Identification of Tumor Targeting Agents by Phage Display

Techniques of the phage display libraries construction have been dramatically improved. This allowed researchers to expand the application field to cancer biology. Tumor targeting -selective delivery of active compounds to the tumor sites for cancer imaging or treatment presents obvious advantages as compared to chemotherapeutic approachkilling rapidly proliferating cells. Tumor-avid peptides can be efficiently identified by means of phage display libraries. The most direct application of peptide-protein phage-displayed libraries is a selection of ligands for individual molecules important for cancer development. This includes identification of ligands for cell surface molecules, mapping proteinprotein interactions and delineation of signal transduction pathways. Enzymes substrates and modulators of their activity can also be identified via phage display-based selection. Recently, more complicated than individual molecules, biological systems started to be used as targets for biopanning. This includes combination of soluble proteins, cellular surfaces and even vasculature or surface of whole organs. In addition, construction and application of cDNA expression libraries in phage-based vectors recently received appreciation. The use of the phage as a vector for targeted gene therapy is also considered. In the current review, we will discuss the selection of tumor-targeting peptides and proteins identified by means of random peptide and cDNA phage-displayed libraries.