ISPO

Acquisition of herpes simplex virus-thymidine kinase gene in human non-small lung cancer cells conferred caspase-activated apoptosis upon ganciclovir sensitization

C-C Chou MS, T-H Yang BS, K Fang PhD

Department of Biology, National Taiwan Normal University, Taipei, Taiwan

AIM: The obstinate nature and aggressive character of human lung cancer cells demand in depth investigation of novel approaches for efficient therapy and treatment. In the present study, we described the occurrence of dose-dependent apoptosis following GCV treatment after delivery of recombinant prodrug herpes simplex virus type I thymidine kinase (HSV-tk) gene in an established metastatic and highly invasive human non-small-cell-lung cancer (NSCLC) cells. This work was to determine whether acquisition of HSV-tk cDNA conferred GCV susceptibility to the selected clones and to understand their mechanism toward apoptotic progression. METHODS: A metastatic and highly invasive human non-small-cell-lung cancer (NSCLC) cell line, CL-1, was transfected with HSV-tk cDNA and the stable propagating clones underwent apoptosis following ganciclovir (GCV) treatment. The efficiency of GCV-induced growth inhibition and the extent of the bystander effect were studied RESULTS: The acquisition of HSV-tk gene conferred GCV susceptibility to the selected clones with characteristic apoptosis. The potent bystander effect was found proportional to the level of HSV-tk expressed. The cells underwent ecotopic transfer of HSV-tk lead to G2/M phase rest after GCV induction that lead to apoptosis. We have identified three steps that occurred in order prior to apoptosis progression: (a) release of cytochrome c; (b) activation of caspase pathway; and (c) transient escalation of endogenous cell cycle regulators, cyclin B1, and tumor suppressor p53. CONCLUSION: HSV-tk/GCV system constitutes an effective treatment in human NSCLC cells and any pathway leading to programmed cell death through caspase activation that ought to bring apoptosis in a variety of NSCLC cells.

KEY WORDS: herpes simplex virus type I thymidine kinase cDNA, human non-small cell lung cancer cells, apoptosis.

For more information, contact biofv033@scc.ntnu.edu.tw

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Apoptosis - Molecular Mechanisms.

http://www.cancerprev.org/Journal/Issues/26/101/1092/4316