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Leukemogenic Kras mutation reprograms multipotent progenitors to facilitate its spread through the hematopoietic system

ABSTRACT: We studied how leukemia-associated mutations subvert normal adult hematopoiesis by genetically inducing them in specifically in murine hematopoietic stem cells (HSC) followed by lineage tracing in native hosts. Leukemia-initiating mutations such as Tet2 or Dnmt3a deletions did not increase the net HSC contribution in the steady state, whereasTet2 deletion slightly accelerated HSC contribution to myeloid lineages following microbial stimulation. In contrast, the leukemia-transforming KrasG12D mutation dramatically accelerated the contribution of mutant HSC to all hematopoietic lineages, rapidly creating a pre-leukemic state. The acceleration was mediated by KrasG12D-carrying multipotent progenitors (MPP) that rapidly outcompeted normal MPP and showed increased proliferation but lacked self-renewal capacity. In addition, mutant progenitor cells expressed the secreted stem/progenitor regulator osteopontin and showed enhanced CXCR4-dependent motility, both of which contributed to the accelerated spread of the mutation to mature cells. Thus, transforming mutations may facilitate their spread from HSC to mature cells via hypercompetitive progenitors, creating a two-component stem/progenitor circuit that underlies leukemogenesis.

ORGANISM(S): Mus musculus

PROVIDER: GSE261879 | GEO | 2025/02/19

REPOSITORIES: GEO

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Project description:Disrupting mutations of the RUNX1 gene are found in 10% of patients with myelodysplasia (MDS) and 30% of patients with acute myeloid leukemia (AML). Previous studies have revealed an increase in hematopoietic stem cells (HSCs) and multipotent progenitor (MPP) cells in conditional Runx1-knockout (KO) mice, but the molecular mechanism is unresolved. We investigated the myeloid progenitor (MP) compartment in KO mice, arguing that disruptions at the HSC/MPP level may be amplified in downstream cells. We demonstrate that the MP compartment is increased more than fivefold in Runx1 KO mice, with a prominent skewing toward megakaryocyte (Meg) progenitors. Runx1- deficient granulocyte-macrophage progenitors are characterized by increased cloning capacity, impaired development into mature cells, and HSC and Meg transcription signatures. An HSC/MPP subpopulation expressing Meg markers was also increased in Runx1-deficient mice. Rescue experiments coupled with transcriptome analysis and Runx1 DNA-binding assays demonstrated that commitment is marked by Runx1 suppression of genes encoding adherence and motility proteins (Tek, Jam3, Plxnc1, Pcdh7, and Selp) that support HSCâMeg interactions with the BM niche. In vitro assays confirmed that enforced Tek expression in HSCs/MPPs increases Meg output. Interestingly, besides this key repressor function of Runx1 to control lineage decisions and cell numbers in progenitors, our study also revealed a critical activating function in erythroblast differentiation, in addition to its known importance in Meg and granulocyte/monocyte (G/M) maturation. Thus both repressor and activator functions of Runx1 at multiple hematopoietic stages and lineages likely contribute to the tumor suppressor activity in MDS and AML. GMP were isolated either from Runx1+/+-Tg(vav-Cre) and Runx1fl/fl-Tg(vav-Cre) mice or from mice transplanted with Runx1fl/fl-Tg(vav-Cre) progenitors engineered to express GFP with RUNX1-ERt2 or ERt2. RUNX1-ERt2 activity was induced by i.p. injection of tamoxifen on 3 consecutive days prior to GMP isolation.

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Leukemogenic Kras mutation reprograms multipotent progenitors to facilitate its spread through the hematopoietic system

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