Tp53-induced glycolysis and apoptosis regulator (TIGAR) protects glioma cells from starvation-induced cell death by up-regulating respiration and improving cellular redox homeostasis

J Biol Chem. 2012 Sep 28;287(40):33436-46. doi: 10.1074/jbc.M112.384578. Epub 2012 Aug 10.

Abstract

Altered metabolism in tumor cells is increasingly recognized as a core component of the neoplastic phenotype. Because p53 has emerged as a master metabolic regulator, we hypothesized that the presence of wild-type p53 in glioblastoma cells could confer a selective advantage to these cells under the adverse conditions of the glioma microenvironment. Here, we report on the effects of the p53-dependent effector Tp53-induced glycolysis and apoptosis regulator (TIGAR) on hypoxia-induced cell death. We demonstrate that TIGAR is overexpressed in glioblastomas and that ectopic expression of TIGAR reduces cell death induced by glucose and oxygen restriction. Metabolic analyses revealed that TIGAR inhibits glycolysis and promotes respiration. Further, generation of reactive oxygen species (ROS) levels was reduced whereas levels of reduced glutathione were elevated in TIGAR-expressing cells. Finally, inhibiting the transketolase isoenzyme transketolase-like 1 (TKTL1) by siRNA reversed theses effects of TIGAR. These findings suggest that glioma cells benefit from TIGAR expression by (i) improving energy yield from glucose via increased respiration and (ii) enhancing defense mechanisms against ROS. Targeting metabolic regulators such as TIGAR may therefore be a valuable strategy to enhance glioma cell sensitivity toward spontaneously occurring or therapy-induced starvation conditions or ROS-inducing therapeutic approaches.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Apoptosis Regulatory Proteins
  • Brain Neoplasms / metabolism*
  • Cell Death
  • Cell Line
  • Cell Line, Tumor
  • Gene Expression Regulation*
  • Gene Expression Regulation, Neoplastic
  • Glioma / metabolism*
  • Glycolysis
  • Humans
  • Hypoxia / metabolism
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Intracellular Signaling Peptides and Proteins / physiology
  • Mice
  • Models, Biological
  • Oxidation-Reduction
  • Oxygen Consumption
  • Pentose Phosphate Pathway
  • Reactive Oxygen Species
  • Tumor Suppressor Protein p53 / genetics

Substances

  • Apoptosis Regulatory Proteins
  • Intracellular Signaling Peptides and Proteins
  • Reactive Oxygen Species
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • TIGAR protein, human