1
|
Kawanishi M, Yagi T, Totsuka Y, Wakabayashi K. DNA Repair and Mutagenesis of ADP-Ribosylated DNA by Pierisin. Toxins (Basel) 2024; 16:331. [PMID: 39195741 DOI: 10.3390/toxins16080331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 07/19/2024] [Accepted: 07/24/2024] [Indexed: 08/29/2024] Open
Abstract
Pierisin is a DNA-targeting ADP-ribosyltransferase found in cabbage white butterfly (Pieris rapae). Pierisin transfers an ADP-ribosyl moiety to the 2-amino group of the guanine residue in DNA, yielding N2-(ADP-ribos-1-yl)-2'-deoxyguanosine (N2-ADPR-dG). Generally, such chemically modified DNA is recognized as DNA damage and elicits cellular responses, including DNA repair pathways. In Escherichia coli and human cells, it has been experimentally demonstrated that N2-ADPR-dG is a substrate of the nucleotide excision repair system. Although DNA repair machineries can remove most lesions, some unrepaired damages frequently lead to mutagenesis through DNA replication. Replication past the damaged DNA template is called translesion DNA synthesis (TLS). In vitro primer extension experiments have shown that eukaryotic DNA polymerase κ is involved in TLS across N2-ADPR-dG. In many cases, TLS is error-prone and thus a mutagenic process. Indeed, the induction of G:C to T:A and G:C to C:G mutations by N2-ADPR-dG in the hypoxanthine phosphoribosyltransferase gene mutation assay with Chinese hamster cells and supF shuttle vector plasmids assay using human fibroblasts has been reported. This review provides a detailed overview of DNA repair, TLS and mutagenesis of N2-ADPR-dG induced by cabbage butterfly pierisin-1.
Collapse
Affiliation(s)
- Masanobu Kawanishi
- Environmental Molecular Toxicology, Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570, Japan
| | - Takashi Yagi
- Environmental Molecular Toxicology, Department of Biological Chemistry, Graduate School of Science, Osaka Metropolitan University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570, Japan
| | - Yukari Totsuka
- Department of Environmental Health Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Keiji Wakabayashi
- Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
| |
Collapse
|
2
|
Xu G, McMahan CA, Walter CA. Early-life exposure to benzo[a]pyrene increases mutant frequency in spermatogenic cells in adulthood. PLoS One 2014; 9:e87439. [PMID: 24489914 PMCID: PMC3906184 DOI: 10.1371/journal.pone.0087439] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/27/2013] [Indexed: 01/21/2023] Open
Abstract
Children are vulnerable to environmental mutagens, and the developing germline could also be affected. However, little is known about whether exposure to environmental mutagens in childhood will result in increased germline mutations in subsequent adult life. In the present study, male transgenic lacI mice at different ages (7, 25 and 60 days old) were treated with a known environmental mutagen (benzo[a]pyrene, B[a]P) at different doses (0, 50, 200 or 300 mg/kg body weight). Mutant frequency was then determined in a meiotic cell type (pachytene spermatocyte), a post-meiotic cell type (round spermatid) and epididymal spermatozoa after at least one cycle of spermatogenesis. Our results show that 1) mice treated with B[a]P at 7 or 25 days old, both being pre-adult ages, had significantly increased mutant frequencies in all spermatogenic cell types tested when they were 60 days old; 2) spermatogenic cells from mice treated before puberty were more susceptible to B[a]P-associated mutagenesis compared to adult mice; and 3) unexpectedly, epididymal spermatozoa had the highest mutant frequency among the spermatogenic cell types tested. These data show that pre-adult exposure to B[a]P increases the male germline mutant frequency in young adulthood. The data demonstrate that exposure to environmental genotoxins at different life phases (e.g., pre-adult and adult) can have differential effects on reproductive health.
Collapse
Affiliation(s)
- Guogang Xu
- Department of Cellular and Structural Biology, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - C. Alex McMahan
- Department of Pathology, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Christi A. Walter
- Department of Cellular and Structural Biology, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Cancer Therapy and Research Center, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Barshop Institute for Longevity and Aging Sciences, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- South Texas Veteran's Health Care System, San Antonio, Texas, United States of America
| |
Collapse
|
3
|
para-Phenylenediamine-induced autophagy in human uroepithelial cell line mediated mutant p53 and activation of ERK signaling pathway. Toxicol In Vitro 2011; 25:1630-7. [DOI: 10.1016/j.tiv.2011.06.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Revised: 06/08/2011] [Accepted: 06/16/2011] [Indexed: 12/22/2022]
|
4
|
Ambrosone CB, Abrams SM, Gorlewska-Roberts K, Kadlubar FF. Hair dye use, meat intake, and tobacco exposure and presence of carcinogen-DNA adducts in exfoliated breast ductal epithelial cells. Arch Biochem Biophys 2007; 464:169-75. [PMID: 17601487 DOI: 10.1016/j.abb.2007.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 05/21/2007] [Accepted: 05/22/2007] [Indexed: 11/23/2022]
Abstract
Diet and environmental exposures to aromatic and heterocyclic amines, and polycyclic aromatic hydrocarbons, are thought to be etiologic factors for breast cancer risk. In this study, we chose to quantify the major DNA adduct derived from one member of each of these classes of carcinogens in epithelial cell DNA isolated from human breast milk. Appreciable adducts were detected for each class, namely 2-amino-6-phenylimidazo[4,5-b]pyridine (PhIP), 4-aminobiphenyl (ABP) and benzo[a]pyrene. The effect of several metabolic genotypes on adduct levels were also investigated and higher PhIP and ABP adducts were associated with the rapid NAT2 and/or rapid NAT1 genotypes. The presence of ABP adducts was also significantly associated with the use of hair coloring products (OR=11.2, 95% CI=1.1-109.2) but not tobacco usage. These data indicate that women are exposed to several classes of dietary and environmental carcinogens and that metabolic genotype can be a susceptibility factor.
