The aim of this study is to screen and identify the human colon cancer vessel specific binding peptides using phage display peptide library by optimizing the screening strategies and procedures. Methods: The subrenal capsular xenograft model bearing colon cancer in immunosuppressed mice and in vitro endothelial cell-colon cancer cell co-culture model were established. Three rounds of in vivo screening in tumor-bearing mice and two rounds of screening in Co-HUVECs were performed in the phage display peptide library.

Randomly, 40 clones were selected to further analyze using sequencing. The abilities of homing and Co-HUVECs binding of positive phage were identified using in vivo binding assay, enzyme Selumetinib concentration linked immunosorbent assay (ELISA) and immunochemical staining. The effect of synthesized peptides on phage binding ability was evaluated Ferrostatin-1 using competitive binding

assay. Finally, the binding specificities of peptides to Co-HUVECs and the blood vessel of colon cancer were determined using immunofluorescence assay. Results: 38 clones were correctly verified using sequencing, and 5 types of amino acid sequences were obtained, named Pep1-5. And the corresponding phages were named as Ph1-5. Ph 1, 3, 4 and 5 can specifically home to the xenograft of human colon cancer, and the binding activities of Ph 1, 4 and 4��8C 5 to Co-HUVECs were significantly higher than that to HUVECs. Ph5 presented the highest binding

activities. Pep5 can specifically inhibited Ph5 homing to colon cancer xenograft and the binding to Co-HUVECs. FITC-Pep5 can specifically bind to Co-HUVECs and human colon cancer vessel. Conclusion: Three colon cancer vessel specific peptides, Pep1, 4 and 5, were obtained, and Pep5 presented the highest binding specificity. Ph5 can specifically bind to Co-HUVECs, and Pep5 mediated the binding to Co-HUVECs. Pep5 can specifically bind to colon cancer vessel, and this provided novel candidate molecules for colon cancer vascular target therapy. Key Word(s): 1. Colon cancer; 2. phage display; 3. angiogenesis; 4. peptide; Presenting Author: ANTHONY AU Additional Authors: SITI NURFATIMAH SHAHPUDIN, AHMAD AIZATABDUL AZIZ, AMINUDINMOHD MUSTAPHA, RAVINDRAN ANKATHIL Corresponding Author: ANTHONY AU Affiliations: universiti sains malaysia Objective: Colorectal cancer (CRC) is a multifactorial disease that occurs due to dietary and lifestyle habits, increasing age and inherited genetic predisposition.