Heat shock proteins 27 and 70

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 oncogenesis and in resistance to chemotherapy. In rodent models, HSP27 or HSP70 over-expression increases tumor growth and metastatic potential. The depletion or inhibition of HSP27 and HS70 frequently reduces the size of the tumors and even can cause their complete involution ( for HSP70). Therefore, the inhibition of HSP70 and HSP27 has become a novel strategy of cancer therapy.