Figure 1.

TOPK is a tumour-specific modulator of radiosensitivity.(A) TOPK was transiently knocked down with siRNA (siTOPK) and post-irradiation clonogenic survival was assessed in cancer-derived cells. Transfection with siNT was used as a control and knockdown efficiency was confirmed by immunoblotting (insets). (B) No significant TOPK-dependent radiosensitisation was detected in HFL-1 and MRC5 cells. (C) TOPK activity was inhibited by 4 h pretreatment with 70–200 nM OTS964 (70 nM for HCT116, DU145, 100 nM for HeLa, 200 nM for HFL-1, MRC5). (D) No significant TOPK-dependent radiosensitisation was detected in HFL-1 and MRC5 cells treated with OTS964. All data are representative of three independent experiments and are presented as mean ± s.d. from triplicate wells. Survival curves were fitted using non-linear regression. Results were analysed by factorial two-way ANOVA, with interaction term significance of P<0.05. PE=plating efficiency; SER₁₀=survival enhancement ratio at a surviving fraction of 0.10.