OBJECTIVETo develop a novel protein carrier which can not only regulate the immune system but also deliver DNA into the tumor cell as an effective non-viral gene delivery system.

METHODSBy using gene engineering techniques, we constructed a fusion protein containing the -COOH end of human hepatitis B virus core antigen (HBcAg), small home-to-cancer peptide ligand RGD and Glutathione S-transferase (GST), which was expressed in E. coli and purified by size exclusion chromatography and affinity chromatography. We labeled it with FITC to observe whether it could bind prostate cancer PC-3 cell lines, and meanwhile used it as a non-viral gene delivery carrier with the plasmid pEGFP-N1 that could express GFP in PC-3 cells. Furthermore, we observed the regulatory function of this fusion protein to the mouse immune system.

RESULTSThe results of SDS-PAGE showed that the new protein carrier was obtained, which It could enter PC-3 cells with DNA in vitro and induce the mouse immune system to produce IgG1 and IgG2alpha simultaneously.

CONCLUSIONThe new protein carrier can be used as a target protein, especially in positive cells and the immune system. It promises to be a good novel carrier for the gene therapy of cancer.