Abstract
The regulatory mechanisms of nontransformed intestinal epithelial cell apoptosis have not been thoroughly investigated. We determined the susceptibility and mechanism of Fas-mediated apoptosis in nontransformed human intestinal epithelial cells (HIPEC) in the presence and absence of inflammatory cytokines. Despite ample expression of Fas, HIPEC were relatively insensitive to Fas-mediated apoptosis in that agonist anti-Fas antibody (CH11) induced a <25% increase in HIPEC apoptosis. Pretreatment of HIPEC with interferon (IFN)-gamma, but not tumor necrosis factor-alpha or granulocyte-macrophage colony-stimulating factor, significantly increased CH11-induced apoptosis of these cells without increasing Fas expression. Increased apoptosis correlated with increased caspase 3 activation but not expression of procaspase 3. Also, there was a significant delay in the onset of Fas-mediated apoptosis in HIPEC, which correlated with the generation of an activated caspase 3 p22/20 subunit. HIPEC required both initiator caspases 8 and 9 activity but expressed significantly less of the zymogen form of these caspases than did control cells. IFN-gamma-mediated sensitization of HIPEC occurred upstream of caspase 9 activation and correlated with a small increase in procaspase 8 expression (<1-fold increase) and a significant increase in expression of an intermediate form (p35) of caspase 4 (3.3-fold increase).
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing*
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Antibodies, Monoclonal / pharmacology
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Antineoplastic Agents / pharmacology*
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Apoptosis / drug effects
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Apoptosis / physiology*
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CASP8 and FADD-Like Apoptosis Regulating Protein
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Carrier Proteins / metabolism
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Caspase 1 / metabolism
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases / metabolism
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Caspases, Initiator
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Cysteine Proteinase Inhibitors / pharmacology
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Enzyme Precursors / metabolism
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Fas-Associated Death Domain Protein
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HT29 Cells
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Humans
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Inhibitor of Apoptosis Proteins
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Interferon-gamma / pharmacology*
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Intestinal Mucosa / cytology*
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Intestinal Mucosa / metabolism
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Intracellular Signaling Peptides and Proteins*
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Jurkat Cells
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Proteins / metabolism
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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Tumor Necrosis Factor-alpha / pharmacology
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fas Receptor / immunology
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fas Receptor / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Antibodies, Monoclonal
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Antineoplastic Agents
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CASP8 and FADD-Like Apoptosis Regulating Protein
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CFLAR protein, human
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Carrier Proteins
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Cysteine Proteinase Inhibitors
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Enzyme Precursors
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FADD protein, human
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Fas-Associated Death Domain Protein
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Inhibitor of Apoptosis Proteins
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Intracellular Signaling Peptides and Proteins
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Proteins
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Proto-Oncogene Proteins c-bcl-2
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Tumor Necrosis Factor-alpha
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fas Receptor
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Interferon-gamma
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CASP3 protein, human
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CASP4 protein, human
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CASP8 protein, human
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CASP9 protein, human
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases
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Caspases, Initiator
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Caspase 1