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O'Connor PJ, Alonso-Amelot ME, Roberts SA, Povey AC. The role of bracken fern illudanes in bracken fern-induced toxicities. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2019; 782:108276. [PMID: 31843140 DOI: 10.1016/j.mrrev.2019.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 03/29/2019] [Accepted: 05/02/2019] [Indexed: 12/24/2022]
Abstract
Bracken fern is carcinogenic when fed to domestic and laboratory animals inducing bladder and ileal tumours and is currently classified as a possible human carcinogen by IARC. The carcinogenic illudane, ptaquiloside (PTQ) was isolated from bracken fern and is widely assumed to be the major bracken carcinogen. However, several other structurally similar illudanes are found in bracken fern, in some cases at higher levels than PTQ and so may contribute to the overall toxicity and carcinogenicity of bracken fern. In this review, we critically evaluate the role of illudanes in bracken fern induced toxicity and carcinogenicity, the mechanistic basis of these effects including the role of DNA damage, and the potential for human exposure in order to highlight deficiencies in the current literature. Critical gaps remain in our understanding of bracken fern induced carcinogenesis, a better understanding of these processes is essential to establish whether bracken fern is also a human carcinogen.
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Affiliation(s)
- P J O'Connor
- Centre for Occupational and Environmental Health, Centre for Epidemiology, Division of Population Health, Health Services Research and Primary Care, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - M E Alonso-Amelot
- Chemical Ecology Group, Faculty of Sciences, University of Los Andes, Mérida 5101, Venezuela
| | - S A Roberts
- Centre for Biostatistics, Division of Population Health, Health Services Research and Primary Care, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK
| | - A C Povey
- Centre for Occupational and Environmental Health, Centre for Epidemiology, Division of Population Health, Health Services Research and Primary Care, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK.
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2
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Rana J, Huang H. Actions of the Klenow fragment of DNA polymerase I and some DNA glycosylases on chemically stable analogues of N7-methyl-2'-deoxyguanosine. Bioorg Med Chem 2013; 21:6886-92. [PMID: 24100157 DOI: 10.1016/j.bmc.2013.09.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/05/2013] [Accepted: 09/12/2013] [Indexed: 10/26/2022]
Abstract
N7-methyl-9-deaza-dG was synthesized and incorporated into oligonucleotides. Thermal melting studies showed that replacement of dG by N7-methyl-9-deaza-dG only slightly decreased DNA duplex stability. Replication of DNA templates containing N7-methyl-9-deaza-dG and the related 7-methyl-7-deaza-dG and 7-deaza-dG by the Klenow fragment of Escherichia coli DNA polymerase I was examined. The dNTP misinsertion frequencies on all three templates were comparably low, although the 7-methyl group significantly slowed down the turnover rates of the polymerase when dCTP was incorporated. The stabilities of N7-methyl-9-deaza-dG and 7-methyl-7-deaza-dG against the actions of formamidopyrimidine DNA glycosylase (Fpg) and human alkyladenine DNA glycosylase (hAAG) were also examined. N7-methyl-9-deaza-dG was stable in the presence of both enzymes. In contrast, 7-methyl-7-deaza-dG was cleaved by Fpg, and possibly by hAAG but at an extremely slow rate. This study suggests that N7-alkyl-9-deaza-dG is a better analogue than 7-alkyl-7-deaza-dG for cellular studies.
