Because of its low sensitivity to radiations, therapeutic ratio of neuroglioma is relatively small. And chemo- therapy is not ideal to the disease, either. Therefore, studies are needed towards finding radio-resistance gene. Human cerebral glioma SHG-44, mouse cerebral glioma C6, and small cell lung cancer NCI-H446 (for compari- son), were irradiated by Co γ-rays to 1, 3 and 8Gy, and changes of DNA/RNA ratios in the cells were studied 60 with LSCM (laser scanning confocal microscopy). It was found that the fluorescence dye of DNA in three kinds of cells in the control group is significantly higher than the RNA fluorescence dye (p<0.01). Degree of the damages to the irradiated NCI-H446 cells increased gradually with the dose, and damages to the cerebral glioma cells was less severe at the same radiation dose as the NCI-H446 cells.
The work studies ROS (Reactive oxygen species) release in Deinococcus radiodurans (DR), the relationship between DR proliferation and ROS concentration, and ROS concentration change and its effect in irradiated DR. The release of O2 increased with the dose, reaching a peak at 700Gy. At doses higher than 1kGy, the O2 re- lease decreased rapidly. Added with DPI, the O2 release decreased markedly, and after radiation the concentration - of O2 was always lower than the control group (without DPI). .- Irradiations of less than 1kGy could stimulate the DR proliferation, which reached a peak at 1kGy and de- creased at higher doses. At 3kGy, the DR proliferation was lower than the control. Added with DPI, the prolifera- tion did not show obvious change bellow 1kGy. The release of H2O2 in DR increased with the dose, reaching a peak when at 1kGy, and decreased rapidly at higher doses. At 3kGy, the H2O2 concentration was about the same as the 500Gy irradiated sample. Most eukaryotic cells have NADPH oxidase, which converts oxygen molecule to O2 through mono-electron .- reduction. DPI can inhibit the activity of NADPH oxidase specifically. We found that DR could release O2 and .- that the O2 release could be inhibited by DPI. The result manifested that the NADPH oxidase did exist in DR. and .- O2 was necessary for the transcription of the proliferation-related genes. We also found that H2O2 may play a role .- in DR proliferation. These provide a new idea for further studies on signal transportation and mechanisms of coor- dination in DR proliferation and repair after irradiation.
