Abstract
Although the cancer stem cell (CSC) concept implies that CSCs are rare, recent reports suggest that CSCs may be frequent in some cancers. We hypothesized that the proportion of leukemia stem cells would vary as a function of the number of dysregulated pathways. Constitutive expression of MN1 served as a 1-oncogene model, and coexpression of MN1 and a HOX gene served as a 2-oncogene model. Leukemia-initiating cell (LIC) number and in vitro expansion potential of LICs were functionally assessed by limiting dilution analyses. LIC expansion potential was 132-fold increased in the 2- compared with the 1-oncogene model, although phenotypically, both leukemias were similar. The 2-oncogene model was characterized by granulocyte-macrophage colony-stimulating factor (GM-CSF) hypersensitivity and activated STAT/ERK signaling. GM-CSF hypersensitivity of the 2-oncogene model (MN1/HOXA9) was lost in Stat5b(-/-) cells, and the LIC expansion potential was reduced by 86- and 28-fold in Stat5b(-/-) and Stat1(-/-) cells, respectively. Interestingly, in 201 acute myeloid leukemia (AML) patients, coexpression of MN1 and HOXA9 was restricted to patients with the poorest prognosis and was associated with highly active STAT signaling. Our data demonstrate the functional heterogeneity of LICs and show that STAT signaling is critical for leukemia stem cell self-renewal in MN1- and HOXA9-expressing leukemias.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Cell Proliferation / drug effects
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Disease Models, Animal
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Female
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Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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Humans
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In Vitro Techniques
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Leukemia, Experimental / genetics
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Leukemia, Experimental / metabolism*
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Leukemia, Experimental / pathology*
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Leukemia, Myeloid, Acute / genetics
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Leukemia, Myeloid, Acute / metabolism
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Leukemia, Myeloid, Acute / pathology
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MAP Kinase Signaling System / drug effects
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Male
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Mice
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Mice, Inbred BALB C
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Mice, Inbred C57BL
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Mice, Knockout
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Models, Biological*
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism
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Neoplastic Stem Cells / drug effects
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Neoplastic Stem Cells / metabolism*
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Neoplastic Stem Cells / pathology*
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Oncogene Proteins / genetics
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Oncogene Proteins / metabolism
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Oncogenes
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Recombinant Proteins
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STAT1 Transcription Factor / deficiency
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STAT1 Transcription Factor / genetics
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STAT1 Transcription Factor / metabolism
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STAT5 Transcription Factor / deficiency
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STAT5 Transcription Factor / genetics
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STAT5 Transcription Factor / metabolism*
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Signal Transduction / drug effects
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Trans-Activators
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Tumor Suppressor Proteins
Substances
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Homeodomain Proteins
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Mn1 protein, mouse
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Neoplasm Proteins
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Oncogene Proteins
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Recombinant Proteins
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STAT1 Transcription Factor
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STAT5 Transcription Factor
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Stat1 protein, mouse
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Stat5b protein, mouse
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Trans-Activators
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Tumor Suppressor Proteins
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homeobox protein HOXA9
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Granulocyte-Macrophage Colony-Stimulating Factor