title: Janus kinase 2: a critical target in chronic myelogenous leukemia.
abstract: The Bcr-Abl tyrosine kinase is the causative factor in most chronic myelogenous leukemia (CML) patients. We have shown that Bcr-Abl is associated with a cluster of signaling proteins, including Janus kinase (Jak) 2, growth factor receptor binding protein 2-associated binder (Gab) 2, Akt, and glycogen synthase kinase (GSK)-3beta. Treatment of CML cell lines and mouse Bcr-Abl+ 32D cells with either Jak2 short interfering RNA or Jak2 kinase inhibitor AG490 inhibited pTyr Gab2 and pSer Akt formation, inhibited the activation of nuclear factor-kappaB, and caused the activation of GSK-3beta, leading to the reduction of c-Myc. Importantly, BaF3 cells expressing T315I and E255K imatinib-resistant mutants of Bcr-Abl underwent apoptosis on exposure to AG490 yet were resistant to imatinib. Similar to wild-type Bcr-Abl+ cells, inhibition of Jak2 by Ag490 treatment resulted in decrease of pSer Akt and c-Myc in imatinib-resistant cells. These results identify Jak2 as a potentially important therapeutic target for CML.
authors.affiliation: Department of Molecular Pathology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Ajoy K
authors.initials: AK
authors.lastname: Samanta
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.forename: Tong
authors.initials: T
authors.lastname: Sun
authors.forename: Hagop
authors.initials: H
authors.lastname: Kantarjian
authors.forename: Ralph B
authors.initials: RB
authors.lastname: Arlinghaus
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D000068877:Imatinib Mesylate; D053614:Janus Kinase 2; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology*; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D010879:Piperazines; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D011743:Pyrimidines; D034741:RNA, Small Interfering; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3