Miscoding Events during DNA Synthesis Past the Nitration-Damaged Base 8-Nitroguanine †
Laboratory of Chemical Biology, Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, New York 11794-8651, USA. Biochemistry
(Impact Factor: 3.02).
07/2005; 44(25):9238-45. DOI: 10.1021/bi050276p
8-Nitro-2'-deoxyguanosine (8-NO(2)-dG) DNA adducts are induced by the reactive nitrogen species and may be associated with the development of cancer in inflammatory tissues. To explore the miscoding potential of 8-NO(2)-dG adduct, an oligodeoxynucleotide containing a single 8-NO(2)-dG adduct was prepared by photochemical synthesis and used as a template in primer extension reactions catalyzed by mammalian DNA polymerases (pol). Primer extension reactions catalyzed by pol alpha or beta were strongly retarded at the 8-NO(2)-dG lesion; a fraction of primers was extended past the lesion by incorporating preferentially dCMP, the correct base, opposite the lesion, accompanied by lesser amounts of dAMP and dGMP incorporation. In contrast, primer extension reactions catalyzed by pol eta or a truncated form of pol kappa (pol kappaDeltaC) readily extended past the 8-NO(2)-dG lesion. Pol eta and kappaDeltaC showed more broad miscoding spectra; direct incorporations of dCMP and dAMP were observed, along with lesser amounts of dGMP and dTMP incorporations and deletions. The miscoding frequencies induced by pol eta and kappaDeltaC were at least 8 times higher than that of pol alpha or beta. Miscoding frequency and specificity of 8-NO(2)-dG varied depending on the DNA polymerases used. These observations were supported by steady-state kinetic studies. 8-NO(2)-dG adduct may play an important role in initiating inflammation driven carcinogenesis.
Available from: Olfat Hammam
- "Cells deficient in Rev1 and Rev3, subunits of DNA polymerase í µí¼, were hypersensitive to nitrative stress, and translesion DNA synthesis past apurinic sites mediated by this polymerase might contribute to extensive point mutations . It has been reported that adenine is preferentially incorporated opposite 8-nitroguanine during DNA synthesis catalyzed by polymerase í µí¼ and í µí¼
ΔC in a cell-free system, suggesting that G:C to T:A transversions can occur . In the ONOO − -treated supF shuttle vector, which was replicated in host Escherichia coli cells, the majority of mutations occurred at G:C base pairs, predominantly involving G:C to T:A transversions . "
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ABSTRACT: Infection and chronic inflammation have been recognized as important factors for carcinogenesis. Under inflammatory conditions, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from inflammatory and epithelial cells and result in oxidative and nitrative DNA damage, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-nitroguanine. The DNA damage can cause mutations and has been implicated in the initiation and/or promotion of inflammation-mediated carcinogenesis. It has been estimated that various infectious agents are carcinogenic to humans (IARC group 1), including parasites (Schistosoma haematobium (SH) and Opisthorchis viverrini (OV)), viruses (hepatitis C virus (HCV), human papillomavirus (HPV), and Epstein-Barr virus (EBV)), and bacterium Helicobacter pylori (HP). SH, OV, HCV, HPV, EBV, and HP are important risk factors for bladder cancer, cholangiocarcinoma, hepatocellular carcinoma, cervical cancer, nasopharyngeal carcinoma, and gastric cancer, respectively. We demonstrated that 8-nitroguanine was strongly formed via inducible nitric oxide synthase (iNOS) expression at these cancer sites of patients. Moreover, 8-nitroguanine was formed in Oct3/4-positive stem cells in SH-associated bladder cancer tissues and in Oct3/4- and CD133-positive stem cells in OV-associated cholangiocarcinoma tissues. Therefore, it is considered that oxidative and nitrative DNA damage in stem cells may play a key role in inflammation-related carcinogenesis.
Available from: Lesley A Iwanejko
- "8-Nitroguanine has previously been incorporated into ODNs in a site-specific manner through photochemical nitration of a single dG residue present in the sequence (12,19). This procedure gave extremely low yields (∼3% based on the starting ODNs) of the hydrolytically unstable nitrated oligonucleotides and the products were only available in nanomole quantities, which was insufficient to perform any physicochemical studies on this lesion (19). "
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ABSTRACT: 8-Nitro-2′-deoxyguanosine (8-nitrodG) is a relatively unstable, mutagenic lesion of DNA that is increasingly believed to be
associated with tissue inflammation. Due to the lability of the glycosidic bond, 8-nitrodG cannot be incorporated into oligodeoxynucleotides
(ODNs) by chemical DNA synthesis and thus very little is known about its physicochemical properties and base-pairing preferences.
Here we describe the synthesis of 8-nitro-2′-O-methylguanosine, a ribonucleoside analogue of this lesion, which is sufficiently stable to be incorporated into ODNs. Physicochemical
studies demonstrated that 8-nitro-2′-O-methylguanosine adopts a syn conformation about the glycosidic bond; thermal melting studies and molecular modelling suggest a relatively stable syn-8-nitroG·anti-G base pair. Interestingly, when this lesion analogue was placed in a primer-template system, extension of
the primer by either avian myeloblastosis virus reverse transcriptase (AMV-RT) or human DNA polymerase β (pol β), was significantly
impaired, but where incorporation opposite 8-nitroguanine did occur, pol β showed a 2:1 preference to insert dA over dC, while
AMV-RT incorporated predominantly dC. The fact that no 8-nitroG·G base pairing is seen in the primer extension products suggests
that the polymerases may discriminate against this pairing system on the basis of its poor geometric match to a Watson–Crick
Available from: Shosuke Kawanishi
- "Wu et al. suggested that cells deficient in subunits of DNA polymerase ζ were hypersensitive to nitrative stress, and trans-lesion DNA synthesis mediated by this polymerase contributes to extensive point mutations . Additionally, DNA polymerases η and κ were also found to be involved in the incorporation of adenine opposite 8-nitroguanine during DNA synthesis in a cell-free system associated with trans-lesion DNA synthesis leading to the G → T transversion . Therefore, 8-nitroguanine is a potential mutagenic DNA lesion involved in inflammation-mediated carcinogenesis. "
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ABSTRACT: Chronic inflammation induced by biological, chemical, and physical factors has been found to be associated with the increased risk of cancer in various organs. We revealed that infectious agents including liver fluke, Helicobacter pylori, and human papilloma virus and noninfectious agents such as asbestos fiber induced iNOS-dependent formation of 8-nitroguanine and 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) in cancer tissues and precancerous regions. Our results with the colocalization of phosphorylated ATM and γ-H2AX with 8-oxodG and 8-nitroguanine in inflammation-related cancer tissues suggest that DNA base damage leads to double-stranded breaks. It is interesting from the aspect of genetic instability. We also demonstrated IL-6-modulated iNOS expression via STAT3 and EGFR in Epstein-Barr-virus-associated nasopharyngeal carcinoma and found promoter hypermethylation in several tumor suppressor genes. Such epigenetic alteration may occur by controlling the DNA methylation through IL-6-mediated JAK/STAT3 pathways. Collectively, 8-nitroguanine would be a useful biomarker for predicting the risk of inflammation-related cancers.
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