Abstract
Expression of the transcription repressor Gfi-1 is required for the maintenance of murine hematopoietic stem cells. In human cells, ectopic expression of Gfi-1 inhibits and RNA interference-mediated Gfi-1 downregulation enhances proliferation and colony formation of p210BCR/ABL expressing cells. To investigate the molecular mechanisms that may explain the effects of perturbing Gfi-1 expression in human cells, Gfi-1-regulated genes were identified by microarray analysis in K562 cells expressing the tamoxifen-regulated Gfi-1-ER protein. STAT 5B and Mcl-1, two genes important for the proliferation and survival of hematopoietic stem cells, were identified as direct and functionally relevant Gfi-1 targets in p210BCR/ABL-transformed cells because: (i) their expression and promoter activity was repressed by Gfi-1 and (ii) when constitutively expressed blocked the proliferation and colony formation inhibitory effects of Gfi-1. Consistent with these findings, genetic or pharmacological inhibition of STAT 5 and/or Mcl-1 markedly suppressed proliferation and colony formation of K562 and CD34+ chronic myelogenous leukemia (CML) cells. Together, these studies suggest that the Gfi-1STAT 5B/Mcl-1 regulatory pathway identified here can be modulated to suppress the proliferation and survival of p210BCR/ABL-transformed cells including CD34+ CML cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Biomarkers, Tumor / genetics
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Biomarkers, Tumor / metabolism
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Blotting, Western
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Cell Proliferation*
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Chromatin Immunoprecipitation
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Colony-Forming Units Assay
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Down-Regulation
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Gene Expression Profiling
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Humans
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Immunoenzyme Techniques
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Indoles
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics*
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / pathology*
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Luciferases / metabolism
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Myeloid Cell Leukemia Sequence 1 Protein
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Oligonucleotide Array Sequence Analysis
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Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors
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Proto-Oncogene Proteins c-bcl-2 / genetics*
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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Pyrroles / pharmacology
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RNA, Messenger / genetics
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Real-Time Polymerase Chain Reaction
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Reverse Transcriptase Polymerase Chain Reaction
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STAT5 Transcription Factor / antagonists & inhibitors
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STAT5 Transcription Factor / genetics*
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STAT5 Transcription Factor / metabolism
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Transcription Factors / antagonists & inhibitors
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Tumor Cells, Cultured
Substances
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Biomarkers, Tumor
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DNA-Binding Proteins
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GFI1 protein, human
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Indoles
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Myeloid Cell Leukemia Sequence 1 Protein
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Proto-Oncogene Proteins c-bcl-2
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Pyrroles
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RNA, Messenger
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STAT5 Transcription Factor
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Transcription Factors
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Luciferases
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obatoclax