BH3-only protein Bim more critical than Puma in tyrosine kinase inhibitor-induced apoptosis of human leukemic cells and transduced hematopoietic progenitors carrying oncogenic FLT3

Blood. 2009 Mar 5;113(10):2302-11. doi: 10.1182/blood-2008-07-167023. Epub 2008 Dec 8.


Constitutively activating internal tandem duplications (ITD) of FLT3 (FMS-like tyrosine kinase 3) are the most common mutations in acute myeloid leukemia (AML) and correlate with poor prognosis. Receptor tyrosine kinase inhibitors targeting FLT3 have developed as attractive treatment options. Because relapses occur after initial responses, identification of FLT3-ITD-mediated signaling events are important to facilitate novel therapeutic interventions. Here, we have determined the growth-inhibitory and proapoptotic mechanisms of 2 small molecule inhibitors of FLT3, AG1295 or PKC412, in hematopoietic progenitor cells, human leukemic cell lines, and primary AML cells expressing FLT3-ITD. Inactivation of the PI3-kinase pathway, but not of Ras-mitogen-activated protein (MAP) kinase signaling, was essential to elicit cytotoxic responses. Both compounds induced up-regulation of proapoptotic BH3-only proteins Bim and Puma, and subsequent cell death. However, only silencing of Bim, or its direct transcriptional activator FOXO3a, abrogated apoptosis efficiently. Similar findings were made in bone marrow cells from gene-targeted mice lacking Bim and/or Puma infected with FLT3-ITD and treated with inhibitor, where loss of Puma only provided transient protection from apoptosis, but loss of Bim preserved clonal survival upon FLT3-ITD inhibition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / drug effects
  • Apoptosis Regulatory Proteins / metabolism*
  • Bcl-2-Like Protein 11
  • Blotting, Western
  • Cell Line, Tumor
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / drug effects
  • Forkhead Transcription Factors / metabolism
  • Hematopoietic Stem Cells / drug effects
  • Humans
  • Immunoprecipitation
  • Leukemia, Myeloid, Acute / genetics
  • Leukemia, Myeloid, Acute / metabolism*
  • Membrane Proteins / drug effects
  • Membrane Proteins / metabolism*
  • Mice
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Phosphatidylinositol 3-Kinases / drug effects
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Kinase Inhibitors / pharmacology*
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Proto-Oncogene Proteins / drug effects
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Small Interfering
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Staurosporine / analogs & derivatives
  • Staurosporine / pharmacology
  • Transduction, Genetic
  • Tyrphostins / pharmacology
  • fms-Like Tyrosine Kinase 3 / antagonists & inhibitors
  • fms-Like Tyrosine Kinase 3 / genetics*


  • 6,7-dimethoxy-2-phenylquinoxaline
  • Apoptosis Regulatory Proteins
  • BBC3 protein, human
  • BCL2L11 protein, human
  • Bcl-2-Like Protein 11
  • Bcl2l11 protein, mouse
  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • Membrane Proteins
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins
  • RNA, Small Interfering
  • Tyrphostins
  • Phosphatidylinositol 3-Kinases
  • FLT3 protein, human
  • Protein-Tyrosine Kinases
  • fms-Like Tyrosine Kinase 3
  • Proto-Oncogene Proteins c-akt
  • Staurosporine
  • midostaurin