Effect of ionizing radiation on the differentiation of ROS 17/2.8 osteoblasts through free radicals

Although the acceleration of bone regeneration by radiation has been report ed, the mechanisms of action of radiation on bone are unclear. The present results indicate that ionizing radiation-stimulated differentiation could r esult from the generation of reactive oxygen species during radiation expos ure. The free radical release is considered as the most important mechanism of bone effect by radiation treatment. In addition, we report that radiati on induced transient activation of c-Jun N-terminal kinase/ stress-activate d protein kinase (JNK/SAPK) activation and the transcription factor, AP-1. The JNK and AP-1 activation is mediated with radiation-released free radica ls in ROS 17/2.8 osteoblasts. These results indicate that ionizing radiatio n at a single dose of up to 5 Gray stimulates differentiation of ROS 17/2.8 osteoblasts via free radial release which may affect JNK/SAPK and AP-1 act ivities.