An RGD-Modified Endostatin Peptide Expressed at E. coli Shows Anti-Tumor Activity In vivo.

Tumor vasculatures express high levels of α(V)ß(3)/α(V)ß(5) and α(5)ß(1) integrins. Peptide containing the RGD (Arg-Gly-Asp) sequence, which is present in ligands of integrins, is effective in targeting therapeutic reagents to tumor vascular endothelium. In this study, we investigated whether the biological activity of endostatin 27 peptides can be enhanced by the addition of an integrin targeting sequence. RGDRGD and GGGRGD sequence were added to the carboxyl terminus of endostatin 27 and 25 peptides, respectively. Modification of endostatin 27 peptides with the RGD motif showed specific and increased binding to endothelial cells and the increased binding is consistent with improved antiangiogenic property. RGD-modified endostatin 27 peptides was more effective than human endostatin and endostatin 27 peptides in inhibiting liver cancer growth in athymic mice. These finding indicates that addition of a vascular targeting sequence can enhance the biological activity of an antiangiogenic peptides molecule.

Insulin-like growth factor-1 fused with thrombopoietin mimetic peptide effectively increase platelets count in vivo.

OBJECTIVE: To design the expression of fusion proteins containing one or 2 thrombopoietin mimetic peptide (TMP). METHODS: This study was conducted at Harbin Pharmaceutical Group Research and Development Center, Harbin, China from June 2009 to January 2010. We designed the protein that was fused to the C-terminus of insulin-like growth factors (IGF-1) by a flexible peptide linker by Dami cell proliferation assay, colony-forming assay, and analysis of platelet in mice to prove our hypothesis. The total number of mice used was 48 in all 4 groups. RESULTS: The fusion proteins were produced in Escherichia coli BL21 (DE3) at up to 26% of the total cell proteins. Subsequent biological activity assays showed that the fusion proteins exhibited higher potency than recombinant human thrombopoietin (TPO). Our results showed that the fusion proteins IGF-1-TMP exhibited higher biological activities than TMP in Dami cell proliferation, human cord blood cell colony-forming assays, and in experiments on acute myeloid radiation sickness mice, which can effectively increase the number of platelets. CONCLUSION: Experiments in mice and biology activity assay, which can effectively increase the number of platelets, indicated that it has a potential role in pharmaceutical applications for the treatment of thrombocytopenia.