The antiapoptotic gene A1/BFL1 is a WT1 target gene that mediates granulocytic differentiation and resistance to chemotherapy.
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.
Division of Pediatric Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD 21231, USA.
Lesley A
LA
Simpson
Emily A
EA
Burwell
Kida A
KA
Thompson
Samira
S
Shahnaz
Allen R
AR
Chen
David M
DM
Loeb
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis; D042381:Granulocyte Precursor Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D051379:Mice; D015778:Minor Histocompatibility Antigens; D038042:Myelopoiesis / Q000187:drug effects / Q000502:physiology*; D041681:NIH 3T3 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects; D025721:WT1 Proteins / Q000096:biosynthesis* / Q000235:genetics
C096816:BCL2-related protein A1; D007377:Interleukin-3; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D025721:WT1 Proteins; D016179:Granulocyte Colony-Stimulating Factor