title: The acute lymphoblastic leukemia-associated JAK2 L611S mutant induces tumorigenesis in nude mice.
abstract: JAK2 plays important roles in the regulation of a variety of cellular processes including cell migration, proliferation, and protection from apoptosis. Recently the L611S point mutation in JAK2 has been identified in a child with acute lymphoblastic leukemia. Here we analyzed the mechanism by which JAK2 exhibits its oncogenicity. In BaF3 murine hematopoietic cells, L611S mutant increased the expression of antiapoptotic proteins including X chromosome-linked inhibitor of apoptosis protein, inhibitor of apoptosis protein, and Bcl-XL. We also showed that JAK2 L611S mutant protects BaF3 cells from cytokine withdrawal-induced apoptotic cell death and leads to cytokine-independent cell growth. Furthermore BaF3 cells expressing JAK2 L611S mutant gained the ability to induce tumorigenesis in nude mice. The L611S mutant also exhibited malignancy, including prompt invasion and spreading into various organs, leading to rapid lethality of the mice. Finally we showed that a specific JAK2 inhibitor, AG490, potently inhibited cytokine-independent cell growth induced by JAK2 L611S mutant via the induction of apoptotic cell death. In addition, treatment with AG490 significantly inhibited the JAK2 L611S mutant-induced tumorigenesis in nude mice. Thus, our results both in vitro and in vivo strongly suggest that L611S mutant of JAK2 harbors potent oncogenic activity, and this probably requires the antiapoptotic signaling pathway.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Keio University, Tokyo, Japan. tago-mg@pha.keio.ac.jp
authors.forename: Megumi
authors.initials: M
authors.lastname: Funakoshi-Tago
authors.forename: Kenji
authors.initials: K
authors.lastname: Tago
authors.forename: Kazuya
authors.initials: K
authors.lastname: Sumi
authors.forename: Miyuki
authors.initials: M
authors.lastname: Abe
authors.forename: Eriko
authors.initials: E
authors.lastname: Aizu-Yokota
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Oshio
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sonoda
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kasahara
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D005434:Flow Cytometry; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D008207:Lymphatic Metastasis; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D017354:Point Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000378:metabolism; D013160:Splenic Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D014162:Transfection; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D016207:Cytokines; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D053614:Janus Kinase 2; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3