Knock-in of an internal tandem duplication mutation into murine FLT3 confers myeloproliferative disease in a mouse model

Blood. 2008 Apr 1;111(7):3849-58. doi: 10.1182/blood-2007-08-109942. Epub 2008 Feb 1.

Abstract

Constitutive activation of FMS-like tyrosine kinase 3 (FLT3) by internal tandem duplication (ITD) mutations is one of the most common molecular alterations known in acute myeloid leukemia (AML). To investigate the role FLT3/ITD mutations play in the development of leukemia, we generated a FLT3/ITD knock-in mouse model by inserting an ITD mutation into the juxtamembrane domain of murine Flt3. FLT3wt/ITD mice developed myeloproliferative disease, characterized by splenomegaly, leukocytosis, and myeloid hypercellularity, which progressed to mortality by 6 to 20 months. Bone marrow (BM) and spleen from FLT3wt/ITD mice had an increased fraction of granulocytes/monocytes and dendritic cells, and a decreased fraction of B-lymphocytes. No sign of acute leukemia was observed over the lifetime of these mice. BM from FLT3wt/ITD mice showed enhanced potential to generate myeloid colonies in vitro. BM from FLT3wt/ITD mice also produced more spleen colonies in the in vivo colony-forming unit (CFU)-spleen assay. In the long-term competitive repopulation assay, BM cells from FLT3wt/ITD mice outgrew the wild-type competitor cells and showed increased myeloid and reduced lymphoid expansion activity. In summary, our data indicate that expression of FLT3/ITD mutations alone is capable of conferring normal hematopoietic stem/progenitor cells (HSPCs) with enhanced myeloid expansion. It also appears to suppress B lymphoid maturation. Additional cooperative events appear to be required to progress to acute leukemia.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Marrow / metabolism
  • Bone Marrow / pathology
  • Cell Membrane / genetics
  • Cell Membrane / metabolism
  • Cell Membrane / pathology
  • Colony-Forming Units Assay
  • Disease Models, Animal
  • Hematopoietic Stem Cells / metabolism*
  • Hematopoietic Stem Cells / pathology
  • Humans
  • Leukemia, Myeloid, Acute / genetics
  • Leukemia, Myeloid, Acute / metabolism
  • Leukemia, Myeloid, Acute / pathology
  • Leukocytes, Mononuclear / metabolism
  • Leukocytes, Mononuclear / pathology
  • Leukocytosis / genetics
  • Leukocytosis / metabolism
  • Leukocytosis / pathology
  • Mice
  • Mice, Transgenic
  • Mutation*
  • Myelopoiesis* / genetics
  • Myeloproliferative Disorders / genetics
  • Myeloproliferative Disorders / metabolism*
  • Myeloproliferative Disorders / pathology
  • Protein Structure, Tertiary / genetics
  • Spleen / metabolism
  • Spleen / pathology
  • Splenomegaly / genetics
  • Splenomegaly / metabolism
  • Splenomegaly / pathology
  • Time Factors
  • fms-Like Tyrosine Kinase 3 / genetics
  • fms-Like Tyrosine Kinase 3 / metabolism*

Substances

  • Flt3 protein, mouse
  • fms-Like Tyrosine Kinase 3