Collapse
|
5
|
Huang YC, Hung WC, Kang WY, Chen WT, Chai CY. p-Phenylenediamine induced DNA damage in SV-40 immortalized human uroepithelial cells and expression of mutant p53 and COX-2 proteins. Toxicol Lett 2007; 170:116-23. [PMID: 17403587 DOI: 10.1016/j.toxlet.2007.02.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 02/21/2007] [Accepted: 02/23/2007] [Indexed: 11/19/2022]
Abstract
p-Phenylenediamine (p-PD) is the main aromatic amine used in the formulation of hair dyes. Some epidemiologic studies have suggested that the use of p-PD-based hair dyes might be related to increased risk of human malignant tumors including bladder cancer and hematopoietic cancers. However, the toxicity and genotoxicity of p-PD on urothelial cells has not been reported yet. Therefore, we investigated the genotoxicity of p-PD on human urothelial cells and study its association with the expression of oncoproteins p53 and cyclooxygenase-2 (COX-2). Our results revealed that p-PD was able to induce DNA damage determined by Comet assay. In addition, our immunocytochemical and Western blotting results showed that p-PD induced overexpression of mutant p53 and COX-2 in a dose-dependent manner. The relationship between mutant p53 and COX-2 expression shows strong correlation. Furthermore, the accumulation of mutant p53 was linearly correlated with Comet scores. These results suggest that p-PD can induce DNA damage and accumulation of mutant p53 and COX-2 proteins; this may be one of the possible mechanisms that cause genotoxic carcinogenesis in the urothelial cells.
Collapse
Affiliation(s)
- Ya-Chun Huang
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | | | | | | | | |
Collapse
|
6
|
Kelsey KT, Hirao T, Hirao S, Devi-Ashok T, Nelson HH, Andrew A, Colt J, Baris D, Morris JS, Schned A, Karagas M. TP53 alterations and patterns of carcinogen exposure in a U.S. population-based study of bladder cancer. Int J Cancer 2005; 117:370-5. [PMID: 15906354 DOI: 10.1002/ijc.21195] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The molecular pathology of bladder cancer has been the subject of considerable interest, and current efforts are targeted toward elucidating the interrelationships between individual somatic gene loss and both etiologic and prognostic factors. Mutation of the TP53 gene has been associated with more invasive bladder cancer, and evidence suggests that TP53 mutation, independent of stage, may be predictive of outcome in this disease. However, there is no consensus in the literature that bladder carcinogen exposure is associated with inactivation of the TP53 gene. Work to date has been primarily hospital based and, as such, subject to possible bias associated with selection of more advanced cases for study. We examined exposure relationships with both TP53 gene mutation and TP53 protein alterations in a population-based study of 330 bladder cancer cases in New Hampshire. Tobacco smoking was not associated with TP53 alterations. We found a higher prevalence of TP53 inactivation (i.e., mutation and nuclear accumulation) among hair dye users (odd ratio [OR] = 4.1; 95% confidence interval [CI] 1.2-14.7), and the majority of these mutations were transversions. Men who had "at risk" occupations were more likely to have mutated TP53 tumors (OR = 2.9; 95% CI 1.1-7.6). There also was a relative absence of TP53 mutation (OR = 0.4; 95% CI 0.0-2.9) and TP53 protein alterations (OR = 0.6; 95% CI 0.3-1.4) in bladder cancers from individuals with higher arsenic exposure. Our data suggest that there is exposure-specific heterogeneity in inactivation of the TP53 pathway in bladder cancers and that integration of the spectrum of pathway alterations in population-based approaches (capturing the full range of exposures to bladder carcinogens) may provide important insights into bladder tumorigenesis.
Collapse
Affiliation(s)
- Karl T Kelsey
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Lee CH, Loechler EL. Molecular modeling of the major benzo[a]pyrene N2-dG adduct in cases where mutagenesis results are known in double stranded DNA. Mutat Res 2003; 529:59-76. [PMID: 12943920 DOI: 10.1016/s0027-5107(03)00107-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The potent mutagen/carcinogen benzo[a]pyrene (B[a]P) is metabolically activated to (+)-anti-B[a]PDE, which induces a full spectrum of mutations (e.g. GC-->TA, GC-->AT, etc.). One hypothesis for this complexity is that different mutations are induced by different conformations of its major adduct [+ta]-B[a]P-N2-dG when bypassed during DNA replication (probably by different DNA polymerases). Previous molecular modeling studies suggested that B[a]P-N2-dG adducts can in principle adopt at least 16 potential conformational classes in ds-DNA. Herein we report on molecular modeling studies with the eight conformations most likely to be relevant to base substitution mutagenesis in 10 cases where mutagenesis has been studied in ds-DNA plasmids in E. coli with B[a]P-N2-dG adducts of differing stereoisomers and DNA sequence contexts, as well as in five cases where the conformation is known by NMR. Of the approximately 11,000 structures generated in this study, the computed lowest energy structures are reported for 120 cases (i.e. eight conformations and 15 examples), and their conformations compared. Of the eight conformations, four are virtually always computed to be high in energy. The remaining four lower energy conformations include two with the BP moiety in the minor groove (designated: BPmi5 and BPmi3), and two base-displaced conformations, one with the dG moiety in the major groove (designated: Gma5) and one with the dG in the minor groove (designated: Gmi3). Interestingly, these four are the only conformations that have been observed for B[a]P-N2-dG adducts in NMR studies. Independent of sequence contexts and adduct stereochemistry, BPmi5 structures tend to look reasonably similar, as do BPmi3 structures, while the base-displaced structures Gma5 and BPmi3 tend to show greater variability in structure. A correlation was sought between modeling and mutagenesis results in the case of the low energy conformations BPmi5, BPmi3, Gma5 and Gma3. Plots of log[(G-->T)/(G-->A)] versus energy[(conformation X)-(conformation Y)] were constructed for all six pairwise combinations of these four conformations, and the only plot giving a straight line involved Gma5 and Gmi3. While this finding is striking, its significance is unclear (as discussed).
