Onalespib (AT13387) is a synthetic, orally bioavailable, small-molecule inhibitor of heat shock protein 90 (Hsp90) with potential antineoplastic activity. Onalespib selectively binds to Hsp90, thereby inhibiting its chaperone function and promoting the degradation of oncogenic signaling proteins involved in tumor cell proliferation and survival. Hsp90, a chaperone protein upregulated in a variety of tumor cells, regulates the folding, stability and degradation of many oncogenic signaling proteins.

HSP90 (AT13387):18 nM

HSP90 competition isothermal calorimetry: Kd values for AT13387 binding to HSP90 are determined with a competition Isothermal Calorimetry (ITC) format. ITC experiments are performed on a Micro Cal VP-ITC at 25 °C in a buffer comprising 25 mM Tris, 100 mM NaCl, 1 mM MgCl2 and 1 mM Tris(2-carboxy- ethyl)phosphine at pH 7.4 in order to maintain the higher affinit

The human cell lines including A375, 22RV1, T474, DU1 45, LNCa P, MCF-7, DA-MB-468 are seeded into 96-well plates before the addition of AT13387 in 0.1% (v/v) DMSO. GI50 are determined using a 10-point dose response curve for three cell doubling times. After AT13387 incubation 10% (v/v), Alamar blueis added, and cells are incubated for a further 4 hours. Fluorescence is read.(Only for Reference)