Month: May 2021

Phage-Displayed Peptides for Targeting Tyrosine Kinase Membrane Receptors in Cancer Therapy

Receptor tyrosine kinases (RTKs) regulate critical physiological processes, such as cell growth, survival, motility, and metabolism. Abnormal activation of RTKs and relative downstream signaling is implicated in cancer pathogenesis. Phage display allows the rapid selection of peptide ligands of membrane receptors. These peptides can target in vitro and in vivo tumor cells and represent a novel therapeutic approach for cancer therapy. Further, they are more convenient compared to antibodies, being less expensive and non-immunogenic. In this review, we describe the state-of-the-art of phage display for development of peptide ligands of tyrosine kinase membrane receptors and discuss their potential applications for tumor-targeted therapy.

The Evolution of Phage Display

Phage display represents a useful technique for studying protein–protein interactions that regulate the biological processes. Bacteriophages, which are viruses infecting bacteria, can express recombinant peptides on their surface coat following the cloning of random short DNA sequences within their genome. The phage display technique was first described in 1985 by George P. Smith, who demonstrated the expression of a foreign insert on a filamentous phage surface following its cloning in frame with the minor coat protein pIII. In the same year, George Pieczenik patented the production of random peptide libraries for phage display (US Patent, 5,866,363). In 1988, the selection of phage ligands of target proteins was improved by using a process called “biopanning”, which significantly reduced antibody requirements compared to the original procedure published in 1985. In the 1990s, combinatorial phage libraries containing 40 million 6-mer peptides or 20 million 15-mer peptides were built. As predicted by Smith, the use of these libraries allowed an effective investigation of the specific affinity binding to antibody epitopes, receptors, or other proteins using simple recombinant DNA methods. What Smith did not imagine was the wide number of applications of his invention in various biomedical fields. The phage display technology was further developed and improved by the following research teams: G. Winter and J. McCafferty of the Medical Research Council, Laboratory of Molecular Biology; R. Lerner and C. Barbas of the Scripps Research Institute; F. Breitling and S. Dübel of the German Cancer Research Center. All these researchers pursued the creation of phage-displayed combinatorial antibodies libraries, which were further improved by several other laboratories in the following years. As recognition of the phage display contribution to scientific advances in chemistry and pharmaceutics, George P. Smith and Sir Gregory P. Winter received the 2018 Nobel Prize in Chemistry “for phage visualization of peptides and antibodies”. More recently, the phage display has been useful for the mapping of antibody binding epitope and the screening of combinatorial peptide libraries in drugs discovery. A timeline of phage display development is shown below. (Viruses . 2021 Apr 9;13(4):649.)