Hypersensitivity to G-CSF in RUNX1 Haploinsufficiency and Leukemia Risk
Overview
RUNX1 haploinsufficiency, a genetic alteration linked to familial platelet disorder with predisposition to myeloid malignancies (FPD/MM), causes hypersensitivity to granulocyte colony-stimulating factor (G-CSF). Both Runx1+/− mice and FPD patient-derived cells show enhanced hematopoietic stem and progenitor cell (HSPC) expansion and mobilization upon G-CSF stimulation, suggesting a mechanism for increased leukemogenesis risk.
Background
RUNX1 is a critical transcription factor frequently mutated in acute leukemia, with germline mutations causing FPD/MM characterized by thrombocytopenia and leukemia predisposition. Runx1 regulates hematopoiesis, and its deficiency affects hematopoietic stem cell function. G-CSF is a cytokine that promotes HSPC proliferation and mobilization, clinically used to treat neutropenia and mobilize stem cells. Recent evidence links RUNX1 mutations and G-CSF signaling abnormalities in leukemogenesis.
Data Highlights
Parameter
Runx1+/− Mice
Wild-Type Mice
G-CSF Dose
250 μg/kg/day × 3 days
250 μg/kg/day × 3 days
HSPC Expansion
Significantly increased
Baseline
Peripheral Mobilization
Enhanced
Normal
Myeloid Differentiation
Blocked
Normal
Key Findings
Runx1+/− mice exhibit hypersensitivity to G-CSF, demonstrated by increased HSPC expansion and mobilization compared to wild-type mice.
FPD patient-derived peripheral blood mononuclear cells with RUNX1 mutations show similar G-CSF hypersensitivity as observed in Runx1+/− mice.
Runx1 haploinsufficiency leads to a block in myeloid differentiation despite increased progenitor cell numbers.
G-CSF treatment combined with RUNX1 deficiency promotes detachment of long-term HSCs from the bone marrow niche, increasing short-term HSC frequency.
RUNX1 mutations disrupt DNA binding and heterodimerization, impairing hematopoietic regulation and contributing to leukemogenesis risk.
Clinical Implications
Clinicians should be aware that patients with RUNX1 haploinsufficiency may exhibit exaggerated responses to G-CSF, potentially increasing immature progenitor pools and leukemia risk. Monitoring hematopoietic parameters during G-CSF therapy in these patients is advisable. Understanding this hypersensitivity may guide safer use of G-CSF and inform surveillance strategies for leukemic transformation in FPD/MM.
Conclusion
RUNX1 haploinsufficiency induces G-CSF hypersensitivity, expanding immature hematopoietic progenitors and potentially facilitating leukemogenesis. These findings elucidate a mechanistic link between RUNX1 mutations and altered cytokine responses in hematopoietic disorders.
References
Okada et al. -- Generation of Runx1+/− mice
Keio University School of Medicine -- Clinical study on FPD patients
