Herpes simplex virus thymidine kinase/ganciclovir-induced cell death is enhanced by co-expression of caspase-3 in ovarian carcinoma cells

Cancer Gene Ther. 2001 Apr;8(4):308-19. doi: 10.1038/sj.cgt.7700305.


There is a need to enhance the efficacy of genetic prodrug activation therapy using herpes simplex virus thymidine kinase (tk) and ganciclovir (GCV) following disappointing results in early clinical trials. tk/GCV has been shown to lead to the activation of caspase-3, a potent executor of apoptosis. We demonstrate that co-expression of pro-caspase-3 with tk/GCV leads to enhanced cell death in ovarian carcinoma cells in vitro. Following transfection with recombinant adenoviral vectors encoding tk, GCV treatment leads to greater cell death in pro-caspase-3-expressing clones of SKOV3 and IGROV1 than control cells, as well as more rapid activation of caspase-3 and more rapid cleavage of PARP. Flow cytometry suggests that there is a greater degree of S-phase block in the pro-caspase-3-expressing clones than in control cells following treatment with tk/GCV. None of these effects is seen following transfection with a control adenovirus that does not encode tk. The increased cell death, early caspase-3 activation and PARP cleavage, and flow cytometric changes seen in pro-caspase-3-expressing cells can be partially inhibited by treatment with benzyloxycarbonyl-val-ala-asp fluoromethylketone, a synthetic caspase inhibitor. Our data suggest that co-expression of pro-caspase-3 may lead to a significant enhancement of the efficacy of tk/GCV therapy.

MeSH terms

  • Adenoviridae / genetics
  • Amino Acid Chloromethyl Ketones / pharmacology
  • Antiviral Agents / pharmacology*
  • Apoptosis*
  • Blotting, Western
  • Caspase 3
  • Caspase Inhibitors
  • Caspases / metabolism*
  • Cell Survival / drug effects
  • Cysteine Proteinase Inhibitors / pharmacology
  • DNA Primers / chemistry
  • Drug Resistance, Neoplasm
  • Female
  • Flow Cytometry
  • Ganciclovir / pharmacology*
  • Genetic Therapy / methods
  • Genetic Vectors
  • Green Fluorescent Proteins
  • Humans
  • L-Lactate Dehydrogenase / metabolism
  • Luminescent Proteins / metabolism
  • Ovarian Neoplasms / enzymology
  • Ovarian Neoplasms / pathology*
  • Poly(ADP-ribose) Polymerases / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Simplexvirus / enzymology*
  • Simplexvirus / genetics
  • Thymidine Kinase / metabolism*
  • Transfection
  • Tumor Cells, Cultured / enzymology*


  • Amino Acid Chloromethyl Ketones
  • Antiviral Agents
  • Caspase Inhibitors
  • Cysteine Proteinase Inhibitors
  • DNA Primers
  • Luminescent Proteins
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • Green Fluorescent Proteins
  • L-Lactate Dehydrogenase
  • Poly(ADP-ribose) Polymerases
  • Thymidine Kinase
  • CASP3 protein, human
  • Caspase 3
  • Caspases
  • Ganciclovir