| Summary: | 碩士 === 國立中正大學 === 生物醫學研究所 === 99 === GS-based and MLV-based replication-competent retrovirus (RCR) vectors used for cancer gene therapy are previously proven to be effective, highly stable, tumor-selective, and persistent. In this investigation, we employed suicide gene therapy and cytokine modulated immunotherapy to treated glioma. First, we compared the gene transfer efficiency of the three replicating retroviral vectors, including ACE (modified from amphotropic murine leukemia virus), CEM (modified from ecotropic murine leukemia virus) and GS (modified from gibbon ape leukemia virus), carrying GFP or dsRed gene as marker, and found GS vector mediated the best spreading efficiency both in vitro and in vivo. In suicide gene therapy, we tested cytosine deaminase::uracil phosphoribosyltransferase (CD::UPRT)/5-FC and nitroreductase (NTR)/CB1954 systems both in vitro and in vivo. In in vitro test, transduction of CD:UPRT could induce more cell death after exposure of 5-FC in RG2 cells than transduction of CD alone. Although there was no significant difference between CD and CD::UPRT in improving animal survival, the group of CD::UPRT still showed greater tumor reduction than that of CD. The other combination NTR/CB1954 displayed excellent cell toxicity and effectively inhibited tumor growth in s.c model. In immune modulated gene therapy, we tested IL-2 and IFN-α, which both have been reported to activate and stimulate the growth of immune cells to destroy tumor. IL-2 was found to reduce tumor size in animal, however, it could not prolong animal survival or activate splenocyte. IFN-α was found not to promote cytotoxicity of splenocyte to destroy tumor cell. In conclusion, the functions of these cytokines need futher investigation for the use of immunotherapy as alternative for tumor gene therapy in the future.
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