title: AML-associated Flt3 kinase domain mutations show signal transduction differences compared with Flt3 ITD mutations.
abstract: Activating mutations of Flt3 are found in approximately one third of patients with acute myeloid leukemia (AML) and are an attractive drug target. Two classes of Flt3 mutations occur: internal tandem duplications (ITDs) in the juxtamembrane and point mutations in the tyrosine kinase domain (TKD). We and others have shown that Flt3-ITD induced aberrant signaling including strong activation of signal transducer and activator of transcription 5 (STAT5) and repression of CCAAT/estradiol-binding protein alpha (c/EBPalpha) and Pu.1. Here, we compared the signaling properties of Flt3-ITD versus Flt3-TKD in myeloid progenitor cells. We demonstrate that Flt3-TKD mutations induced autonomous growth of 32D cells in suspension cultures. However, in contrast to Flt3-ITD and similar to wild-type Flt3 (Flt3-WT), Flt3-TKD cannot support colony formation in semisolid media. Also, in contrast to Flt3-ITD, neither Flt3-WT nor Flt3-TKD induced activation or induction of STAT5 target genes. Flt3-TKD also failed to repress c/EBPalpha and Pu.1. No significant differences were observed in receptor autophosphorylation and the phosphorylation of Erk-1 and -2, Akt, and Shc. Importantly, TKD but not ITD mutations were a log power more sensitive toward the tyrosine kinase inhibitor protein kinase C 412 (PKC412) than Flt3-WT. In conclusion, Flt3-ITD and Flt3-TKD mutations display differences in their signaling properties that could have important implications for their transforming capacity and for the design of mutation-specific therapeutic approaches.
authors.affiliation: Department of Medicine, Hematology/Oncology and Interdisciplinary Center for Clinical Research, University Münster, Germany.
authors.forename: Chunaram
authors.initials: C
authors.lastname: Choudhary
authors.forename: Joachim
authors.initials: J
authors.lastname: Schwäble
authors.forename: Christian
authors.initials: C
authors.lastname: Brandts
authors.forename: Lara
authors.initials: L
authors.lastname: Tickenbrock
authors.forename: Bülent
authors.initials: B
authors.lastname: Sargin
authors.forename: Thomas
authors.initials: T
authors.lastname: Kindler
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Berdel
authors.forename: Carsten
authors.initials: C
authors.lastname: Müller-Tidow
authors.forename: Hubert
authors.initials: H
authors.lastname: Serve
mesh_terms: D000208:Acute Disease; D000818:Animals; D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism; D009115:Muridae; D016297:Mutagenesis, Site-Directed; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D050799:STAT5 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020080:Tandem Repeat Sequences; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; C015482:protein kinase modulator; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D019311:Staurosporine; C059539:midostaurin