ATRA can enhance apoptosis that is induced by Flt3 tyrosine kinase inhibition in Flt3-ITD positive cells.
Among activating Flt3 mutations that have been shown in 25-30% of acute myeloid leukaemia (AML) Flt3-internal tandem duplication (ITD) mutations are predominant. We investigated the influence of all-trans-retinoic acid (ATRA) and granulocyte colony stimulating factor (G-CSF) for their effects on differentiation and apoptosis in human cell lines with different Flt3 variants (THP-1 versus MV4-11 and MOLM13) dependent on the inhibition of Flt3 tyrosine kinase by the bis(lH-2-indolyl)methanone D-65476. While myeloid differentiation was not observed in both Flt3-ITD cell lines (MV4-11 and MOLM13), we demonstrate an enhanced proapoptotic effect of D-65476 in the presence of ATRA that was restricted to the Flt3-ITD expressing cells. The combined treatment with ATRA and D-65476 also led to a pronounced down-regulation of surviv in on mRNA and protein level in Flt3-ITD but not in Flt3 wildtype expressing cells (THP-1). Surprisingly, there was no differential expression of important proteins like Bcl-X(L), Bcl-2 or Bax that might explain enhanced apoptosis. Furthermore, Akt phosphorylation after stimulation with Flt3 ligand dependent on D-65476 was not affected by pretreatment with ATRA. We suggest that regulation of inhibitors of apoptosis might play a crucial role how ATRA can increase the proapoptotic effect of Flt3 inhibitors in myeloid leukemia cells expressing Flt3-ITD. This effect can potentially be exploited for the treatment of Flt3-ITD positive acute myeloid leukemia.
Department of Internal Medicine II, Oncology and Hematology, Erlanger Allee 101, Friedrich Schiller University, 07740 Jena, Germany. sebastian.scholl@med.uni-jena.de
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S
Scholl
R
R
Müller
J H
JH
Clement
I F
IF
Loncarevic
F D
FD
Böhmer
K
K
Höffken
D017209:Apoptosis / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D009154:Mutation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*; D051941:fms-Like Tyrosine Kinase 3 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics
C463260:D-65476; D007211:Indoles; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D016179:Granulocyte Colony-Stimulating Factor; D014212:Tretinoin; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3