Inhibition of USP9X induces apoptosis in FLT3-ITD-positive AML cells cooperatively by inhibiting the mutant kinase through aggresomal translocation and inducing oxidative stress

Cancer Lett. 2019 Jul 1;453:84-94. doi: 10.1016/j.canlet.2019.03.046. Epub 2019 Apr 1.


FLT3-ITD and FLT3-TKD are the most frequent mutations in acute myeloid leukemia (AML) with the former associated with a poor prognosis. Here we show that inhibition of the deubiquitinase USP9X by its inhibitor WP1130 or EOAI3402143 (G9) induces apoptosis preferentially in cells transformed by these mutant kinases, including FLT3-ITD-positive AML cell line MV4-11 and primary AML cells. Mechanistically, WP1130 induced aggresomal translocation of the mutant kinases, particularly FLT3-ITD in its activated and autophosphorylated conformation, to block the downstream signaling events, which was aggravated by knock down of USP9X. Moreover, USP9X physically associated with FLT3-ITD to inhibit its K63-linked polyubiquitination, while FLT3-ITD induced tyrosine phosphorylation and degradation of USP9X through the ubiquitin/proteasome pathway. WP1130 or G9 also induced oxidative stress to stimulate stress-related MAP kinase pathways and DNA damage responses to activate in cooperation with inhibition of FLT3-ITD signaling the intrinsic mitochondria-mediated apoptotic pathway, which was synergistically enhanced by BH3 mimetics and prevented by overexpression of Bcl-xL or Mcl-1. Thus, USP9X represents a promising target for novel therapies against therapy-resistant FLT3-ITD-positive AML.

Keywords: BH3 mimetics; Deubiquitinase; EOAI3402143; Mcl-1; WP1130.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Cell Line, Tumor
  • Cyanoacrylates / pharmacology
  • Down-Regulation / drug effects
  • HL-60 Cells
  • Humans
  • K562 Cells
  • Leukemia, Myeloid, Acute / drug therapy*
  • Leukemia, Myeloid, Acute / genetics
  • Leukemia, Myeloid, Acute / metabolism*
  • Leukemia, Myeloid, Acute / pathology
  • Mutation
  • Myeloid Cell Leukemia Sequence 1 Protein / metabolism
  • Oxidative Stress / physiology
  • Phosphorylation
  • Pyridines / pharmacology
  • Signal Transduction / drug effects
  • U937 Cells
  • Ubiquitin Thiolesterase / antagonists & inhibitors*
  • Ubiquitin Thiolesterase / genetics
  • Ubiquitin Thiolesterase / metabolism
  • Ubiquitination
  • fms-Like Tyrosine Kinase 3 / metabolism*


  • Cyanoacrylates
  • MCL1 protein, human
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Pyridines
  • USP9X protein, human
  • degrasyn
  • FLT3 protein, human
  • fms-Like Tyrosine Kinase 3
  • Ubiquitin Thiolesterase