title: [Molecular mechanism of γ-aminobutyric acid inhibitory on the growth of cholangiocarcinoma QBC939 cell line].
abstract: OBJECTIVE
  To explore the molecular mechanism of γ-aminobutyric acid (GABA) inhibitory on the growth of cholangiocarcinoma cell line (QBC939).
  
  
  METHODS
  QBC939 cells were cultured in different groups and treated with GABA, GABA + bicuculine (A receptor antagonist), GABA + phaclofen (B receptor antagonist) for 48 hours. MTT assay was used to determine the proliferation of QBC939 cells. Annexin V-FITC/PI binding assay was used to detect apoptosis in the QBC939 cells. Western blot was applied to check the expression of signal transducer and activator of transcription 3 (STAT3) and phosphorylation-STAT3 (p-STAT3) proteins in different groups of QBC939 cells. Animal models of cholangiocarcinoma bearing nude mice were established by subcutaneous injection of QBC939 cells and randomized into 2 groups: control and GABA-treated groups. The effect of GABA was evaluated after 5 weeks, including the body weight and tumor volume. The expression of p-STAT3 was detected by immunohistochemistry and Western blot in xenograft tumors.
  
  
  RESULTS
  MTT and FCM assays both showed that the effect of GABA inhibitory on the proliferation (15.30% ± 0.80% vs. 2.66% ± 0.74%, t = 23.15, P = 0.00) and induced apoptosis (23.15% ± 0.21% vs. 4.30% ± 0.69%, t = 52.40, P = 0.00) of QBC939 cells could be antagonized by phaclofen, but not bicuculine. The expression of STAT3 and p-STAT3 proteins were all observed in the QBC939 cells and GABA significantly down-regulated p-STAT3 protein expression (0.77 ± 0.00 vs. 0.45 ± 0.01, t = 63.14, P = 0.00), this action was also antagonized by phaclofen (0.45 ± 0.01 vs. 0.76 ± 0.01, t = 56.25, P = 0.00). Xenograft tumor volume ((0.62 ± 0.03) cm³ vs. (0.34 ± 0.03) cm³, t = 13.45, P = 0.00) and the expression of p-STAT3 protein were significantly decreased in GABA-treated group as compared with control group.
  
  
  CONCLUSIONS
  GABA may inhibit the growth of cholangiocarcinoma cells QBC939 through GABA(B) receptor, and down-regulation of the p-STAT3 expression perhaps is one of its anti-tumor mechanisms.
authors.affiliation: Department of General Surgery, Affiliated Provincial Hospital of Anhui Medical University, Hefei 230001, China.
authors.forename: Cheng-lin
authors.initials: CL
authors.lastname: Zhu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Huang
authors.forename: Chen-hai
authors.initials: CH
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Xie
authors.forename: Kai
authors.initials: K
authors.lastname: Zhu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001650:Bile Duct Neoplasms / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018281:Cholangiocarcinoma / Q000473:pathology*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D050796:STAT3 Transcription Factor / Q000378:metabolism; D047368:Tumor Burden; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D005680:gamma-Aminobutyric Acid