The modification of radiation effect by nucleoside related compounds on a murine tumor given with local radiotherapy and on survival following whole body irradiation

: We have evaluated the effect of nucleoside related compounds on a murine tumor given with local radiotherapy and on the survival rate following whole body irradiation. C3H/He mouse transplanted FM3A tumor and ddY mice were used. The enhancement ratio (ER) for the tumor treated by radiation and nucleoside related compounds was 1.02-1.67. For the normal tissue, Ara-A and BVAU given with radiation had no effect on the survival rate. In the combination of 50-800 mg/kg of ACV and whole body irradiation, the 50% survival day after 7 Gy was shorter than that of radiation alone. When 25-400 mg/kg of 3'-dG was given with radiation, the 50% survival day was longer. When combined with radiation, LD50/30 for ACV and 3'-dG were 3.9 and 6.3 Gy, respectively. ACV showed radiosensitizing effect with Dose modifying factor (DMF) at 1.1, on the other hand, 3'-dG showed radioprotective effect with DMF at 1.47. Our results suggested that some nucleoside analogues might be useful as radiosensitizer.