Collapse
Affiliation(s)
- Chiu Hong Lee
- Biology Department, Boston University, 5 Cummington Street, Boston, MA 02215, USA
| | | |
Collapse
|
8
|
Abstract
Traditionally, the use of rodent models in assessing the carcinogenic potential of chemicals has been expensive and lengthy, and the relevance of the carcinogenic effect to humans is often not fully understood. Today, however, with the rapid advances in molecular biology, genetically altered mice containing genes relevant to humans (e.g. oncogenes, tumor suppressor genes) and reporter genes (e.g. lacI) provide powerful tools for examining specific chemical-gene interactions thereby allowing a better understanding of the mechanisms of carcinogenesis in a shorter period of time. This paper will cover an overview of ongoing validation efforts, followed by examples of studies using several genetically engineered models including the p53def mouse model and the Big Blue transgenic mouse model. Specifically, examples where transgenic models were integrated into the testing program based on specific hypotheses dealing with genetic alterations in cancer genes and reporter genes will be discussed. The examples will highlight possible ways genetically altered mice may be integrated into a comprehensive research and testing strategy and thereby provide an improved estimation of human health risks.
Collapse
Affiliation(s)
- R C Sills
- Laboratory of Experimental Pathology, MD: B3-08, National Institute Environmental Health Sciences, PO Box 12233, Research Triangle Park, NC 27709, USA.
| | | | | |
Collapse
|
9
|
Suzuki T, Wang X, Miyata Y, Saeki K, Kohara A, Kawazoe Y, Hayashi M, Sofuni T. Hepatocarcinogen quinoline induces G:C to C:G transversions in the cII gene in the liver of lambda/lacZ transgenic mice (MutaMouse). Mutat Res 2000; 456:73-81. [PMID: 11087898 DOI: 10.1016/s0027-5107(00)00128-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Quinoline is carcinogenic to the liver in rodents, but it is not clear whether it acts by a genotoxic mechanism. We previously demonstrated that quinoline does induce gene mutation in the liver of lambda/lacZ transgenic mice. In the present report, we reveal the molecular nature of the mutations induced by quinoline in the lambda cII gene, which is also a phenotypically selectable marker in the lambda transgene. (The cII gene has 294bp, which enables much easier sequence analysis than the original lacZ gene (3kb)). The liver cII mutant frequency was nine times higher in quinoline-treated mice than in control mice. Sequence analysis revealed that quinoline induced primarily G:C to C:G transversions (25 of 34). Thus, we have confirmed that quinoline is genotoxic in its target organ, and the G:C to C:G transversion is the molecular signature of quinoline-induced mutations.
Collapse
Affiliation(s)
- T Suzuki
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Kozack R, Seo KY, Jelinsky SA, Loechler EL. Toward an understanding of the role of DNA adduct conformation in defining mutagenic mechanism based on studies of the major adduct (formed at N(2)-dG) of the potent environmental carcinogen, benzo[a]pyrene. Mutat Res 2000; 450:41-59. [PMID: 10838133 DOI: 10.1016/s0027-5107(00)00015-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The process of carcinogenesis is initiated by mutagenesis, which often involves replication past damaged DNA. One question - what exactly is a DNA polymerase seeing when it incorrectly copies a damaged DNA base (e.g., inserting dATP opposite a dG adduct)? - has not been answered in any case. Herein, we reflect on this question, principally by considering the mutagenicity of one activated form of benzo[a]pyrene, (+)-anti-B[a]PDE, and its major adduct [+ta]-B[a]P-N(2)-dG. In previous work, [+ta]-B[a]P-N(2)-dG was shown to be capable of inducing>95% G-->T mutations in one sequence context (5'-TGC), and approximately 95% G-->A mutations in another (5'-AGA). This raises the question - how can a single chemical entity induce different mutations depending upon DNA sequence context? Our current working hypothesis is that adduct conformational complexity causes adduct mutational complexity, where DNA sequence context can affect the former, thereby influencing the latter. Evidence supporting this hypothesis was discussed recently (Seo et al., Mutation Res. [in press]). Assuming this hypothesis is correct (at least in some cases), one goal is to consider what these mutagenic conformations might be. Based on molecular modeling studies, 16 possible conformations for [+ta]-B[a]P-N(2)-dG are proposed. A correlation between molecular modeling and mutagenesis work suggests a hypothesis (Hypothesis 3): a base displaced conformation with the dG moiety of the adduct in the major vs. minor groove gives G-->T vs. G-->A mutations, respectively. (Hypothesis 4, which is a generalized version of Hypothesis 3, is also proposed, and can potentially rationalize aspects of both [+ta]-B[a]P-N(2)-dG and AP-site mutagenesis, as well as the so-called "A-rule".) Finally, there is a discussion of how conformational complexity might explain some unusual mutagenesis results that suggest [+ta]-B[a]P-N(2)-dG can become trapped in different conformations, and why we think it makes sense to interpret adduct mutagenesis results by modeling ds-DNA (at least in some cases), even though the mutagenic event must occur at a ss/ds-DNA junction in the presence of a DNA polymerase.
