Glutathione depletion causes a JNK and p38MAPK-mediated increase in expression of cystathionine-gamma-lyase and upregulation of the transsulfuration pathway in C6 glioma cells

Neurochem Int. 2010 Mar;56(4):611-9. doi: 10.1016/j.neuint.2010.01.004. Epub 2010 Jan 12.


Cancer cells have a high demand for cysteine as precursor of the antioxidant, glutathione, that is required to promote cell growth and division. Uptake of cystine by the x(c)(-) cystine-glutamate exchanger provides the majority of cysteine, but a significant percentage may be derived from methionine, via a transsulfuration pathway. Our aim was to evaluate the relative contribution of the exchanger and the transsulfuration pathway to glutathione synthesis in astrocytoma/glioblastoma cells, using the C6 glioma cell line as a model system. Blockade of the x(c)(-) exchanger with the gliotoxins l-alphaaminoadipate or l-beta-N-oxalylamino-l-alanine (400 microM) caused a loss of cellular cysteine and depletion in glutathione to 51% and 54% of control, respectively, after 24 h. Inhibition of the transsulfuration pathway with propargylglycine (1 mM, 24 h) depleted glutathione to 77% of control. Co-incubation of cells with gliotoxin and propargylglycine reduced glutathione to 39% of control at 24 h and to 20% at 48 h. Expression of cystathionine-gamma-lyase, the rate-limiting enzyme of the transsulfuration pathway, was significantly increased following incubation of the cells with gliotoxins. Incubation of C6 cells with diethylmaleate for 3 h led to a significant reduction in glutathione (63%), whereas expression of cystathionine-gamma-lyase was increased by 1.5-fold. Re-feeding methionine to diethylmaleate-treated cells incubated in the absence of cystine or methionine resulted in a significant recovery in glutathione that was blocked by propargylglycine. Co-incubation of C6 cells with diethylmaleate and the JNK-inhibitor, SP600125, abolished the increase in expression of cystathionine-gamma-lyase that had been observed in the presence of diethylmaleate alone. Similar results were obtained with the p38(MAPK) inhibitor, SB203580. It is concluded that glutathione depletion causes a JNK- and p38(MAPK)-mediated increase in expression of cystathionine-gamma-lyase that promotes flux through the transsulfuration pathway to compensate for loss of glutathione in C6 glioma cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2-Aminoadipic Acid / pharmacology
  • Blotting, Western
  • Cell Line, Tumor
  • Cell Survival / physiology
  • Cystathionine gamma-Lyase / antagonists & inhibitors
  • Cystathionine gamma-Lyase / biosynthesis*
  • Cystathionine gamma-Lyase / genetics
  • Cysteine / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Fluorometry
  • Glutathione / physiology*
  • Humans
  • Indicators and Reagents
  • MAP Kinase Kinase 4 / antagonists & inhibitors
  • MAP Kinase Kinase 4 / physiology*
  • Oncogene Protein v-akt / genetics
  • Oncogene Protein v-akt / physiology
  • Phosphorylation
  • Sulfur / metabolism*
  • Up-Regulation / physiology
  • p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • p38 Mitogen-Activated Protein Kinases / physiology*


  • Enzyme Inhibitors
  • Indicators and Reagents
  • 2-Aminoadipic Acid
  • Sulfur
  • Oncogene Protein v-akt
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4
  • Cystathionine gamma-Lyase
  • Glutathione
  • Cysteine