Dynamic heterogeneity towards drug resistance in AML cells is primarily driven by epigenomic mechanism unveiled by multi-omics analysis.

[INTRODUCTION] Acute myeloid leukemia (AML) is a hematologic malignancy characterized by aggressive proliferation and chemoresistance, leading to poor patient outcomes. Despite advances in chemotherapy, resistance mechanisms remain inadequately understood, particularly at the cellular and molecular level.

[OBJECTIVES] This study aims to elucidate the cellular and molecular mechanisms underlying drug resistance in AML cells.

[METHODS] A multi-omics approach was employed, integrating single-cell RNA sequencing (scRNA-seq), chromatin accessibility profiling (scATAC-seq), DNA methylation analysis, and whole-exome sequencing (WES). AML cell lines (KG-1a, Kasumi-1, and HL-60) were treated with standard chemotherapeutic agents, including cytarabine (Ara-C), daunorubicin (DNR), azacitidine (AZA), and decitabine (DEC). Additionally, we developed a novel multiplexed scRNA-seq strategy, NAMUL-seq, to enhance the efficiency and scalability of single-cell transcriptomic research.

[RESULTS] We observed substantial cellular heterogeneity and dynamic transcriptomic trajectories in AML cells subjected to various treatments, uncovering a tendency for reprogramming towards a more stem-like state. Notably, Ara-C-resistant KG-1a cells predominantly originated from G2/M phase subpopulations, suggesting a resistance mechanism linked to specific cell cycle stages. Our findings further indicate that rapid Ara-C resistance is primarily driven by epigenomic changes, including alterations in DNA methylation, chromatin architecture, and transcription factor activity, whereas exonic mutations played a minimal role.

[CONCLUSION] This study demonstrates that AML drug resistance is predominantly driven by epigenomic mechanisms rather than genetic mutations. This study provides a detailed cellular and molecular characterization of AML drug response and resistance, identifying potential therapeutic targets and laying the groundwork for future efforts to overcome chemoresistance.