The p38-MK2-HuR pathway potentiates EGFRvIII-IL-1β-driven IL-6 secretion in glioblastoma cells

Oncogene. 2015 May 28;34(22):2934-42. doi: 10.1038/onc.2014.225. Epub 2014 Aug 4.

Abstract

The microenvironment of glioblastoma (GBM) contains high levels of inflammatory cytokine interleukin 6 (IL-6), which contributes to promote tumour progression and invasion. The common epidermal growth factor receptor variant III (EGFRvIII) mutation in GBM is associated with significantly higher levels of IL-6. Furthermore, elevated IL-1β levels in GBM tumours are also believed to activate GBM cells and enhance IL-6 production. However, the crosstalk between these intrinsic and extrinsic factors within the oncogene-microenvironment of GBM causing overproduction of IL-6 is poorly understood. Here, we show that EGFRvIII potentiates IL-1β-induced IL-6 secretion from GBM cells. Importantly, exacerbation of IL-6 production is most effectively attenuated in EGFRvIII-expressing GBM cells with inhibitors of p38 mitogen-activated protein kinase (p38 MAPK) and MAPK-activated protein kinase 2 (MK2). Enhanced IL-6 production and increased sensitivity toward pharmacological p38 MAPK and MK2 inhibitors in EGFRvIII-expressing GBM cells is associated with increased MK2-dependent nuclear-cytoplasmic shuttling and accumulation of human antigen R (HuR), an IL-6 mRNA-stabilising protein, in the cytosol. IL-1β-stimulated activation of the p38 MAPK-MK2-HuR pathway significantly enhances IL-6 mRNA stability in GBM cells carrying EGFRvIII. Further supporting a role for the p38 MAPK-MK2-HuR pathway in the development of inflammatory environment in GBM, activated MK2 is found in more than 50% of investigated GBM tissues and correlates with lower grade and secondary GBMs. Taken together, p38 MAPK-MK2-HuR signalling may enhance the potential of intrinsic (EGFRvIII) and extrinsic (IL-1β) factors to develop an inflammatory GBM environment. Hence, further improvement of brain-permeable and anti-inflammatory inhibitors targeting p38 MAPK, MK2 and HuR may combat progression of lower grade gliomas into aggressive GBMs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain Neoplasms* / genetics
  • Brain Neoplasms* / metabolism
  • Brain Neoplasms* / pathology
  • ELAV Proteins / metabolism
  • ELAV-Like Protein 1
  • ErbB Receptors / pharmacology*
  • Glioblastoma* / genetics
  • Glioblastoma* / metabolism
  • Glioblastoma* / pathology
  • Humans
  • Inflammation / genetics
  • Inflammation / metabolism
  • Interleukin-1beta / pharmacology*
  • Interleukin-6 / metabolism*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • MAP Kinase Signaling System / physiology*
  • Protein Serine-Threonine Kinases / metabolism
  • Tumor Cells, Cultured
  • Tumor Microenvironment / drug effects
  • Tumor Microenvironment / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • ELAV Proteins
  • ELAV-Like Protein 1
  • ELAVL1 protein, human
  • IL6 protein, human
  • Interleukin-1beta
  • Interleukin-6
  • Intracellular Signaling Peptides and Proteins
  • epidermal growth factor receptor VIII
  • MAP-kinase-activated kinase 2
  • ErbB Receptors
  • Protein Serine-Threonine Kinases
  • p38 Mitogen-Activated Protein Kinases