Abstract
Constitutively active PI3K catalytic subunit alpha (PIK3CA) interfered with apoptosis induction downstream of death receptor-signaling complex formation allowing robust caspase-8 activation without triggering the execution steps of apoptosis. In mutant PIK3CA-expressing cells, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and CD95L stimulated nuclear factor kappaB (NFkappaB) activation, invasion, and transition to an amoeboid-like morphology. NFkappaB activation and adoption of amoeboid shape were inhibited by caspase-8 knockdown or FLIP-S expression, but only the cell morphology alterations required caspase-8 activity. Furthermore, we identified caspase-8-mediated, caspase-3-independent cleavage of the protein kinase rho-associated, coiled-coil containing protein kinase 1 as a novel mechanism for acquiring amoeboid shape and enhanced invasiveness in response to TRAIL and CD95L. Taken together, we provide evidence that mutated PIK3CA converts the 'tumor surveillance' activity of cancer cell-expressed death receptors and caspase-8 toward tumor promotion.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Chloromethyl Ketones / pharmacology
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Apoptosis / drug effects
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Apoptosis / genetics*
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CASP8 and FADD-Like Apoptosis Regulating Protein / genetics
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Caspase 8 / genetics
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Caspase 8 / metabolism*
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Caspase Inhibitors
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Cell Shape / drug effects
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Cell Shape / genetics
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Class I Phosphatidylinositol 3-Kinases
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Cysteine Proteinase Inhibitors / pharmacology
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Fas Ligand Protein / pharmacology*
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HCT116 Cells
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Humans
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I-kappa B Kinase / metabolism
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Interleukin-8 / metabolism
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Mutation, Missense / physiology*
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Neoplasm Invasiveness / genetics
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Phosphatidylinositol 3-Kinases / genetics*
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Proto-Oncogene Proteins c-akt / metabolism
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Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism
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Signal Transduction / drug effects
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Signal Transduction / genetics
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TNF-Related Apoptosis-Inducing Ligand / pharmacology*
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bcl-2-Associated X Protein / genetics
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fas Receptor / metabolism
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rho-Associated Kinases / antagonists & inhibitors
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rho-Associated Kinases / genetics
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rho-Associated Kinases / metabolism*
Substances
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Amino Acid Chloromethyl Ketones
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BAX protein, human
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CASP8 and FADD-Like Apoptosis Regulating Protein
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Caspase Inhibitors
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Cysteine Proteinase Inhibitors
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FAS protein, human
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Fas Ligand Protein
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Interleukin-8
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Receptors, TNF-Related Apoptosis-Inducing Ligand
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TNF-Related Apoptosis-Inducing Ligand
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TNFSF10 protein, human
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bcl-2-Associated X Protein
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benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
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fas Receptor
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Phosphatidylinositol 3-Kinases
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Class I Phosphatidylinositol 3-Kinases
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PIK3CA protein, human
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Proto-Oncogene Proteins c-akt
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ROCK1 protein, human
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rho-Associated Kinases
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I-kappa B Kinase
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CASP8 protein, human
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Caspase 8