To investigate the activated status of DNA-PKcs in glioma progression, we first evaluated the expression levels of phosphorylated-DNA-PKcs (Ser 2056, p-DNA-PKcs S2056) in human gliomas and their paired adjacent nontumorous tissues or normal human brain tissues using immunoblotting. As shown in Figure 1A, p-DNA-PKcs was significantly higher in 7 human glioma specimens than their respective adjacent nontumorous tissues or 2 normal brains. Immunohistochemistry (IHC) analysis in a cohort of 217 paraffin-embedded glioma samples further confirmed the overexpression of p-DNA-PKcs in 57.2% of gliomas (124/217) as compared with corresponding non-tumor tissues (62/217, 28.6%; Figure 1B - 1C, Supplementary Table S1). We then assessed the relationship between p-DNA-PKcs levels and the clinical features of glioma. Strong expressions of p-DNA-PKcs were positively correlated with higher grade tumor status (Figure 1D - 1E, Supplementary Figure S1), and also closely associated with worse survival of glioma as determined by the Kaplan-Meier and log-rank tests for survival analysis (OS, p < 0.0001; Figure 1F). More importantly, multi-variate analysis through Cox regression model with all 6 parameters (p-DNA-PKcs level, age, gender, tumor location, debulking degree, tumor grade) identified the independent prognostic significance of p-DNA-PKcs (hazard ratio: 3.052; p < 0.001; 95% CI: 2.204 - 4.572), which was not linked to known prognostic factors such as ages and tumor grades (Supplementary Table S2).