1. DNAPKcs is required for DNA repair in the presence of androgen.
DNAPKcs is required for DNA repair in the presence of androgen. A, C4-2 cells were transfected with a pool of siRNAs directed against the PRKDC transcript or control siRNA for 96 hours then treated with 2 Gy ionizing radiation (IR). Cells were fixed at the indicated time points, stained with α-γ-H2AX and α-53BP1 antibodies, and analyzed by confocal microscopy. Foci were counted and plotted as average foci per cell set relative to control at each time point. B, same as A, but cells were counted 5 days after treatment and cell number set relative to control. C, same as A, but relative expression of transcript levels was analyzed and normalized to GAPDH mRNA at 24 hours after treatment. D, C4-2 cells were cultured in hormone-proficient media for 24 hours then treated with combinations of DHT (1 hour pretreatment), 2 Gy IR, and 1 μmol/L DNAPKcs inhibitor. Cells were fixed at the indicated time points, stained with α-γ-H2AX and α-53BP1 antibodies, and analyzed by confocal microscopy. Foci were counted and plotted as average foci per cell set relative to control at each time point. E, same as D, but cells were counted 5 days posttreatment and cell number set relative to control. F, C4-2 cells transfected with linearized pEYFP plasmid were treated as indicated and activity assessed. G, model describing the feedback circuit of AR and DNAPKcs expression and activity controlling DNA repair and tumor cell survival *, P < 0.05; **, P < 0.01 value. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; DSB, double-strand break.
Jonathan F. Goodwin et al. Cancer Discovery 2013;3:
©2013 by American Association for Cancer Research