IFN-beta induces serine phosphorylation of Stat-1 in Ewing's sarcoma cells and mediates apoptosis via induction of IRF-1 and activation of caspase-7.
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.
INSERM U 365, Institut Curie, Paris, France.
J
J
Sancéau
J
J
Hiscott
O
O
Delattre
J
J
Wietzerbin
D015088:2',5'-Oligoadenylate Synthetase / Q000235:genetics; D017209:Apoptosis; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D050856:Interferon Regulatory Factor-1; D000077190:Interferon alpha-2; D000068556:Interferon beta-1a; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000378:metabolism / Q000494:pharmacology; D016899:Interferon-beta / Q000378:metabolism* / Q000494:pharmacology; D053613:Janus Kinase 1; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; D012512:Sarcoma, Ewing; D012694:Serine / Q000378:metabolism*; D015398:Signal Transduction; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494227:IRF9 protein, human; D050856:Interferon Regulatory Factor-1; D000077190:Interferon alpha-2; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D010750:Phosphoproteins; D011506:Proteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D012694:Serine; D016899:Interferon-beta; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D015088:2',5'-Oligoadenylate Synthetase; C505520:CASP7 protein, human; D053179:Caspase 7; D020169:Caspases; D000068556:Interferon beta-1a