Pim-1 Kinase Phosphorylates and Stabilizes 130 kDa FLT3 and Promotes Aberrant STAT5 Signaling in Acute Myeloid Leukemia with FLT3 Internal Tandem Duplication
| Autor: | Douglas E. Linn, Maria R. Baer, Mehmet Burcu, Karthika Natarajan, Yun Qiu, Yingqiu Xie |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
FLT3 Internal Tandem Duplication
Proteasome Endopeptidase Complex Cell signaling Glycosylation Calnexin lcsh:Medicine Apoptosis Endoplasmic Reticulum Receptor tyrosine kinase Cell Line Mice 03 medical and health sciences fluids and secretions 0302 clinical medicine Proto-Oncogene Proteins c-pim-1 hemic and lymphatic diseases STAT5 Transcription Factor Serine Animals Humans Phosphorylation lcsh:Science Heat-Shock Proteins STAT5 Cell Proliferation 030304 developmental biology 0303 health sciences Multidisciplinary biology ZAP70 lcsh:R hemic and immune systems Molecular biology Leukemia Myeloid Acute fms-Like Tyrosine Kinase 3 030220 oncology & carcinogenesis Mutation embryonic structures biology.protein Tyrosine lcsh:Q Signal transduction Research Article Signal Transduction |
| Zdroj: | PLoS ONE PLoS ONE, Vol 8, Iss 9, p e74653 (2013) |
| ISSN: | 1932-6203 |
| Popis: | The type III receptor tyrosine kinase fms-like tyrosine kinase 3 (FLT3) is expressed on both normal hematopoietic stem cells and acute myeloid leukemia (AML) cells and regulates their proliferation. Internal tandem duplication (ITD) mutation of FLT3 is present in a third of AML cases, results in constitutive activation and aberrant signaling of FLT3, and is associated with adverse treatment outcomes. While wild-type (WT) FLT3 is predominantly a 150 kDa complex glycosylated cell surface protein, FLT3-ITD is partially retained in the endoplasmic reticulum as a 130 kDa underglycosylated species associated with the chaperones calnexin and heat shock protein (HSP) 90, and mediates aberrant STAT5 signaling, which upregulates the oncogenic serine/threonine kinase Pim-1. FLT3 contains a Pim-1 substrate consensus serine phosphorylation site, and we hypothesized that it might be a Pim-1 substrate. Pim-1 was indeed found to directly interact with and serine-phosphorylate FLT3. Pim-1 inhibition decreased the expression and half-life of 130 kDa FLT3, with partial abrogation by proteasome inhibition, in association with decreased FLT3 binding to calnexin and HSP90, and increased 150 kDa FLT3 expression and half-life, with abrogation by inhibition of glycosylation. These findings were consistent with Pim-1 stabilizing FLT3-ITD as a 130 kDa species associated with calnexin and HSP90 and inhibiting its glycosylation to form the 150 kDa species. Pim-1 knockdown effects were similar. Pim-1 inhibition also decreased phosphorylation of FLT3 at tyrosine 591 and of STAT5, and expression of Pim-1 itself, consistent with inhibition of the FLT3-ITD-STAT5 signaling pathway. Finally, Pim-1 inhibition synergized with FLT3 inhibition in inducing apoptosis of FLT3-ITD cells. This is, to our knowledge, the first demonstration of a role of Pim-1 in a positive feedback loop promoting aberrant signaling in malignant cells. |
| Databáze: | OpenAIRE |
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