Bicistronical Expression of the Recombinant Human IL-18-EGF and Its Effects on NK Cell and the Human Hepatoma Cells

Abstract: Recombinant human IL-18- EGF tumor targeting molecular was due to prokaryotic bicistronical expression system， and the effects of this fusion protein on human natural killer cell (NK cell) and hepatocellular carcinnoma cell line SMMC-7721 were investigated. A bicistronical expression system pET28a(+)-proIL-18-EGFCaspase- 4/BL21 was constructed to express recombinant human IL-18-EGF. The recombinant protein was purified and its effect on human natural killer cell was studied. CCK-8 method was used to observe NK cell proliferation ability stimulated by IL-18-EGF and the IFN-γ secreted by NK cell was determined by ELISA. IL-18-EGF was labeled by Cy3 dye to observe its ability of binding with the tumor cell surface EGFR. After IL-18-EGF and NK cells were incubated for 24 h， the culture supernatant was took to hepatocellular carcinoma cell SMMC-7721. Then wound healing assay and Transwell assay were used to study the suppressions of migration and invasion of hepatocellular carcinoma cell， respectively. The experimental results showed that the recombinant human IL-18-EGF can promote NK cell proliferation and increase the IFN-γ secreted by NK cell. IL-18-EGF can specially bind to tumor cell surface EGFR. Wound healing assay indicated that the capacity of filling blank area in the IL-18-EGF group was higher than that in the control group. Cell invasion assay results showed that the average amount of invading cells in the IL-18-EGF group (94.6±2.9， 101.8±4.0 and 116.2±4.5 after 12， 24， 48 h， respectively) was significantly lower than the control group (128.6±8.5， 133.0±7.5 and 138.8±5.4 after 12， 24， 48 h， respectively， P<0.05). The results suggest that IL-18-EGF can inhibit migration and invasion of hepatocellular carcinoma cell and improve human immune ability. It may be used in the treatment of liver cancer as a auxiliary drug.

CSTR: 32200.14.cjcb.2012.08.0006