Oxidative damage of Chinese hamster fibroblasts induced by t-butyl hydroperoxide and by X-rays

The aim of this study was to investigate the mechanism(s) of X-ray-mediated cell damage in comparison to mechanism(s) of organic hydroperoxide cytotoxicity and to find the main targets for the two different kinds of cell inactivation. Damage of Chinese hamster fibroblasts induced by tert-butyl hydroperoxide (t-BHP) or X-irradiation was measured by the colony-formation assay and the average single colony volume. DNA double-strand breaks (dsb) were determined by constant-field gel electrophoresis. The contents of peroxides, of SH-groups and the size of inactivated cells were tested for oxidative modifications. Oxidative damage of fibroblasts induced by t-BHP or by X-rays inhibits cell proliferation. Simultaneously, irradiation causes an increase of DNA dsb with the dose, while incubation with t-BHP yields only a very few DNA dsb. Neither chemically induced oxidation nor irradiation significantly changed the amount of membrane lipid peroxides. Oxidation with t-BHP but not irradiation leads to a loss of the membrane SH-groups and to an increase of cell diameter. The similar decrease of cell proliferation can be caused by DNA dsb without detectable membrane damage (X-radiation) as by membrane damage with nearly no DNA dsb (chemically induced oxidative stress). (C) 2003 Elsevier Science B.V. All rights reserved.