Abstract
We previously demonstrated that manganese superoxide dismutase (MnSOD) stably transfected human hepatocellular carcinoma cell line, HLE (Motoori et al., Cancer Res. 61:5382-5388, 2001), was resistant to X-irradiation. Cell death induced by X-irradiation occurred through mitochondrial ROS induction and lipid peroxidation. Laser-microscopic quantitative examination of ROS using HPF (Setsukinai et al., J Biol Chem, 278:3170-3175, 2003; Indo et al., Mitochondrion 7:106-118, 2007) showed the development of intracellular ROS at mitochondrial region, and reached at maximum at two hours following x-irradiation. Further, the development of superoxide anions following x-irradiation, was proved by using EPR technique. To examine the main component of mitochondrial inner-membrane, cardiolipin was tested for the oxidation following x-irradiation. The results showed that cardiolipin extracted from irradiated cells showed lipid oxidation, while cardiolipin it-self did not show change in oxidation at two hours following x-irradiation. Thus, cardiolipin-oxidation of intra-mitochondrial membrane following x-irradiation was not originated by cardiolipin-itself oxidation, but by other mechanisms caused by in situ situation was suggested.
