title: Autophagy is a survival mechanism of acute myelogenous leukemia precursors during dual mTORC2/mTORC1 targeting.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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 catalytic mTOR targeting agents and autophagy inhibitors may provide a unique approach to target primitive leukemic precursors in AML.
authors.affiliation: Authors' Affiliations: Robert H. Lurie Comprehensive Cancer Center of Northwestern University; Division of Hematology/Oncology, Department of Medicine; Department of Radiology, Northwestern University, Feinberg School of Medicine; and Division of Hematology-Oncology, Department of Medicine, Jesse Brown VA Medical Center, Chicago, Illinois.
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Altman
authors.forename: Amy
authors.initials: A
authors.lastname: Szilard
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Goussetis
authors.forename: Antonella
authors.initials: A
authors.lastname: Sassano
authors.forename: Marco
authors.initials: M
authors.lastname: Colamonici
authors.forename: Elias
authors.initials: E
authors.lastname: Gounaris
authors.forename: Olga
authors.initials: O
authors.lastname: Frankfurt
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Giles
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Eklund
authors.forename: Elspeth M
authors.initials: EM
authors.lastname: Beauchamp
authors.forename: Leonidas C
authors.initials: LC
authors.lastname: Platanias
mesh_terms: D001343:Autophagy / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism*; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*
chemical_list: D046912:Multiprotein Complexes; D047428:Protein Kinase Inhibitors; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases