Figure 1.

Effect of eIF4A1 knockdown on tumor cell translational efficiency, radiosensitivity, and radiation induced γH2AX foci. A. Tumor cell lines were transfected with non-targeting siRNA (siNT) or siRNA against eIF4A1 (sieIF4A1). 72 hours post-transfection, cell lysates were immunoblotted for eIF4A1 with GAPDH as a loading control. Normalized ratios of eIF4A1 to GAPDH are shown below the blots. B. Polysome profiling was performed on eIF4A1 knockdown U251 and HeLa cells 72 hours post-transfection. Translational efficiencies (TEs) calculated from the polysome profiles are shown. C. Clonogenic survival analysis of U251 and HeLa cells. 72 hours post-transfection, cells were plated at clonal density and colonies determined after 12–14 days. DEFs were calculated at a surviving fraction of 0.1. Values represent the mean ± SEM for 3 independent experiments. D. γH2AX foci analysis of U251 and HeLa cells. siNT and sieIF4A1 cells were plated 72 hours post-transfection, irradiated (2Gy) the next day, and collected at the indicated time points for foci analysis. γH2AX foci were counted in 50 cells per treatment group. Values represent the mean ± SEM for 3 independent experiments. * p<0.05 by Student’s t-test.