T-LAK cell-originated protein kinase presents a novel therapeutic target in FLT3-ITD mutated acute myeloid leukemia
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Houda Alachkar1, Martin Mutonga1, Gregory Malnassy1, Jae-Hyun Park1, Noreen Fulton1, Alex Woods1, Liping Meng1, Justin Kline1, Gordana Raca1, Olatoyosi Odenike1, Naofumi Takamatsu2, Takashi Miyamoto2, Yo Matsuo2, Wendy Stock1, Yusuke Nakamura1
1Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, IL, USA
2OncoTherapy Science, Inc., Kanagawa, Japan
Yusuke Nakamura, e-mail: email@example.com
Keywords: AML, FLT3-ITD, TOPK, CEBPA, kinase inhibitor
Received: July 08, 2015 Accepted: September 22, 2015 Published: October 02, 2015
Gain-of-function mutations of FLT3 (FLT3-ITD), comprises up to 30% of normal karyotype acute myeloid leukemia (AML) and is associated with an adverse prognosis. Current FLT3 kinase inhibitors have been tested extensively, but have not yet resulted in a survival benefit and novel therapies are awaited. Here we show that T-LAK cell-originated protein kinase (TOPK), a mitotic kinase highly expressed in and correlated with more aggressive phenotype in several types of cancer, is expressed in AML but not in normal CD34+ cells and that TOPK knockdown decreased cell viability and induced apoptosis. Treatment of AML cells with TOPK inhibitor (OTS514) resulted in a dose-dependent decrease in cell viability with lower IC50 in FLT3-mutated cells, including blasts obtained from patients relapsed after FLT3-inhibitor treatment. Using a MV4-11-engrafted mouse model, we found that mice treated with 7.5 mg/kg IV daily for 3 weeks survived significantly longer than vehicle treated mice (median survival 46 vs 29 days, P < 0.001). Importantly, we identified TOPK as a FLT3-ITD and CEBPA regulated kinase, and that modulating TOPK expression or activity resulted in significant decrease of FLT3 expression and CEBPA phosphorylation. Thus, targeting TOPK in FLT3-ITD AML represents a novel therapeutic approach for this adverse risk subset of AML.
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