Abstract
Patients afflicted with meningiomas are most often treated with radiation therapy followed by surgical resection. However, resistance to radiation treatment has been well documented among different cancers of the brain. In this study, we demonstrate that the malignant meningioma cells (IOMM-Lee cells) overexpress MMP-9 at both the mRNA and protein levels after radiation treatment. We confirmed an increase in the invasive potential of irradiated cells through spheroid migration and matrigel invasion assays. Knockdown of MMP-9 using an adenoviral siRNA construct blocked MMP-9 expression, reduced the invasive nature of cells, and subsequently led to apoptosis. Western blot analysis revealed the activation of ERK, Akt and Fas as well as a decrease in c-JUN levels. Cleavage of PARP and TUNEL-positive characteristics confirmed apoptotic cell death in Ad-MMP-9 infected cells. Treatment with U0126 and transfection with dominant negative ERK plasmid resulted in the decreased phosphorylation of ERK and Akt. Ectopic expression of HA myr-Akt was found to be associated with an increase in pERK, and treatment with LY294002 was shown to block the phosphorylation of Akt and ERK with the restoration of c-JUN. In conclusion, our data suggest that radiation increases MMP-9 expression and the invasive nature of IOMM-Lee cells, both of which can be reversed with siRNA-mediated downregulation of MMP-9, which leads to ERK and Akt-mediated apoptosis.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenoviridae
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Apoptosis / physiology
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Apoptosis / radiation effects*
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Blotting, Western
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Cell Movement
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Cell Proliferation / radiation effects
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Collagen / metabolism
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Down-Regulation
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Drug Combinations
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Enzyme Activation / radiation effects
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Enzyme Inhibitors / pharmacology
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Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / metabolism*
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Humans
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In Situ Nick-End Labeling
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JNK Mitogen-Activated Protein Kinases / metabolism
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Laminin / metabolism
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Matrix Metalloproteinase 9 / genetics
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Matrix Metalloproteinase 9 / metabolism*
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Matrix Metalloproteinase Inhibitors
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Meningeal Neoplasms / genetics
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Meningeal Neoplasms / metabolism
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Meningeal Neoplasms / pathology*
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Meningioma / genetics
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Meningioma / metabolism
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Meningioma / pathology*
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Plasmids
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Proteoglycans / metabolism
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Proto-Oncogene Proteins c-akt / antagonists & inhibitors
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Proto-Oncogene Proteins c-akt / genetics
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Proto-Oncogene Proteins c-akt / metabolism*
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RNA Interference*
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RNA, Small Interfering / pharmacology
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Spheroids, Cellular
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Transfection
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Tumor Cells, Cultured
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X-Rays
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fas Receptor / metabolism
Substances
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Drug Combinations
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Enzyme Inhibitors
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FAS protein, human
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Laminin
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Matrix Metalloproteinase Inhibitors
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Proteoglycans
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RNA, Small Interfering
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fas Receptor
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matrigel
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Collagen
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Proto-Oncogene Proteins c-akt
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Extracellular Signal-Regulated MAP Kinases
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JNK Mitogen-Activated Protein Kinases
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Matrix Metalloproteinase 9