Collapse
Affiliation(s)
- R Kozack
- Department of Biology, Boston University, Boston, MA 02215, USA
| | | | | | | |
Collapse
|
11
|
Shane BS, de Boer J, Watson DE, Haseman JK, Glickman BW, Tindall KR. LacI mutation spectra following benzo[a]pyrene treatment of Big Blue mice. Carcinogenesis 2000; 21:715-25. [PMID: 10753208 DOI: 10.1093/carcin/21.4.715] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mutation spectrum of the lacI gene from the liver of C57Bl6 Big Blue transgenic mice treated with benzo[a]pyrene (B[a]P) has been compared with the spectrum of spontaneous mutations observed in the liver of untreated Big Blue mice. Mice were treated with B[a]P for 3 days followed by a partial hepatectomy one day after the last injection. Liver tissue was removed for analysis at hepatectomy and, again, 3 days later at the time of sacrifice. Earlier, we reported that the lacI mutant frequency in these B[a]P-treated mice was elevated in the liver both at the time of hepatectomy and at sacrifice; however, a statistically significant increase in the mutant frequency was observed only at sacrifice. In this study, the DNA sequence spectra of lacI mutations observed in the liver of B[a]P-treated Big Blue mice at hepatectomy and at time of sacrifice were compared with each other and with the spectrum of spontaneous liver mutations. No differences were observed between the two B[a]P-treatment spectra. However, mutation frequencies of both GC-->TA and GC-->CG at the time of hepatectomy and at sacrifice were significantly elevated compared with the spontaneous frequency of these same transversions. Also, the frequency of AT-->TA transversions was significantly higher than the spontaneous frequency at the time of hepatectomy but not at sacrifice. The frequency of all other classes of mutations scored was not significantly different from the frequency of these same events in the spontaneous spectra. These data support the view that B[a]P treatment results in the induction of GC-->TA and GC-->CG transversions within 1 day of the last injection and they provide insights regarding the relative roles of benzo[a]pyrene-7,8-diol-9, 10-epoxide and radical cations of B[a]P in B[a]P-induced mutagenesis in vivo. Finally, these data provide evidence for B[a]P-induced mutagenesis under conditions where no statistical increase in mutant frequency could be shown.
Collapse
Affiliation(s)
- B S Shane
- Institute for Environmental Studies, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | | | | | | | | |
Collapse
|
12
|
Heflich RH, Neft RE. Genetic toxicity of 2-acetylaminofluorene, 2-aminofluorene and some of their metabolites and model metabolites. Mutat Res 1994; 318:73-114. [PMID: 7521935 DOI: 10.1016/0165-1110(94)90025-6] [Citation(s) in RCA: 174] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
2-Acetylaminofluorene and 2-aminofluorene are among the most intensively studied of all chemical mutagens and carcinogens. Fundamental research findings concerning the metabolism of 2-acetylaminofluorene to electrophilic derivatives, the interaction of these derivatives with DNA, and the carcinogenic and mutagenic responses that are associated with the resulting DNA damage have formed the foundation upon which much of genetic toxicity testing is based. The parent compounds and their proximate and ultimate mutagenic and carcinogenic derivatives have been evaluated in a variety of prokaryotic and eukaryotic assays for mutagenesis and DNA damage. The reactive derivatives are active in virtually all systems, while 2-acetylaminofluorene and 2-aminofluorene are active in most systems that provide adequate metabolic activation. Knowledge of the structures of the DNA adducts formed by 2-acetylaminofluorene and 2-aminofluorene, the effects of the adducts on DNA conformation and synthesis, adduct distribution in tissues, cells and DNA, and adduct repair have been used to develop hypotheses to understand the genotoxic and carcinogenic effects of these compounds. Molecular analysis of mutations produced in cell-free, bacterial, in vitro mammalian, and intact animal systems have recently been used to extend these hypotheses.
Collapse
Affiliation(s)
- R H Heflich
- Division of Genetic Toxicology, National Center for Toxicological Research, Jefferson, AR 72079
| | | |
Collapse
|
13
|
Fronza G, Campomenosi P, Iannone R, Abbondandolo A. The 4-nitroquinoline 1-oxide mutational spectrum in single stranded DNA is characterized by guanine to pyrimidine transversions. Nucleic Acids Res 1992; 20:1283-7. [PMID: 1561085 PMCID: PMC312171 DOI: 10.1093/nar/20.6.1283] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
4-Nitroquinoline-1-oxide is a potent mutagen and carcinogen which induces two main guanine adducts at positions C8 and N2. In ds or ss damaged DNA the ratio C8/N2 adducts is 1:2 and 8-10:1, respectively. In bacteria and yeast 4NQO has been shown to be a base substitution mutagen acting at G residues inducing mainly G to A transitions. We determined the mutational spectrum induced by the 4NQO metabolite, acetoxy-4-aminoquinoline 1-oxide, in the M13lacZ'/E. coli lacZ delta M15 alpha complementation assay using ssDNA. Among 68 Ac-4HAQO induced mutants, G to Pyr transversion was the most frequent base substitution observed. By comparison with dsDNA based systems, our data suggest that dGuo-C8-AQO induces G to Pyr transversions. A mechanism to explain how this lesion may induce transversions is proposed.
