We used retroviral vector pLXSN to construct recombinant retroviral vectors with the human apoptosis gene, interleukin-l? converting enzyme (ICE). The vectors were introduced into packaging cell line PA317 by electroporation method. The G418 resistant colonies were selected, and the supematants of the colonies were used to infect the human hepatocellular carcinoma cell line SMMC7721. G418 resistant colonies of SMMC7721 were named SMMC7721-MCE and SMMC7721-neo. The results of RT-PCR analysis showed that exogenous hICE gene had successfully integrated into the genome of SMMC7721-hICE cells. The proliferation rate and tumorigenicity of cells in nude mice were examined. Our data showed that the growth rate and the tumorigenicity of SMMC7721-hICE cells in nude mice were considerablely decreased comparing with parent SMMC7721 and SMMC7721-neo. These results suggested that the retroviral vector expressing hICE gene was successfully constructed and could suppress the growth ability and tumorigenicity of human hepatocellular carcinoma cells, which provided a basis for further investigation of hICE gene therapy.

Cytotoxic T lymphowcytes (CTL) play a major role in host anti-tumor immune responses. A major obstacle to the application of adoptive immunotherapy in the treatment of human maligancy is the inability to generate enough activated CTLs since the cytotoxic T cell undergoes activation induced apoptosis during destroying tumor cells. It is important to study how to limit activaton induced apoptosis of T cell so as to maximize the number of CTL and to enhance the tumor cytotoxicity. We have used CD3-induced Jurkat cell line as an activated T cell apoptosis model and introduced the anti-sense ICE cDNA into Jurkat T cells with retroviral vector. The effect on apoptosis of Jurkat cell induced by anti-CD3 or anti-Fas monoclonal antibody was evaluated after transfection with antisense human ICE. We found that the level of ICE expression in Jurkat cell transduced by the vector decreased and apoptosis was minimized in antisense ICE-transfected Jurkat cell after anti-CD3 or anti-Fas treatment. These results suggest that antisense blocking of ICE expression can partially inhibit Jurkat cell apoptosis induced by anti-CD3 or anti-Fas. Thus, applying antisense blocking of ICE to gene therapy may block the apoptosis of activated T cells, furthennore, enhance the antitumor effect.

Objective: To investigate the cytotoxicity of ICE gene transfection in Combination with Antitumor Chemicals killing Hepatocellular Carcinoma Cells in vitro.Methods: The recombinant plasmid pLXSN-hICE was transferred to virus packing cell PA317 by electroporation method. And then the retrovirus containing human ICE cDNA generated by these PA317 cells were used to transfect human hepatocellular carcinoma cell line HepG2. The apoptosis of transferred cells were examined by gel electrophoresis. The influence of chemotherapeutic drug Carbo-platin to the proliferation of hepatocellular carcinoma cell line SMMC7721 and its derivative cells(SMMC7721-hICE,SMMC7721-antisence hICE,SMMC7721-neo)was observed by incorporation of 3H-TDR. Results: Electrophoresis of DNA displayed the apoptosis ladder of HepG2 transfected by ICE gene. The proliferation of SMMC7721-hICE was significantly suppressed in vitro induced by Carbo-alatin compared to the other three cell lines. Conclusion: ICE gene transfection could greatly increase the susceptibility of SMMC7721 cells to apoptotic cell death following chemotherapy. These findings suggest that combining ICE gene transfection with utilizing antitumor drugs would represent a novel approach for the effective treatment of hepatocellular carcinoma.