Abstract 2736: Mutation of histone H2A at glutamate 121 is frequently observed in cancer patient samples and promotes cancer-associated cellular properties

Background: Histones are essential proteins that facilitate DNA compaction into nucleosomes and chromatin fibers. Their dynamics are crucial for various cellular processes, including regulation of gene expression, cellular differentiation, maintenance of cell identity, DNA replication and DNA repair. By surveying the cBioPortal of Cancer genomics we previously found that approximately 11% of cancer patients had alterations of histone H2A genes, primarily missense mutations of unknown significance. The most commonly mutated H2A residue was a glutamate at amino acid position 121. Prior work by others has demonstrated that mutation of H2A at E121 caused decreased ACF-dependent nucleosome sliding in vitro and impaired yeast growth. Objective: To determine the effect of the histone H2A glutamate to lysine mutation at amino acid 121 (H2A-E121K) on gene expression and cell growth properties relevant to cancer. Methods: We expressed HA-tagged wild type or mutant histone H2A-E121K at near physiological levels in the lung epithelial cell line BEAS-2B using a "minigene" construct which drove expression from a native H2A promoter and 3’ UTR regulatory region. Using live cell imaging we determined the effect of H2A-E121K on cell proliferation, apoptosis and migration in normal serum free media or growth factor deprived conditions. We measured the rate of serum-induced EMT signatures by immunoblotting for proteins such as claudin and cadherins. We investigated how expression of H2A-E121K may alter chromatin accessibility and gene expression by ATAC-seq and RNA-seq. Results: Expression of H2A-E121K promoted both proliferation and survival of lung epithelial cell line BEAS-2B when cultured in normal media or under growth factor deprived conditions. The H2A-E121K mutant promoted colony formation. Cells expressing H2A-E121K had altered chromatin accessibility and gene expression compared to cells expressing WT H2A. Conclusions: Expression of the histone H2A-E121K mutation promotes cancer-associated cellular properties in lung epithelial cells. Citation Format: Richard L. Bennett, Jixiu Shan, Anthony J. Lamberto, Rishika Cherukuru, Kimberly Espinoza Pereira, Pierre Priam, Jonathan D. Licht. Mutation of histone H2A at glutamate 121 is frequently observed in cancer patient samples and promotes cancer-associated cellular properties [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2736.