Sun J, Chen Y, Li M, Ge Z
Research Laboratory of Free Radical Medicine, The First Military Medical University, Guangzhou, China.
Free Radic Biol Med. 1998 Mar 1;24(4):586-93. doi: 10.1016/s0891-5849(97)00291-8.
Exposure of cells to ionizing radiation leads to formation of reactive oxygen species (ROS) that are associated with radiation-induced cytotoxicity. The antioxidant enzymes manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD), and glutathione peroxidase (GPx), are key intracellular antioxidants in the metabolism of ROS. We investigated the potential role of the three antioxidant enzymes in radioresistance by analyzing cell morphology, cell viability, and cellular radioresistance in stably transfected CHO cell lines overexpressing MnSOD, CuZnSOD, and GPx, respectively. We found that overexpression of human MnSOD substantially protected cells from ionizing radiation injury. Relative to MnSOD, GPx could slightly reduce the radiation sensitivity while the radioresistance in CuZnSOD expressing cells did not change significantly. The results suggested that MnSOD may play a central role in protecting cells against reactive oxygen species injury during ionizing radiation exposure among MnSOD, CuZnSOD, and GPx.
细胞暴露于电离辐射会导致活性氧（ROS）的形成，而活性氧与辐射诱导的细胞毒性有关。抗氧化酶锰超氧化物歧化酶（MnSOD）、铜锌超氧化物歧化酶（CuZnSOD）和谷胱甘肽过氧化物酶（GPx）是细胞内活性氧代谢中的关键抗氧化剂。我们通过分析分别稳定转染了过表达MnSOD、CuZnSOD和GPx的CHO细胞系的细胞形态、细胞活力和细胞辐射抗性，研究了这三种抗氧化酶在辐射抗性中的潜在作用。我们发现，人MnSOD的过表达能显著保护细胞免受电离辐射损伤。相对于MnSOD，GPx可略微降低辐射敏感性，而表达CuZnSOD的细胞的辐射抗性没有明显变化。结果表明，在MnSOD、CuZnSOD和GPx中，MnSOD在电离辐射暴露期间保护细胞免受活性氧损伤方面可能起核心作用。
