Objective To investigate the dose-response pattern on the inducible expression of PIG3 mRNA in normal human lymphoblastoid AHHI cells by 60Co γ-rays,and its possibility for developing novel radiation biodosimeter.Methods Laser confocal fluorescent microscopy was used to detect the γ-H2AX foci,a biomarker of DNA double-strand break.After irradiation with 0,1,2,4,6,8 and 10 Gy of 60Coγ- rays,AHH-1 cells were harvested at 4,10 and 24 h post-irradiation,and subjected to total RNA extraction and detection of PIG3 mRNA expression by quantitative real-time PCR.Results PIG3 protein foci were formed in the nuclei at 30 min after irradiation,and a part of these PIG3 foci were colocalized with γH2AX foci.After irradiation,PIG3 mRNA level was enhanced with the increased time of postirradiation,and remained an increased level at least till 24 h.The radiation-inducible expression of PIG3 mRNA was demonstrated in a dose-dependent manner.The dose-dependent range at 4 h post-irradiation was 0 - 6 Gy,and at 10 h and 24 h was 0 - 10 Gy.Conclusions PIG3 involves in the cellular response to DNA double-strand break.The dose-dependent inducible response of PIG3 mRNA expression might provide a valuable candidate for developing a novel radiation biodosimeter.