title: FLT3 regulates beta-catenin tyrosine phosphorylation, nuclear localization, and transcriptional activity in acute myeloid leukemia cells.
abstract: Deregulated accumulation of nuclear beta-catenin enhances transcription of beta-catenin target genes and promotes malignant transformation. Recently, acute myeloid leukemia (AML) cells with activating mutations of FMS-like tyrosine kinase-3 (FLT3) were reported to display elevated beta-catenin-dependent nuclear signaling. Tyrosine phosphorylation of beta-catenin has been shown to promote its nuclear localization. Here, we examined the causal relationship between FLT3 activity and beta-catenin nuclear localization. Compared to cells with wild-type FLT3 (FLT3-WT), cells with the FLT3 internal tandem duplication (FLT3-ITD) and tyrosine kinase domain mutation (FLT3-TKD) had elevated levels of tyrosine-phosphorylated beta-catenin. Although beta-catenin was localized mainly in the cytoplasm in FLT3-WT cells, it was primarily nuclear in FLT3-ITD cells. Treatment with FLT3 kinase inhibitors or FLT3 silencing with RNAi decreased beta-catenin tyrosine phosphorylation and nuclear localization. Conversely, treatment of FLT3-WT cells with FLT3 ligand increased tyrosine phosphorylation and nuclear accumulation of beta-catenin. Endogenous beta-catenin co-immunoprecipitated with endogenous activated FLT3, and recombinant activated FLT3 directly phosphorylated recombinant beta-catenin. Finally, FLT3 inhibitor decreased tyrosine phosphorylation of beta-catenin in leukemia cells obtained from FLT3-ITD-positive AML patients. These data demonstrate that FLT3 activation induces beta-catenin tyrosine phosphorylation and nuclear localization, and thus suggest a mechanism for the association of FLT3 activation and beta-catenin oncogeneic signaling in AML.
authors.affiliation: Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. tomokaji@med.nagoya-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kajiguchi
authors.forename: E J
authors.initials: EJ
authors.lastname: Chung
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Stine
authors.forename: H
authors.initials: H
authors.lastname: Kiyoi
authors.forename: T
authors.initials: T
authors.lastname: Naoe
authors.forename: M J
authors.initials: MJ
authors.lastname: Levis
authors.forename: L
authors.initials: L
authors.lastname: Neckers
authors.forename: J B
authors.initials: JB
authors.lastname: Trepel
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000208:Acute Disease; D000818:Animals; D045744:Cell Line, Tumor; D015973:Gene Expression Regulation, Leukemic; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000502:physiology; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins / Q000494:pharmacology; D051379:Mice; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D019311:Staurosporine / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic / Q000502:physiology*; D020032:Tyrphostins / Q000494:pharmacology; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*; D051941:fms-Like Tyrosine Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
chemical_list: D007377:Interleukin-3; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D020032:Tyrphostins; D051176:beta Catenin; C084881:flt3 ligand protein; C106250:6,7-dimethoxy-3-phenylquinoxaline; D019000:Phosphotyrosine; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D019311:Staurosporine; C059539:midostaurin