Gene delivery using a receptor-mediated gene transfer system targeted to hepatocellular carcinoma cells

For gene therapy to be effective in cancers, it is necessary to deliver therapeutic genes into cells with high specificity and efficiency. In this study, we examined the in vitro and in vivo gene delivery efficiency of a new, growth receptor-mediated gene transfer system in hepatocellular carcinoma (HCC). The effects of transfection of wild-type p53 using this system were also studied. The system consisted of a ligand oligopeptide for epidermal growth factor receptor (EGFR) recognition, a polypeptide for DNA binding, and an endosome-releasing oligopeptide for endosomolysis. Two human HCC cell lines and a normal liver cell line were used, and pCMV-β-galactosidase (β-gal) was used as a reporter gene. Both HCC cell lines had strong expression of EGFR and the in vitro transfer efficiency peaked at day 5 at about 50%. This finding was in contrast to the normal liver cell line, which had weak EGFR expression and less than 1% transfer efficiency throughout. For in vivo gene transfer in tumors produced by inoculating HCC cells in nude mice and with the vector-β-gal gene complex injected peritumorally, β-gal expression was detected within the tumors at 12 hr, peaked at day 5 involving about 50% of the tumor cells and persisted at 2 weeks. Using this vector system, transfection of wild-type p53 into Huh-7 cells that had mutated p53 resulted in significant growth inhibition of cancer cells accompanied by a decreased G2/M phase and increased p53 protein. In conclusion, this receptor-mediated gene transfer system appears to work specifically in HCC cells with high efficiency, and may be promising in delivering apoptotic and other genes into HCC cells.