Heat Shock Proteins 27 and 70: Anti-Apoptotic Proteins with Tumorigenic Properties

Heat shock proteins (HSP) HSP27 and HSP70 are expressed in response to a wide variety of physiological and environmental insults including anticancer chemotherapy, thus allowing the cell to survive to lethal conditions. Several mechanisms account for the cytoprotective effect of HSP27 and HSP70. (1) Both proteins are powerful chaperones. (2) They both inhibit key effectors of the apoptotic machinery at the pre and post-mitochondrial level. (3) They participate in the proteasome-mediated degradation of proteins under stress conditions, thereby contributing to the so called "protein triage". In cancer cells, the expression of HSP27 and/or HSP70 is abnormally high, and both HSP27 and HSP70 may participate in…