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Affiliation(s)
- Jagruti Rana
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA
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Kim J, Matsunaga N, Koyanagi S, Ohdo S. Clock gene mutation modulates the cellular sensitivity to genotoxic stress through altering the expression of N-methylpurine DNA glycosylase gene. Biochem Pharmacol 2009; 78:1075-82. [DOI: 10.1016/j.bcp.2009.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/09/2009] [Accepted: 06/11/2009] [Indexed: 11/26/2022]
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Druckrey H. Specific Carcinogenic and Teratogenic Effects of ‘Indirect’ Alkylating Methyl and Ethyl compounds, and their Dependency on Stages of Ontogenic Developments. Xenobiotica 2008. [DOI: 10.3109/00498257309151524] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Rajcsanyi PM, Csillag M, Kriskovics E. Separation of Nucleic Acid Constituents by Column Liquid Chromatography. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/03602547408068431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Elder RH, Jansen JG, Weeks RJ, Willington MA, Deans B, Watson AJ, Mynett KJ, Bailey JA, Cooper DP, Rafferty JA, Heeran MC, Wijnhoven SW, van Zeeland AA, Margison GP. Alkylpurine-DNA-N-glycosylase knockout mice show increased susceptibility to induction of mutations by methyl methanesulfonate. Mol Cell Biol 1998; 18:5828-37. [PMID: 9742100 PMCID: PMC109169 DOI: 10.1128/mcb.18.10.5828] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alkylpurine-DNA-N-glycosylase (APNG) null mice have been generated by homologous recombination in embryonic stem cells. The null status of the animals was confirmed at the mRNA level by reverse transcription-PCR and by the inability of cell extracts of tissues from the knockout (ko) animals to release 3-methyladenine (3-meA) or 7-methylguanine (7-meG) from 3H-methylated calf thymus DNA in vitro. Following treatment with DNA-methylating agents, increased persistence of 7-meG was found in liver sections of APNG ko mice in comparison with wild-type (wt) mice, demonstrating an in vivo phenotype for the APNG null animals. Unlike other null mutants of the base excision repair pathway, the APNG ko mice exhibit a very mild phenotype, show no outward abnormalities, are fertile, and have an apparently normal life span. Neither a difference in the number of leukocytes in peripheral blood nor a difference in the number of bone marrow polychromatic erythrocytes was found when ko and wt mice were exposed to methylating or chloroethylating agents. These agents also showed similar growth-inhibitory effects in primary embryonic fibroblasts isolated from ko and wt mice. However, treatment with methyl methanesulfonate resulted in three- to fourfold more hprt mutations in splenic T lymphocytes from APNG ko mice than in those from wt mice. These mutations were predominantly single-base-pair changes; in the ko mice, they consisted primarily of AT-->TA and GC-->TA transversions, which most likely are caused by 3-meA and 3- or 7-meG, respectively. These results clearly show an important role for APNG in attenuating the mutagenic effects of N-alkylpurines in vivo.
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Affiliation(s)
- R H Elder
- CRC Section of Genome Damage and Repair, Paterson Institute for Cancer Research, Christie Hospital (NHS) Trust, Manchester M20 4BX, United Kingdom.
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8
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Lyngdoh RHD. Comparison of alkyl group labilities in O-and N-alkylated DNA bases: A semiempirical molecular orbital study. J CHEM SCI 1993. [DOI: 10.1007/bf02866914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Shuker DE, Prevost V, Friesen MD, Lin D, Ohshima H, Bartsch H. Urinary markers for measuring exposure to endogenous and exogenous alkylating agents and precursors. ENVIRONMENTAL HEALTH PERSPECTIVES 1993; 99:33-37. [PMID: 8319651 PMCID: PMC1567034 DOI: 10.1289/ehp.939933] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Noninvasive methodologies for measuring carcinogen exposure in humans, based on the use of urinary markers, are being developed and validated for use in molecular epidemiological studies. A range of 3-alkyladenines can be determined in urine samples by an immunoaffinity purification-GC/MS approach [3-methyladenine, 3-ethyladenine, 3-(2-hydroxyethyl)adenine, and 3-benzyladenine]. Using this method, recent results in human subjects suggest that urinary 3-alkyladenines are potentially useful markers of alkylating agent exposure, particularly where the backgrounds of such adducts are much lower than 3-methyladenine. Urinary excretion of S-benzylmercapturic acid has been studied in experimental animals as a marker of exposure to benzylating agents such as N-nitroso-methylbenzylamine. 3-Nitrotyrosine (NTyr) is formed in vivo in tissue or blood proteins after exposure to nitrosating and/or nitrating agents such as tetranitromethane. After turnover of proteins, NTyr is released and excreted in urine as metabolites 3-nitro-4-hydroxy-phenylacetic acid and 3-nitro-4-hydroxyphenylacetic acid, which are determined by GC with a thermal energy analyzer. The sensitivity and specificity, combined with ease of use, of these noninvasive biomonitoring approaches means that they may be readily incorporated into molecular epidemiological studies in which exposure to nitrosating and alkylating agents may be important risk factors.
