Effect of heparin-superoxide dismutase on γ-radiation induced DNA damage in vitro and in vivo.

The effects of heparin-superoxide dismutase (SOD) conjugate (heparin-SOD) on γ-radiation induced DNA damage in vivo and in vitro were evaluated. Plasmid pcDNA3.0 solution was mixed with heparin-SOD, SOD, and a mixture of heparin and SOD (heparin + SOD), respectively, and irradiated with (60)Co at a dosage of 120 Gy. DNA injury was analyzed using agarose gel electrophoresis. The results showed that the degree of injury of pcDNA3.0 mixed with heparin-SOD, SOD, or heparin + SOD was less than that of untreated pcDNA3.0, and among them the degree of injury of pcDNA3.0 mixed with heparin-SOD was the least. It also showed that the protective effect increased with an increase of heparin-SOD concentration. The effects of SOD and heparin-SOD on the DNA damage and tumor inhibition rate of (60)Co γ-radiation exposure on tumor-bearing mice were also studied. Agarose gel electrophoresis showed that, when different SOD samples were administered before irradiation, the thymus DNA injuries of heparin-SOD, SOD, or heparin + SOD groups were more serious than that of the control group, and the DNA injuries of heparin-SOD or heparin + SOD groups were the most serious, which contradicted the above in vitro experiments. However, when heparin-SOD was administered post irradiation, it showed a repairing effect on the injured DNA.