Impaired histone inheritance promotes tumor progression.

Area of Science:

• Epigenetics
• Molecular Biology
• Cancer Biology

Background:

• Faithful inheritance of parental histones is vital for maintaining epigenetic information and cellular identity.
• Parental histone deposition onto replicating DNA relies on the MCM2 subunit of DNA helicase.
• The role of aberrant parental histone partitioning in human diseases, particularly cancer, remains largely unexplored.

Purpose of the Study:

• To investigate the impact of impaired histone inheritance on cancer progression.
• To model defective parental histone binding using an MCM2-2A mutation in breast cancer cells.
• To understand how altered histone inheritance affects epigenetic landscapes and gene expression in cancer.

Main Methods:

• Introduction of an MCM2-2A mutation (impaired parental histone binding) into MCF-7 breast cancer cells.
• Analysis of histone modification landscapes, focusing on H3K27me3, in progeny cells.
• Assessment of gene expression changes related to development, proliferation, and epithelial-to-mesenchymal transition.
• Orthotopic implantation of modified cells to evaluate tumor growth and metastasis in vivo.

Main Results:

• Impaired histone inheritance led to reprogramming of histone modification landscapes, notably reducing the repressive H3K27me3 mark.
• Decreased H3K27me3 levels resulted in derepression of genes involved in development, cell proliferation, and epithelial-to-mesenchymal transition.
• These epigenetic alterations conferred fitness advantages, promoting tumor growth and metastasis following orthotopic implantation.

Conclusions:

• Impaired inheritance of parental histones can significantly drive tumor progression.
• Aberrant histone deposition contributes to epigenetic reprogramming, influencing cancer cell phenotypes.
• This mechanism highlights a novel pathway linking histone inheritance to cancer development and spread.