HSP90 buffers deleterious genetic variations in BRCA1.

Area of Science:

• Molecular Biology
• Cancer Genetics
• Drug Discovery

Background:

• Protein-folding chaperone HSP90 is known to buffer genetic variation.
• The clinical relevance of HSP90's buffering role in human diseases, particularly cancer, is not well understood.

Purpose of the Study:

• To investigate the role of HSP90 in buffering mutations within the BRCA1 gene.
• To determine the clinical significance of HSP90-buffered BRCA1 mutations in cancer predisposition and therapy resistance.

Main Methods:

• Analysis of HSP90-buffered BRCA1 mutations in cancer cell lines.
• Assessment of protein stability and function of BRCA1 variants.
• Evaluation of PARP inhibitor resistance and the effect of HSP90 inhibition.

Main Results:

• HSP90 buffers mutations in the BRCA1 BRCT domain, stabilizing variant proteins.
• HSP90-stabilized BRCA1 variants retain function and confer resistance to PARP inhibitors.
• Low-level HSP90 inhibition reverses PARP inhibitor resistance, demonstrating synthetic lethality.

Conclusions:

• HSP90 buffering of BRCA1 mutations reduces their clinical severity and promotes their accumulation.
• HSP90 plays a critical role in cancer predisposition and therapy resistance associated with BRCA1 mutations.
• Targeting HSP90 presents a potential therapeutic strategy for overcoming PARP inhibitor resistance in BRCA1-mutated cancers.