Abstract
Activity of the Axl receptor tyrosine kinase is positively correlated with tumor metastasis; however, its detailed role in the mechanism of tumor invasion is still not completely understood. Here, we show that Axl enhances the expression of matrix metalloproteinase 9 (MMP-9), required for Axl-mediated invasion both in vitro and in vivo. We found that the highly selective MEK1/2 inhibitors U0126 and PD98059, and the expressed dominant-negative form of extracellular signal-regulated kinase (ERK), completely block Axl-mediated MMP-9 activation. In contrast, the phosphatidylinositol 3-kinase inhibitor LY294002 and wortmannin had little effect on activation. Interestingly, however, the Axl ligand Gas6 is not involved in Axl-mediated MMP-9 activation. Mutation of Glu59(Axl) and Thr77(Axl) dramatically reduced Gas6-Axl binding but continued to induce MMP-9 activation. In addition, overexpression of Axl-activated ERK and enhanced nuclear factor-kappaB (NF-kappaB) transactivation and brahma-related gene-1 (Brg-1) translocation. Exposure to the NF-kappaB inhibitor silibinin, which inhibits IkappaBalpha kinase activity, or overexpression of the dominant-negative mutant IkappaB and Brg-1 strikingly inhibited Axl-mediated MMP-9 activation. These data indicate that coordination of ERK signaling and NF-kappaB and Brg-1 activation are indispensable to regulation of Axl-dependent MMP-9 gene transcription. Together with previous data, our results provide a plausible mechanism for Axl-mediated tumor invasion and establish a functional link between the Axl and MMP-9 signaling pathways.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus / drug effects
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Active Transport, Cell Nucleus / genetics
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Axl Receptor Tyrosine Kinase
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Cell Line, Tumor
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Cell Nucleus / genetics
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Cell Nucleus / metabolism*
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DNA Helicases / genetics
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DNA Helicases / metabolism*
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Enzyme Induction / drug effects
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Enzyme Induction / genetics
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Enzyme Inhibitors / pharmacology
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Humans
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I-kappa B Kinase / antagonists & inhibitors
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I-kappa B Kinase / genetics
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I-kappa B Kinase / metabolism
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Intercellular Signaling Peptides and Proteins / genetics
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Intercellular Signaling Peptides and Proteins / metabolism
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MAP Kinase Kinase 1 / antagonists & inhibitors
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MAP Kinase Kinase 1 / genetics
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MAP Kinase Kinase 1 / metabolism
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MAP Kinase Kinase 2 / antagonists & inhibitors
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MAP Kinase Kinase 2 / genetics
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MAP Kinase Kinase 2 / metabolism
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MAP Kinase Signaling System / drug effects
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MAP Kinase Signaling System / genetics
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Matrix Metalloproteinase 9 / biosynthesis*
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Matrix Metalloproteinase 9 / genetics
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Mutation
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NF-kappa B / genetics
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NF-kappa B / metabolism*
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Neoplasm Invasiveness
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Oncogene Proteins / genetics
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Oncogene Proteins / metabolism*
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Phosphatidylinositol 3-Kinases / genetics
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Protein Binding / drug effects
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Protein Binding / genetics
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Proto-Oncogene Proteins
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Receptor Protein-Tyrosine Kinases / genetics
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Receptor Protein-Tyrosine Kinases / metabolism*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcription, Genetic* / drug effects
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Transcription, Genetic* / genetics
Substances
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Enzyme Inhibitors
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Intercellular Signaling Peptides and Proteins
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NF-kappa B
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Nuclear Proteins
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Oncogene Proteins
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Phosphoinositide-3 Kinase Inhibitors
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Proto-Oncogene Proteins
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Transcription Factors
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growth arrest-specific protein 6
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MAP2K2 protein, human
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Receptor Protein-Tyrosine Kinases
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I-kappa B Kinase
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MAP Kinase Kinase 1
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MAP Kinase Kinase 2
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MAP2K1 protein, human
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Matrix Metalloproteinase 9
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SMARCA4 protein, human
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DNA Helicases
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Axl Receptor Tyrosine Kinase
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AXL protein, human