Synergistic killing of FLT3ITD-positive AML cells by combined inhibition of tyrosine-kinase activity and N-glycosylation
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Dimitrios Tsitsipatis1,6, Ashok Kumar Jayavelu1,7, Jörg P. Müller1, Reinhard Bauer1, Dirk Schmidt-Arras2, Siavosh Mahboobi3, Tina M. Schnöder4,5, Florian Heidel4,5, Frank-D. Böhmer1
1Institute of Molecular Cell Biology, CMB, Jena University Hospital, Jena, Germany
2Institute of Biochemistry, Christian-Albrechts-University Kiel, Kiel, Germany
3Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Regensburg, Germany
4Innere Medizin II, Hämatologie und Onkologie, Universitätsklinikum Jena, Jena, Germany
5Leibniz Institute on Aging, Fritz-Lipmann-Institute, Jena, Germany
6Current address: Institute of Nutrition, Department of Nutrigenomics, Friedrich-Schiller-University, Jena, Germany
7Current address: Max-Planck Institute of Biochemistry, Department of Proteomics and Signal Transduction, Martinsried, Germany
Frank-D. Böhmer, email: firstname.lastname@example.org
Keywords: acute myeloid leukemia, FLT3ITD, tunicamycin, selective cytotoxicity
Received: May 11, 2016 Accepted: February 16, 2017 Published: February 28, 2017
Fms-like tyrosine kinase 3 (FLT3) with internal tandem duplications (ITD) is a major oncoprotein in acute myeloid leukemia (AML), and confers an unfavorable prognosis. Interference with FLT3ITD signaling is therefore pursued as a promising therapeutic strategy. In this study we show that abrogation of FLT3ITD glycoprotein maturation using low doses of the N-glycosylation inhibitor tunicamycin has anti-proliferative and pro-apoptotic effects on FLT3ITD-expressing human and murine cell lines. This effect is mediated in part by arresting FLT3ITD in an underglycosylated state and thereby attenuating FLT3ITD-driven AKT and ERK signaling. In addition, tunicamycin caused pronounced endoplasmatic reticulum stress and apoptosis through activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK) and activation of the gene encoding CCAAT-enhancer-binding protein homologous protein (CHOP). PERK inhibition with a small molecule attenuated CHOP induction and partially rescued cells from apoptosis. Combination of tunicamycin with potent FLT3ITD kinase inhibitors caused synergistic cell killing, which was highly selective for cell lines and primary AML cells expressing FLT3ITD. Although tunicamycin is currently not a clinically applicable drug, we propose that mild inhibition of N-glycosylation may have therapeutic potential in combination with FLT3 kinase inhibitors for FLT3ITD-positive AML.
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