A Novel Design Of A Multifunctional IFN-γ::CBD Fusion Protein Possesses Potent Antitumor Effect

It is well known that IFN-γ possesses strong antitumor and immune regulatory activities, but the clinical application is limited due to its severe systemic side effects. Matrix metalloproteinases 2(MMP2), a major enzyme for the degradation of extracellular matrix in tumor, is critical for tumor invasion and metastasis. MMP2 functions depending on two main domains, a catalytic domain and a collagen binding domain(C BD). In this study, we engineered a fusion protein IFN-γ-CBD which was composed with the IFN-γ mature peptide and the MMP2 CBD peptide for tumor therapy by local delivery. The IFN-γ-CBD with a collagen binding domain would retain in the tumor, the extracellular matrix of which was rich in collagen. Thus the CBD avoided systemic spread of the recombination protein, which was benefit for maintaining a long-term high concentration of this protein at tumor local region and decreasing systemic side effects. By in vitro and in vivo tests, we showed that the fusion protein IFN-γ-CBD was successfully expressed and purified, and that it possessed all the expected properties including collagen binding activity and natural IFN-γ capabilities. Surprisingly we found the recombination CBD domain could inhibit the degradation of the extracellular matrix so as to suppress tumor metastasis by competing with tumor-derived MMP2 for the collagen binding sites. In tumor animal models, this fusion protein achieved an antitumor effect through inhibiting angiogenesis, tumor metastasis and exerting inner immune responses. This fusion protein IFN-γ-CBD binds collagen-rich tissue, directly inhibits tumor growth and arouses the immune responses, which is suggested to be a promising antitumor drug for clinical application.