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Pietschmann, K.* ; Bolck, H.A.* ; Buchwald, M.* ; Spielberg, S.* ; Polzer, H. ; Spiekermann, K. ; Bug, G.* ; Heinzel, T.* ; Böhmer, F.D.* ; Krämer, O.H.*

Breakdown of the FLT3-ITD/STAT5 axis and synergistic apoptosis induction by the histone deacetylase inhibitor panobinostat and FLT3-specific inhibitors.

Mol. Cancer Ther. 11, 2373-2383 (2012)
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Activating mutations of the class III receptor tyrosine kinase FLT3 are the most frequent molecular aberration in acute myeloid leukemia (AML). Mutant FLT3 accelerates proliferation, suppresses apoptosis, and correlates with poor prognosis. Therefore, it is a promising therapeutic target. Here, we show that RNA interference against FLT3 with an internal tandem duplication (FLT3-ITD) potentiates the efficacy of the histone deacetylase inhibitor (HDACi) panobinostat (LBH589) against AML cells expressing FLT3-ITD. Similar to RNA interference, tyrosine kinase inhibitors (TKI; AC220/cpd.102/PKC412) in combination with LBH589 exhibit superior activity against AML cells. Median dose-effect analyses of drug-induced apoptosis rates of AML cells (MV4-11 and MOLM-13) revealed combination index (CI) values indicating strong synergism. AC220, the most potent and FLT3-specific TKI, shows highest synergism with LBH589 in the low nanomolar range. A 4-hour exposure to LBH589 + AC220 already generates more than 50% apoptosis after 24 hours. Different cell lines lacking FLT3-ITD as well as normal peripheral blood mononuclear cells are not significantly affected by LBH589 + TKI, showing the specificity of this treatment regimen. Immunoblot analyses show that LBH589 + TKI induce apoptosis via degradation of FLT3-ITD and its prosurvival target STAT5. Previously, we showed the LBH589-induced proteasomal degradation of FLT3-ITD. Here, we show that activated caspase-3 also contributes to the degradation of FLT3-ITD and that STAT5 is a direct target of this protease. Our data strongly emphasize HDACi/TKI drug combinations as promising modality for the treatment of FLT3-ITD-positive AMLs.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter ACUTE MYELOID-LEUKEMIA; ACUTE MYELOGENOUS LEUKEMIA; TYROSINE KINASE INHIBITOR; ACTIVATING MUTATION; FLT3 MUTATIONS; CELL-LINES; AML CELLS; IN-VITRO; LBH589; COMBINATION
ISSN (print) / ISBN 1535-7163
e-ISSN 1538-8514
Quellenangaben Band: 11, Heft: 11, Seiten: 2373-2383 Artikelnummer: , Supplement: ,
Verlag American Association for Cancer Research (AACR)
Begutachtungsstatus Peer reviewed