beta1 integrin antagonism on adherent, differentiated human neuroblastoma cells triggers an apoptotic signaling pathway.
Integrin receptors mediate several functions including prevention of matrix detachment-induced apoptosis (anoikis) of several adherent cell types. We report here that antagonists of beta1 integrins trigger an apoptotic signaling pathway in adherent differentiated LAN-5 human neuroblastoma cells, a cell line which represents a model system for the study of human neurons. The pathway is characterized by cytochrome c release into the cytoplasm, and activation of caspase-9 and caspase-3, 4-6h after treatment; cleavage products of caspase-8 and caspase-2 were not detectable in the cells. Coordinate inactivation of cell survival pathways, including cleavage of focal adhesion kinase, decreased expression of protein kinase B, and reduced phosphorylation of the pro-apoptotic protein, Bad, also characterized the signaling pathway. These events occurred in adherent cells; DNA fragmentation and detachment followed as late events 18-24h after addition of beta1 integrin antagonists. zDEVD-fmk, an irreversible inhibitor of caspase-3-like enzymes, and cytochalasin D, an actin depolymerizing agent, blocked caspase-3 cleavage and delayed cell death. In contrast to these results, undifferentiated, adherent and dividing LAN-5 cells did not die in response to beta1 integrin antagonists. These studies identify a distinct apoptotic pathway which is triggered by antagonists of beta1 integrins on differentiated adherent neuronal cells.
Bonfoco
E
E
Department of Immunology, The Scripps Research Institute, La Jolla, CA 90237, USA.
Chen
W
W
Paul
R
R
Cheresh
D A
DA
Cooper
N R
NR
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D003574:Cytochrome c Group / Q000378:metabolism; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D019012:Integrin beta1 / Q000276:immunology*; D009447:Neuroblastoma / Q000473:pathology / Q000503:physiopathology*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000737:chemistry; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D051025:bcl-Associated Death Protein
D000911:Antibodies, Monoclonal; C494819:BAD protein, human; D002352:Carrier Proteins; D003574:Cytochrome c Group; D019012:Integrin beta1; D011518:Proto-Oncogene Proteins; D051025:bcl-Associated Death Protein; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases