Measurement of 7,8-dihydro-8-oxo-2'-deoxyguanosine metabolism in MCF-7 cells at low concentrations using accelerator mass spectrometry.
Growing evidence suggests that oxidative damage to cells generates mutagenic 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG), which may initiate diseases related to aging and carcinogenesis. Kinetic measurement of 8-oxodG metabolism and repair in cells has been hampered by poor assay sensitivity and by difficulty characterizing the flux of oxidized nucleotides through the relevant metabolic pathways. We report here the development of a sensitive and quantitative approach to characterizing the kinetics and metabolic sources of 8-oxodG in MCF-7 human breast cancer cells by accelerator mass spectrometry. We observed that [(14)C]8-oxodG at medium concentrations of up to 2 pmol/ml was taken up by MCF-7 cells, phosphorylated to mono-, di-, and triphosphate derivatives, and incorporated into DNA. Oxidative stress caused by exposure of the cells to 17beta-estradiol resulted in a reduction in the rate of [(14)C]8-oxodG incorporation into DNA and an increase in the ratio of 8-oxodG monophosphate (8-oxodGMP) to 8-oxodG triphosphate (8-oxodGTP) in the nucleotide pool. 17beta-Estradiol-induced oxidative stress up-regulated the nucleotide pool cleansing enzyme MTH1 and possibly other Nudix-related pyrophosphohydrolases. These data support the conclusion that 8-oxodGTP is formed in the nucleotide pool by both 8-oxodG metabolism and endogenous reactive oxygen species. The metabolism of 8-oxodG to 8-oxodGTP, followed by incorporation into DNA is a mechanism by which the cellular presence of this oxidized nucleoside can lead to mutations.
Hah
Sang Soo
SS
Chemistry, Materials, and Life Sciences Directorate and Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, 7000 East Avenue, L-452, Livermore, CA 94551, USA.
Mundt
Janna M
JM
Kim
Hyung M
HM
Sumbad
Rhoda A
RA
Turteltaub
Kenneth W
KW
Henderson
Paul T
PT
D000080242:8-Hydroxy-2'-Deoxyguanosine; D001943:Breast Neoplasms / Q000737:chemistry* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002851:Chromatography, High Pressure Liquid; D004273:DNA, Neoplasm / Q000737:chemistry / Q000378:metabolism; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005260:Female; D006801:Humans; D013058:Mass Spectrometry
D004273:DNA, Neoplasm; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine