title: Ku80 is highly expressed in lung adenocarcinoma and promotes cisplatin resistance.
abstract: BACKGROUND
  Ku80 is crucially implicated in DNA repair, apoptosis, and chemoresistance. In this study, we aimed to assess the expression of Ku80 in clinical lung adenocarcinoma specimens, and investigate its role in the regulation of cisplatin sensitivity in cisplatin resistant human lung adenocarcinoma cells A549/DDP.
  
  
  METHODS
  Tumor specimens and medical records of 106 patients with operable lung adenocarcinoma were obtained from 1998 to 2003. Ku80 mRNA and protein levels of the tumor samples, cultured human lung adenocarcinoma cells A549 cells and their cisplatin resistant variant A549/DDP cells were examined by reverse transcription PCR and western blot analysis. Ku80-specific siRNA or control scramble siRNA was transfected into A549/DDP cells, then cell sensitivity to cisplatin was examined by 3-(4,5-dimethylthia-zol-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis was assessed by flow cytometric analysis. In addition, the levels of cleaved caspase-3 and cleaved PARP in the treated cells were detected by western blot analysis.
  
  
  RESULTS
  Total 83.3% (20/24) cisplatin-resistant tumors had high Ku80 expression, while 8.3% (4/48) cisplatin-sensitive tumors had high Ku80 expression (p < 0.01). Univariate analysis indicated that overall survival and progression-free survival were significantly better in lung adenocarcinoma patients with low vs. high Ku80 expression level (p < 0.01). Ku80 mRNA and protein expression levels were significantly increased in A549/DDP cells compared to parental A549 cells. siRNA mediated knockdown of Ku80 resensitized A549/DDP cells to cisplatin-induced apoptosis.
  
  
  CONCLUSIONS
  Ku80 expression level could predict the outcome and the sensitivity to cisplatin-based chemotherapy in patients with lung adenocarcinoma. Ku80-siRNA could be utilized as a therapeutic strategy to resensitize nonresponders to cisplatin.
authors.affiliation: Department of Respiratory Medicine, The Second Affiliated Hospital of Jilin University, Changchun, China.
authors.forename: Qingshan
authors.initials: Q
authors.lastname: Ma
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Minyu
authors.initials: M
authors.lastname: Xu
authors.forename: Jinzhi
authors.initials: J
authors.lastname: Yin
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Su
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D054316:Biomarkers, Pharmacological / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000008:administration & dosage*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018572:Disease-Free Survival; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000072200:Ku Autoantigen; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism
chemical_list: D034961:Antigens, Nuclear; D054316:Biomarkers, Pharmacological; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D053148:Caspase 3; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D002945:Cisplatin