Targeting the PI3K/Akt/mTOR signaling pathway in B-precursor acute lymphoblastic leukemia and its therapeutic potential

Leukemia. 2014 Apr;28(4):739-48. doi: 10.1038/leu.2013.226. Epub 2013 Jul 29.

Abstract

B-precursor acute lymphoblastic leukemia (B-pre ALL) is a malignant disorder characterized by the abnormal proliferation of B-cell progenitors. The prognosis of B-pre ALL has improved in pediatric patients, but the outcome is much less successful in adults. Constitutive activation of the phosphatidylinositol 3-kinase (PI3K), Akt and the mammalian target of rapamycin (mTOR) (PI3K/Akt/mTOR) network is a feature of B-pre ALL, where it strongly influences cell growth and survival. RAD001, a selective mTORC1 inhibitor, has been shown to be cytotoxic against many types of cancer including hematological malignancies. To investigate whether mTORC1 could represent a target in the therapy of B-pre ALL, we treated cell lines and adult patient primary cells with RAD001. We documented that RAD001 decreased cell viability, induced cell cycle arrest in G0/G1 phase and caused apoptosis in B-pre ALL cell lines. Autophagy was also induced, which was important for the RAD001 cytotoxic effect, as downregulation of Beclin-1 reduced drug cytotoxicity. RAD001 strongly synergized with the novel allosteric Akt inhibitor MK-2206 in both cell lines and patient samples. Similar results were obtained with the combination CCI-779 plus GSK 690693. These findings point out that mTORC1 inhibitors, either as a single agent or in combination with Akt inhibitors, could represent a potential therapeutic innovative strategy in B-pre ALL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Autophagy / drug effects
  • Cell Cycle Checkpoints / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Everolimus
  • Heterocyclic Compounds, 3-Ring / pharmacology
  • Humans
  • Mechanistic Target of Rapamycin Complex 1
  • Multiprotein Complexes / antagonists & inhibitors
  • Oxadiazoles / pharmacology
  • Phosphoinositide-3 Kinase Inhibitors*
  • Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / drug therapy*
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Signal Transduction / drug effects*
  • Sirolimus / analogs & derivatives
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases / antagonists & inhibitors*

Substances

  • GSK690693
  • Heterocyclic Compounds, 3-Ring
  • MK 2206
  • Multiprotein Complexes
  • Oxadiazoles
  • Phosphoinositide-3 Kinase Inhibitors
  • temsirolimus
  • Everolimus
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Sirolimus