Establishment And Application Of Animal Models For Treating Human Tumors

To test the tumoricidal effect of a glycoprotein extracted from sweet potato, COS-1 cells, human glioma cells (SHG-44) and human ovarian cancer cells were cultured in the medium containing different concentrations of the glycoprotein and their morphological changes were observed under microscope. Within one week of incubation, no morphological change was evident. Cell death occurred at the eighth day and all died until the 10th day post incubation. The minimal dose of tumoricidal effect of the protein was 1.5 μ g/rnl. which had no effect on primary chicken embryo fibroblast cells.To carry out gene therapy studies for human cancers, mouse models were established by transferring human ovarian carcinoma (SKOV3) tissues into the oxter of nude mice, with a successful rate of 100%. The coding region for human endostatin (hES) was subcloned from a commercial recombinant plasmid and fused with the signal peptide sequence for human growth hormone by PCR amplification. The correctness of the hybrid gene was confirmed by sequence analysis following subcloning into pGEM-T vector. The gene fragment was subcloned into a prokaryotic expression vector pGEX-6p-l and the GST-ES fusion protein of about 46kDa was expressed in E. coli by IPTG induction. The polyclonal antibodies specific to hES were prepared by immunization of mice with the purified fusion protein or hES-containing eukaryotic expression vector pcDNA3-hES. The recombinant vector was mixed with liposome and then transfected into COS-1 cells. The expression was revealed in cytoplasm by indirectfluorescent assay. The pcDNA3-ES vector was administered via muscular injection to nude mice before or after tumor transplantation and significant inhibition of the tumor growth was inhibited observed. These data indicate that the established animal model and gene therapy strategy are useful for treating human tumors.