Silencing of elongation factor-2 kinase potentiates the effect of 2-deoxy-D-glucose against human glioma cells through blunting of autophagy

Cancer Res. 2009 Mar 15;69(6):2453-60. doi: 10.1158/0008-5472.CAN-08-2872. Epub 2009 Feb 24.

Abstract

2-Deoxy-d-glucose (2-DG), a synthetic glucose analogue that acts as a glycolytic inhibitor, is currently being evaluated in the clinic as an anticancer agent. In this study, we observed that treatment of human glioma cells with 2-DG activated autophagy, a highly conserved cellular response to metabolic stress and a catabolic process of self-digestion of intracellular organelles for energy use and survival in stressed cells. The induction of autophagy by 2-DG was associated with activation of elongation factor-2 kinase (eEF-2 kinase), a structurally and functionally unique enzyme that phosphorylates eEF-2, leading to loss of affinity of this elongation factor for the ribosome and to termination of protein elongation. We also showed that inhibition of eEF-2 kinase by RNA interference blunted the 2-DG-induced autophagic response, resulted in a greater reduction of cellular ATP contents, and increased the sensitivity of tumor cells to the cytotoxic effect of 2-DG. Furthermore, the blunted autophagy and enhanced 2-DG cytotoxicity were accompanied by augmentation of apoptosis in cells in which eEF-2 kinase expression was knocked down. The results of this study indicate that the energy stress and cytotoxicity caused by 2-DG can be accelerated by inhibition of eEF-2 kinase, and suggest that targeting eEF-2 kinase-regulated autophagic survival pathway may represent a novel approach to sensitizing cancer cells to glycolytic inhibitors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / drug effects*
  • Cell Line, Tumor
  • Deoxyglucose / pharmacology*
  • Drug Synergism
  • Elongation Factor 2 Kinase / antagonists & inhibitors*
  • Elongation Factor 2 Kinase / genetics
  • Elongation Factor 2 Kinase / metabolism
  • Enzyme Activation / drug effects
  • Glioblastoma / drug therapy*
  • Glioblastoma / enzymology*
  • Glioblastoma / genetics
  • Glioblastoma / pathology
  • Humans
  • RNA, Small Interfering / genetics
  • Transfection

Substances

  • RNA, Small Interfering
  • Deoxyglucose
  • Elongation Factor 2 Kinase