A myeloid maturation program initiated by nucleotide depletion during S phase [Cut & Run]

Certain cancers, such as acute myeloid leukemia (AML), are caused by malignant stem cells that fail maturation. We sought to mechanistically understand how metabolism might regulate cell fate decisions and to identify metabolic differentiation agents that might be leveraged therapeutically.  We find that nucleotide – purine, pyrimidine, and deoxynucleotide – depletion leads to AML differentiation by way of replication stress. Modulation of nucleotide pools leads to transcriptional reprogramming, epigenetic remodeling, and initiation of differentiation which is dependent on the myeloid regulating transcription-factor PU.1. By single-cell RNA sequencing and microscopy, we find that reprogramming downstream of nucleotide depletion occurs as cells undergo replication stress and that the cell fate decision is initiated prior to completion of the cell cycle. Together, these findings suggest that nucleotide metabolism is a critical determinant of hematopoietic progenitor cell fate, clarify the coordination of the fate decision with the cell cycle, and expand upon the class of inhibitors that can be developed or repurposed as novel differentiation therapy.