Abstract
UT-7 is a human megakaryoblastic leukemia cell line with absolute dependence on interleukin-3, granulocyte-macrophage colony-stimulating factor, or erythropoietin (EPO) for growth and survival. We investigated the effect of thrombopoietin (TPO), the ligand for the receptor encoded by c-mpl proto-oncogene, on the proliferation and differentiation of UT-7 and its sublines. We found that UT-7/GM, which is a subline of UT-7, but neither UT-7 nor UT-7/EPO, can proliferate in response to TPO. The subline, UT-7/TPO, was established from UT-7/GM by culture at lower concentrations of TPO. UT-7/TPO cells had morphologically mature megakaryocytic characteristics such as developed demarcation membrane in the cytoplasm and multinucleated appearance. This was also confirmed by the high expression of platelet factor-4 and glycoprotein IIb at the mRNA levels and by the high level of DNA content. UT-7/TPO can be maintained by TPO alone, with a doubling time of 24 hours in log growth phase. In the absence of TPO, the majority of the cells died within a few days. Thus, UT-7/TPO has an absolute dependence on TPO for growth and survival and has mature megakaryocytic features. The mRNA for c-mpl was detected in UT-7/TPO and, to a lesser degree, in UT-7/GM. The mRNA level of NF- E2 p45, reported to be an erythroid-specific transcription factor, was upregulated in UT-7/TPO, whereas it was down-regulated in the erythroid subline, UT-7/EPO. There were no significant differences in GATA-1 and GATA-2 mRNA levels among UT-7 and its sublines. Not only EPO but also TPO induced the tyrosine phosphorylation of JAK2 tyrosine kinase and STAT5-related protein. These findings indicate that UT-7/TPO would be a useful model with which to analyze the gene regulation of megakaryocytic maturation-associated proteins and to study the specific actions of TPO.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Differentiation / drug effects
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Cell Division / drug effects
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Cell Survival
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DNA, Neoplasm / analysis
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DNA-Binding Proteins / biosynthesis
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Erythroid-Specific DNA-Binding Factors
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Erythropoietin / pharmacology
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GATA1 Transcription Factor
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GATA2 Transcription Factor
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Gene Expression Regulation, Leukemic / drug effects
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Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology
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Humans
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Interleukin-3 / pharmacology
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Janus Kinase 2
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Leukemia, Megakaryoblastic, Acute / pathology*
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Megakaryocytes / drug effects*
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Megakaryocytes / metabolism
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Milk Proteins*
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NF-E2 Transcription Factor
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NF-E2 Transcription Factor, p45 Subunit
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism
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Ploidies
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Protein-Tyrosine Kinases / metabolism
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Proto-Oncogene Mas
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Proto-Oncogene Proteins / biosynthesis
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Proto-Oncogene Proteins / genetics
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Receptors, Cytokine*
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Receptors, Thrombopoietin
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STAT5 Transcription Factor
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Thrombopoietin / pharmacology*
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Trans-Activators / metabolism
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Transcription Factors / biosynthesis
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Transcription Factors / genetics
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Tumor Cells, Cultured* / drug effects
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Tumor Cells, Cultured* / metabolism
Substances
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DNA, Neoplasm
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DNA-Binding Proteins
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Erythroid-Specific DNA-Binding Factors
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GATA1 Transcription Factor
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GATA1 protein, human
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GATA2 Transcription Factor
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GATA2 protein, human
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Interleukin-3
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MAS1 protein, human
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Milk Proteins
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NF-E2 Transcription Factor
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NF-E2 Transcription Factor, p45 Subunit
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NFE2 protein, human
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Neoplasm Proteins
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Proto-Oncogene Mas
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Proto-Oncogene Proteins
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Receptors, Cytokine
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Receptors, Thrombopoietin
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STAT5 Transcription Factor
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Trans-Activators
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Transcription Factors
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Erythropoietin
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MPL protein, human
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Granulocyte-Macrophage Colony-Stimulating Factor
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Thrombopoietin
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Protein-Tyrosine Kinases
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JAK2 protein, human
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Janus Kinase 2