title: Mutations in the tyrosine kinase domain of FLT3 define a new molecular mechanism of acquired drug resistance to PTK inhibitors in FLT3-ITD-transformed hematopoietic cells.
abstract: Activating mutations in the juxtamembrane domain (FLT3-length mutations, FLT3-LM) and in the protein tyrosine kinase domain (TKD) of FLT3 (FLT3-TKD) represent the most frequent genetic alterations in acute myeloid leukemia (AML) and define a molecular target for therapeutic interventions by protein tyrosine kinase (PTK) inhibitors. We could show that distinct activating FLT3-TKD mutations at position D835 mediate primary resistance to FLT3 PTK inhibitors in FLT3-transformed cell lines. In the presence of increasing concentrations of the FLT3 PTK inhibitor SU5614, we generated inhibitor resistant Ba/F3 FLT3-internal tandem duplication (ITD) cell lines (Ba/F3 FLT3-ITD-R1-R4) that were characterized by a 7- to 26-fold higher IC50 (concentration that inhibits 50%) to SU5614 compared with the parental ITD cells. The molecular characterization of ITD-R1-4 cells demonstrated that specific TKD mutations (D835N and Y842H) on the ITD background were acquired during selection with SU5614. Introduction of these dual ITD-TKD, but not single D835N or Y842H FLT3 mutants, in Ba/F3 cells restored the FLT3 inhibitor resistant phenotype. Our data show that preexisting or acquired mutations in the PTK domain of FLT3 can induce drug resistance to FLT3 PTK inhibitors in vitro. These findings provide a molecular basis for the evaluation of clinical resistance to FLT3 PTK inhibitors in patients with AML.
authors: Department of Medicine III, University Hospital Grosshadern, Luwig-Maximilians University, Munich, Germany.
authors: Ksenia
authors: K
authors: Bagrintseva
authors: Ruth
authors: R
authors: Schwab
authors: Tobias M
authors: TM
authors: Kohl
authors: Susanne
authors: S
authors: Schnittger
authors: Sabine
authors: S
authors: Eichenlaub
authors: Joachim W
authors: JW
authors: Ellwart
authors: Wolfgang
authors: W
authors: Hiddemann
authors: Karsten
authors: K
authors: Spiekermann
mesh_terms: D000208:Acute Disease; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002461:Cell Line, Transformed / Q000187:drug effects / Q000502:physiology; D003561:Cytarabine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007951:Leukemia, Myeloid; D020935:MAP Kinase Signaling System / Q000502:physiology; D008894:Milk Proteins; D016296:Mutagenesis; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; 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; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology; D051941:fms-Like Tyrosine Kinase 3
chemical_list: C407689:6,7-dimethoxy-2-phenylquinoxaline; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007211:Indoles; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; C416849:SU 5614; D015534:Trans-Activators; D020032:Tyrphostins; D003561:Cytarabine; D019833:Genistein; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D019311:Staurosporine; C059539:midostaurin