Overexpression of Ogg1 in mammalian cells: effects on induced and spontaneous oxidative DNA damage and mutagenesis

• Published in: Carcinogenesis (New York) 1999-09, Vol.20 (9), p.1863-1868
• Main Authors: Hollenbach, Stephan, Dhénaut, Andreia, Eckert, Inge, Radicella, J. Pablo, Epe, Bernd
• Format: Article
• Language: English
• Subjects: 7,8-Dihydro-8-oxoguanine; 8-dihydro-8-guanine; 8-oxoG; [R]-1-[(10-chloro-4-oxo-3-phenyl-4H-benzo[a]quinolizin-1-yl)-carbonyl]-2-pyrrolidinemethanol; Animals; Biological and medical sciences; Bromates - toxicity; Cell Line - drug effects; Cell Line - radiation effects; Cell physiology; Cricetinae; Cricetulus; DNA Damage; DNA Repair; DNA-Formamidopyrimidine Glycosylase; Effects of physical and chemical agents; Enzyme Induction; Female; Fpg protein; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genes, Reporter; gpt; gpt gene; guanine phosphoribosyl transferase; Molecular and cellular biology; Mutagenesis; N-Glycosyl Hydrolases - biosynthesis; N-Glycosyl Hydrolases - genetics; N-Glycosyl Hydrolases - physiology; OGG1 gene; Ogg1 protein; Ovary; Oxidants - toxicity; oxidative damage; Oxidative Stress; Photochemistry; Photosensitizing Agents - pharmacology; Polymerase Chain Reaction; Pyrrolidines - pharmacology; Quinolizines - pharmacology; Ro19-8022; Transfection
• ISSN: 0143-3334; 1460-2180
• DOI: 10.1093/carcin/20.9.1863

Chinese hamster ovary cell lines (AA8 and AS52) were stably transfected to overexpress hOgg1 protein, the human DNA repair glycosylase for 7,8-dihydro-8-oxoguanine (8-oxoG). In the transfectants, the repair rate of 8-oxoG residues induced by either potassium bromate or the photosensitizer [R]-1-[(10-chloro-4-oxo-3-phenyl-4H-benzo[a]quinolizin-1-yl)-carbonyl]-2-pyrrolidinemethanolplus light was up to 3-fold more rapid than in the parental cells. However, the improved repair had little effect on the mutagenicity of potassium bromate in the guanine phosphoribosyl transferase (gpt) locus of the OGG1-transfected AS52 cells. The steady-state (background) levels of DNA base modifications sensitive to Fpg protein, which include 8-oxoG, in cells not exposed to a damaging agent were not reduced by the overexpression of Ogg1 protein. Moreover, the spontaneous mutation rates in the gpt locus were similar in OGG1-transformed and vector-only-transformed cells. The results demonstrate the potential of Ogg1 protein to remove its substrate modifications from most of the chromosomal DNA. They indicate, on the other hand, that the Ogg1 protein alone may not be rate limiting for the repair of the residual substrate modifications observed in cells under normal growth conditions.