Incorporation of extracellular 8-oxodG into DNA and RNA requires purine nucleoside phosphorylase in MCF-7 cells

Janna M. Mundt, Sang Soo Hah, Rhoda A. Sumbad, Vern L. Schramm, Paul T. Henderson

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

7,8-Dihydro-8-oxo-2′-deoxyguanosine (8-oxodG) is a well-known marker of oxidative stress. We report a mechanistic analysis of several pathways by which 8-oxodG is converted to nucleotide triphosphates and incorporated into both DNA and RNA. Exposure of MCF-7 cells to [14C]8-oxodG combined with specific inhibitors of several nucleotide salvage enzymes followed with accelerator mass spectrometry provided precise quantitation of the resulting radiocarbon-labeled species. Concentrations of exogenously dosed nucleobase in RNA reached one per 106 nucleotides, 5-6-fold higher than the maximum observed in DNA. Radiocarbon incorporation into DNA and RNA was abrogated by Immucillin H, an inhibitor of human purine nucleoside phosphorylase (PNP). Inhibition of ribonucleotide reductase (RR) decreased the radiocarbon content of the DNA, but not in RNA, indicating an important role for RR in the formation of 8-oxodG-derived deoxyribonucleotides. Inhibition of deoxycytidine kinase had little effect on radiocarbon incorporation in DNA, which is in contrast to the known ability of mammalian cells to phosphorylate dG. Our data indicate that PNP and RR enable nucleotide salvage of 8-oxodG in MCF-7 cells, a previously unrecognized mechanism that may contribute to mutagenesis and carcinogenesis.

Original languageEnglish (US)
Pages (from-to)228-236
Number of pages9
JournalNucleic Acids Research
Volume36
Issue number1
DOIs
StatePublished - Jan 2008

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Purine-Nucleoside Phosphorylase
MCF-7 Cells
Ribonucleotide Reductases
RNA
Nucleotides
DNA
Deoxycytidine Kinase
Deoxyribonucleotides
Mutagenesis
Mass Spectrometry
Carcinogenesis
Oxidative Stress
8-oxo-7-hydrodeoxyguanosine
Enzymes

ASJC Scopus subject areas

  • Genetics

Cite this

Incorporation of extracellular 8-oxodG into DNA and RNA requires purine nucleoside phosphorylase in MCF-7 cells. / Mundt, Janna M.; Hah, Sang Soo; Sumbad, Rhoda A.; Schramm, Vern L.; Henderson, Paul T.

In: Nucleic Acids Research, Vol. 36, No. 1, 01.2008, p. 228-236.

Research output: Contribution to journalArticle

Mundt, Janna M. ; Hah, Sang Soo ; Sumbad, Rhoda A. ; Schramm, Vern L. ; Henderson, Paul T. / Incorporation of extracellular 8-oxodG into DNA and RNA requires purine nucleoside phosphorylase in MCF-7 cells. In: Nucleic Acids Research. 2008 ; Vol. 36, No. 1. pp. 228-236.
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