pci-32765 and Leukemia--Neutrophilic--Chronic

Granulocyte-colony stimulating factor receptor (G-CSFR) controls myeloid progenitor proliferation and differentiation to neutrophils. Mutations in CSF3R (encoding G-CSFR) have been reported in patients with chronic neutrophilic leukemia (CNL) and acute myeloid leukemia (AML); however, despite years of research, the malignant downstream signaling of the mutated G-CSFRs is not well understood. Here, we used a quantitative phospho-tyrosine analysis to generate a comprehensive signaling map of G-CSF induced tyrosine phosphorylation in the normal versus mutated (proximal: T618I and truncated: Q741x) G-CSFRs. Unbiased clustering and kinase enrichment analysis identified rapid induction of phospho-proteins associated with endocytosis by the wild type G-CSFR only; while G-CSFR mutants showed abnormal kinetics of canonical Stat3, Stat5, and Mapk phosphorylation, and aberrant activation of Bruton's Tyrosine Kinase (Btk). Mutant-G-CSFR-expressing cells displayed enhanced sensitivity (3-5-fold lower IC50) for ibrutinib-based chemical inhibition of Btk. Primary murine progenitor cells from G-CSFR-Q741x knock-in mice validated activation of Btk by the mutant receptor and retrovirally transduced human CD34

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Animals; Cell Proliferation; Cell Transformation, Neoplastic; Cells, Cultured; Humans; Leukemia, Myeloid, Acute; Leukemia, Neutrophilic, Chronic; Mice; Mutation; Phosphoproteins; Phosphorylation; Piperidines; Precursor Cells, B-Lymphoid; Protein-Tyrosine Kinases; Proteome; Pyrazoles; Pyrimidines; Receptors, Granulocyte Colony-Stimulating Factor