation of DB[a,l]P treatment. Levels of dG adducts were comparable
in both tissues. Collectively, our results support that DB[a,l]P is predominantly metabolized to (−)-anti-DB[a,l]PDE, and the
levels and persistence of (−)-anti-trans-DB[a,l]PDE-N6-dA may, in part, explain the carcinogenicity of DB[a,l]P in the oral tissues but not in the
tongue.
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Affiliation(s)
- Shang-Min Zhang
- Dept. of Biochemistry and Molecular Biology, Penn State College of Medicine , Hershey, Pennsylvania 17033, United States
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7
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Rodríguez FA, Liu Z, Lin CH, Ding S, Cai Y, Kolbanovskiy A, Kolbanovskiy M, Amin S, Broyde S, Geacintov NE. Nuclear magnetic resonance studies of an N2-guanine adduct derived from the tumorigen dibenzo[a,l]pyrene in DNA: impact of adduct stereochemistry, size, and local DNA sequence on solution conformations. Biochemistry 2014; 53:1827-41. [PMID: 24617538 PMCID: PMC3985812 DOI: 10.1021/bi4017044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
![]()
The
dimensions and arrangements of aromatic rings (topology) in
adducts derived from the reactions of polycyclic aromatic hydrocarbon
(PAH) diol epoxide metabolites with DNA influence the distortions
and stabilities of double-stranded DNA, and hence their recognition
and processing by the human nucleotide excision repair (NER) system.
Dibenzo[a,l]pyrene (DB[a,l]P) is a highly tumorigenic six-ring PAH, which
contains a nonplanar and aromatic fjord region that is absent in the
structurally related bay region five-ring PAH benzo[a]pyrene (B[a]P). The PAH diol epoxide–DNA
adducts formed include the stereoisomeric 14S and
14Rtrans-anti-DB[a,l]P-N2-dG
and the stereochemically analogous 10S- and 10R-B[a]P-N2-dG
(B[a]P-dG) guanine adducts. However, nuclear magnetic
resonance (NMR) solution studies of the 14S-DB[a,l]P-N2-dG
adduct in DNA have not yet been presented. Here we have investigated
the 14S-DB[a,l]P-N2-dG adduct in two different sequence contexts
using NMR methods with distance-restrained molecular dynamics simulations.
In duplexes with dC opposite the adduct deleted, a well-resolved base-displaced
intercalative adduct conformation can be observed. In full duplexes,
in contrast to the intercalated 14R stereoisomeric
adduct, the bulky DB[a,l]P residue
in the 14S adduct is positioned in a greatly widened
and distorted minor groove, with significant disruptions and distortions
of base pairing at the lesion site and two 5′-side adjacent
base pairs. These unique structural features are significantly different
from those of the stereochemically analogous but smaller B[a]P-dG adduct. The greater size and different topology of
the DB[a,l]P aromatic ring system
lead to greater structurally destabilizing DNA distortions that are
partially compensated by stabilizing DB[a,l]P-DNA van der Waals interactions, whose combined effects
impact the NER response to the adduct. These structural results broaden
our understanding of the structure–function relationship in
NER.
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Affiliation(s)
- Fabián A Rodríguez
- Department of Chemistry, New York University , New York, New York 10003, United States
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8
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Kropachev K, Kolbanovskiy M, Liu Z, Cai Y, Zhang L, Schwaid AG, Kolbanovskiy A, Ding S, Amin S, Broyde S, Geacintov NE. Adenine-DNA adducts derived from the highly tumorigenic Dibenzo[a,l]pyrene are resistant to nucleotide excision repair while guanine adducts are not. Chem Res Toxicol 2013; 26:783-93. [PMID: 23570232 DOI: 10.1021/tx400080k] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The structural origins of differences in susceptibilities of various DNA lesions to nucleotide excision repair (NER) are poorly understood. Here we compared, in the same sequence context, the relative NER dual incision efficiencies elicited by two stereochemically distinct pairs of guanine (N(2)-dG) and adenine (N(6)-dA) DNA lesions, derived from enantiomeric genotoxic diol epoxides of the highly tumorigenic fjord region polycyclic aromatic hydrocarbon dibenzo[a,l]pyrene (DB[a,l]P). Remarkably, in cell-free HeLa cell extracts, the guanine adduct with R absolute chemistry at the N(2)-dG linkage site is ∼35 times more susceptible to NER dual incisions than the stereochemically identical N(6)-dA adduct. For the guanine and adenine adducts with S stereochemistry, a similar but somewhat smaller effect (factor of ∼15) is observed. The striking resistance of the bulky N(6)-dA in contrast to the modest to good susceptibilities of the N(2)-dG adducts to NER is interpreted in terms of the balance between lesion-induced DNA distorting and DNA stabilizing van der Waals interactions in their structures, that are partly reflected in the overall thermal stabilities of the modified duplexes. Our results are consistent with the hypothesis that the high genotoxic activity of DB[a,l]P is related to the formation of NER-resistant and persistent DB[a,l]P-derived adenine adducts in cellular DNA.
