1. The fusion protein AML1-ETO in acute myeloid leukemia with translocation t(8;21) induces c-jun protein expression via the proximal AP-1 site of the c-jun promoter in an indirect, JNK-dependent manner.
- Author
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Elsässer A, Franzen M, Kohlmann A, Weisser M, Schnittger S, Schoch C, Reddy VA, Burel S, Zhang DE, Ueffing M, Tenen DG, Hiddemann W, and Behre G
- Subjects
- Core Binding Factor Alpha 2 Subunit, Granulocyte Colony-Stimulating Factor physiology, Humans, JNK Mitogen-Activated Protein Kinases, Phosphorylation, Proto-Oncogene Mas, RUNX1 Translocation Partner 1 Protein, Signal Transduction, Transcriptional Activation, U937 Cells, Chromosomes, Human, Pair 21, Chromosomes, Human, Pair 8, Genes, jun, Leukemia, Myeloid, Acute genetics, Mitogen-Activated Protein Kinases physiology, Oncogene Proteins, Fusion genetics, Promoter Regions, Genetic, Proto-Oncogene Proteins c-jun genetics, Transcription Factor AP-1 physiology, Transcription Factors genetics, Translocation, Genetic
- Abstract
Overexpression of proto-oncogene c-jun and constitutive activation of the Jun N-terminal kinase (JNK) signaling pathway have been implicated in the leukemic transformation process. However, c-jun expression and the role of the JNK signaling pathway have not been investigated in primary acute myeloid leukemia (AML) cells with frequently observed balanced rearrangements such as t(8;21). In the present study, we report elevated c-jun mRNA expression in AML patient bone marrow cells with t(8;21), t(15;17) or inv(16), and a high correlation in mRNA expression levels of AML1-ETO and c-jun within t(8;21)-positive AML patient cells. In myeloid U937 cells, c-jun mRNA and protein expression increase upon inducible expression of AML1-ETO. AML1-ETO transactivates the human c-jun promoter through the proximal activator protein (AP-1) site by activating the JNK pathway. Overexpression of JNK-inhibitor JIP-1 and chemical JNK inhibitors reduce the transactivation capacity of AML1-ETO on the c-jun promoter and the proapoptotic function of AML1-ETO in U937 cells. An autocrine mechanism involving granulocyte-colony stimulating factor (G-CSF) and G-CSF receptor (G-CSF-R) might participate in AML1-ETO mediated JNK-signaling, because AML1-ETO induces G-CSF and G-CSF-R expression, and G-CSF-R-neutralizing antibodies reduce AML1-ETO-induced JNK phosphorylation. These data suggest a model in which AML1-ETO induces proto-oncogene c-jun expression via the proximal AP-1 site of the c-jun promoter in a JNK-dependent manner.
- Published
- 2003
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