[CAS NO. 934343-74-5]  HSP990 (NVP-HSP990)

NVP-HSP990 is based on a 2-amino-4-methyl-7,8-dihydropyrido[4,3-d]pyrimidin-5(6H)-one scaffold, which is structurally distinct from other known HSP90 inhibitors. NVP-HSP990 binds to the N-terminal ATP-binding domain of HSP90. NVP-HSP990 exhibits single digit nanomolar IC50 values on three of the HSP90 isoforms (HSP90α, HSP90β, and GRP94) and 320 nM IC50 value on the fourth (TRAP-1), with selectivity against unrelated enzymes, receptors, and kinases. NVP-HSP990 dissociates the HSP90-p23 complex, depleted client protein c-Met, and induced Hsp70 in c-Met amplified GTL-16 gastric tumor cells. NVP-HSP990 potently inhibites the growth of human cell lines and primary patient samples from a variety of tumor types. NVP-HSP990 displays dose- and time-dependent effects on HSP90 client proteins. NVP-HSP990 inhibits Glioma tumor-initiating cells (GIC) proliferation in all GIC lines, with IC50 values ranging approximately between 10 and 500 nM. Olig2 is a functional marker associated with cell proliferation and response to NVP-HSP990, as NVP-HSP990 attenuated cell proliferation in Olig2-high GIC lines. In addition, NVP-HSP990 disrupted cell-cycle control mechanism by decreasing CDK2 and CDK4 and elevating apoptosis-related molecules.