Etoposide protects mice from radiation-induced bone marrow death

Etoposide is known to inhibit the activity of topoisomerase II, and to possess radiosensitizing effects. In this paper we show that pretreatment of mice with etoposide one day before whole-body irradiation had a protective effect against radiation-induced bone marrow death. The LD50/30 of mice given radiation alone was 8.26 Gy while that of mice given etoposide one day before whole-body irradiation was 10.35 Gy. The number of endogenous colony-forming units surviving in whole body-irradiated mice was significantly increased by pretreatment with etoposide.