Signaling Functions of Extracellular Hsp90 (eHsp90) in Cancer Metastasis

Heat shock protein 90 (Hsp90) is a highly conserved eukaryotic molecular chaperone. Hsp90 is abundantly expressed in normal cells, and even more abundant in cancer cells, from which it is also secreted. Homeostatic and cancer-supporting roles for intracellular Hsp90 have both been identified. Hsp90 in the extracellular space (extracellular Hsp90, or eHsp90) has been shown to support each step during cancer progression, and could potentially be targeted in order to safely prevent metastasis without affecting critical intracellular functions of Hsp90. This chapter will highlight pro-metastatic signaling functions of eHsp90.