Phosphorylated DEK sustains leukemia stem cells by enabling PBX3-driven transcriptional reprogramming [ATAC-seq 2]

Here, through phosphoproteomic profiling of normal hematopoietic stem and progenitor cells (HSPCs) versus LSC-enriched population, we identify DEK phosphorylation as a critical modification during leukemogenesis. Functional studies in MLL-AF9- and HOXA9/MEIS1-driven AML mouse models, as well as patient-derived xenografts (PDXs), demonstrate that DEK deficiency impairs LSC maintenance and AML development.

Moreover, DEK deletion enhances LSC chemosensitivity to the standard-of-care combination of azacitidine and venetoclax (Aza/Ven), whereas DEK overexpression confers robust chemoresistance. Mechanistically, DEK recruits the transcription factor GABPA to drive overexpression of transcriptional cofactor PBX3, a key oncogenic driver in AML, thereby sustaining a leukemogenic transcriptional program. This DEK-GABPA interaction strictly depends on DEK phosphorylation at Ser301/303/306/307 (the 4S site), which stabilizes the conformation of the DEK-GABPA complex.