A Mutant Recombinant Human Endostatin Containing The Rgdrgd Sequence Suppresses Tumor Growth In A Mouse Xenograft Model

The clinical use of endostatin has been hampered by its insolubility, instability, and frequent dosing schedule. In the current study, we genetically engineered a mutant recombinant human endostatin (rhES) by introducing an integrin binding motif RGDRGD via site-directed mutagenesis. MTT assays showed an IC50 of 185 mu g/mL for wildtype rhES and 27 mu g/mL for the mutant rhES (P<0.05). Wound assays further demonstrated a migration inhibitory rate of 69.0% for wildtype rhES and 90.0% for the mutant rhES (P<0.05). Mouse xenograft assays showed a tumor inhibitory rate of 40.7% for the wildtype rhES group and 51.1% for the mutant rhES. Immunohistochemical staining further revealed that the mutant rhES caused a more significant reduction in mean microvessel density and VEGF and PCNA expression than wildtype rhES (P<0.05). These findings demonstrate that the mutant rhES with the RGDRGD motif possesses more potent tumor inhibitory effects than wildtype rhES. The mutant rhES may be further studied as a biological agent to improve tumor therapeutic efficacy.