Allele-Specific Chromatin Recruitment and Therapeutic Vulnerabilities of ESR1 Activating Mutations

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Estrogen receptor alpha (ER) mutations in the ligand-binding domain (LBD) are implicated in endocrine therapy resistance in metastatic ER-positive breast cancer.
• Understanding the molecular mechanisms of these mutations is crucial for developing effective treatment strategies.

Purpose of the Study:

• To investigate the chromatin recruitment, transcriptional network, and genetic vulnerabilities associated with clinically relevant ER mutations.
• To elucidate how these ER mutants contribute to endocrine therapy resistance and a pro-metastatic phenotype.

Main Methods:

• Utilized breast cancer models harboring specific ER mutations.
• Performed genome-wide ER binding site analysis to identify unique recruitment patterns.
• Conducted genetic screens to identify essential genes for mutant ER-driven growth.

Main Results:

• ER mutants demonstrated ligand-independent functions mimicking estradiol-bound wild-type ER.
• Identified allele-specific neomorphic properties promoting a pro-metastatic phenotype.
• Discovered unique ER mutant recruitment mediating allele-specific transcriptional programs and identified essential genes for their growth.

Conclusions:

• ER mutations can confer ligand-independent activity and neomorphic functions, driving endocrine therapy resistance.
• These findings reveal the mechanisms of resistance and highlight potential therapeutic targets for metastatic ER-positive breast cancer.