A CD44 specific peptide developed by phage display for targeting gastric cancer

Objective: To develop a peptide probe that could be used for gastric cancer detection via binding to CD44 protein with specificity and affinity. Results: A 12-mer phage peptide library was screened against immobilized CD44 protein. Bound phage counts using ELISA were performed to identify phage clones carrying the most highly selective peptide, which termed RP-1. Immunofluorescence and flow cytometry analysis indicated that the consensus peptide RP-1 could bind to CD44-positive gastric cancer cells with mean fluorescence intensities significantly higher than that of CD44-negative cells. CD44 knockdown led to decreased binding activity of RP-1 to the same cell line. Tissue array technique was used to identify the relationship (r = 0.556) between peptide binding and CD44 detection on gastric cancer tissues. Further, the hyaluronan-binding domain of CD44 was docked with RP-1 using computer modeling/docking approaches, revealing a RP-1/CD44 interaction with geometrical and energy match (−8.6 kcal/mol). Conclusions: The RP-1 peptide we screened exhibits affinity and specificity to CD44 on cells and has the potential to be used as a candidate probe for gastric cancer cell targeting.