P-2b-60 1 Effect of Continuous Gamma Ray Exposure on Human Cell Growth and Functions

To evaluate biological effects of the radioactive wastes in the environment, we continuously exposed mammalian cells to low dose rate ionizing radiation. Growth of a human osteosarcoma was partially inhibited by the continuous irradiation with 0.08 Gy/h for 40 h, although apoptosis was not detected even at 6.12 Gy/h. Protein expressions of p53 and its down stream target p21, was increased above 0.08 Gy/h. On the other hand, transcription activity of p53 was significantly increased at 0.01 Gy/h. Continuous irradiation enhanced transcription activities of E2F and PPAR, and cytokine productions of T cells and macrophages, while suppressing AP-1 activity. These results suggest the possible way to utilize low dose rate-radiation for biological reactions involved in human diseases