Identification of cellular responses to low-dose radiation by the profiling of phosphorylated proteins in human B-lymphoblast IM-9 cells.

PURPOSE: The aim of this study was to explore the potential for radiation-specific signaling of various LDIR-induced effects in human B-lymphoblast IM-9 cells. MATERIALS AND METHODS: Human lymphoblast IM-9 cells were exposed to ionizing radiation at 0.1 and 2 Gy using a 137Cs γ-irradiator at a dose rate of 0.8 Gy/min. Cell viability and DNA fragmentation were determined using MTT assay and TUNEL assay at 24 h after irradiation. Profiling of protein phosphorylation by radiation was identified using a phospho-antibody array at 4 h after irradiation and Dataset of the profiling was analyzed by IPA. RESULTS: Cell survival and apoptotic signaling were not affected by 0.1 Gy of radiation, whereas 2 Gy induced cellular damage. The analysis of low-dose ionizing radiation (LDIR) or high-dose ionizing radiation (HDIR)-specific responses by IPA generated different results. Various cell maintenance functions were only apparent following the analysis of increased protein phosphorylation by LDIR, whereas several cancer formation- and development-related functions were only detected following the analysis of increased protein phosphorylation by HDIR. CONCLUSIONS: The LDIR-induced protein phosphorylation patterns might be involved in various cell survival responses or cellular maintenance functions, which provide important insight into our understanding of the different effects of LDIR and HDIR.