PRC2 loss impairs small cell lung cancer tumorigenesis and enhances sensitivity to G9a/GLP inhibition

Area of Science:

• Oncology
• Epigenetics
• Molecular Biology

Background:

• Small cell lung cancer (SCLC) lacks effective targeted therapies, necessitating novel treatment strategies.
• Epigenetic modifications, particularly those involving Polycomb repressive complex 2 (PRC2), are implicated in SCLC immune evasion and chemoresistance.
• Understanding PRC2's structural and enzymatic roles is key to developing new SCLC treatments.

Purpose of the Study:

• To investigate the role of PRC2's structural and enzymatic functions in SCLC pathogenesis.
• To identify potential drug targets and combination therapies for SCLC by analyzing the PRC2 interactome.
• To evaluate the therapeutic potential of combining EZH2 inhibitors with other agents in SCLC.

Main Methods:

• Utilized an autochthonous SCLC mouse model with conditional deletion of Eed, a core PRC2 component.
• Administered enzymatic inhibitors targeting EZH2 and conducted a combination drug screen.
• Performed transcriptomic analysis to elucidate molecular mechanisms of drug action and identified novel PRC2 interactome targets.

Main Results:

• Conditional deletion of Eed prevented SCLC tumor formation, highlighting PRC2's structural importance.
• EZH2 inhibition alone did not affect tumor growth but altered the PRC2 interactome.
• Combining EZH2 inhibition with G9a/GLP inhibition sensitized neuroendocrine cancer cells and induced an oxidative stress response.

Conclusions:

• PRC2's structural functions are critical for SCLC development, offering a distinct therapeutic avenue.
• Combination therapy involving EZH2 and G9a/GLP inhibitors shows potential for SCLC treatment by inducing oxidative stress.
• Targeting the PRC2 interactome and leveraging combination strategies represent promising approaches to overcome SCLC chemoresistance and immune evasion.