| Summary: | 碩士 === 國立中正大學 === 分子生物研究所 === 96 === Replication-competent retrovirus (RCR) vectors, based on murine leukemia virus (MLV), have been proven to be effective for cancer gene therapy. The therapeutic efficacies of RCR vectors depend on viral replication ability and gene transduction efficiency in vivo, and therefore it is essential to detect RCR vectors spread in tumor. We constructed an RCR vector containing a cytosine deaminase::GFP fusion protein cassette to allow us to conveniently monitor suicide gene delivery for cancer therapy. Furthermore, we improved genomic stability of RCR vectors by replacement of IRES with 2A and demonstrated genome stability of RCR vector is obviously depended on length of transgene cassette. On the other hand, we sought to examine the therapeutic effect of RCR vector carrying the yeast cytosine deaminase (yCD) gene, which converts the nontoxic prodrug 5-fluorocytosine (5-FC) to cytotoxin 5-fluorouracil (5-FC), in the subcutaneous hepatocellular carcinoma (HCC) model. In addition to subcutaneous model, orthotopic hepatocellular carcinoma model was established in athymus mice by intrahepatic injection of Huh-7 HCC cells. The enzymatic fuction of CD delivered by RCR vector was preserved in tumor and mediated significant tumor growth inhibition after intra-tumoral GS4-yCD followed by serial 5-FC prodrug administration, and higher initial titer virus was injected, the more significant growth inhibition effect was observed. Notably, there was no detectable RCR vector spread to normal tissue by real-time PCR and immunohistochemical analysis.
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