title: Identifying and characterizing a novel activating mutation of the FLT3 tyrosine kinase in AML.
abstract: The FLT3 receptor is activated by juxtamembrane insertion mutations and by activation loop point mutations in patients with acute myeloid leukemia (AML). In a systematic tyrosine kinase gene exon resequencing study, 21 of 24 FLT3 exons were sequenced in samples from 53 patients with AML, 9 patients with acute lymphoblastic leukemia (ALL), and 3 patients with myelodysplasia samples. Three patients had novel point mutations at residue N841 that resulted in a change to isoleucine in 2 samples and to tyrosine in 1 sample. Introduction of FLT3-N841I cDNA into Ba/F3 cells led to interleukin-3 (IL-3)-independent proliferation, receptor phosphorylation, and constitutive activation of signal transducer and activator of transcription 5 (STAT5) and extracellular regulatory kinase (ERK), suggesting that the N841I mutation confers constitutive activity to the receptor. An FLT3 inhibitor (PKC412) inhibited the growth of Ba/F3-FLT3N841I cells (IC(50) 10 nM), but not of wild-type Ba/F3 cells cultured with IL-3. PKC412 also reduced tyrosine phosphorylation of the mutant receptor and inhibited STAT5 phosphorylation. Examination of the FLT3 autoinhibited structure showed that N841 is the key residue in a hydrogen-bonding network that likely stabilizes the activation loop. These results suggest that mutations at N841 represent a significant new activating mutation in patients with AML and that patients with such mutations may respond to small-molecule FLT3 inhibitors such as PKC412.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney St, D720C, Boston, MA 02115, USA.
authors.forename: Jingrui
authors.initials: J
authors.lastname: Jiang
authors.forename: J Guillermo
authors.initials: JG
authors.lastname: Paez
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Lee
authors.forename: Ronghai
authors.initials: R
authors.lastname: Bo
authors.forename: Richard M
authors.initials: RM
authors.lastname: Stone
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: DeAngelo
authors.forename: Ilene
authors.initials: I
authors.lastname: Galinsky
authors.forename: Brian M
authors.initials: BM
authors.lastname: Wolpin
authors.forename: Anna
authors.initials: A
authors.lastname: Jonasova
authors.forename: Paula
authors.initials: P
authors.lastname: Herman
authors.forename: Edward A
authors.initials: EA
authors.lastname: Fox
authors.forename: Titus J
authors.initials: TJ
authors.lastname: Boggon
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Eck
authors.forename: Ellen
authors.initials: E
authors.lastname: Weisberg
authors.forename: James D
authors.initials: JD
authors.lastname: Griffin
authors.forename: D Gary
authors.initials: DG
authors.lastname: Gilliland
authors.forename: Matthew
authors.initials: M
authors.lastname: Meyerson
authors.forename: William R
authors.initials: WR
authors.lastname: Sellers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002455:Cell Division / Q000187:drug effects; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D006860:Hydrogen Bonding; D007377:Interleukin-3 / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D010766:Phosphorylation; 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*; D015398:Signal Transduction; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D019311:Staurosporine; C059539:midostaurin