Overexpression of cyclooxygenase-2 in human HepG2, Bel-7402 and SMMC-7721 hepatoma cell lines and mechanism of cyclooxygenase-2 selective inhibitor celecoxib-induced cell growth inhibition and apoptosis

World J Gastroenterol. 2005 Oct 28;11(40):6281-7. doi: 10.3748/wjg.v11.i40.6281.


Aim: To investigate the cyclooxygenase-2 (COX-2) expression level in human HepG2, Bel-7402 and SMMC-7721 hepatoma cell lines and the molecular mechanism of COX-2 selective inhibitor celecoxib-induced cell growth inhibition and cell apoptosis.

Methods: Hepatoma cells were cultured and treated with celecoxib. Cell in situ hybridization (ISH) and immunocytochemistry were used to detect COX-2 mRNA and protein expression. Proliferating cell nuclear antigen and phosphorylated Akt were also detected by immunocytochemistry assay. Cell growth rates were assessed by 3-(4, 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium (MTT) bromide colorimetric assay. Celecoxib-induced cell apoptosis was measured by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and flow cytometry (FCM). The phosphorylated Akt and activated fragments of caspase-9, caspase-3 were examined by Western blotting analysis.

Results: Increased COX-2 mRNA and protein expression were detected in all three hepatoma cell lines. Celecoxib could significantly inhibit cell growth and the inhibitory effect was in a dose- and time-dependent manner evidenced by MTT assays and morphological changes. The apoptotic index measured by TUNEL increased correspondingly with the increased concentration of celecoxib and the reaction time. With 50 micromol/L celecoxib treatment for 24 h, the apoptotic index of HepG2, BEL-7402 and SMMC-7721 cells was 25.01+/-3.08%, 26.40+/-3.05%, and 30.60+/-2.89%, respectively. Western blotting analysis showed remarkable activation of caspase-9, caspase-3 and dephosphorylation of Akt (Thr(308)). Immunocytochemistry also showed the reduction of PCNA expression and phosphorylation Akt (Thr(308)) after treatment with celecoxib.

Conclusion: COX-2 mRNA and protein overexpression in HepG2, Bel-7402 and SMMC-7721 cell lines correlate with the increased cell growth rate. Celecoxib can inhibit proliferation and induce apoptosis of hepatoma cell strains in a dose- and time-dependent manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis / physiology
  • Carcinoma, Hepatocellular*
  • Caspase 3
  • Caspase 9
  • Caspases / metabolism
  • Celecoxib
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Cyclooxygenase 2 Inhibitors / pharmacology*
  • Enzyme Activation
  • Humans
  • In Situ Hybridization
  • Liver Neoplasms*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Pyrazoles / pharmacology*
  • RNA, Messenger / metabolism
  • Sulfonamides / pharmacology*


  • Cyclooxygenase 2 Inhibitors
  • Pyrazoles
  • RNA, Messenger
  • Sulfonamides
  • Cyclooxygenase 2
  • Proto-Oncogene Proteins c-akt
  • CASP3 protein, human
  • CASP9 protein, human
  • Caspase 3
  • Caspase 9
  • Caspases
  • Celecoxib