Background & objective: DNA double-strand break (DSB) is the main mechanism of tumor cell death after irradiation. Homologous recombination (HR) and DNA nonhomologous end-joining (NHEJ) are two important ways to repair DSB. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of NHEJ, plays a major role during DSB. This study was to investigate the expression of DNA-PKcs in nasopharyngeal carcinoma (NPC), and analyze its correlation to the clinicopathologic features and prognosis of NPC.
Methods: The expression of DNA-PKcs protein in 223 specimens of NPC tissues was detected by immunohistochemistry. The correlation of DNA-PKcs expression to clinicopathologic features and prognosis of NPC were analyzed.
Results: The overexpression rate of DNA-PKcs in 223 NPC specimens was 36.8%. The expression of DNA-PKcs had no significant correlations to gender, age, pathological type and N staging of NPC (P>0.05), but had remarkable correlations to TNM, T and M staging (P<0.05). The 5-year overall survival rate was significantly lower in the patients with overexpression of DNA-PKcs than in those with low expression of DNA-PKcs (54.6% vs. 79.4%, P<0.05). T, N, M staging and the expression of DNA-PKcs were independent predictors for the overall survival of NPC (P<0.05).
Conclusions: DNA-PKcs is positively expressed in the majority of NPC tissues. The expression level of DNA-PKcs is an important factor affecting the prognosis of NPC, which could be used as a prognostic predictor for NPC.