Induction and Rejoining of DNA Single-Strand Breaks in Relation to Cellular Growth in Human Cells Exposed to Three Hydroperoxides at 0°C and 37°C |
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Authors: | Bj rn E. Sandstr m |
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Affiliation: | Bjö,rn E. Sandströ,m |
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Abstract: | There was a 5-fold increase in cytotoxicity for cumene hydroperoxide, 10-fold for tert-butyl hydroperoxide and 25-fold for hydrogen peroxide, under metabolizing conditions (37°C) in comparison to nonmetabolizing conditions (0°C), when human P31 cells were exposed for 60 min. The induction of DNA single-strand breaks correlated poorly with cytotoxicity. Hydrogen peroxide was by far the most effective agent inducing single-strand breaks irrespective of temperature. Cumene hydroperoxide produced fewer strand breaks than tert-butyl hydroperoxide despite its greater cytotoxicity at either 37°C or at 0°C. The pattern of single-strand break induction did not change with temperature. The number of breaks, however, increased when the cells were exposed at 37°C. The pattern of rejoining was similar for hydrogen peroxide- and tert-butyl hydroperoxide-induced breaks at both temperatures whereas the rejoining of cumene hydroperoxide-induced breaks deviated somewhat from this pattern. The results indicate that there is no clear-cut relationship between induction of DNA single-strand breaks and cytotoxicity after hydroperoxide exposure. |
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Keywords: | Cytotoxicity DNA damage DNA repair hydroperoxides ionizing radiation oxidative stress |
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