title: Targeted drug regulation on methylation of p53-BAX mitochondrial apoptosis pathway affects the growth of cholangiocarcinoma cells.
abstract: OBJECTIVE
  To study the mechanism of 5-aza-2-deoxycytidine (DAC; a methylation inhibitor) on growth of the human cholangiocarcinoma QBC939 cell line.
  
  
  METHODS
  A colourimetric assay was used to detect growth of QBC939 cells treated with DAC (0.1-100 μmol/l) over 24 h, 48 h and 72 h. Cell morphology was observed by transmission electron microscopy (TEM). The cell cycle and apoptosis were analysed by flow cytometry. Hypermethylation of the promoters of the p53-BAX mitochondrial apoptosis genes cyclin-dependent kinase inhibitor 2A (CDKN2A), death-associated protein kinase 1 (DAPK1) and PYD and CARD domain containing (PYCARD) was detected by methylation-specific polymerase chain reaction, with and without DAC treatment.
  
  
  RESULTS
  DAC inhibited QBC939 cell growth with a half maximal inhibitory concentration of 5 μmol/l at 72 h. After DAC treatment, apoptosis was observed by TEM. Flow cytometric analysis of propidium iodide-positive cells demonstrated increased apoptosis of DAC-treated QBC939 cells (43.04%) compared with untreated cells (4.31%). DAC treatment resulted in demethylation of the gene promoters of CDKN2A and DAPK1 in QBC939 cells.
  
  
  CONCLUSIONS
  DAC induces apoptosis of QBC939 cells by reactivation of hypermethylated p53-BAX mitchondrial apoptosis genes in cholangiocarcinoma cells.
authors.affiliation: Department of Hepatobiliary Surgery, Affiliated Yantai Yuhuangding Hospital, Qingdao University Medical College, Yantai, China. liu634@263.net
authors.forename: X-F
authors.initials: XF
authors.lastname: Liu
authors.forename: H
authors.initials: H
authors.lastname: Jiang
authors.forename: C-S
authors.initials: CS
authors.lastname: Zhang
authors.forename: S-P
authors.initials: SP
authors.lastname: Yu
authors.forename: Z-Q
authors.initials: ZQ
authors.lastname: Wang
authors.forename: H-L
authors.initials: HL
authors.lastname: Su
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D001374:Azacitidine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018281:Cholangiocarcinoma / Q000235:genetics / Q000473:pathology* / Q000648:ultrastructure; D019175:DNA Methylation / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D051028:bcl-2-Associated X Protein / Q000235:genetics*
chemical_list: D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D001374:Azacitidine