AML-associated Flt3 kinase domain mutations show signal transduction differences compared with Flt3 ITD mutations.
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.
Choudhary
Chunaram
C
Department of Medicine, Hematology/Oncology and Interdisciplinary Center for Clinical Research, University Münster, Germany.
Schwäble
Joachim
J
Brandts
Christian
C
Tickenbrock
Lara
L
Sargin
Bülent
B
Kindler
Thomas
T
Fischer
Thomas
T
Berdel
Wolfgang E
WE
Müller-Tidow
Carsten
C
Serve
Hubert
H
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
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