Imipramine blue sensitively and selectively targets FLT3-ITD positive acute myeloid leukemia cells

• Type of Material: Article
• Authors: Jonathan Metts, Emory University; Heath Bradley, Emory University; Zhengqi Wang, Emory University; Neil P. Shah, University of California San Francisco; Reuben Kapur, Indiana University; Jack Arbiser, Emory University; Kevin Bunting, Emory University
• Language: English
• Date: 2017-06-30
• Publisher: Nature Publishing Group
• Publication Version: Final Published Version
• Copyright Statement: © 2017 The Author(s).
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1038/s41598-017-04796-1
• Title of Journal or Parent Work: Scientific Reports
• ISSN: 2045-2322
• Volume: 7
• Issue: 1
• Start Page: 4447
• End Page: 4447
• Grant/Funding Information: We acknowledge the generous support of the Emory + Children’s Pediatric Research Center Flow Cytometry Core and the Emory Integrated Imaging Core. NIHR01DK059380, Cure Childhood Cancer Foundation, The Sam Robb Fund, Aflac Cancer & Blood Disorders Center of Children’s Healthcare of Atlanta.
• Keywords: DISEASE; APOPTOSIS; MECHANISMS; THERAPEUTIC TARGET; Multidisciplinary Sciences; ENDOPLASMIC-RETICULUM; CALCIUM; INTERNAL TANDEM DUPLICATION; Science & Technology - Other Topics; Science & Technology; ROS; INHIBITOR; DNA-DAMAGE
• Research Categories: Health Sciences, Immunology; Health Sciences, Oncology

Abstract

Aberrant cytokine signaling initiated from mutant receptor tyrosine kinases (RTKs) provides critical growth and survival signals in high risk acute myeloid leukemia (AML). Inhibitors to FLT3 have already been tested in clinical trials, however, drug resistance limits clinical efficacy. Mutant receptor tyrosine kinases are mislocalized in the endoplasmic reticulum (ER) of AML and play an important role in the non-canonical activation of signal transducer and activator of transcription 5 (STAT5). Here, we have tested a potent new drug called imipramine blue (IB), which is a chimeric molecule with a dual mechanism of action. At 200-300 nM concentrations, IB is a potent inhibitor of STAT5 through liberation of endogenous phosphatase activity following NADPH oxidase (NOX) inhibition. However, at 75-150 nM concentrations, IB was highly effective at killing mutant FLT3-driven AML cells through a similar mechanism as thapsigargin (TG), involving increased cytosolic calcium. IB also potently inhibited survival of primary human FLT3/ITD + AML cells compared to FLT3/ITD neg cells and spared normal umbilical cord blood cells. Therefore, IB functions through a mechanism involving vulnerability to dysregulated calcium metabolism and the combination of fusing a lipophilic amine to a NOX inhibiting dye shows promise for further pre-clinical development for targeting high risk AML.