Abstract
Many different types of cancer originate from aberrant signaling from the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase (RTK), arising through different translocation events and overexpression. Further, activating point mutations in the ALK domain have been recently reported in neuroblastoma. To characterize signaling in the context of the full-length receptor, we have examined whether ALK is able to activate Rap1 and contribute to differentiation/proliferation processes. We show that ALK activates Rap1 via the Rap1-specific guanine-nucleotide exchange factor C3G, which binds in a constitutive complex with CrkL to activated ALK. The activation of the C3G/Rap1 pathway results in neurite outgrowth of PC12 cells, which is inhibited by either overexpression of Rap1GAP or siRNA-mediated knockdown of Rap1 itself or the guanine nucleotide exchange factor C3G. Significantly, this pathway also appears to function in the regulation of proliferation of neuroblastoma cells such as SK-N-SH and SH-SY5Y, because abrogation of Rap1 activity by Rap1-specific siRNA or overexpression of Rap1GAP reduces cellular growth. These results suggest that ALK activation of Rap1 may contribute to cell proliferation and oncogenesis of neuroblastoma driven by gain-of-function mutant ALK receptors.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / metabolism
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Anaplastic Lymphoma Kinase
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Animals
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Cell Proliferation
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Cell Transformation, Neoplastic
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Enzyme Activation / drug effects
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Extracellular Signal-Regulated MAP Kinases / metabolism
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GTPase-Activating Proteins / genetics
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Gene Expression Regulation, Neoplastic
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Gene Knockdown Techniques
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Guanine Nucleotide-Releasing Factor 2 / deficiency
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Guanine Nucleotide-Releasing Factor 2 / genetics
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Guanine Nucleotide-Releasing Factor 2 / metabolism*
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Humans
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Mice
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Neurites / metabolism
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Neuroblastoma / genetics
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Neuroblastoma / pathology*
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Nuclear Proteins / metabolism
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PC12 Cells
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Protein Kinase Inhibitors / pharmacology
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Protein-Tyrosine Kinases / antagonists & inhibitors
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Protein-Tyrosine Kinases / metabolism*
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Pyrimidines / pharmacology
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Rats
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Receptor Protein-Tyrosine Kinases
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rap1 GTP-Binding Proteins / deficiency
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rap1 GTP-Binding Proteins / genetics
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rap1 GTP-Binding Proteins / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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CRKL protein
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GTPase-Activating Proteins
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Guanine Nucleotide-Releasing Factor 2
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NVP-TAE684
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Nuclear Proteins
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Protein Kinase Inhibitors
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Pyrimidines
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ALK protein, human
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Alk protein, mouse
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Alk protein, rat
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Anaplastic Lymphoma Kinase
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Protein-Tyrosine Kinases
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Receptor Protein-Tyrosine Kinases
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Extracellular Signal-Regulated MAP Kinases
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rap1 GTP-Binding Proteins