Allele-Specific Gene Regulation, Phenotypes, and Therapeutic Vulnerabilities in Estrogen Receptor Alpha-Mutant...

Area of Science:

• Endocrinology
• Cancer Biology
• Genomics

Background:

• Activating estrogen receptor alpha (ER; ESR1) mutations are found in endometrial and breast cancers, leading to estrogen-independent receptor activity.
• While ER mutations are studied in breast cancer, their specific impact on endometrial cancer remains less understood.

Purpose of the Study:

• To investigate allele-specific differences between ER mutations (Y537S and D538G) in endometrial cancer using CRISPR-Cas9 modeling.
• To identify novel therapeutic targets for ER-mutant endometrial cancer.

Main Methods:

• Utilized CRISPR-Cas9 to model ER-Y537S and ER-D538G mutations in endometrial cancer.
• Analyzed changes in gene expression, ER binding, and chromatin accessibility.
• Employed Rapid Immunoprecipitation and Mass Spectrometry of Endogenous Proteins (RIMS-EP) to identify ER-associated proteins.
• Assessed the therapeutic potential of inhibiting candidate proteins CDK9 and NCOA3.

Main Results:

• Mutant ER significantly altered gene expression, ER binding, and chromatin accessibility, leading to thousands of gene expression changes.
• ER-mutant cells exhibited increased cancer-associated phenotypes: migration, invasion, anchorage-independent growth, and in vivo growth.
• CDK9 and NCOA3 were identified as ER-associated proteins; their inhibition reduced cancer cell growth and migration.

Conclusions:

• ER mutations induce distinct molecular and phenotypic changes in endometrial cancer cells.
• Targeting CDK9 and NCOA3 represents a potential therapeutic strategy for ER-mutant endometrial cancer.