A Mutation in Histone H2B Represents a New Class of Oncogenic Driver

Area of Science:

• Cancer Biology
• Epigenetics
• Molecular Biology

Background:

• Core histone mutations are increasingly identified in cancer genomics databases.
• These mutations are often found in globular domains and their functional impact on nucleosome stability is poorly understood.

Purpose of the Study:

• To identify and characterize novel cancer-associated mutations in core histones.
• To investigate the functional consequences of these mutations on nucleosome stability, gene regulation, and cellular transformation.

Main Methods:

• Analysis of cancer genomics data to identify recurrent histone mutations.
• Biochemical characterization of a specific histone H2B mutation (H2B-E76K) in vitro and in yeast.
• Functional studies in mammalian cell lines (MCF10A) assessing proliferation, colony formation, gene expression, and chromatin accessibility.

Main Results:

• A novel set of cancer-associated core histone mutations predicted to destabilize nucleosomes was identified.
• The H2B-E76K mutation disrupts histone-histone interactions, leading to unstable nucleosomes and impaired gene repression.
• H2B-E76K expression in normal cells promotes proliferation, cooperates with oncogenic mutations, and alters gene expression and chromatin accessibility.

Conclusions:

• Mutations in core histone globular domains can drive an oncogenic program through nucleosome dysfunction.
• These findings reveal a new mechanism of epigenetic dysfunction in cancer involving nucleosome destabilization and altered gene expression.
• Histone mutations represent a significant avenue for understanding cancer development and epigenetic dysregulation.