β1 integrin antagonism on adherent, differentiated human neuroblastoma cells triggers an apoptotic signaling pathway

• Published in: Neuroscience Vol. 101; no. 4; pp. 1145 - 1152
• Main Authors: Bonfoco, E, Chen, W, Paul, R, Cheresh, D.A, Cooper, N.R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2000; Elsevier
• Subjects: apoptosis; Bad; Biological and medical sciences; caspase-3; cytochrome c; Fak; Fundamental and applied biological sciences. Psychology; Isolated neuron and nerve. Neuroglia; Vertebrates: nervous system and sense organs; β1 integrin; EDTA, ethylenediaminetetra-acetate; apoptosis; DR3, death receptor 3 for TRAIL; Apaf-1, apoptotic protease activating factor-1; Bcl-2, B cell lymphoma 2; FADD, Fas-associated death domain; HRP, horse radish peroxidase; PBS, phosphate-buffered saline; β1 integrin; TNF-R1, tumor necrosis factor receptor type 1; Ac-LEHD-pNA, Ac-Leu-Glu-His-Asp-paranitroaniline; cytochrome c; caspase-3; CED, C. elegans death gene; Bad; FAK, Focal adhesion kinase; IgG, immunoglobulin G; Fak; IFN-gamma, interferon gamma; FITC, fluorescein isthiocyanate; RGD, Arg-Gly-Asp; PI-3K, phosphoinositol-3-kinase; Akt/PKB, protein kinase B; MTT, 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide; Bcl-X L, B cell lymphoma long isoform; Cytochrome c; Human; Antagonism; Integrin; Cell line; Neuron; In vitro; Apoptosis
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(00)00429-2

Integrin receptors mediate several functions including prevention of matrix detachment-induced apoptosis (anoikis) of several adherent cell types. We report here that antagonists of β1 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, 4–6 h 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 18–24 h after addition of β1 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 β1 integrin antagonists. These studies identify a distinct apoptotic pathway which is triggered by antagonists of β1 integrins on differentiated adherent neuronal cells.