Identification of a novel colon adenocarcinoma cell targeting peptide using phage display library biopanning

Abstract

Phage display is well recognized as a promising high-throughput screening tool for the discovery of novel cancer-targeting peptides. Here, we screened a phage display library of 7-mer random peptides through in vitro biopanning to isolate peptide ligands binding to SW480 human colon adenocarcinoma cells. Three rounds of negative and positive selection caused a remarkable enrichment of colon cancer cell-binding phage clones with a significant enhancement of phage recovery efficiency (about 157-fold). A number of phage clones were picked out from the eluted phages of last selection round and sequenced. According to the results of cell binding assay and phage cell-based ELISA, one of the isolated peptides denoted as CCBP1 (with the sequence HAMRAQP) was indicated to have the highest binding efficiency, selectivity, and specificity toward colon cancer cells with no significant binding to control cells. Peptide competitive inhibition assay revealed that binding of the phage-displayed CCBP1 is competitively inhibited by the same free peptide, suggesting that CCBP1 specific binding to the target cell is independent of the phage context. Taken together, our findings provide support for the notion that CCBP1 binds specifically to colon cancer cells and might be a potential lead candidate for targeted delivery of imaging agents or therapeutic genes/drugs to colon tumors.

Targeting Peptides: The New Generation of Targeted Drug Delivery Systems

“…The technique is very laborious and time-consuming and requires the production of large amounts of the target protein, but most of the targeting peptides with diagnostic and targeting applications have been identified through this method [ 8 , 37 , 38 , 39 ]. For example, a 7-residue peptide was identified by Bakhshinejad and Sadeghizadeh using a commercial library, which was able to target colon carcinoma cells with no significant binding to normal cells [ 40 ]. Other peptides were identified to improve the binding affinity of antibodies for the treatment of SARS-CoV-2 variants and increase their neutralization potency [ 41 ].…”

“…Finally, in order to increase immune checkpoint inhibitors’ (ICIs) specificity, Li and co-workers improved the affinity of the LC4 peptide to create a system able to increase the ICIs’ tumor-targeting and reduce side effects, thereby increasing anti-cancer activity [ 42 ]. The widespread use of this technique led it to have many commercially available random peptide libraries from companies, with different characteristics such as the number of amino acid residues or different chemical modifications [ 40 , 43 ].…”