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Affiliation(s)
- Konstantin Kropachev
- Department of Chemistry, New York University , New York, New York 10003, United States
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9
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Yin J, Wang Z, Song M, Zhao C, Wang H. Plastic antibody for DNA damage: fluorescent imaging of BPDE–dG adducts in genomic DNA. Analyst 2013; 138:4958-66. [DOI: 10.1039/c3an00467h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Tang Y, Liu Z, Ding S, Lin CH, Cai Y, Rodriguez FA, Sayer JM, Jerina DM, Amin S, Broyde S, Geacintov NE. Nuclear magnetic resonance solution structure of an N(2)-guanine DNA adduct derived from the potent tumorigen dibenzo[a,l]pyrene: intercalation from the minor groove with ruptured Watson-Crick base pairing. Biochemistry 2012; 51:9751-62. [PMID: 23121427 DOI: 10.1021/bi3013577] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The most potent tumorigen identified among the polycyclic aromatic hydrocarbons (PAH) is the nonplanar fjord region dibenzo[a,l]pyrene (DB[a,l]P). It is metabolically activated in vivo through the widely studied diol epoxide (DE) pathway to form covalent adducts with DNA bases, predominantly guanine and adenine. The (+)-11S,12R,13R,14S DE enantiomer forms adducts via its C14 position with the exocyclic amino group of guanine. Here, we present the first nuclear magnetic resonance solution structure of a DB[a,l]P-derived adduct, the 14R-(+)-trans-anti-DB[a,l]P-N(2)-dG (DB[a,l]P-dG) lesion in double-stranded DNA. In contrast to the stereochemically identical benzo[a]pyrene-derived N(2)-dG adduct (B[a]P-dG) in which the B[a]P rings reside in the B-DNA minor groove on the 3'-side of the modifed deoxyguanosine, in the DB[a,l]P-derived adduct the DB[a,l]P rings intercalate into the duplex on the 3'-side of the modified base from the sterically crowded minor groove. Watson-Crick base pairing of the modified guanine with the partner cytosine is broken, but these bases retain some stacking with the bulky DB[a,l]P ring system. This new theme in PAH DE-DNA adduct conformation differs from (1) the classical intercalation motif in which Watson-Crick base pairing is intact at the lesion site and (2) the base-displaced intercalation motif in which the damaged base and its partner are extruded from the helix. The structural considerations that lead to the intercalated conformation of the DB[a,l]P-dG lesion in contrast to the minor groove alignment of the B[a]P-dG adduct, and the implications of the DB[a,l]P-dG conformational motif for the recognition of such DNA lesions by the human nucleotide excision repair apparatus, are discussed.
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Affiliation(s)
- Yijin Tang
- Department of Chemistry, New York University, New York, NY 10003, USA
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11
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Kiwamoto R, Rietjens IMCM, Punt A. A Physiologically Based in Silico Model for trans-2-Hexenal Detoxification and DNA Adduct Formation in Rat. Chem Res Toxicol 2012; 25:2630-41. [DOI: 10.1021/tx3002669] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Reiko Kiwamoto
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen,
The Netherlands
| | | | - Ans Punt
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen,
The Netherlands
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12
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Olson KC, Sun D, Chen G, Sharma AK, Amin S, Ropson IJ, Spratt TE, Lazarus P. Characterization of dibenzo[a,l]pyrene-trans-11,12-diol (dibenzo[def,p]chrysene) glucuronidation by UDP-glucuronosyltransferases. Chem Res Toxicol 2011; 24:1549-59. [PMID: 21780761 DOI: 10.1021/tx200178v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dibenzo[a,l]pyrene (DB[a,l]P) (dibenzo[def,p]chrysene) is a highly carcinogenic polycyclic aromatic hydrocarbon (PAH) that has been identified in tobacco smoke and is found in our environment due to incomplete combustion of organic matter. Its metabolites are known to form stable DNA adducts in bacteria and mammalian cells, and can lead to tumors in animal models. Glucuronidation of major metabolites of DB[a,l]P by the uridine-5'-diphosphate glucuronosyltransferase (UGT) family of enzymes is an important route of detoxification of this pro-carcinogen. The focus of the current study was to characterize the glucuronidation of the pro-carcinogenic enantiomers DB[a,l]P-(+)-trans-11S,12S-diol and DB[a,l]P-(-)-trans-11R,12R-diol. Glucuronidation assays with HEK293 cell lines overexpressing individual human UGT enzymes demonstrated that UGTs 1A1, 1A4, 1A7, 1A8, 1A9, 1A10, and 2B7 glucuronidated one or both DB[a,l]P-trans-11,12-diol enantiomers. Three glucuronide conjugates were observed in activity assays with UGTs 1A1 and 1A10, while two glucuronides were formed by UGTs 1A7, 1A8, and 1A9, and one glucuronide was made by UGT1A4 and UGT2B7. Enzyme kinetic analysis indicated that UGT1A9 was the most efficient UGT at forming both the (+)-DB[a,l]P-11-Gluc and (-)-DB[a,l]P-11-Gluc products, while UGTs 1A1 and 1A10 were the most efficient at forming the (+)-DB[a,l]P-12-Gluc product (as determined by k(cat)/K(M)). Incubations with human liver microsomes showed the formation of three diastereomeric glucuronide products: (+)-DB[a,l]P-11-Gluc, (+)-DB[a,l]P-12-Gluc, and (-)-DB[a,l]P-11-Gluc, with an average overall ratio of 31:32:37 in four liver specimens. Human bronchus and trachea tissue homogenates demonstrated glucuronidation activity against both DB[a,l]P-trans-11,12-diol enantiomers, with both tissues producing the (+)-DB[a,l]P-11-Gluc and (+)-DB[a,l]P-12-Gluc with little or no formation of (-)-DB[a,l]P-11-Gluc. These results indicate that multiple UGTs are involved in the stereospecific glucuronidation of DB[a,l]P-trans-11,12-diol in a pattern consistent with their expression in respiratory tract tissues and that glucuronidation may be an important first-line detoxification mechanism of DB[a,l]P metabolites.