Collapse
Affiliation(s)
- G Fronza
- Laboratory of Mutagenesis, National Institute for Research on Cancer (IST), Genova, Italy
| | | | | | | |
Collapse
|
14
|
Ford GP, Herman PS. Conformational preferences and energetics of N–O heterolyses in aryl nitrenium ion precursors: ab initio and semiempirical molecular orbital calculations. ACTA ACUST UNITED AC 1991. [DOI: 10.1039/p29910000607] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
15
|
Barbin A, Bartsch H. Nucleophilic selectivity as a determinant of carcinogenic potency (TD50) in rodents: a comparison of mono- and bi-functional alkylating agents and vinyl chloride metabolites. Mutat Res 1989; 215:95-106. [PMID: 2811916 DOI: 10.1016/0027-5107(89)90222-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using published data, the carcinogenic potency (TD50) in rodents of a series of monofunctional alkylating agents, bifunctional antitumor drugs and the vinyl chloride (VC) metabolites chloroethylene oxide (CEO) and chloroacetaldehyde (CAA) was compared to their nucleophilic selectivity (Swain and Scott's constant s or initial ratio of 7-/O6-alkylguanine in DNA). A positive correlation between the log of TD50 estimates and the s values for a series of 14, mostly monofunctional, alkylating agents was observed. This linear relationship also included 2 bifunctional chloroethylnitrosoureas, although their carcinogenic potency was compared to their initial 7-/O6-alkylguanine ratio rather than their s values (n = 16, r = 0.91, p less than 0.005). In addition, the carcinogenic potency of 2 alkyl sulfates, which is not yet known accurately, may correlate with their nucleophilic selectivity through the same relationship. By contrast, 2 methyl halides and 5 bifunctional antitumor drugs (nitrogen mustards and azyridinyl derivatives) did not follow this linear relationship: at similar nucleophilic selectivity, they were more potent carcinogens than the above 18 alkylating agents; this may hold true for CEO and CAA too, although further carcinogenicity experiments are needed to calculate their precise TD50 values. The possible molecular mechanisms involved in tumor induction by these agents are discussed on the basis of these findings. Comparison of the estimated TD50 for CEO, CAA and VC in rodents confirms that CEO is the ultimate carcinogenic metabolite of VC and suggests that only a very small proportion of metabolically generated CEO is available for DNA alkylation in vivo.
Collapse
Affiliation(s)
- A Barbin
- International Agency for Research on Cancer, Lyon, France
| | | |
Collapse
|
16
|
Loechler EL. Adduct-induced base-shifts: a mechanism by which the adducts of bulky carcinogens might induce mutations. Biopolymers 1989; 28:909-27. [PMID: 2742984 DOI: 10.1002/bip.360280502] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Most carcinogens have been shown to be mutagens, and DNA adducts are formed when mutagenic/carcinogenic substances react with DNA. It is generally believed these adducts (or their derivatives) induce misreplication events that result in mutations. Many of the more potently mutagenic substances are bulky and three-dimensionally complex, such as the polycyclic aromatic hydrocarbons, aromatic amines, and aflatoxins; little is known about the mechanisms by which they induce mutations. Several theories exist and herein an additional mechanism is proposed by which bulky adducts might induce mutations at GC base pairs. Molecular modeling in conjunction with molecular mechanical calculation is used to assess if the mutagen/carcinogen moiety of the adduct might be able to shift the position of the base moiety of the adduct in such a way that misreplication events might be facilitated. This mechanism is referred to as adduct-induced base-shift, and two classes appeared possible; adduct-induced base-wobble and adduct-induced base-rotation. The latter has been proposed previously. By adduct-induced, base-wobble, the mutagen/carcinogen moiety of the adduct induces a shift in the position of the base moiety of the adduct with respect to the helix axis, which might facilitate mispairing events that are reminisent of non-Watson/Crick pairing that occurs at the wobble base of tRNA during translation. For example, in some guanine adducts, the guanine appears more thymine-like, which might facilitate G.A mispairing and thereby ultimately GC to TA transversion mutations. Adduct-induced base-rotation involves the rotation of the adducted base from the anti to the syn conformation and a variety of mispairing events might result.
Collapse
|
17
|
Bigger CA, Strandberg J, Yagi H, Jerina DM, Dipple A. Mutagenic specificity of a potent carcinogen, benzo[c]phenanthrene (4R,3S)-dihydrodiol (2S,1R)-epoxide, which reacts with adenine and guanine in DNA. Proc Natl Acad Sci U S A 1989; 86:2291-5. [PMID: 2648399 PMCID: PMC286898 DOI: 10.1073/pnas.86.7.2291] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mutations were induced in the supF gene of the pS189 shuttle vector by treatment with optically active benzo[c]phenanthrene (4R,3S)-dihydrodiol (2S,1R)-epoxide in vitro and replication in human cells. The induced mutation frequency was 60-fold greater than the spontaneous rate, and most of the mutations analyzed were transversions (86%), which principally consisted of similar numbers of A.T----T.A and G.C----T.A changes. The unusual susceptibility of A.T pairs to mutation by this chemical agent is consistent with its chemical reactivity toward adenine and argues that the mutations are targeted to the adducts formed. The central base in the sequences 5'-AGA-3', 5'-AAC-3', and 5'-GAG-3' was particularly susceptible to mutation. Twelve "hotspots" in the supF gene accounted for most mutations seen. Some of these hotspots differed from those found by others for racemic benzo[a]pyrene dihydrodiol epoxide and, even when a hotspot was common, the mutagenic changes were not always the same. Although adenine insertion opposite a noninstructional lesion could account for most of the data, no single mutagenic mechanism could encompass all of it. The cellular machinery that converts chemical damage to mutations must determine the mutational result to a large extent, but the findings herein show that the chemical agent itself plays a large role in determining both the location and the nature of the mutations that arise.
