Polycomb Directed Cell Fate Decisions in Development and Cancer

Area of Science:

• Epigenetics
• Molecular Biology
• Cellular Biology

Background:

• Polycomb group (PcG) proteins are conserved transcription regulators controlling cellular identity.
• Mammalian PcG proteins form Polycomb Repressive Complex 1 (PRC1) and 2 (PRC2).
• PRC1 and PRC2 epigenetically modify chromatin to repress gene expression and stabilize chromatin structure.

Purpose of the Study:

• To review current understanding of PRC2's role in mammalian transcription regulation.
• To elucidate PRC2's function in orchestrating temporal and tissue-specific gene expression for cell identity and fate.
• To highlight PRC2 dysregulation's link to aggressive cancers and EZH2 as a therapeutic target.

Main Methods:

• Literature review of recent insights into PRC2 function.
• Analysis of PRC2's role in gene expression and chromatin modification.
• Examination of PRC2 dysregulation in cancer development.

Main Results:

• PRC2 catalyzes histone H3 lysine 27 methylation (H3K27me1/2/3), forming heterochromatin.
• PRC2 activity is regulated by the EZH2, EED, and SUZ12 protein complex.
• PRC2 dysregulation promotes phenotypic plasticity and epigenetic reprogramming, leading to aggressive neuroendocrine carcinomas.

Conclusions:

• PRC2 is crucial for maintaining cell identity through precise gene expression control.
• Dysregulation of PRC2, particularly EZH2, is implicated in aggressive cancers like prostate, small cell lung, and Merkel cell carcinoma.
• EZH2 represents a significant, actionable therapeutic target for these malignancies.