The synergistic effect of c-Myb hyperactivation and Pu.1 deficiency in inducing Pelger-Huët anomaly and promoting sAML transformation

Patients with acute myeloid leukemia developed from myelodysplastic syndrome (MDS/AML) have poor prognosis with more complex genetic mutations. Genomic analyses have shown complex association among mutant genes, including co-occurring and mutually exclusive. It has been reported that hyperactivation of MYB or deficiency of PU.1 could induce myeloid preleukemia. The simultaneous abnormal expression of these two proteins has been documented in some AML patients. However, the association of MYB and PU.1 in the pathogenesis of malignant hematopoiesis remains unclear. In this study, we used the c-Myb-hyperactivation and Pu.1-deficient double-strain (c-mybhyper;pu.1G242D/G242D) zebrafish to clarify the synergistic role of c-Myb and Pu.1 in promoting MDS/AML development. We found that the c-mybhyper;pu.1G242D/G242D mutant displayed excessive expansion and differentiation arrest of neutrophils, and progressed to MDS/AML with a high ratio. Interestingly, a group of poorly differentiated Pelger-Huët-like neutrophils was identified in c-mybhyper;pu.1G242D/G242D adulthood and might be associated with MDS/AML progression. Moreover, treated the c-mybhyper;pu.1G242D/G242D zebrafish with a combination of the cell cycle inhibitor cytarabine (Ara-C) and the differential inducer all-trans retinoic acid (ATRA) could effectively relieve the leukemic symptoms. Our findings revealed that c-Myb hyperactivation and Pu.1 deficiency synergistically induced MDS/AML. Furthermore, c-mybhyper;pu.1G242D/G242D zebrafish might serve as a suitable MDS/AML model for drug screening. Kidney marrow of the wildtype, c-mybhyper, pu.1G242D/G242D, c-mybhyper;pu.1G242D/G242D zebrafish were isolated separetely. Blood cells were collected from these tissues by pipetting and filtering and analyzed using scRNAseq.