Abstract 1427: Characterization of epigenetic regulation of MYC in acute myeloid leukemia

Abstract Abnormal epigenetic regulation of MYC gene expression is a key driver of aberrant proliferation in Acute Myeloid Leukemia (AML). Using functional and single-cell genomics, we identified enhancer hijacking as a mechanism of MYC overexpression in AML cells, describing a new mechanism of oncogenesis. The c-MYC transcription factor is an integral regulator of healthy hematopoiesis and is aberrantly upregulated in multiple malignancies, including AML. The c-MYC protein acts as a fulcrum that balances the differentiation and proliferation of blood cells. Therefore, it represents a target for therapeutic intervention because it acts upstream of a network of additional regulatory factors. However, c-MYC is classically considered undruggable because of its lack of enzymatic function and the high likelihood of treatment-related toxicity owing to its role in nearly all tissues. Recent data have shown that MYC transcription depends on interactions with distal enhancer DNA elements, including the MYC Blood Enhancer Cluster (BENC). Previous studies have demonstrated that the BENC interacts with the MYC promoter to control c-MYC-dependent hematopoiesis and the aberrant upregulation of MYC transcription in AML. Additionally, previous characterization of the BENC suggests that eight discrete subregions (BENC modules) independently control the differentiation programs necessary for specific myeloid cell types. Using single-cell ATAC-seq on AML patient samples, we demonstrate that module-specific BENC activation patterns differ between AMLs that display differentiated and primitive phenotypes. However, the functional implications of these patterns remain unknown. We created a map of BENC chromatin activity using CUT&Tag for H3K27ac in human hematopoietic stem and progenitor cell populations isolated by FACS. We also used CRISPR knockout followed by cell culture to demonstrate the functional requirements of each BENC module during healthy human hematopoietic differentiation. Additionally, we used CRISPRi to validate the role of each BENC module in AML cell survival and demonstrated that the proliferative rates of AML cells are sensitive to module-specific BENC inhibition. Our data indicate that BENC usage patterns differ between AML and healthy human hematopoietic cells and suggest that AML cells hijack BENC modules to aberrantly upregulate MYC during disease progression. Further characterization of the factors involved in MYC regulation by the BENC will provide a framework for identifying and testing new drugs to selectively reverse MYC overexpression in AML, with the ultimate goal of improving the treatment outcomes for this difficult-to-treat and highly morbid disease. Citation Format: William S. Streitfeld, William M. Yashar, Itallia V. Pacentine, Thai T. Nguyen, Samantha J. Worme, Gürkan G. Yardimci, Andrew C. Adey, Theodore P. Braun. Characterization of epigenetic regulation of MYC in acute myeloid leukemia [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 1427.