The oncometabolite 2-hydroxyglutarate inhibits microglial activation via the AMPK/mTOR/NF-κB pathway

Acta Pharmacol Sin. 2019 Oct;40(10):1292-1302. doi: 10.1038/s41401-019-0225-9. Epub 2019 Apr 23.

Abstract

Microglia, the brain-resident macrophage, is known as the innate immune cell type in the central nervous system. Microglia is also the major cellular component of tumor mass of gliomas that plays a key role in glioma development. Mutations of isocitrate dehydrogenases 1 and 2 (IDH1/2) frequently occur in gliomas, which leads to accumulation of oncometabolic product 2-hydroxyglutarate (2HG). Moreover, IDH1/2 mutations were found to correlate with better prognosis in glioma patients. In the present study, we investigated the effects of the 2HG on microglial inflammatory activation. We showed that the conditioned media (CM) from GL261 glioma cells stimulated the activation of BV-2 microglia cells, evidenced by markedly increased expression of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), CCL2 (C-C motif chemokine ligand 2) and CXCL10 (C-X-C motif chemokine 10). CM-induced expression of proinflammatory genes was significantly suppressed by pretreatment with a synthetic cell-permeable 2HG (1 mM) or a nuclear factor-κB (NF-κB) inhibitor BAY11-7082 (10 μM). In lipopolysaccharide (LPS)- or TNF-α-stimulated BV-2 microglia cells and primary microglia, pretreatment with 2HG (0.25-1 mM) dose-dependently suppressed the expression of proinflammatory genes. We further demonstrated that 2HG significantly suppressed LPS-induced phosphorylation of IκB kinase α/β (IKKα/β), IκBα and p65, IκB degradation, and nuclear translocation of p65 subunit of NF-κB, as well as NF-κB transcriptional activity. Similarly, ectopic expression of mutant isocitrate dehydrogenase 1 (IDH1) (R132H) significantly decreased TNF-α-induced activation of NF-κB signaling pathway. Finally, we revealed that activation of adenosine 5'-monophosphate-activated protein kinase (AMPK) and subsequent inhibition of mammalian target of rapamycin (mTOR) signaling contributed to the inhibitory effect of 2HG on NF-κB signaling pathway in BV-2 cells. Taken together, these results, for the first time, show that oncometabolite 2HG inhibits microglial activation through affecting AMPK/mTOR/NF-κB signaling pathway and provide evidence that oncometabolite 2HG may regulate glioma development via modulating microglial activation in tumor microenvironment.

Keywords: 2-Hydroxyglutarate; AMPK; BAY11-7082; NF-κB; glioma; inflammation; mTOR; microglia; oncometabolite.

MeSH terms

  • AMP-Activated Protein Kinases / antagonists & inhibitors*
  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Glutarates / pharmacology*
  • HEK293 Cells
  • Humans
  • Lipopolysaccharides / antagonists & inhibitors
  • Lipopolysaccharides / pharmacology
  • Mice
  • Microglia / drug effects*
  • Microglia / metabolism
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / metabolism
  • Structure-Activity Relationship
  • TOR Serine-Threonine Kinases / antagonists & inhibitors*
  • TOR Serine-Threonine Kinases / metabolism
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Glutarates
  • Lipopolysaccharides
  • NF-kappa B
  • Tumor Necrosis Factor-alpha
  • alpha-hydroxyglutarate
  • MTOR protein, human
  • mTOR protein, mouse
  • TOR Serine-Threonine Kinases
  • AMP-Activated Protein Kinases