[Eukaryotic expression and tumor-targeting modification of human mutated-IL-18 fusion gene]

Interleukin-18 (IL-18) is a proinflammatory cytokinin. This protein has a role in regulating immune responses and exhibits significant anti- tumor activities. Epidermal growth factor (EGF) is an important growth factor that plays a central role in the regulation of cell cycle and differentiation. It was proposed that a targeted delivery of IL-18 by generation of IL-18-EGF fusion protein might decrease adverse effects and result in enhancing cytotoxic and antitumor activities. In the present study, a fusion protein, consisting of EGFR binding domain fused to human IL18 mature peptide via a linker peptide of (Gly4ser) 3, was constructed and expressed in the insect cell line Sf9 using Bac-to-Bac baculovirus expression system. We showed that the purified recombinant fusion protein induced similar levels of IFN-gamma to that of native IL-18 protein in human PBMC in the presence of ConA. Furthermore, EGF Receptor competitive test in human epithelial cancer A431 cell line showed that EGF- IL18 fusion protein can specifically bind with EGFR by competing with native EGF protein. The results suggested that EGF-IL18 fusion protein could specifically be targeted on tumor cells. The work may provide a new insight into the cytokinin for the tumor treatment.