Identification of an allosteric small-molecule inhibitor selective for the inducible form of heat shock protein 70

Chem Biol. 2014 Dec 18;21(12):1648-59. doi: 10.1016/j.chembiol.2014.10.016. Epub 2014 Dec 11.


Inducible Hsp70 (Hsp70i) is overexpressed in a wide spectrum of human tumors, and its expression correlates with metastasis, poor outcomes, and resistance to chemotherapy in patients. Identification of small-molecule inhibitors selective for Hsp70i could provide new therapeutic tools for cancer treatment. In this work, we used fluorescence-linked enzyme chemoproteomic strategy (FLECS) to identify HS-72, an allosteric inhibitor selective for Hsp70i. HS-72 displays the hallmarks of Hsp70 inhibition in cells, promoting substrate protein degradation and growth inhibition. Importantly, HS-72 is selective for Hsp70i over the closely related constitutively active Hsc70. Studies with purified protein show HS-72 acts as an allosteric inhibitor, reducing ATP affinity. In vivo HS-72 is well-tolerated, showing bioavailability and efficacy, inhibiting tumor growth and promoting survival in a HER2+ model of breast cancer. The HS-72 scaffold is amenable to resynthesis and iteration, suggesting an ideal starting point for a new generation of anticancer therapeutics targeting Hsp70i.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Allosteric Regulation / drug effects
  • Animals
  • Benzimidazoles / chemistry*
  • Benzimidazoles / metabolism
  • Benzimidazoles / pharmacokinetics
  • Benzimidazoles / pharmacology*
  • Biological Availability
  • Caspases / metabolism
  • Cell Proliferation / drug effects
  • Drug Evaluation, Preclinical
  • Enzyme Activation / drug effects
  • HEK293 Cells
  • HSP70 Heat-Shock Proteins / antagonists & inhibitors*
  • HSP70 Heat-Shock Proteins / chemistry
  • HSP70 Heat-Shock Proteins / metabolism*
  • Humans
  • Mice
  • Models, Molecular
  • Nipecotic Acids / chemistry*
  • Nipecotic Acids / metabolism
  • Nipecotic Acids / pharmacokinetics
  • Nipecotic Acids / pharmacology*
  • Permeability
  • Piperidines / chemistry*
  • Piperidines / metabolism
  • Piperidines / pharmacokinetics
  • Piperidines / pharmacology*
  • Protein Aggregates / drug effects
  • Protein Structure, Tertiary
  • Xenograft Model Antitumor Assays


  • Benzimidazoles
  • HS-72 compound
  • HSP70 Heat-Shock Proteins
  • Nipecotic Acids
  • Piperidines
  • Protein Aggregates
  • Caspases