Mutagenicity of oxidative DNA damage in Chinese hamster V79 cells |
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Authors: | Takeuchi T; Matsugo S; Morimoto K |
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Institution: | Department of Hygiene and Preventive Medicine, Osaka University School of Medicine, Suita, Japan. |
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Abstract: | We have investigated the mutagenicity of oxidative DNA damage induced in
V79 Chinese hamster lung fibroblast, and measured 8- hydroxydeoxyguanosine
(8OHdG) levels as an indicator of this damage. A hydroxyl radical
generator, N,N'-bis(2-hydroxyperoxy-2-methoxyethyl)-
1,4,5,8-naphthalene-tetra -carboxylic-diimide (NP-III), induced 8OHdG in
V79 upon irradiation with 366 nm ultraviolet light (UV) for 15 min. 8OHdG
was determined by HPLC with electrochemical detection after anaerobic
sample processing. The 8OHdG level in the cells treated without NP-III was
0.49 per 10(5) dG, whereas levels in the cells treated with 5, 10 or 20
microM NP-III and UV irradiation were 1.84, 4.06 or 6.95 per 10(5) dG,
respectively. The 8OHdG induced by 20 microM NP-III with UV irradiation
decreased rapidly, and the half-life of the induced 8OHdG was approximately
6 h. NP-III with UV irradiation also induced DNA strand breaks in all cells
uniformly, as determined by single cell gel assay. Mutant frequencies at
the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in V79 were
determined as the number of 6-thioguanine-resistant cells per 10(6) cells.
Mutant frequency of the cells without NP-III was 8.0, and frequencies of
the cells treated with 5, 10 or 20 microM NP-III and UV irradiation were
14.9, 20.6 or 24.7 respectively. Treatment with 20 microM NP-III and UV
irradiation decreased the cell number, determined 3 days after the
treatment, to 20.8%. These findings indicate that acutely induced oxidative
DNA damage including mutagenic 8OHdG is only weakly mutagenic in V79.
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