Selection of Cancer Stem Cell-Targeting Agents Using Bacteriophage Display

There is a growing need to develop tumor targeting agents for aggressive cancers. Aggressive cancers frequently relapse and are resistant to various therapies. Cancer stem cells (CSCs) are believed to be the cause of relapse and the aggressive nature of many cancers. Targeting CSCs could lead to novel diagnostic and treatment options. Bacteriophage (phage) display is a powerful tool developed by George Smith in 1985 to aid in the discovery of CSC targeting agents. Phage display selections are typically performed in vitro against an immobilized target. There are inherent disadvantages with this technique that can be circumvented by performing phage display selections in vivo. However, in vivo phage display selections present new challenges. A combination of both in vitro and in vivo selections, however, can take advantage of both selection methods. In this chapter, we discuss in detail how to isolate a CSC like population of cells from an aggressive cancer cell line, perform in vivo and in vitro phage display selections against the CSCs, and then characterize the resulting phage/peptides for further use as a diagnostic and therapeutic tool.