Early and Delayed Induction of DSBs by Nontargeted Effects in ICR Mouse Lymphocytes afterIn VivoX Irradiation

• DOI: 10.1667/rr14053.1
• Publication Date: 2016-06-28T14:50:06Z
• Authors: Mitsuaki Ojima; Keiko Iwashita; Genro Kashino; Shinko Kobashigawa; Noriko Sasano; Akiko Takeshita; Nobuhiko Ban; Michiaki Kai
• Keywords: 0301 basic medicine; Mice, Inbred ICR; 0303 health sciences; Time Factors; X-Rays; Bystander Effect; Coculture Techniques; Mice; 03 medical and health sciences; Animals; DNA Breaks, Double-Stranded; Female; Lymphocytes; Tumor Suppressor p53-Binding Protein 1

The goal of this study was to determine whether in vivo X irradiation induces nontargeted effects, such as delayed effects and bystander effects in ICR mouse lymphocytes. We first examined the generation of DNA double-strand breaks (DSBs) in lymphocytes, isolated from ICR mice exposed to 1 Gy X irradiation, by enumeration of p53 binding protein 1 (53BP1) foci, and observed that the number of 53BP1 foci reached their maximum 3 days postirradiation and decreased to background level 30 days postirradiation. However, the number of 53BP1 foci was significantly increased in lymphocytes isolated from ICR mice 90-365 days postirradiation. This result indicates that in vivo X irradiation induced delayed DSBs in ICR mouse lymphocytes. We next counted the number of 53BP1 foci in lymphocytes isolated from sham-irradiated ICR mice that had been co-cultured with lymphocytes isolated from 1 Gy X-irradiated ICR mice, and observed a significant increase in the number of 53BP1 foci 1-7 days postirradiation. This result indicates that in vivo X irradiation induced bystander effects in ICR mouse lymphocytes. These findings suggest that in vivo X irradiation induces early and delayed nontargeted effects in ICR mouse lymphocytes.