title: Identification of a novel activating mutation (Y842C) within the activation loop of FLT3 in patients with acute myeloid leukemia (AML).
abstract: Fms-like tyrosine kinase 3 (FLT3) receptor mutations as internal tandem duplication (ITD) or within the kinase domain are detected in up to 35% of patients with acute myeloid leukemia (AML). N-benzoyl staurosporine (PKC412), a highly effective inhibitor of mutated FLT3 receptors, has significant antileukemic efficacy in patients with FLT3-mutated AML. Mutation screening of FLT3 exon 20 in AML patients (n = 110) revealed 2 patients with a novel mutation (Y842C) within the highly conserved activation loop of FLT3. FLT3-Y842C-transfected 32D cells showed constitutive FLT3 tyrosine phosphorylation and interleukin 3 (IL-3)-independent growth. Treatment with PKC412 led to inhibition of proliferation and apoptotic cell death. Primary AML blasts bearing FLT3-Y842C mutations showed constitutive FLT3 and signal transducer and activator of transcription 5 (STAT-5) tyrosine phosphorylation. Ex vivo PKC412 treatment of primary blasts resulted in suppression of constitutive FLT3 and STAT-5 activation and apoptotic cell death. Inspection of the FLT3 structure revealed that Y842 is the key residue in regulating the switch from the closed to the open (= active) conformation of the FLT3 activation loop. Overall, our data suggest that mutations at Y842 represent a significant new activating mutation in AML blasts. Since FLT3 tyrosine kinase inhibitors (TKIs) such as PKC412 are currently being investigated in clinical trials in AML, extended sequence analysis of FLT3 may be helpful in defining the spectrum of TKI-sensitive FLT3 mutations in AML.
authors.affiliation: Johannes-Gutenberg University Mainz, 3rd Med Department, Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kindler
authors.forename: Frank
authors.initials: F
authors.lastname: Breitenbuecher
authors.forename: Stefan
authors.initials: S
authors.lastname: Kasper
authors.forename: Eli
authors.initials: E
authors.lastname: Estey
authors.forename: Francis
authors.initials: F
authors.lastname: Giles
authors.forename: Eric
authors.initials: E
authors.lastname: Feldman
authors.forename: Gerhard
authors.initials: G
authors.lastname: Ehninger
authors.forename: Gary
authors.initials: G
authors.lastname: Schiller
authors.forename: Virginia
authors.initials: V
authors.lastname: Klimek
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Nimer
authors.forename: Alois
authors.initials: A
authors.lastname: Gratwohl
authors.forename: Chuna Ram
authors.initials: CR
authors.lastname: Choudhary
authors.forename: Constan
authors.initials: C
authors.lastname: Mueller-Tidow
authors.forename: Hubert
authors.initials: H
authors.lastname: Serve
authors.forename: Harald
authors.initials: H
authors.lastname: Gschaidmeier
authors.forename: Pamela S
authors.initials: PS
authors.lastname: Cohen
authors.forename: Christoph
authors.initials: C
authors.lastname: Huber
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000235:genetics*; D051379:Mice; D008894:Milk Proteins / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D019000:Phosphotyrosine / Q000378:metabolism; 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; D015534:Trans-Activators / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D004268:DNA-Binding Proteins; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D019000:Phosphotyrosine; D014443:Tyrosine; C497970:FLT3 protein, human; C497971:Flt3 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3