Hijacking client instability to selectively disrupt HSP90-driven glucocorticoid receptor activation

Area of Science:

• Molecular Biology
• Biochemistry
• Cancer Research

Background:

• Heat Shock Protein 90 (HSP90) is crucial for protein folding and activation, making it a cancer target.
• Current HSP90 inhibitors face limitations due to broad client depletion and protective heat shock responses.

Purpose of the Study:

• To develop a client-directed strategy to modulate HSP90 activity by targeting unstable client protein regions.
• To design peptide mimics that compete with chaperone engagement for HSP90 clients.

Main Methods:

• Computational energy-decomposition analysis of the glucocorticoid receptor (GR) ligand-binding domain.
• Identification and design of GR-derived peptide mimics.
• In vitro binding assays with purified HSP90 and cell-based assays in triple-negative breast cancer cells.

Main Results:

• Identified unstable substructures in GR that sample unfolded conformations.
• Developed cell-permeable GR peptide mimics that selectively bind HSP90.
• Demonstrated that these peptides induce GR degradation and potentiate anti-cancer drug response.

Conclusions:

• A novel framework integrating computational analysis and rational design of client-derived peptides to modulate HSP90-dependent pathways.
• This approach offers a therapeutic strategy by targeting weak, client-specific interactions within proteostasis networks.
• Highlights potential for developing new cancer therapeutics by targeting chaperone-client interactions.