The antiapoptotic gene A1/BFL1 is a WT1 target gene that mediates granulocytic differentiation and resistance to chemotherapy

Blood. 2006 Jun 15;107(12):4695-702. doi: 10.1182/blood-2005-10-4025. Epub 2006 Feb 16.


Previous work has demonstrated that WT1 (-Ex5/-KTS) potentiates granulocyte colony-stimulating factor (G-CSF)-mediated granulocytic differentiation. This WT1 isoform suppresses cyclin E, which may contribute to the prodifferentiation effect by slowing proliferation, but WT1 target genes that affect survival might also be involved. We screened a cDNA array and identified the bCL2 family member A1/BFL1 as a new WT1 target gene in 32D cl3 murine myeloblast cells. Induction of WT1 (-Ex5/-KTS) expression is accompanied by up-regulation of A1 on the cDNA array, and this up-regulation was confirmed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Moreover, both promoter-reporter assays and chromatin immunoprecipitation assays suggest that this isoform of WT1 activates the promoter directly. Constitutive expression of A1 in 32D cl3 cells induces spontaneous granulocytic differentiation, with both morphologic and cell-surface antigen changes, as well as resistance both to chemotherapy and to withdrawal of interleukin-3 (IL-3). Finally, we note an association between WT1 expression and A1 expression in primary acute myeloid leukemia samples. Taken together, these results demonstrate that A1 is a new WT1 target gene involved in both granulocytic differentiation and resistance to cell death, and suggests that these genes might play an important role in the biology of high-risk leukemias.

Publication types

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

MeSH terms

  • Animals
  • Cell Differentiation / drug effects
  • Cell Differentiation / physiology*
  • Drug Resistance, Neoplasm / drug effects
  • Drug Resistance, Neoplasm / genetics
  • Granulocyte Colony-Stimulating Factor / biosynthesis
  • Granulocyte Precursor Cells / cytology
  • Granulocyte Precursor Cells / metabolism*
  • Humans
  • Interleukin-3 / pharmacology
  • Leukemia, Myeloid, Acute / drug therapy
  • Leukemia, Myeloid, Acute / genetics
  • Leukemia, Myeloid, Acute / metabolism
  • Mice
  • Minor Histocompatibility Antigens
  • Myelopoiesis / drug effects
  • Myelopoiesis / physiology*
  • NIH 3T3 Cells
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Up-Regulation / drug effects
  • WT1 Proteins / biosynthesis*
  • WT1 Proteins / genetics


  • BCL2-related protein A1
  • Interleukin-3
  • Minor Histocompatibility Antigens
  • Proto-Oncogene Proteins c-bcl-2
  • WT1 Proteins
  • Granulocyte Colony-Stimulating Factor