title: IFN-gamma priming up-regulates IFN-stimulated gene factor 3 (ISGF3) components, augmenting responsiveness of IFN-resistant melanoma cells to type I IFNs.
abstract: IFN-stimulated gene factor 3 (ISGF3) mediates transcriptional activation of IFN-sensitive genes (ISGs). The component subunits of ISGF3, STAT1alphabeta, STAT2, and p48-ISGF3gamma, are tyrosine phosphorylated before their assembly into a complex. Subsequently, the ISGF3 complex is translocated to the nucleus. We have recently established that the responsiveness of human melanoma cell lines to type I IFNs correlates directly with their intracellular levels of ISGF3 components, particularly STAT1. In the present study, we show that pretreating IFN-resistant melanoma cell lines with IFN-gamma (IFN-gamma priming) before stimulation with type I IFN also results in increased levels of ISGF3 components and enhanced DNA-binding activation of ISGF3. In addition, IFN-gamma priming of IFN-resistant melanoma cell lines increased expression of type I IFN-induced ISG products, including ISG54, 2'-5'-oligoadenylate synthase, HLA class I, B7-1, and ICAM-1 Ags. Furthermore, IFN-gamma priming enhanced the antiviral effect of IFN-beta on the IFN-resistant melanoma cell line, MM96. These results support a role for IFN-gamma priming in up-regulating ISGF3, thereby augmenting the responsiveness of IFN-resistant melanoma cell lines to type I IFN and providing a molecular basis and justification for using sequential IFN therapy, as proposed by others, to enhance the use of IFNs in the treatment of melanoma.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: L H
authors.initials: LH
authors.lastname: Wong
authors.forename: I
authors.initials: I
authors.lastname: Hatzinisiriou
authors.forename: R J
authors.initials: RJ
authors.lastname: Devenish
authors.forename: S J
authors.initials: SJ
authors.lastname: Ralph
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D004591:Electrophoresis, Polyacrylamide Gel; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D000077190:Interferon alpha-2; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D008545:Melanoma / Q000188:drug therapy / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D007370:Interferon Type I; D000077190:Interferon alpha-2; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D007371:Interferon-gamma