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Affiliation(s)
- D E Shuker
- Unit of Environmental Carcinogenesis and Host Factors, International Agency for Research on Cancer, Lyon, France
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Church KM, Wurdeman RL, Zhang Y, Chen FX, Gold B. N-(2-chloroethyl)-N-nitrosoureas covalently bound to nonionic and monocationic lexitropsin dipeptides. Synthesis, DNA affinity binding characteristics, and reactions with 32P-end-labeled DNA. Biochemistry 1990; 29:6827-38. [PMID: 2168742 DOI: 10.1021/bi00481a011] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The synthesis and characterization of a series of compounds that contain an N-alkyl-N-nitrosourea functionality linked to DNA minor groove binding bi- and tripeptides (lexitropsins or information-reading peptides) based on methylpyrrole-2-carboxamide subunits are described. The lexitropsins (lex) synthesized have either a 3-(dimethylamino)propyl or propyl substituent on the carboxyl terminus. The preferred DNA affinity binding sequences of these compounds were footprinted in 32P-end-labeled restriction fragments with methidiumpropyl-EDTA.Fe(II), and in common with other structural analogues, e.g., distamycin and netropsin, these nitrosoureas recognize A-T-rich runs. The affinity binding of the compound with the dimethylamino terminus, which is ionized at near-neutral pH, appeared stronger than that observed for the neutral dipeptide. The sequence specificity for DNA alkylation by (2-chloroethyl)nitrosourea-lex dipeptides (Cl-ENU-lex), with neutral and charged carboxyl termini, using 32P-end-labeled restriction fragments, was determined by the conversion of the adducted sites into single-strand breaks by sequential heating at neutral pH and exposure to base. The DNA cleavage sites were visualized by polyacrylamide gel electrophoresis and autoradiography. The alkylation of DNA by Cl-ENU-lex was compared to that by N-(2-chloroethyl)-N'-cyclohexyl-N-nitrosourea (CCNU), which has no DNA affinity binding properties. While all the Cl-ENU compounds generate DNA breaks as a consequence of the formation of N7-alkyl-guanine, the Cl-ENU-lex compounds induced, in a time- and dose-dependent fashion, intense DNA cleavage bands at adenine, cytosine, and thymine residues associated with affinity binding sites. These non-G cleavages induced by Cl-ENU-lex were inhibited by the coaddition of distamycin at concentrations that did not affect G alkylation break sites. CCNU, even at much higher concentrations, does not generate any similar detectable lesions at non-G sites. Therefore, linking the Cl-ENU moiety to minor groove binders is a viable strategy to qualitatively and quantitatively control the delivery and release of the ultimate DNA alkylating agent in a sequence-dependent fashion.
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Affiliation(s)
- K M Church
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805
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11
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Leutzinger EE, Miller PS, Kan LS. Studies on the hydrolysis of 3-methyl-2′-deoxycytidine in aqueous solution A synthesis of 3-methyl-2′-deoxyuridine. ACTA ACUST UNITED AC 1982. [DOI: 10.1016/0167-4781(82)90083-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Margison GP. Chronic or acute administration of various dialkylnitrosamines enhances the removal of O6-methylguanine from rat liver DNA in vivo. Chem Biol Interact 1982; 38:189-201. [PMID: 6173138 DOI: 10.1016/0009-2797(82)90039-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Abstract
There are examples of short-term prescreening tests for carcinogenicity that fail to agree with the results of animal bioassays. Factors which may lead to such discordant results are discussed in terms of the present understanding of the mechanisms of chemical carcinogenesis and the quality of the results obtained in vivo and in vitro.
