Polycomb deficiency drives a FOXP2-high aggressive state targetable by epigenetic inhibitors

Area of Science:

• Oncology
• Epigenetics
• Molecular Biology

Background:

• Polycomb Repressive Complex 2 (PRC2) targeting the histone methyltransferase EZH2 is a validated cancer therapy.
• Understanding PRC2's role in diverse cancer systems is crucial for expanding its therapeutic utility.

Purpose of the Study:

• To investigate the role of EZH2 in KRAS-driven lung adenocarcinoma.
• To identify potential therapeutic vulnerabilities associated with EZH2 loss or inhibition in this cancer model.

Main Methods:

• Utilized a genetic model to delete Ezh2 in KRAS-driven lung adenocarcinomas.
• Employed three-dimensional (3D) cultures and in vivo experiments to assess tumor behavior and drug sensitivity.
• Analyzed gene expression changes, including FOXP2, and histone modifications (H3K27me3).

Main Results:

• Ezh2 haplo-insufficient tumors were less lethal and lower grade compared to Ezh2 fully-insufficient tumors, which were poorly differentiated and metastatic.
• EZH2-deficient tumors demonstrated sensitivity to H3K27 demethylase or BET inhibitors.
• PRC2 loss led to FOXP2 de-repression, promoting migration and stemness, which was targetable by BET inhibition.
• Poorly differentiated human lung cancers exhibited an H3K27me3-low state, suggesting potential benefit from BET inhibitors.

Conclusions:

• PRC2 plays diverse roles in KRAS-driven lung adenocarcinomas, influencing tumor grade, differentiation, and metastasis.
• EZH2 deficiency creates specific vulnerabilities exploitable by epigenetic therapies like BET inhibitors.
• 3D culture models are valuable for exploring epigenetic drug sensitivities in cancer research.
• A subset of poorly differentiated lung cancers with low H3K27me3 may benefit from BET inhibition, alone or in combination with EZH2 inhibition.