Inducible MLL-AF9 expression drives an AML program during human pluripotent stem cell-derived hematopoietic differentiation [ATAC-Seq]

The t(9; 11) (p22; q23) translocation produces the MLL-AF9 fusion protein, which is found in up to 25% of de novo AML cases in children. Despite major advances, a comprehensive understanding of context-dependent MLL-AF9-mediated gene programs during early hematopoiesis is challenging. Here, we generated a human inducible pluripotent stem cell (hiPSC) model with doxycycline dose-dependent MLL-AF9 expression. We exploit MLL-AF9 expression as an oncogenic hit to uncover epigenetic and transcriptomic effects on iPSC-derived hematopoietic development and the transformation into (pre-) leukemic states. In doing so, we observed disruption of early myelomonocytic development and expansion of a CD34+ early hematopoietic progenitor compartment upon MLL-AF9 activation. Indeed, we identified gene profiles consistent with primary MLL-AF9 AMLs. We exploit this system to uncover a highly confident MLL-AF9-associated gene core set that faithfully represent primary MLL-AF9 AMLs, including known and thus far unknown factors in MLL-AF9 AMLs. Our system allows for careful chemically controlled and stepwise in vitro iPSC-derived differentiation under serum-free and feeder-free conditions. For a disease that currently lacks effective treatments, our system provides a novel entry-point into exploring potential novel biomarkers and targets for personalized therapeutic strategies. Overall design: ATAC-seq data for MLL-AF9 induced (myeloid) differentiated iPS cells and its untreated counterpart.