[Screening phage display library for isolation of human colon cancer cell-binding peptide ligands]

Recently, phage display libraries have received enormous attention for identification and isolation of pharmaceutical molecules with diagnostic and therapeutic properties. Peptide libraries are known as one of the most important and widely used types of phage display libraries. In the current study, we aimed to screen the Ph.D.[TM]-7 phage display peptide library through biopanning for the identification of human colon adenocarcinoma-binding peptide ligands. Three rounds of biopanning were performed on SW480 as the target cell and fibroblast [HF-SF-PI3], AGS, KYSE-30 and Huh-7 as control cells. The displayed peptide-encoding regions in the genome of SW480-binding phages obtained from the final round of panning were amplified by plaque-PCR and subsequently sequenced. Bioinformatic tools were used to determine the sequence of target cell-binding peptides and further characterization of these peptides. Biopanning of the phage library led to the enrichment of several peptides among which the peptide with sequence "HAMRAQP" was the most dominant. Bioinformatic analysis of the isolated peptides indicated that they are not target unrelated peptides [TUP]. The peptides, in particular those with the highest frequency, due to having the capability of specific binding to SW480 cells represent the potential for use in targeting of therapeutic genes and drugs to colon cancer cells