title: JAK3, STAT, and MAPK signaling pathways as novel molecular targets for the tyrphostin AG-490 regulation of IL-2-mediated T cell response.
abstract: AG-490 is a member of the tyrphostin family of tyrosine kinase inhibitors. While AG-490 has been considered to be a Janus kinase (JAK)2-specific inhibitor, these conclusions were primarily drawn from acute lymphoblastic leukemia cells that lack readily detectable levels of JAK3. In the present study, evidence is provided that clearly demonstrates AG-490 potently suppresses IL-2-induced T cell proliferation, a non-JAK2-dependent signal, in a dose-dependent manner in T cell lines D10 and CTLL-2. AG-490 blocked JAK3 activation and phosphorylation of its downstream counterpart substrates, STATs. Inhibition of JAK3 by AG-490 also compromised the Shc/Ras/Raf/mitogen-activated protein kinase (MAPK) signaling pathways as measured by phosphorylation of Shc and extracellular signal-related kinase 1 and 2 (ERK1/2). AG-490 effectively inhibited tyrosine phosphorylation and DNA binding activities of several transcription factors including STAT1, -3, -5a, and -5b and activating protein-1 (AP-1) as judged by Western blot analysis and electrophoretic mobility shift assay. These data suggest that AG-490 is a potent inhibitor of the JAK3/STAT, JAK3/AP-1, and JAK3/MAPK pathways and their cellular consequences. Taken together, these findings support the notion that AG-490 possesses previously unrecognized clinical potential as an immunotherapeutic drug due to its inhibitory effects on T cell-derived signaling pathways.
authors: Laboratory of Molecular Immunoregulation, Division of Basic Sciences, National Cancer Institute, Frederick, MD 21702, USA.
authors: L H
authors: LH
authors: Wang
authors: R A
authors: RA
authors: Kirken
authors: R A
authors: RA
authors: Erwin
authors: C R
authors: CR
authors: Yu
authors: W L
authors: WL
authors: Farrar
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D001665:Binding Sites / Q000187:drug effects / Q000276:immunology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000494:pharmacology; D053616:Janus Kinase 3; D008213:Lymphocyte Activation / Q000187:drug effects; D008894:Milk Proteins; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology* / Q000276:immunology; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007376:Interleukin-2; D008894:Milk Proteins; D011506:Proteins; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D055765:Shc Signaling Adaptor Proteins; D015534:Trans-Activators; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D019000:Phosphotyrosine; D004247:DNA; D011505:Protein-Tyrosine Kinases; D053616:Janus Kinase 3; D017871:Calcium-Calmodulin-Dependent Protein Kinases