title: The functional status of DNA repair pathways determines the sensitization effect to cisplatin in non-small cell lung cancer cells.
abstract: OBJECTIVE
  Cisplatin can cause a variety of DNA crosslink lesions including intra-strand and inter-strand crosslinks (ICLs), which are associated with the sensitivity of cancer cells to cisplatin. Here, we aimed to assess the contribution of the Fanconi anemia (FA), homologous recombination (HR) and nucleotide excision repair (NER) pathways to cisplatin resistance in non-small cell lung cancer (NSCLC)-derived cells.
  
  
  METHODS
  The expression of FA, HR and NER pathway-associated genes was assessed by RT-qPCR and Western blotting. siRNAs were used to knock down the expression of these genes. CCK-8 and flow cytometry assays were used to assess the viability and apoptotic rate of NSCLC-derived cells, respectively. Immunofluorescence and alkaline comet assays were used to assess the repair of ICLs.
  
  
  RESULTS
  We found that acquired cisplatin-resistant NSCLC-derived A549/DR cells exhibited markedly enhanced FA and HR repair pathway capacities compared to its parental A549 cells and another independent NSCLC-derived cell line, Calu-1, which possesses a moderate innate resistance to cisplatin. siRNA-mediated silencing of the FA-associated genes FANCL and RAD18 and the HR-associated genes BRCA1 and BRCA2 significantly potentiated the sensitivity of A549/DR cells to cisplatin compared to A549 and Calu-1 cells, suggesting that the acquired cisplatin resistance in A549/DR cells may be attributed to enhanced FA and HR pathway capacities responsible for ICL repair. Although we found that expression knockdown of the NER-associated genes XPA and ERCC1 sensitized the three NSCLC-derived cell lines to cisplatin, the sensitization effect was more significant in Calu-1 cells than in A549 and A549/DR cells, implying that the innate cisplatin resistance in Calu-1 cells may result from an increased NER activity.
  
  
  CONCLUSIONS
  Our results indicate that the functional status of DNA repair pathways determine the sensitivity of NSCLC cells to cisplatin. Direct targeting of the pathway that is involved in cisplatin resistance may be an effective strategy to surmount cisplatin resistance in NSCLC.
authors.affiliation: Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, 438 North Jiefang Street, Zhenjiang, 212001, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, 438 North Jiefang Street, Zhenjiang, 212001, China. lijian541226@163.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Medical Science, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Yong-Chang
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Institute of Medical Science, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Qian
authors.affiliation: Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, 438 North Jiefang Street, Zhenjiang, 212001, China.
authors.forename: Yu-Jiao
authors.initials: YJ
authors.lastname: Chen
authors.affiliation: Department of Pulmonary Medicine, Affiliated Hospital of Jiangsu University, 438 North Jiefang Street, Zhenjiang, 212001, China.
authors.forename: Jin-Yu
authors.initials: JY
authors.lastname: Su
authors.affiliation: Institute of Medical Science, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.affiliation: Institute of Medical Science, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Lan
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000627:therapeutic use; D020552:Comet Assay; D004260:DNA Repair / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin
keywords: Cisplatin sensitivity; DNA repair pathway; Gene silencing; Non-small cell lung cancer