Collapse
Affiliation(s)
- C A Bigger
- Bionetics Research, Inc., National Cancer Institute-Frederick Cancer Research Facility, MD 21701
| | | | | | | | | |
Collapse
|
18
|
Dixon K, Roilides E, Hauser J, Levine AS. Studies on direct and indirect effects of DNA damage on mutagenesis in monkey cells using an SV40-based shuttle vector. Mutat Res 1989; 220:73-82. [PMID: 2538742 DOI: 10.1016/0165-1110(89)90012-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We are using an SV40-based shuttle vector, pZ189, to study mechanisms of mutagenesis in mammalian cells. The vector can be treated with mutagens in vitro and replicated in animal cells; resulting mutants can be selected and amplified in bacteria for DNA sequencing. This versatile vector system has allowed us to explore several different questions relating to the mutagenic process. We have studied the direct effects of template damage caused by UV or benzo[a]pyrene diolepoxide by treating vector DNA with these agents and then replicating the damaged DNA in monkey cells. Mutational mechanisms were deduced from the spectrum of mutations induced in the supF target gene of the vector DNA. To study the role of indirect effects of DNA damage on mutagenesis in mammalian cells, we have treated the cells and the vector DNA separately with DNA-damaging agents. We find that pretreatment of cells with DNA-damaging agents, or with conditioned medium from damaged cells, causes an enhancement of mutagenesis of a UV-damaged vector. Thus, DNA damage can act indirectly to enhance the mutagenic process. We also have preliminary evidence that pZ189 can be used in an in vitro DNA replication system to study the process of mutation fixation on the biochemical level. We believe that the pZ189 vector will prove to be as useful for in vitro studies of mutational mechanisms as it has been for in vivo studies.
Collapse
Affiliation(s)
- K Dixon
- Section on Viruses and Cellular Biology, National Institute of Child Health and Human Development, Bethesda, MD 20892
| | | | | | | |
Collapse
|
19
|
Paules RS, Cordeiro-Stone M, Mass MJ, Poirier MC, Yuspa SH, Kaufman DG. Benzo[alpha]pyrene diol epoxide I binds to DNA at replication forks. Proc Natl Acad Sci U S A 1988; 85:2176-80. [PMID: 3127827 PMCID: PMC279952 DOI: 10.1073/pnas.85.7.2176] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The distribution of lesions in DNA caused by (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [alpha]pyrene (B[alpha]P diol epoxide-I) was studied in synchronized C3H/10T1/2 cells treated in S phase. Sites of carcinogen modification of DNA were identified by polyclonal rabbit antibodies elicited against DNA modified with B[alpha]P diol epoxide-I in vitro. This antigenic DNA contained trans-(7R)-N2-[10-(7 beta,8 alpha,9 alpha-trihydroxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene)-yl]- deoxyguanosine; other adducts were not detected by liquid chromatography. In this study, DNA replication forks with antibodies bound to B[alpha]P diol epoxide-I adducts were detected by electron microscopy. The frequency of replication forks containing carcinogen adducts associated with the fork junction was found to be 8-fold higher than expected for an average distribution. The proportion of replication forks that were apparently blocked at the site of the DNA damage increased when replication was allowed to occur after carcinogen exposure. These results support the conclusions that the fork junction is particularly vulnerable to adduction by B[alpha]P diol epoxide-I and that B[alpha]P diol epoxide-I adducts block the displacement of replication forks during DNA synthesis in intact cells.
Collapse
Affiliation(s)
- R S Paules
- Department of Pathology, University of North Carolina, Chapel Hill 27599
| | | | | | | | | | | |
Collapse
|
20
|
Roilides E, Gielen JE, Tuteja N, Levine AS, Dixon K. Mutational specificity of benzo[a]pyrene diolepoxide in monkey cells. Mutat Res 1988; 198:199-206. [PMID: 3127698 DOI: 10.1016/0027-5107(88)90055-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Benzo[a]pyrene diolepoxide (BPDE) is thought to be the major mutagenic and carcinogenic intermediate in benzo[a]pyrene metabolism in mammalian cells. In order to test the mutagenic specificity of this compound in mammalian cells, we have used the pZ189 shuttle vector system to identify and analyze point mutations induced when DNA treated in vitro with BPDE is replicated in monkey cells. We find that point mutations occur almost exclusively at G.C base pairs; G.C----T.A and G.C----C.G transversions and single base pair deletions occur most frequently. This pattern is consistent with the known preferential covalent binding of BPDE to G residues.
Collapse
Affiliation(s)
- E Roilides
- Section on Viruses and Cellular Biology, National Institute of Child Health and Human Development, Bethesda, MD 20892
| | | | | | | | | |
Collapse
|
21
|
Abstract
The nature of hydrogen bonding between normal and modified bases has been re-examined. It is proposed that hydrogen-bonding schemes may involve tautomeric, ionized or conformational forms (syn, anti and wobble). Several important cases are presented or reviewed in which physical evidence indicates the existence of ionized base pairs. When thermodynamic values determined in aqueous solution under physiological conditions are considered, it can be argued that base ionization will contribute substantially to the stability of many biologically relevant base pairs containing modified bases. A significant incidence of ionized bases in DNA may have important kinetic ramifications for the further chemical reactivity of both the modified base and its cross-strand pairing partner. Moreover, DNA structure at and surrounding ionized base pairs may be altered. For this reason, the model presented in this study should be useful as DNA-sequence analysis becomes more commonly applied to the study of mutagenesis.
