Regulation of Ionizing Radiation-induced Apoptosis by MnSOD Gene Transfection

Ionizing radiation induces the production of superoxide radicals (O(2)(-).) which play a role in apoptosis generation. Manganese superoxide dismutase (MnSOD) is a mitochondrial antioxidant enzyme involved in scavenging O(2)(-). This study is designed to investigate the effect of MnSOD on ionizing radiation-induced apoptosis. The eukaryotic expressing vector, pHbetaAPr-3p-neo, containing sense and antisense human MnSOD cDNA have been introduced into Chinese hamster ovary (CHO) cells respectively by gene transfection method and the MnSOD overexpressing cell lines have been used in this study. It was found that the cell clone overexpressing sense MnSOD could effectively prevent 8 Gy X-ray-induced apoptosis in CHO cells, whereas the clone overexpressing antisense MnSOD increased their sensitivity. Further studies also demonstrated that alterations of mitochondrial membrane potential (deltapsi(m)) may play an important role in the regulatory mechanisms of MnSOD on ionizing radiation-induced apoptosis.