Identification of one vasculature specific phage-displayed peptide in human colon cancer

Blood vessels of tumors might carry specific markers that are usually related to angiogenesis. Investigating these heterogeneous molecules in different tumor vessels might be beneficial for promoting antiangiogenic therapy. In this study, in vivo screening of phage displayed peptide library was used to identify the peptides binding selectively to endothelial cells of human colon cancer. After four rounds of selection, one phage was obtained with a cyclic 7-mer peptide CPHSKPCLC homing to human colon adenocarcinoma. The results of ELISA and competitive inhibition assay clearly showed that the peptide bound specifically to the colon cancer xenograft in comparision with control organs, such as brain, heart, liver, spleen and kidney. This peptide was also identified to bind more heavily to human umbilical vein endothelial cells (HUVEC) than to gastric cancer cells, esophageal cancer cells, colon cancer cells and liver cancer cells. Immunohistochemical results showed that this phage peptide could bind to the endothelial cells of human colon cancer. The peptide might then be a potential candidate for targeted drug delivery in antivascular therapy and diagnosis of colon cancer.