VER-82576 (NVP-BEP800), a synthetic HSP90β inhibitor (IC50: 58 nM), exhibits >70-fold selectivity against Hsp90 family members Trap-1 and Grp94.

HSP90 β:58 nM

Competitive binding fluorescent polarization assay: Recombinant Hsp90β, TAMRA-radicicol, or various concentrations of NVP-BEP800 is added in assay buffer (50 mM TRIS pH 7.4, 5 mM MgCl2, 150 mM KCl, and 0.1% CHAPS), mixed, and incubated at room temperature for 30 to 45 minutes prior to reading. The 2D-FIDA-based HTS assay based on confocal technologies monitors the decreased fluorescence polarization on displacement of the high affinity ligand TAMRA-radicicol from Hsp90β by NVP-BEP800. The concentration of NVP-BEP800 which inhibits Hsp90β by 50% is determined from the competition curve.

Cells are exposed to NVP-BEP800 for 24 hours. Cell proliferation is determined using either sulforhodamine B for adherent cells or MTS assay for suspension cells or those showing low adherence. Cell death is determined using a ToxiLight nondestructive cytotoxicity bioassay kit. Cell cycle progression is determined by RNase A/propidium iodide staining following fixation in 70% ethanol. Caspase-3/7 activity is determined using a homogeneous caspase activity kit.(Only for Reference)