Downstream effect of CSF3R and RUNX1 mutations that underlie leukemic transformations in congenital neutropenia (CN)

Ca. 70% of CN patients with AML carry CSF3R and RUNX1 mutations (Skokowa et al 2014). We established an in vitro model utilizing lin- bone marrow cells from C57BL/6 – 1d715csf3r mice (with homozygous d715G CSF3R mutations) transduced with lentivirus vectors carrying RUNX1 wildtype or RUNX1 missense mutations. Cells transduced with RUNX1 mutants showed diminished in vitro myeloid differentiation and elevated replating capacity, compared to WT. mRNA expression analysis of transduced cells using Pathway analysis (IPA) and Motif activity response analysis (using ISMARA) revealed that the highest activated motif in RUNX1-Mutants was Irf2_Irf1_Irf8_Irf9_Irf7 motif. Correspondingly, IPA Pathway analysis showed that Interferon Signaling was highly upregulated in cells transduced with RUNX1 mutants, compared to WT RUNX1. Additionally, pathway analysis showed the upregulation and activation of IL-6, IL-8-, Toll like Receptor- and TREM1 signaling pathways. This data suggests that the mutated RUNX1 may cause activation of the pro-inflammatory cell state propagating proliferation, which may be emerging as a cause of clonal hematopoiesis and consequently may lead to MDS/AML.