Identification of C8-methylguanine in the hydrolysates of DNA from rats administered 1,2-dimethylhydrazine. Evidence for in vivo DNA alkylation by methyl radicals.

Netto, L.E.S.; Ramakrishna, N. V. S.; Kolar, Carol; Cavalieri, Ercole L.; Rogan, Eleanor G.; Lawson, Terence; Augusto, Ohára

doi:10.1016/s0021-9258(19)36641-4

Cited by 33 publications

(25 citation statements)

References 36 publications

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“…dAMP .. dTMP. 1,2-Dimethylhydrazine induces both O 6 MeG and 8MeG in similar amounts in the DNA of rats (122). However, the mutation frequencies of 8MeG are two orders of magnitude less than those of O 6 MeG (125).…”

Section: -Methylguaninementioning

confidence: 89%

“…8-Methylguanine (8MeG) was shown to be produced in vitro in RNA (120) and DNA (121) by methyl radicals generated by oxidation of 1,2dimethylhydrazine and methylhydrazine, respectively. Proof of in vivo DNA alkylation by carbon-centered radicals was given by Netto et al (122) who detected 8MeG in DNA isolated from the liver and colon of rats administered 1,2-dimethylhydrazine. Other studies have shown that this lesion can also be produced in vitro and in vivo by genotoxic agents such as tert-butylhydroperoxide, diazoquinones and arenediazonium ions (123).…”

Section: -Methylguaninementioning

confidence: 99%

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Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation

2009

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The reaction of DNA-damaging agents with the genome results in a plethora of lesions, commonly referred to as adducts. Adducts may cause DNA to mutate, they may represent the chemical precursors of lethal events and they can disrupt expression of genes. Determination of which adduct is responsible for each of these biological endpoints is difficult, but this task has been accomplished for some carcinogenic DNA-damaging agents. Here, we describe the respective contributions of specific DNA lesions to the biological effects of low molecular weight alkylating agents.

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Section: -Methylguaninementioning

confidence: 89%

Section: -Methylguaninementioning

confidence: 99%

Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation

2009

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“…The standard incubation mixture (250 mL, final volume) contained guanine (1.5 mM), ethanol (75 mM), ferrous sulfate (6.0 mM), and hydrogen peroxide (4.5 mM) at pH 1 under a nitrogen flux. After 30 min of incubation at room temperature, the pH was increased to 11−12 with NaOH to precipitate excess iron ions that were removed by filtration ( , ). The obtained supernatant was acidified to pH 4−5 and submitted to treatment with Chelex-100 for 10−12 h to completely remove iron ions.…”

Section: Methodsmentioning

confidence: 99%

“…These species, as is the case of other free radicals, attack purine bases by substituting at their C8 position. More recently, analogous C8-substituted guanine adducts have been demonstrated to be formed from DNA attack by carbon-centered radical metabolites of genotoxic compounds such as methylated hydrazines ( , ), tert -butylhydroperoxide (), diazoquinones (), and arenediazonium ions (). These alkylated guanines have also been shown to be produced in vivo.…”

Section: Introductionmentioning

confidence: 99%

Nucleic Acid Alkylation by Free Radical Metabolites of Ethanol. Formation of 8-(1-Hydroxyethyl)guanine and 8-(2-Hydroxyethyl)guanine Adducts

Nakao

Augusto

1998

Chem. Res. Toxicol.