Collapse
|
22
|
Hingerty BE, Broyde S. Carcinogen-base stacking and base-base stacking in dCpdG modified by (+) and (-) anti-BPDE. Biopolymers 1985; 24:2279-99. [PMID: 4092090 DOI: 10.1002/bip.360241209] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
23
|
Beland FA, Kadlubar FF. Formation and persistence of arylamine DNA adducts in vivo. ENVIRONMENTAL HEALTH PERSPECTIVES 1985; 62:19-30. [PMID: 4085422 PMCID: PMC1568675 DOI: 10.1289/ehp.856219] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Aromatic amines are urinary bladder carcinogens in man and induce tumors at a number of sites in experimental animals including the liver, mammary gland, intestine, and bladder. In this review, the particular pathways involved in the metabolic activation of aromatic amines are considered as well as the specific DNA adducts formed in target and nontarget tissue. Particular emphasis is placed on the following compounds: 1-naphthylamine, 2-naphthylamine, 4-aminobiphenyl, 4-acetylaminobiphenyl, 4-acetylamino-4'-fluorobiphenyl, 3,2'-dimethyl-4-aminobiphenyl, 2-acetylaminofluorene, benzidine, N-methyl-4-aminoazobenzene, 4-aminoazobenzene, and 2-acetylaminophenanthrene.
Collapse
|
24
|
Bailleul B, Galiègue-Zouitina S, Loucheux-Lefebvre MH. Conformations of poly(dG-dC).poly(dG-dC) modified by the O-acetyl derivative of the carcinogen 4-hydroxyaminoquinoline 1-oxide. Nucleic Acids Res 1984; 12:7915-27. [PMID: 6093058 PMCID: PMC320215 DOI: 10.1093/nar/12.20.7915] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Poly(dG-dC).poly(dG-dC) has been modified by reaction with 4-acetoxyaminoquinoline 1-oxide (Ac-4 HAQO), the ultimate carcinogen of 4-nitroquinoline 1-oxide. The circular dichroism (CD) spectra of the modified and unmodified polymers have been compared under various experimental conditions. The CD spectra were recorded in 1 mM phosphate, 50% (v/v) ethanol, 3.8 M LiCl and 95% (v/v) ethanol, conditions in which poly(dG-dC).poly(dG-dC) adopts the B-, Z-, C- and A-form respectively. In 1 mM phosphate buffer, poly(dG-dC).poly(dG-dC) modified by Ac-4 HAQO seems not to contain regions in the Z-form. Z-form induction could be progressively obtained by the addition of ethanol as follows: in the buffer with about 30% ethanol the modified polymer started to adopt the Z structure, while 40% of ethanol in the buffer was necessary for the unmodified polymer. In the 50% ethanol-1 mM phosphate buffer mixture (v/v), poly(dG-dC).poly(dG-dC) was entirely in the Z-form while poly(dG-dC).poly(dG-dC) modified by Ac-4 HAQO remained partially in the B-form. Enzymatic digestions with the nuclease S1 which is specific of the single-stranded DNA were carried out in order to support the modified poly(dG-dC).poly(dG-dC) CD study conclusions. The role played by the two major adducts on the conformational characteristics of modified polymer is discussed.
Collapse
|
25
|
Hingerty B, Broyde S. A conformational analysis of the (+) anti BPDE adduct to the guanine amino group of dCpdG. J Biomol Struct Dyn 1983; 1:905-12. [PMID: 6443880 DOI: 10.1080/07391102.1983.10507492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The (+) anti isomer of benz[a]pyrene diol epoxide (BPDE), 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenz [a] pyrene has been identified as the probable tumorigenic lesion in mammalian systems. It forms a predominant adduct with DNA at N2 of guanine. In order to elucidate its conformation in atomic resolution detail, minimized conformational potential energy calculations were performed for the adduct with dCpdG. A global conformation search involving about 1000 trials was made. The lowest energy conformation had stacking between the hydrocarbon and the adjacent cytidine, in agreement with CD studies on modified GpU and UpG. This conformer differed from the B form most notably in the guanine glycosidic torsion, which is high anti. The next lowest energy form had torsion angles like the B form, with guanine-cytidine stacking. These two conformers differ in energy by only 2.1 kcal./mole, suggesting that their relative stability could easily be reversed in larger polymers, or under specific environmental conditions. Other conformations, with base-hydrocarbon or base-base stacking are also found, at somewhat higher energies. The Z form is at 7.8 kcal./mole. Thus, this adduct stabilizes the B form, in contrast with the N2 linked AAF adduct, which stabilizes the Z conformation.
Collapse
Affiliation(s)
- B Hingerty
- Health and Safety Research Division, Oak Ridge National Laboratory, TN 37830
| | | |
Collapse
|
26
|
Taylor ER, Miller KJ, Bleyer AJ. Interactions of molecules with nucleic acids. X. Covalent intercalative binding of the carcinogenic BPDE I(+) to kinked DNA. J Biomol Struct Dyn 1983; 1:883-904. [PMID: 6443879 DOI: 10.1080/07391102.1983.10507491] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A theoretical model is proposed for the covalent binding of (+) 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene denoted by BPDE I(+), to N2 on guanine. The DNA must kink a minimum of 39 degrees to allow proper hybrid configurations about the C10 and N2 atoms involved in bond formation and to allow stacking of the pyrene moiety with the non-bonded adjacent base pair. Conservative (same sugar puckers and glycosidic angles as in B-DNA) and non-conservative (alternating sugar puckers as in intercalation sites) conformations are found and they are proposed structures in pathways connecting B-DNA, an intercalation site, and a kink site in the formation of a covalently intercalative bound adduct of BPDE I(+) to N2 on guanine. Stereographic projections are presented for (3') and (5') binding in the DNA. Experimental data for bending of DNA by BPDE, orientation of BPDE in DNA and unwinding of superhelical DNA is explained. The structure of a covalent intercalative complex is predicted to result from the reaction. Also, an anti----syn transition of guanine results in a structure which allows the DNA to resume its overall B-form. The only change is that guanine has been rotated by 200 degrees about its glycosidic bond so that the BPDE I(+) is bound in the major groove. The latter step may allow the DNA to be stored with an adduct which may produce an error in the genetic code.
