Identifying and characterizing a novel activating mutation of the FLT3 tyrosine kinase in AML.
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.
Jiang
Jingrui
J
Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney St, D720C, Boston, MA 02115, USA.
Paez
J Guillermo
JG
Lee
Jeffrey C
JC
Bo
Ronghai
R
Stone
Richard M
RM
DeAngelo
Daniel J
DJ
Galinsky
Ilene
I
Wolpin
Brian M
BM
Jonasova
Anna
A
Herman
Paula
P
Fox
Edward A
EA
Boggon
Titus J
TJ
Eck
Michael J
MJ
Weisberg
Ellen
E
Griffin
James D
JD
Gilliland
D Gary
DG
Meyerson
Matthew
M
Sellers
William R
WR
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
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