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Alcohol consumption is associated with an increased risk of several types of malignancy by mechanisms that remain to be elucidated. Most of the ingested ethanol is converted to acetaldehyde but the formation of free radical metabolites such as the 1-hydroxyethyl radical has been also demonstrated to occur in vitro and in vivo. Here we tested the possibility of ethanol-derived free radicals alkylating nucleic acid and nucleic acid components. Ethanol oxidation by Fenton systems has been extensively used to mimic ethanol metabolism to free radical intermediates and it was also employed in our studies. Two adducts, 8-(1-hydroxyethyl)guanine and 8-(2-hydroxyethyl)guanine, were isolated in incubations containing guanine/ethanol/hydrogen peroxide/iron(II) at pH 1 under anaerobic conditions. The adducts were produced in comparable yields and were characterized by ultraviolet absorption, mass spectrometry, and proton nuclear magnetic resonance spectroscopy. Both adducts were also produced in incubations containing DNA and RNA at pH 4 and 7. Under these conditions, the obtained yields of 8-(1-hydroxyethyl)guanine were about 10 times higher than those of 8-(2-hydroxyethyl)guanine. Higher yields of both adducts were obtained at pH 4 than at pH 7 and with RNA as compared with DNA. As expected, nucleic acid oxidation products such as 8-oxo-7,8-dihydroguanine and 8-oxo-7,8-dihydroadenine were also produced under the employed experimental conditions. Their yields tended to increase in the presence of ethanol, particularly at pH 4, suggesting that ethanol can protect oxidized bases from further degradation. Parallel spin-trapping experiments with alpha-4-pyridyl-1-oxide N-tert-butylnitrone and 3,5-dibromo-4-nitrosobenzenesulfonic acid confirmed that ethanol was oxidized to both the 1-hydroxyethyl and 2-hydroxyethyl radicals by hydrogen peroxide/iron(II) at pH 4-7 in the presence and in the absence of nucleic acids. The results demonstrate that free radical metabolites of ethanol can alkylate nucleic acids in vitro. Both the 1-hydroxyethyl and 2-hydroxyethyl radicals may play a role in ethanol-mediated toxicity.

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“…Chemical (11) and biochemical (12) studies on radical methylation reveal that the C8-position of the guanine moiety is the most reactive site to form 8-methylguanine (8-MeGua). 8-MeGua has been detected in the liver and colon DNA of rats treated with DMH (13).…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Miscoding Specificity, and Thermodynamic Stability of Oligodeoxynucleotide Containing 8-Methyl-2‘-deoxyguanosine

Kohda

Tsunomoto

Minoura

et al. 1996

Chem. Res. Toxicol.

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8-Methyl-2'-deoxyguanosine (8-MedG) was synthesized by reacting dG under the methyl radical generating system and incorporated into oligodeoxynucleotides using phosphoramidite techniques. The site-specifically modified oligodeoxynucleotide containing a single 8-MedG was then used as a template for primer extension reactions catalyzed by the 3' --> 5' exonuclease-free (exo-) Klenow fragment of Escherichia Coli DNA polymerase I and mammalian DNA polymerase alpha. Primer extension catalyzed by the exo- Klenow fragment readily passed the 8-MedG lesion in the template while that catalyzed by pol alpha was retarded opposite the lesion. The fully extended products formed during DNA synthesis were analyzed to quantify the miscoding specificities of 8-MedG. Both DNA polymerases incorporated primarily dCMP, the correct base opposite the lesion, along with small amounts of incorporation of dGMP and dAMP. In addition, two-base deletion was observed only when the exo- Klenow fragment was used. The thermodynamic stability of 8-MedG in the duplex was also studied. The duplex containing 8-MedG:dG was more thermally and thermodynamically stable than that of dG:dG. The duplex containing 8-MedG:dA was more thermodynamically stable than that of dG:dA. We conclude that 8-MedG is a miscoding lesion and capable of generating G --> C and G --> T transversions and deletion in cells.

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Identification of C8-methylguanine in the hydrolysates of DNA from rats administered 1,2-dimethylhydrazine. Evidence for in vivo DNA alkylation by methyl radicals.

Cited by 33 publications

References 36 publications

Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation

Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation

Nucleic Acid Alkylation by Free Radical Metabolites of Ethanol. Formation of 8-(1-Hydroxyethyl)guanine and 8-(2-Hydroxyethyl)guanine Adducts

Synthesis, Miscoding Specificity, and Thermodynamic Stability of Oligodeoxynucleotide Containing 8-Methyl-2‘-deoxyguanosine

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