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Affiliation(s)
- Kristine C Olson
- Molecular Epidemiology and Cancer Control Program, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA
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13
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Cai Y, Ding S, Geacintov NE, Broyde S. Intercalative conformations of the 14R (+)- and 14S (-)-trans-anti-DB[a,l]P-N⁶-dA adducts: molecular modeling and MD simulations. Chem Res Toxicol 2011; 24:522-31. [PMID: 21361377 DOI: 10.1021/tx1004002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Among the polycyclic aromatic hydrocarbon class of chemical carcinogens, dibenzo[a,l]pyrene (DB[a,l]P) is the most potent tumorigen that has been identified to date. Structurally, it is bulky with six aromatic rings, and it contains the nonplanar fjord-region. The conformational properties of DB[a,l]P-derived DNA adducts responsible for its extraordinary carcinogenicity are hence of great interest. We have carried out molecular modeling and MD simulations for the 14R (+)- and 14S (-)-trans-anti-DB[a,l]P-N⁶-dA adducts derived from the reactions of the DB[a,l]P diol epoxides with adenine in double-stranded DNA. The structures are based on the classically intercalated NMR solution structures of the analogous fjord-region benzo[c]phenanthrene-derived-N⁶-dA adducts. One objective was to gain insight on the impact of the more bulky DB[a,l]P ring system on the structural characteristics of the intercalative adduct conformations. A further objective was to elucidate the effect of the flexible twist associated with the sterically hindered aromatic ring in the fjord-region on the intercalated conformations, for comparison with the intercalated but planar bay-region benzo[a]pyrene-derived-N⁶-dA adducts. For the DB[a,l]P-N⁶-dA adducts, our results show that the 14R (+)-adduct is more favorably intercalated on the 5'-side of the modified adenine than the stereoisomeric 14S (-)-adduct, intercalated on its 3'-side. The 14R (+)-adduct manifests better van der Waals stacking interactions with flanking base pairs, less perturbed Watson-Crick hydrogen bonding, less local groove enlargement, less unwinding, and a lower solvent exposure than the 14S (-)-adduct. These structural findings are consistent with observed thermodynamic melting data, UV absorption properties, and fluorescence quenching studies. By contrast, the NMR solution structures for the analogous but less bulky B[c]Ph-derived adducts reveal no such stereoisomeric effect, while the planar bay-region benzo[a]pyrene-derived-N⁶-dA adducts do. Differences in nucleotide excision repair susceptibilities of the fjord and bay region adducts stem from distinctions in their intercalative conformations, produced by the intrinsic topological variations in their polycyclic aromatic ring systems.
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Affiliation(s)
- Yuqin Cai
- Department of Biology, New York University, New York, NY 10003, United States
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Hang B. Formation and repair of tobacco carcinogen-derived bulky DNA adducts. J Nucleic Acids 2010; 2010:709521. [PMID: 21234336 PMCID: PMC3017938 DOI: 10.4061/2010/709521] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/16/2010] [Accepted: 09/17/2010] [Indexed: 01/08/2023] Open
Abstract
DNA adducts play a central role in chemical carcinogenesis. The analysis of formation and repair of smoking-related DNA adducts remains particularly challenging as both smokers and nonsmokers exposed to smoke are repetitively under attack from complex mixtures of carcinogens such as polycyclic aromatic hydrocarbons and N-nitrosamines. The bulky DNA adducts, which usually have complex structure, are particularly important because of their biological relevance. Several known cellular DNA repair pathways have been known to operate in human cells on specific types of bulky DNA adducts, for example, nucleotide excision repair, base excision repair, and direct reversal involving O6-alkylguanine DNA alkyltransferase or AlkB homologs. Understanding the mechanisms of adduct formation and repair processes is critical for the assessment of cancer risk resulting from exposure to cigarette smoke, and ultimately for developing strategies of cancer prevention. This paper highlights the recent progress made in the areas concerning formation and repair of bulky DNA adducts in the context of tobacco carcinogen-associated genotoxic and carcinogenic effects.
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Affiliation(s)
- Bo Hang
- Life Sciences Division, Department of Cancer and DNA Damage Responses, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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