Autophagy is a survival mechanism of acute myelogenous leukemia precursors during dual mTORC2/mTORC1 targeting

Jessica K. Altman, Amy Szilard, Dennis J. Goussetis, Antonella Sassano, Marco Colamonici, Elias Gounaris, Olga Frankfurt, Francis J. Giles, Elizabeth A. Eklund, Elspeth M. Beauchamp, Leonidas C. Platanias*

*Corresponding author for this work

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Purpose: To examine whether induction of autophagy is a mechanism of leukemic cell resistance to dual mTORC1/mTORC2 inhibitors in acute myelogenous leukemia (AML) leukemic progenitors. Experimental Design: Combinations of different experimental approaches were used to assess induction of autophagy, including immunoblotting to detect effects on LC3II and p62/SQTM1 expression and on ULK1 phosphorylation, immunofluorescence, and electron microscopy. Functional responses were assessed using cell viability and apoptosis assays, and clonogenic leukemic progenitor assays in methylcellulose. Results: We provide evidence that treatment of AML cells with catalytic mTOR inhibitors results in induction of autophagy, which acts as a regulatory mechanism to promote leukemic cell survival. Such induction of autophagy by dual mTORC1/mTORC2 inhibitors partially protects primitive leukemic precursors from the inhibitory effects of such agents and limits their activities. Simultaneous blockade of the autophagic process using chloroquine or by knockdown of ULK1 results in enhanced antileukemic responses. Conclusions: Dual targeting of mTORC2 and mTORC1 results in induction of autophagy in AML cells. Combinations of catalyticmTORtargeting agents and autophagy inhibitors may provide a unique approach to target primitive leukemic precursors in AML.

Original languageEnglish (US)
Pages (from-to)2400-2409
Number of pages10
JournalClinical Cancer Research
Volume20
Issue number9
DOIs
StatePublished - May 1 2014

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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