The sensitivity to DNA single strand breakage in mitochondria, but not in nuclei, of Chinese hamster V79 and variant cells correlates with their cellular sensitivity to hydrogen peroxide

Abstract

To investigate whether a relation exists between the level of DNA damage by and cytotoxicity of hydrogen peroxide, we measured the initial level of H 2O 2-induced nuclear and mitochondrial DNA single strand breaks in Chinese hamster V79 and H 2O 2-resistant variant cells (Hpr-4) with an alkaline elution technique and a quantitative Southern blot technique, respectively. The frequency of DNA single strand breaks in mitochondrial DNA induced by H 2O 2 was more than one hundred times that of nuclear DNA in the parent V79 cells. While a similar frequency of nuclear DNA single strand breaks was generated in V79 and Hpr-4 cells at an equidose of H 2O 2, a lower number of mitochondrial DNA single strand breaks were generated in Hpr-4 cells than in V79 cells by H 2O 2 in the range of 100 μM to 5 mM. The sensitivity to mitochondrial DNA single strand break-induction correlated with the cellular sensitivity to H 2O 2 in Chinese hamster V79 and variant cells.