Development and characterization of a novel C-terminal inhibitor of Hsp90 in androgen dependent and independent prostate cancer cells.

Publisher: BioMed Central Country of Publication: England NLM ID: 100967800 Publication Model: Electronic Cited Medium: Internet ISSN: 1471-2407 (Electronic) Linking ISSN: 14712407 NLM ISO Abbreviation: BMC Cancer Subsets: MEDLINE

Original Publication: London : BioMed Central, [2001-

Antineoplastic Agents/*therapeutic use ; HSP90 Heat-Shock Proteins/*antagonists & inhibitors ; Neoplasm Proteins/*antagonists & inhibitors ; Prostatic Neoplasms/*drug therapy ; Prostatic Neoplasms/*metabolism; Animals ; Blotting, Western ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Growth Inhibitors/pharmacology ; HSP90 Heat-Shock Proteins/metabolism ; Humans ; Male ; Neoplasm Proteins/metabolism ; Novobiocin/pharmacology ; Protein Binding/drug effects ; Rats

Background: The molecular chaperone, heat shock protein 90 (Hsp90) has been shown to be overexpressed in a number of cancers, including prostate cancer, making it an important target for drug discovery. Unfortunately, results with N-terminal inhibitors from initial clinical trials have been disappointing, as toxicity and resistance resulting from induction of the heat shock response (HSR) has led to both scheduling and administration concerns. Therefore, Hsp90 inhibitors that do not induce the heat shock response represent a promising new direction for the treatment of prostate cancer. Herein, the development of a C-terminal Hsp90 inhibitor, KU174, is described, which demonstrates anti-cancer activity in prostate cancer cells in the absence of a HSR and describe a novel approach to characterize Hsp90 inhibition in cancer cells.
Methods: PC3-MM2 and LNCaP-LN3 cells were used in both direct and indirect in vitro Hsp90 inhibition assays (DARTS, Surface Plasmon Resonance, co-immunoprecipitation, luciferase, Western blot, anti-proliferative, cytotoxicity and size exclusion chromatography) to characterize the effects of KU174 in prostate cancer cells. Pilot in vivo efficacy studies were also conducted with KU174 in PC3-MM2 xenograft studies.
Results: KU174 exhibits robust anti-proliferative and cytotoxic activity along with client protein degradation and disruption of Hsp90 native complexes without induction of a HSR. Furthermore, KU174 demonstrates direct binding to the Hsp90 protein and Hsp90 complexes in cancer cells. In addition, in pilot in-vivo proof-of-concept studies KU174 demonstrates efficacy at 75 mg/kg in a PC3-MM2 rat tumor model.
Conclusions: Overall, these findings suggest C-terminal Hsp90 inhibitors have potential as therapeutic agents for the treatment of prostate cancer.

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CA120458 United States CA NCI NIH HHS; R01 CA125392 United States CA NCI NIH HHS

0 (Antineoplastic Agents)
0 (Growth Inhibitors)
0 (HSP90 Heat-Shock Proteins)
0 (Neoplasm Proteins)
17EC19951N (Novobiocin)

Date Created: 20111102 Date Completed: 20120214 Latest Revision: 20211020

20231215

PMC3240935

10.1186/1471-2407-11-468

22039910