title: [Reversal effect of 5-Aza-dc on cisplatin-resistance in human NSCLC cells in vitro].
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of 5-aza-2'-deoxycytidine (5-Aza-dc), a methylation inhibitor, on cisplatin-resistance in non-small cell lung cancer cell line A549/DDP and to explore its possible mechanism.
  
  
  METHODS
  MTT assay was used to test the cytotoxicity of 5-Aza-dc on A549/DDP cells, and the IC(50) and cisplatin resistance index of A540/DDP cells at 48 hours after 5-Aza-dc (0 µmol/L, 20 µmol/L, 40 µmol/L) treatment at different concentrations. MSP, fluorescence quantitative RT-PCR (real-time RT-PCR) and Western blot were used to detect the hMLH1 methylation status, mRNA and protein expressions, respectively.
  
  
  RESULTS
  The IC(50) value of cisplatin in A549/DDP cells was 30.15 ± 0.76 µmol/L. The MTT assay results demonstrated that during the 5-Aza-dc treatment for 48 hours, the dose of 20 µmol/L was non-toxic and 40 µmol/L was low-toxic. 5-Aza-dc at those two doses reduced IC(50) value of cisplatin to 16.54 ± 0.35 µmol/L (RI = 1.82) and 6.82 ± 0.16 µmol/L (RI = 4.42), respectively. MSP, real-time RT-PCR and Western blot showed that 5-Aza-dc at non-toxic and low-toxic doses removed the partial hMLH1-hypermethylation, and up-regulated hMLH1 mRNA and protein expressions.
  
  
  CONCLUSIONS
  Low dose 5-Aza-dc can partially reverse the cisplatin-resistance in A549/DDP cells, which may be achieved through removal of hMLH1 hypermethylation and increased expression of hMLH1 gene. 5-Aza-dc may have a role in increasing the efficacy of chemotherapy for patients whose tumors are lack of hMLH1 expression because of hMLH1 promoter hypermethylation.
authors.affiliation: Department of Oncology, the Second Xiang-Ya Hospital, Changsha 410011, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
authors.forename: Chun-hong
authors.initials: CH
authors.lastname: Hu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology*; D001374:Azacitidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D019175:DNA Methylation; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000964:Antimetabolites, Antineoplastic; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D000077209:Decitabine; D000070957:MutL Protein Homolog 1; D001374:Azacitidine; D002945:Cisplatin