title: Canstatin inhibits Akt activation and induces Fas-dependent apoptosis in endothelial cells.
abstract: Canstatin, a 24-kDa peptide derived from the C-terminal globular non-collagenous (NC1) domain of the alpha2 chain of type IV collagen, was previously shown to induce apoptosis in cultured endothelial cells and to inhibit angiogenesis in vitro and in vivo. In this report, we demonstrate that canstatin inhibits the phosphorylation of Akt, focal adhesion kinase, mammalian target of rapamycin, eukaryotic initiation factor-4E-binding protein-1, and ribosomal S6 kinase in cultured human umbilical vein endothelial cells. It also induces Fas ligand expression, activates procaspases 8 and 9 cleavage, reduces mitochondrial membrane potential, and increases cell death (as determined by propidium iodide staining). Canstatin-induced activation of procaspases 8 and 9 as well as the induced reduction in mitochondrial membrane potential and cell viability were attenuated by the forced expression of FLICE-inhibitory protein. Canstatin-induced procaspase 8 activation and cell death were also inhibited by a neutralizing anti-Fas antibody. Collectively, these data indicate that canstatin-induced apoptosis is associated with phosphatidylinositol 3-kinase/Akt inhibition and is dependent upon signaling events transduced through membrane death receptors.
authors.affiliation: Division of Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachussetts 02215, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Panka
authors.forename: James W
authors.initials: JW
authors.lastname: Mier
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017209:Apoptosis / Q000187:drug effects*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D024141:Collagen Type IV / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008928:Mitochondria / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors*; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases; D019014:fas Receptor / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D024141:Collagen Type IV; C087000:EIF4EBP1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D019014:fas Receptor; D011494:Protein Kinases; C546842:MTOR protein, human; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases