Fig. 1: Radiosensitizing effect of doranidazole on GSCs.

a Survival curves for the indicated numbers (n) of mice exposed to 0 or 15 Gy of radiation 10 days after orthotopic implantation of 1000 GSC-H cells, with or without administration of doranidazole (200 mg/kg, i.p.) 30 min before irradiation. PBS phosphate-buffered saline. Representative experiment, n = 2 independent experiments performed. GSC-H cells cultured under normoxic (b) or hypoxic (c) conditions were incubated for 30 min in the absence or presence of 3 mM doranidazole, exposed to 2 Gy of radiation, and then subjected to immunofluorescence staining of γH2AX at 30 min after irradiation. Nuclei were stained with Hoechst 33342. The boxed regions of the left images are shown at higher magnification in the right images. Scale bars, 10 µm. The number of γH2AX foci per nucleus was determined for all nuclei from n = 3 independent experiments, including a total of >150 nuclei per group. GSC-H cells were incubated for 3 h in the absence or presence of 3 mM doranidazole under normoxic d, f or hypoxic e, g conditions, exposed to the indicated doses of radiation d, e, and then subjected to a colony formation assay for 10 days under normoxic conditions. The surviving fraction d, e and plating efficiency f, g determined as the mean ± s.d. from n = 3 d, e or n = 4 f, g independent experiments are shown. Statistical analysis was performed with the log-rank test a; the unpaired two-tailed Student’s t-test b, c; two-way ANOVA followed by Sidak’s post hoc test d, e, with the P values being for comparison of plus or minus doranidazole at 10 Gy; or the paired two-tailed Student’s t-test f, g.