Selection of a specific binding peptide targeting to blood vessel of human gastric cancer in vivo and modeling of its three dimensional structure

    ZHI Min, XIAO Gaoª²Keng, ZHI Hui, DONG Lei, QIAO Taiª²Dong, FAN Daiª²Ming, WU Kaiª²Chun

    1Department of Gastroenterology, Second Hospital, Xi¡¯an Jiaotong University, Xi¡¯an 710004, China, 2Institute of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi¡¯an 710033, China, 3Shenyang Pharmaceutical University, Shenyang 110016, China

    ¡¾Abstract¡¿ AIM: To identify and analyze a peptide binding specifically to blood vessels of human gastric cancer by phage displayed C7C peptide library in vivo and to model its three dimensional structure of the peptide by computer. METHODS: Animal models were established using subrenal capsular assay (SRCA) in immunosupressed mice implanted with human gastric cancer xenografts. The phage displayed C7C peptide library was injected intravenously into mice. After 4 rounds of selection, 14 clones were picked up randomly and sequenced individually. The homing ability to human umbilical vein endothelial cells (HUVEC ) of peptide CGNSNPKSC was determined by cellª²ELISA, with SGC7901, Ecaª²109, LoVo and Hepª²G2 cells as control. Its three dimensional structure of peptide CGNSNPKSC was also established by computer modeling techniques. RESULTS: Fourteen clones were obtained and they displayed two kinds of peptides. The binding ability of a cyclic peptide of CGNSNPKSC toward HUVEC was higher than that of SGC7901, Ecaª²109, Hepª²G2 and LoVo cells. The three dimensional structure of the peptide of CGNSNPKSC was modeled successfully. CONCLUSION: The peptide of CGNSNPKSC has high binding ability to HUVEC and its stable structure and highly hydrophilic character help it form a flexible epitope of antigen. The peptide of CGNSNPKSC can be used in target therapy of tumor angiogenesis. ......