title: [Expression and clinical significance of DNA-PKcs in nasopharyngeal carcinoma].
abstract: 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.
authors.affiliation: State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, PR China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Yan
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Liu
authors.forename: Mu-Sheng
authors.initials: MS
authors.lastname: Zeng
authors.forename: Li-Bing
authors.initials: LB
authors.lastname: Song
authors.forename: Yun-Fei
authors.initials: YF
authors.lastname: Xia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000378:metabolism*; D010315:Particle Accelerators; D011379:Prognosis; D016016:Proportional Hazards Models; D015996:Survival Rate; D055815:Young Adult
chemical_list: D003037:Cobalt Radioisotopes; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human