Enhanced baculovirus-mediated transduction of human cancer cells by tumor-homing peptides

Tumor cells and vasculature offer specific targets for the selective delivery of therapeutic genes. To achieve tumor-specific gene transfer, baculovirus tropism was manipulated by viral envelope modification using baculovirus display technology. LyP-1, F3, and CGKRK tumor-homing peptides, originally identified by in vivo screening of phage display libraries, were fused to the transmembrane anchor of vesicular stomatitis virus G protein and displayed on the baculoviral surface. The fusion proteins were successfully incorporated into budded virions, which showed two- to fivefold-improved binding to human breast carcinoma (MDA-MB-435) and hepatocarcinoma (HepG2) cells. The LyP-1 peptide inhibited viral binding to MDA-MB-435 cells with a greater magnitude and specificity than the CGKRK and F3 peptides. Maximal 7- and 24-fold increases in transduction, determined by transgene expression level, were achieved for the MDA-MB-435 and HepG2 cells, respectively. The internalization of each virus was inhibited by ammonium chloride treatment, suggesting the use of a similar endocytic entry route. The LyP-1 and F3 peptides showed an apparent inhibitory effect in transduction of HepG2 cells with the corresponding display viruses. Together, these results imply that the efficiency of baculovirus-mediated gene delivery can be significantly enhanced in vitro when tumor-targeting ligands are used and therefore highlight the potential of baculovirus vectors in cancer gene therapy.