Overexpression of mitochondrial manganese superoxide dismutase protects against radiation-induced cell death in the human hepatocellular carcinoma cell line HLE

We investigated the potential role of mitochondrial manganese superoxide di smutase (Mn-SOD) in protective activity against irradiation by analyzing ce ll viability by a colony formation assay and by detecting apoptosis in stab ly human Mn-SOD gene-transfected HLE, a hepatocellular carcinoma cell line. We found that overexpression of Mn-SOD reduced the levels of reactive oxyg en species in the mitochondria and intracellular phospholipid peroxidation product (4-hydroxy-2-nonenal) and prevented cell death. The production of i ntracellular nitric oxide after irradiation was not changed by Mn-SOD overe xpression, The results suggested that Mn-SOD might play an important role i n protecting cells against radiation-induced cell death by controlling the generation of mitochondrial reactive oxygen species and intracellular lipid peroxidation,