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O'Connor PJ, Saffhill R. The action of rat cytosol enzymes on some methylated nucleic acid components produced by the carcinogenic N-nitroso compounds. Chem Biol Interact 1979; 26:91-102. [PMID: 466746 DOI: 10.1016/0009-2797(79)90095-4] [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: 12/15/2022]
Abstract
The stabilities of several alkylated nucleic acid components have been examined in the presence of cytosol extracts from a variety of rat tissues. An activity capable of demethylating O6-methyldeoxyguanosine was readily detectable in all tissues examined; arranged in approximate order of decreasing specific activity these are as follows: small intestine, spleen, kidney, lung, liver, skin, heart and brain. The in vitro requirements for the activity derived from liver and the observations that O6-methylguanine and its deoxynucleoside 5'-monophosphate are insensitive to the action of these extracts suggests that this activity may be due to an enzyme which resembles adenosine deaminase. In contrast to the ready degradation of O6-methyldeoxyguanosine the corresponding ethyl derivative was degraded very much more slowly but there was no evidence for other activities against the O4- and O2-methyldeoxythymidines. Similarly, no demethylation of the N-substituted deoxynucleosides, 3-methyldeoxycytidine 3-methldeoxythymidine, 1-methyldeoxyadenosine and 7-methyldeoxyguanosine, was detected.
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Margison GP, Margison JM, Montesano R. Persistence of methylated bases in ribonucleic acid of syrian golden hamster liver after administration of dimethylnitrosamine. Biochem J 1979; 177:967-73. [PMID: 444213 PMCID: PMC1186464 DOI: 10.1042/bj1770967] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
1. Syrian golden hamster liver ribosomal RNA was isolated up to 96 h after administration of [14C]dimethylnitrosamine at 25 mg/kg or 2.5 mg/kg body weight. 2. The chemical alkyation products, 7-methylguanine, 3-methylcytosine, O6-methylguanosine and 1-methyladenosine, were measured after acidic or enzymic hydrolysis of the RNA to bases or mononucleosides followed by ion-exchange chromatography. 3. Between 7 and 96 h, the relative amounts of alkylation products did not change with time even though the absolute amounts fell by approx. 80% and 51% after the high and low doses respectively. 4. The results suggest that base specific excision repair does not exist for RNA alkylation products in this experimental system.
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Ho TL, Ho HC, Hamilton LD. Biochemical significance of the hard and soft acids and bases principle. Chem Biol Interact 1978; 23:65-84. [PMID: 359185 DOI: 10.1016/0009-2797(78)90042-x] [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: 12/14/2022]
Abstract
The hard and soft acids and bases (HSAB) principle, which states that hard acids bind preferentially to hard bases and soft acids to soft bases, may serve to assess specific chemico-biological interactions. As living systems are composed mainly of "hard" elements, molecular events taking place within the cell are dominated by "hard-hard interactions". On this premise, it becomes likely that extraneous "soft" agents are particularly injurious to life. In the HSAB context a selected number of variegated phenomena are briefly discussed qualitatively; these include biocidal actions, heavy metal poisoning, chemical carcinogenesis, some enzymic reactions, and nucleic acid complexations. Although the HSAB principle cannot be used as a tool for mechanistic explanations of biochemical processes, it may provide clues to likely target molecules and the loci of action.
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17
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Troll W, Shapiro R. Action of Environmental Agents on Nucleic Acids and Their Metabolism. Compr Physiol 1977. [DOI: 10.1002/cphy.cp090140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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O'Connor PJ, Salisbury JG, Margison GP. Resistance of alkylated DNA to degradation by deoxyribonuclease II at neutral and acid pH. Chem Biol Interact 1976; 14:313-23. [PMID: 8218 DOI: 10.1016/0009-2797(76)90110-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Methylation of a calf thymus DNA substrate by dimethyl sulphate (DMS) leads to an inhibition of deoxyribonuclease II activity which is gradually lost with time. The extent of this initial inhibition is linearly related to the amount of methylated products in DNA and quantitatively similar effects were found when the enzyme was used under either acid or neutral conditions. Deoxyribonuclease II was shown to produce 3'-phosphate termini under both acid and neutral conditions and thus, irrespective of the ionic conditions for the action of this enzyme in vivo the effects demonstrated here are of potential significance. Local denaturation of the methylated DNA may be partly responsible for these inhibitory effects but it is likely that the methyl purines also play a more direct role.
