Progress in the study of small molecule inhibitors of HSP90

HSP90, which is the biomarker of cell stress and endogenous protective protein, functions as a molecular chaperone. Many client proteins of HSP90, including EGFR, Met, Raf-1, IKK and p53, play important roles in the occurrence and development of tumor. Binding of HSP90 inhibitors triggers the deactivation of HSP90, resulting in client protein degradation, and hence inhibits the tumor growth by blocking multiple targets involved in signaling of tumor proliferation. This review summarizes recent development of small molecule inhibitors bound to N-terminal of HSP90.