title: Interferon-beta interrupts interleukin-6-dependent signaling events in myeloma cells.
abstract: Type I interferons (IFNs-alpha and IFN-beta) bind to a common receptor to exert strong antiproliferative activity on a broad range of cell types, including interleukin-6 (IL-6)-dependent myeloma cells. In this study, we investigated the effect of IFN-beta pretreatment on IL-6-stimulated mitogenic signaling in the human myeloma cell line U266. IL-6 induced transient tyrosine phosphorylation of the IL-6-receptor signal-transducing subunit gp130, the gp130-associated protein tyrosine kinases Jak1,Jak2, and Tyk2, the phosphotyrosine phosphatase PTP1D/Syp, the adaptor protein Shc and the mitogen-activated protein kinase Erk2, and accumulation of GTP-bound p21ras. Prior treatment of U266 cells with IFN-beta downregulated IL-6-induced tyrosine phosphorylation of gp130, Jak2, PTP1D/Syp, Shc, and Erk2, and GTP-loading of p21ras. Further analysis indicated that treatment with IFN-beta disrupted IL-6-induced binding of PTP1D/Syp to gp130 and the adaptor protein Grb2; IFN-beta pretreatment also interfered with IL-6-induced interaction of Shc with Grb2 and a 145-kD tyrosine-phosphorylated protein. These results suggest a novel mechanism whereby type I IFNs interrupt IL-6-promoted mitogenesis of myeloma cells in part by preventing the formation of essential signaling complexes leading to p21ras activation.
authors.affiliation: Division of Cancer Biology, Sunnybrook Health Science Centre, Toronto, Canada.
authors.forename: L C
authors.initials: LC
authors.lastname: Berger
authors.forename: R G
authors.initials: RG
authors.lastname: Hawley
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051380:GRB2 Adaptor Protein; D006801:Humans; D016899:Interferon-beta / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008938:Mitosis / Q000187:drug effects; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000187:drug effects*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014407:Tumor Cells, Cultured / Q000187:drug effects; D000093242:Interleukin-6 Inhibitors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051380:GRB2 Adaptor Protein; D016899:Interferon-beta; D015850:Interleukin-6; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D011494:Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D011506:Proteins; D016283:Proto-Oncogene Proteins p21(ras); D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D000093242:Interleukin-6 Inhibitors; C495948:GRB2 protein, human; C528024:SHC1 protein, human; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; C501009:HRAS protein, human