Hematopoiesis in germline RUNX1mutation carriers: impact of inflammation and the bone marrow niche

Hematopoiesis
impact
in germline RUNX1 mutation carriers:
of inflammation and the bone marrow niche
PROJECT SUMMARY/ABSTRACT
Germline variants that confer risk for leukemia have been recognized increasingly with 15-20% of acute
leukemia patients having at least 1 first-degree relative afflicted with leukemia. Germline variants are now
included for the first time in the revised leukemia classification scheme outlined by the World Health
Organization, and new clinical guidelines now include testing for inherited susceptibility as a critical element of
patient diagnostics. It is devastating for these patients and their family members to live with the knowledge of
having increased risk for developing cancer in their lifetimes. Thus, for these patients, early cancer detection,
disease monitoring, and prevention would be life-changing, but require a comprehensive understanding of
molecular changes that occur prior to overt leukemia. The long-term goal of this study is to identify the
mechanisms that regulate hematopoiesis at the premalignant stage in patients with germline RUNX1 mutations
[also called familial platelet disorder (FPD)]. These individuals have life-long thrombocytopenia, qualitative
platelet aggregation defects, and a risk of developing a variety of hematopoietic malignancies. The acquisition
of secondary mutations occurs over time in FPD patients leading to leukemia development. However, the
intrinsic and/or extrinsic factors that render pre-leukemic cells vulnerable to acquire secondary mutations are
unknown. To fill this knowledge gap, we performed single-cell transcriptome profiling of primary FPD bone
marrow samples and identified unique transcriptional changes in FPD progenitors compared to healthy
controls. Consistent these changes, FPD progenitors have impaired megakaryocytic but enhanced myeloid
differentiation. Cytokine profiling of bone marrow hematopoietic and mesenchymal stromal cells (MSCs) show
that there is increased cytokine production within the bone marrow, leading to chronic inflammatory stress,
which may confer a growth advantage to FPD progenitors. Moreover, FPD stromal cells also show defective
differentiation, clonogenic capacity, and deregulated gene expression that may further promote an
inflammatory state. Thus, we hypothesize that early transcriptomic changes in FPD stem/progenitors
cooperate with inflammatory microenvironmental signals to provide a growth advantage to these pre-leukemic
cells and alter their differentiation. Wewill test our hypothesis using the following aims: 1)Identify how early
transcriptomic changes alter hematopoiesis of FPD cells. 2) Determine the impact of inflammatory cytokines
and their blockade in FPD evolution. 3) Assess the role of the FPD stromal microenvironment on growth and
differentiation of FPD and healthy stem/progenitors. To achieve our goals, we have assembled several tools,
including primary stem/progenitor/and stromal cells, iPSCs, xenograft and transgenic mouse models,
CRISPR/Cas9
hematopoiesis
targeting
and
editing technique, and 3D co-culture models. This project will advance our understanding of
in FPD patients and will provide the molecular basis for the rational design of new therapeutics
of RUNX1-mediated changes and the inflammatory microenvironment to normalize hematopoiesis
delay or prevent leukemia in FPD patients.

Grant Number: 5R01HL155426-04
NIH Institute/Center: NIH
Principal Investigator: Anupriya Agarwal