Features of Ras activation by a mislocalized oncogenic tyrosine kinase: FLT3 ITD signals through K-Ras at the plasma membrane of acute myeloid leukemia cells.
FMS-like tyrosine kinase 3 with internal tandem duplication (FLT3 ITD) is an important oncoprotein in acute myeloid leukemia (AML). Owing to its constitutive kinase activity FLT3 ITD partially accumulates at endomembranes, a feature shared with other disease-associated, mutated receptor tyrosine kinases. Because Ras proteins also transit through endomembranes we have investigated the possible existence of an intracellular FLT3-ITD/Ras signaling pathway by comparing Ras signaling of FLT3 ITD with that of wild-type FLT3. Ligand stimulation activated both K- and N-Ras in cells expressing wild-type FLT3. Live-cell Ras-GTP imaging revealed ligand-induced Ras activation at the plasma membrane (PM). FLT3-ITD-dependent constitutive activation of K-Ras and N-Ras was also observed primarily at the PM, supporting the view that the PM-resident pool of FLT3 ITD engaged the Ras/Erk pathway in AML cells. Accordingly, specific interference with FLT3-ITD/Ras signaling at the PM using PM-restricted dominant negative K-RasS17N potently inhibited cell proliferation and promoted apoptosis. In conclusion, Ras signaling is crucial for FLT3-ITD-dependent cell transformation and FLT3 ITD addresses PM-bound Ras despite its pronounced mislocalization to endomembranes.
Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, 07743 Jena, Germany.
Susanne
S
Köthe
Jörg P
JP
Müller
Sylvia-Annette
SA
Böhmer
Todor
T
Tschongov
Melanie
M
Fricke
Sina
S
Koch
Christian
C
Thiede
Robert P
RP
Requardt
Ignacio
I
Rubio
Frank D
FD
Böhmer
D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D011905:Genes, ras; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D015398:Signal Transduction; D020080:Tandem Repeat Sequences; D014407:Tumor Cells, Cultured; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
C497970:FLT3 protein, human; C497971:Flt3 protein, mouse; D051941:fms-Like Tyrosine Kinase 3; D018631:ras Proteins
AML; Endomembrane; FLT3; FLT3 ITD; Leukemia; Localization; Oncogenic RTK; Plasma membrane; Ras