To test whether antitumor activity could be increased by combining the above two mechanisms, this study examined the therapeutic effect of combination gene therapy using a murine granulocyte-macrophage colony-stimulating factor (mGM-CSF) gene and a human endostatin (hED) gene on a rat orthotopic liver tumor model.
The results demonstrated that combined administration of p21(WAF-1) and GM-CSF could remarkably inhibit the growth of subcutaneously transplanted hepatomaHepa cells, and significantly increase the survival rate of tumor-bearing mice.
The results showed that combined gene transfer of p21WAF-1 and GM-CSF could inhibit the growth of pre-established tumor more effectively and prolong the survival time of hepatoma-bearing mice more significantly than the transfer of a single gene.
Therefore, these results suggest that combining expression of GM-CSF and B70 may enhance NK-mediated cytotoxicity, and then induce the antitumor immunity in hepatoma transplanted into nude mice.