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Magin MN, O'Connor PJ, Craig AW, Margison GP. The effect of hormone induced stress upon the extent of alkylation of rat liver nucleic acids by N-methyl-N-nitrosourea. ZEITSCHRIFT FUR KREBSFORSCHUNG UND KLINISCHE ONKOLOGIE. CANCER RESEARCH AND CLINICAL ONCOLOGY 1975; 84:217-22. [PMID: 128216 DOI: 10.1007/bf00312243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An examination was made of the effect of treatment with methylating agents of varying carcinogenic potency and with stress inducing hormones upon DNA synthesis in the resting liver of the rat. With the methylating agents an early stimulation of DNA synthesis was observed, but this was depressed below the control levels at later times and with higher doses; hormone administration also resulted in a depression of DNA synthesis but, without any initial stimulation at the dosage employed. Under conditions of induced stress it was found that the extent of reaction of N-methyl-N-nitrosourea with cellular macromolecules was enhanced. This appeared to be a general effect upon the liver cell since both DNA and rRNA were affected in a similar manner.
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Margison GP, O'Connor PJ. Role of apurinic sites in the resistance of methylated oligodeoxyribonucleotides to degradation by spleen exonuclease. Biochem J 1975; 151:249-56. [PMID: 1218080 PMCID: PMC1172353 DOI: 10.1042/bj1510249] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of introducing methyl groups into DNA substrates was studied by using the spleen exonuclease (EC 3.1.4.1), an enzyme which hydrolyses oligonucleotides in a sequential manner by splitting off 3'-phosphomononucleotides starting from the 5'-hydroxyl terminus. Analyses of oligodeoxyribonucleotide 3'-phosphate substrates after reaction in vitro with dimethyl sulphate demonstrated that the resultant methylation pattern differed from the previously found for native DNA, particularly with respect to the relative amounts of 1- and 3-methyladenine produced. Although after treatment with increasing amounts of dimethyl sulphate the substrate became progressively resistant to degradation by the exonuclease, the methylation products themselves were only partially responsible for the observed inhibition of enzyme activity. The incomplete degradation encountered was apparently due to the presence of apurinic sites, which arose as secondary lesions after the spontaneous release of the labile alkyl purines from the methylated substrate. Inhibition of enzyme activity appeared to be competitive, being characterized by constant values for apparent Vmax, and increased values for apparent Km. the interpretation of this, however, is complicated by the complex nature of the substrate, and these aspects are considered in some detail.
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O'Connor PJ, Marigison GP, Craig AW. Phosphotriesters in rat liver deoxyribonucleic acid after the administration of the carcinogen NN-dimethylnitrosamine in vivo. Biochem J 1975; 145:475-82. [PMID: 168868 PMCID: PMC1165247 DOI: 10.1042/bj1450475] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
After treatment with NN-di[14C]methylnitrosamine, samples of DNA were isolated from rat livers by a conventional phenol procedure and examined for the presence of phosphotriesters. A method of capable of detecting relatively small amounts of 14C-labelled phosphotriesters was developed and used to establish that these products account for 10-12% of the total methylation pattern found after treatment with this agent in vitro. The significance of the presence of phosphotriesters in DNA is discussed.
