A stem cell model identifies two alternative cell fates in CBFA2T3::GLIS2-driven acute megakaryoblastic leukemia initiation (Multiome scRNA-seq/scATAC-seq)

CBFA2T3::GLIS2 (CG) is an oncogenic fusion protein found in high-risk pediatric acute megakaryoblastic leukemia (AMKL). To gain insight into its leukemogenic mechanism, we developed a disease model based on genetically modified human induced pluripotent stem cells. We found that CG expression disrupts myeloid differentiation in this model via two alternate paths: either by delaying differentiation of aberrant megakaryocytes (aMK) or by locking aberrant megakaryocyte progenitors (aMKP) in a proliferative state akin to AMKL tumor cells. We characterized the gene-regulatory networks characterizing both cell states by single-cell and epigenome analysis, and observed that CG sustains aMKPs along with cooperators GATA2 and ERG, while repressing differentiation factors like CEBPA, LYL1, and NFE2. In contrast, aMKs maintained many differentiation factors and did not up-regulate regulators of self-renewal. In future, our findings may contribute to improved diagnostic and therapeutic procedures aimed at interconverting cell states in CG-positive patients.