ASAH1-mediated sphingolipid metabolic reprogramming in venetoclax resistance of AML: beyond the monocytic phenotypes.

BACKGROUND: Venetoclax (VEN) in combination with hypomethylating agents has emerged as a pivotal therapy for elderly acute myeloid leukemia (AML) patients ineligible for intensive chemotherapy. However, monocytic AML exhibit greater resistance to VEN-based regimens compared to non-monocytic AML. Identifying exploitable vulnerabilities will mitigate resistance and relapse. METHODS: We conducted a comprehensive analysis of VEN resistance mechanisms in monocytic AML by integrating bulk AML datasets, single-cell RNA sequencing (scRNA-seq) of AML patient bone marrow and patient-derived xenograft (PDX) models, as well as lipidomic sequencing of induced VEN-resistant cell lines. Additionally, we examined the monocytic markers in VEN-resistant cell lines and assessed VEN sensitivity after knocking down the key sphingolipid metabolism gene ASAH1. RESULTS: Analysis of bulk RNA-seq data revealed elevated expression of sphingolipid metabolism genes in the French-American-British (FAB) M5 subtype, which exhibited poor response to VEN-based treatment. Further analysis of scRNA-seq data showed that monocytic AML cells surviving VEN treatment demonstrated the highest sphingolipid metabolism score, particularly in CD14⁺ITGAX⁺ monocytic AML cells. Notably, induced VEN-resistant cell lines exhibited significantly increased monocytic markers and differential sphingolipid metabolism profiles compared to parental cells. Among the key regulators of sphingolipid metabolism, ASAH1 was upregulated, while SPHK1 was downregulated. Knocking down ASAH1 enhanced VEN sensitivity without reducing the expression of monocytic markers CD14/CD64. CONCLUSIONS: These findings suggest that aberrant sphingolipid metabolism contribute to AML resistance to VEN.