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Singer B, Fraenkel-conrat H. Correlation between amino acid exchanges in coat protein of TMV mutants and the nature of the mutagens. Virology 1974; 60:485-90. [PMID: 4367490 DOI: 10.1016/0042-6822(74)90342-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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24
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Goth R, Rajewsky MF. Molecular and cellular mechanisms associated with pulse-carcinogenesis in the rat nerbous system by ethyinitrosourea: ethylation of nucleic acids and elimination rates of ethylated bases from the DNA of different tissues. ZEITSCHRIFT FUR KREBSFORSCHUNG UND KLINISCHE ONKOLOGIE. CANCER RESEARCH AND CLINICAL ONCOLOGY 1974; 82:37-64. [PMID: 4280214 DOI: 10.1007/bf00304382] [Citation(s) in RCA: 148] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Stewart BW, Swann PF, Holsman JW, Magee PN. Cellular injury and carcinogenesis. Evidence for the alkylation of rat liver nucleic acids in vivo by N-nitrosomorpholine. ZEITSCHRIFT FUR KREBSFORSCHUNG UND KLINISCHE ONKOLOGIE. CANCER RESEARCH AND CLINICAL ONCOLOGY 1974; 82:1-12. [PMID: 4280212 DOI: 10.1007/bf00304379] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Margison GP, O'Connor PJ. Biological implications of the instability of the N-glycosidic bone of 3-methyldeoxyadenosine in DNA. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 331:349-56. [PMID: 4360077 DOI: 10.1016/0005-2787(73)90021-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Miller CT, Lawley PD, Shah SA. Cellular reactions of O6-methylguanine, a product of some alkylating carcinogens. Biochem J 1973; 136:387-93. [PMID: 4590203 PMCID: PMC1165965 DOI: 10.1042/bj1360387] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cultures of a purine-requiring mutant of Chinese hamster ovary cells (CHO-104b), randomly bred hamster embryo cells, or Escherichia coli B(s-1) were treated with non-toxic doses of (3)H-labelled O(6)-methylguanine. DNA and RNA were isolated and subjected to enzymic digestion to nucleosides at pH8. The products of digestion were analysed by ion-exchange chromatography on columns of Dowex 50 (NH(4) (+) form) at pH8.9. No (3)H-labelled O(6)-methylguanosine was detected in nucleic acid digests. (3)H-labelled O(6)-methylguanine was O-demethylated yielding [(3)H]guanine in CHO-104b cells. Radioactivity in nucleic acid digests was associated with thymidine, guanosine, deoxyguanosine and an unidentified early-eluting product. Reports of similar unidentified products from nucleic acids labelled with various agents are discussed.
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Craddock VM. The pattern of methylated purines formed in DNA of intact and regenerating liver of rats treated with the carcinogen dimethylnitrosamine. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 312:202-10. [PMID: 4353091 DOI: 10.1016/0005-2787(73)90365-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Margison GP, Capps MJ, O'Connor PJ, Craig AW. Loss of 7-methylguanine from rat liver DNA after methylation in vivo with methylmethanesulphonate or dimethylnitrosamine. Chem Biol Interact 1973; 6:119-24. [PMID: 4698159 DOI: 10.1016/0009-2797(73)90078-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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O'Connor PJ, Capps MJ, Craig AW. Comparative studies of the hepatocarcinogen N,N-dimethylnitrosamine in vivo: reaction sites in rat liver DNA and the significance of their relative stabilities. Br J Cancer 1973; 27:153-66. [PMID: 4694387 PMCID: PMC2008841 DOI: 10.1038/bjc.1973.19] [Citation(s) in RCA: 122] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The reaction of the hepatocarcinogen N,N-dimethylnitrosamine has been compared with that of methyl methanesulphonate, a methylating agent which is not a liver carcinogen. Consistent differences have been observed in the reaction of rat liver DNA in vivo with these agents; O(6)-alkylation and the production of unidentified acid-labile products were distinctive features of the reaction with the carcinogenic nitroso compound but were undetectable or in low yield, respectively, after reaction with the alkyl sulphonate. Evidence has been obtained for the excision of these reaction products in animals treated with the hepatocarcinogen and the significance of their relative stabilities is discussed.
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