HSP70 inhibition by the small-molecule 2-phenylethynesulfonamide impairs protein clearance pathways in tumor cells.

Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Molecular Cancer Research (Impact Factor: 4.35). 06/2011; 9(7):936-47. DOI: 10.1158/1541-7786.MCR-11-0019
Source: PubMed

ABSTRACT The evolutionarily conserved stress-inducible HSP70 molecular chaperone plays a central role in maintaining protein quality control in response to various forms of stress. Constitutively elevated HSP70 expression is a characteristic of many tumor cells and contributes to their survival. We recently identified the small-molecule 2-phenylethyenesulfonamide (PES) as a novel HSP70 inhibitor. Here, we present evidence that PES-mediated inhibition of HSP70 family proteins in tumor cells results in an impairment of the two major protein degradation systems, namely, the autophagy-lysosome system and the proteasome pathway. HSP70 family proteins work closely with the HSP90 molecular chaperone to maintain the stability and activities of their many client proteins, and PES causes a disruption in the HSP70/HSP90 chaperone system. As a consequence, many cellular proteins, including known HSP70/HSP90 substrates, accumulate in detergent-insoluble cell fractions, indicative of aggregation and functional inactivation. Overall, PES simultaneously disrupts several cancer critical survival pathways, supporting the idea of targeting HSP70 as a potential approach for cancer therapeutics.

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