Abstract
Four human cell lines derived from Ewing's sarcoma, EW-7, EW-1, COH and ORS, were investigated to establish the effects of human recombinant interferon-alpha2a and human recombinant interferon-beta on cell proliferation and apoptosis. All four cell lines were much more sensitive to the antiproliferative effects of IFN-beta than of IFN-alpha. Analysis of the early signals triggered by IFN-alpha and IFN-beta demonstrated that the two IFNs were similarly effective in inducing tyrosine phosphorylation of the Jak-1 and Tyk-2 kinases and the transcription factors Stat-1 and Stat-2. Interestingly, an additional rapid phosphorylation of Stat-1 on serine was observed after IFN-beta treatment, with concomitant activation of p38 mitogen-activated protein kinase. In these cells, Stat-1 Ser727 phosphorylation in response to IFN-beta was found to be impaired by p38 MAPkinase inhibitor (SB203580). IFN-beta induced the formation of the Interferon Stimulated Gene Factor 3 complex more efficiently than IFN-alpha, as well as sustained induction of IRF-1, which may account for its greater induction of 2'5'oligo(A)synthetase and greater inhibition of cell proliferation. IFN-beta, but not IFN-alpha, induced apoptosis in wild-type p53 EW-7 and COH cell lines, but not in the mutated p53 EW-1 or ORS cell lines. The apoptosis induced by IFN-beta in EW-7 and COH cell lines appeared to be mediated by IRF-1 and involved the activation of caspase-7. Ectopic expression of IRF-1 induced apoptosis in all four cell lines which correlated with the activation of caspase-7 and with the downregulation of the Bcl-2 oncoprotein, as observed for IFN-beta-induced apoptosis in parental EW-7 and COH cell lines.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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2',5'-Oligoadenylate Synthetase / genetics
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Apoptosis*
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Caspase 7
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Caspases / metabolism*
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Cell Division / drug effects
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DNA-Binding Proteins / biosynthesis*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Enzyme Activation
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Gene Expression / drug effects
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Humans
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Interferon Regulatory Factor-1
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Interferon alpha-2
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Interferon beta-1a
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Interferon-Stimulated Gene Factor 3
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Interferon-Stimulated Gene Factor 3, gamma Subunit
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Interferon-alpha / metabolism
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Interferon-alpha / pharmacology
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Interferon-beta / metabolism*
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Interferon-beta / pharmacology
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Janus Kinase 1
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Mitogen-Activated Protein Kinases / metabolism
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Phosphoproteins / biosynthesis*
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Phosphoproteins / genetics
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Phosphorylation
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Promoter Regions, Genetic
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Protein-Tyrosine Kinases / metabolism
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Proteins / metabolism
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Recombinant Proteins
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STAT1 Transcription Factor
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Sarcoma, Ewing
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Serine / metabolism*
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Signal Transduction
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TYK2 Kinase
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Trans-Activators / metabolism*
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Transcription Factors / metabolism
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Tumor Cells, Cultured
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p38 Mitogen-Activated Protein Kinases
Substances
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DNA-Binding Proteins
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IRF1 protein, human
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IRF9 protein, human
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Interferon Regulatory Factor-1
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Interferon alpha-2
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Interferon-Stimulated Gene Factor 3
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Interferon-Stimulated Gene Factor 3, gamma Subunit
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Interferon-alpha
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Phosphoproteins
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Proteins
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Recombinant Proteins
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STAT1 Transcription Factor
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STAT1 protein, human
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Trans-Activators
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Transcription Factors
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Serine
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Interferon-beta
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Protein-Tyrosine Kinases
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JAK1 protein, human
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Janus Kinase 1
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TYK2 Kinase
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TYK2 protein, human
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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2',5'-Oligoadenylate Synthetase
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CASP7 protein, human
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Caspase 7
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Caspases
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Interferon beta-1a