Collapse
Affiliation(s)
- E R Taylor
- Department of Chemistry, Rensselaer Polytechnic Institute, Troy, New York 12181
| | | | | |
Collapse
|
27
|
|
28
|
Abstract
Minimized conformational potential energy calculations have been performed for AAF linked to dCpdG at the guanine amino group. This is a model for the minor AAF adduct observed in DNA, whose conformational influence has been difficult to ascertain. A global minimum energy conformation was computed with torsion angles like those of the dCpdG residue of Z-DNA. This conformation was incorporated into a larger polymer model at a B-Z junction, with the carcinogen residing in the groove in the Z direction. Local minimum energy conformations of the B type were also computed. In addition, two minima were found with fluorenecytidine stacking. These results suggest that existing B-Z junctions may be vulnerable to modification by AAF at the guanine amino group, or that such junctions may be induced by the carcinogen if the base sequence is appropriate. Otherwise the carcinogen can be located in the minor groove of the B helix (5, 10, 11) or covalently intercalated (13-15).
Collapse
|
29
|
Foster PL, Eisenstadt E, Miller JH. Base substitution mutations induced by metabolically activated aflatoxin B1. Proc Natl Acad Sci U S A 1983; 80:2695-8. [PMID: 6405385 PMCID: PMC393894 DOI: 10.1073/pnas.80.9.2695] [Citation(s) in RCA: 184] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We have determined the base substitutions generated by metabolically activated aflatoxin B1 in the lacI gene of a uvrB- strain of Escherichia coli. By monitoring over 70 different nonsense mutation sites, we show that activated aflatoxin B1 specifically induced GxC leads to TxA transversions. One possible pathway leading to this base change involves depurination at guanine residues. We consider this mechanism of mutagenesis in the light of our other findings that the carcinogens benzo[a]pyrene diol epoxide and N-acetoxyacetylaminofluorene also specifically induce GxC leads to TxA transversions.
Collapse
|
30
|
|
31
|
Schmid SE, Daune MP, Fuchs RP. Repair and mutagenesis of plasmid DNA modified by ultraviolet irradiation or N-acetoxy-N-2-acetylaminofluorene. Proc Natl Acad Sci U S A 1982; 79:4133-7. [PMID: 7051005 PMCID: PMC346591 DOI: 10.1073/pnas.79.13.4133] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Plasmid DNA was modified in vitro to various extents with N-acetoxy-N-2-acetylaminofluorene or UV irradiation. The modified plasmid DNAs were then used to transform Escherichia coli strains having different repair capabilities. Both survival and mutagenesis frequencies of the plasmid were measured as a function of the number of lesions per plasmid molecule. The majority of N-2-acetylaminofluorene (AAF) adducts, like thymine dimers, were repaired by the excision (uvrA+-dependent) pathway. In rec+ strains, dose-dependent mutagenesis occurred in either AAF- or UV-modified plasmid DNA. This is in contrast with results obtained in recA- strains, in which only AAF adducts gave rise to a lower, but dose-dependent, mutagenesis frequency. In these recA- strains there was no UV mutagenesis. Unlike what is observed with phages, induction of the "SOS" functions by UV irradiation of the bacteria prior to transformation did not increase the survival or the mutagenesis of the plasmid.
Collapse
|
32
|
Eisenstadt E, Warren AJ, Porter J, Atkins D, Miller JH. Carcinogenic epoxides of benzo[a]pyrene and cyclopenta[cd]pyrene induce base substitutions via specific transversions. Proc Natl Acad Sci U S A 1982; 79:1945-9. [PMID: 7043469 PMCID: PMC346098 DOI: 10.1073/pnas.79.6.1945] [Citation(s) in RCA: 135] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We have determined the spectrum of base-pair substitution mutations induced in the lacI gene of a uvrB- strain of Escherichia coli by two polycyclic aromatic hydrocarbons--(+/-)7 alpha,8 beta-dihydroxy-9 beta,10 beta-epoxy-7,8,9,10 tetrahydrobenzo[a]pyrene (BPDE), and 3,4-epoxycylopenta[cd]pyrene (CPPE). Approximately 10% of all lacI mutations induced by either BPDE or CPPE are nonsense mutations, suggesting that base-pair substitutions are a large fraction of the mutational events induced by these agents in the uvrB- bacteria. Both carcinogens specifically induced the G . C leads to T . A and, to a lesser extent, the A . T leads to T . A transversions. One possible mechanism for transversion induction at G . C sites by BPDE might involve carcinogen binding to the exocyclic amino group of guanine in the template strand followed by a rotation of the modified base around its glycosylic bond from the anti to the syn conformation. This could allow specific pairing of modified bases with an imino tautomer of adenine.
Collapse
|
33
|
Sage E, Gabelman N, Mendez F, Bases R. Immunocytological detection of AAF-DNA adducts in HeLa cell nuclei. Cancer Lett 1981; 14:193-204. [PMID: 7032688 DOI: 10.1016/0304-3835(81)90130-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Acetylaminofluorene-DNA adducts (AAF-DNA) were detected in the nuclei of HeLa cells exposed to N-acetoxy-2-acetylaminofluorene (N-Ac-AAF), using an immunocytological technique and specific antibodies directed against AAF modified DNA. The proportion of cells exhibiting specific nuclear immunoreactivity was dose-dependent. The time course of disappearance of adduct specific nuclear immunoreactivity was compared with removal of N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF) and other adducts.
Collapse
|