Tumor necrosis factor-like weak inducer of apoptosis stimulation of glioma cell survival is dependent on Akt2 function

Mol Cancer Res. 2009 Nov;7(11):1871-81. doi: 10.1158/1541-7786.MCR-09-0194. Epub 2009 Oct 27.

Abstract

Malignant gliomas are the most common primary brain tumors. Despite intensive clinical investigation and significant technical advances in surgical and radiation treatment, the impact on clinical outcome for patients with malignant gliomas is disappointing. We have previously shown that tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, can stimulate glioma cell survival via binding to the Fn14 receptor, activation of the NF-kappaB pathway, and upregulation of BCL-X(L) gene expression. Here, we show that TWEAK treatment of glioma cells leads to phosphorylation of Akt and BAD. TWEAK stimulation results in the phosphorylation of both Akt1 and Akt2. However, small interfering RNA (siRNA)-mediated depletion of either Akt1 or Akt2 showed that BAD serine 136 phosphorylation is dependent specifically on Akt2 function. Depletion of Akt2 expression by siRNA also abrogates TWEAK-stimulated glioma cell survival, whereas no effect on glioma cell survival was observed after siRNA-mediated depletion of Akt1 expression. Surprisingly, although siRNA-mediated depletion of BAD in glioma cells abrogates cytotoxic- and chemotherapy-induced apoptosis, TWEAK still displays a strong protective effect, suggesting that BAD serine 136 phosphorylation plays a minor role in TWEAK-Akt2-induced glioma cell survival. We also report here that AKT2 gene expression levels increased with glioma grade and inversely correlate with patient survival. Additionally, immunohistochemical analysis showed that Akt2 expression positively correlates with Fn14 expression in glioblastoma multiforme specimens. We hypothesize that the TWEAK-Fn14 signaling axis functions, in part, to enhance glioblastoma cell survival by activation of the Akt2 serine/threonine protein kinase.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Brain Neoplasms / drug therapy
  • Brain Neoplasms / genetics
  • Brain Neoplasms / metabolism*
  • Brain Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Cytokine TWEAK
  • Gene Expression Profiling
  • Glioblastoma / drug therapy
  • Glioblastoma / genetics
  • Glioblastoma / metabolism
  • Glioblastoma / pathology
  • Glioma / drug therapy
  • Glioma / genetics
  • Glioma / metabolism*
  • Glioma / pathology*
  • Humans
  • Immunohistochemistry
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • RNA, Small Interfering / administration & dosage
  • RNA, Small Interfering / genetics
  • Receptors, Tumor Necrosis Factor / metabolism
  • TWEAK Receptor
  • Transfection
  • Tumor Necrosis Factors / metabolism
  • Tumor Necrosis Factors / pharmacology*
  • bcl-Associated Death Protein / deficiency
  • bcl-Associated Death Protein / genetics

Substances

  • BAD protein, human
  • Cytokine TWEAK
  • RNA, Small Interfering
  • Receptors, Tumor Necrosis Factor
  • TNFRSF12A protein, human
  • TNFSF12 protein, human
  • TWEAK Receptor
  • Tumor Necrosis Factors
  • bcl-Associated Death Protein
  • AKT1 protein, human
  • AKT2 protein, human
  • Proto-Oncogene Proteins c-akt