IL-8 is a mediator of NF-κB induced invasion by gliomas

J Neurooncol. 2011 Jan;101(2):227-35. doi: 10.1007/s11060-010-0261-2. Epub 2010 Jun 25.

Abstract

Glioblastoma (GBM) is the most common and deadly form of primary brain tumor with a median survival of eleven months, despite use of extensive chemotherapy, radiotherapy and surgery. We have previously shown that nuclear factor-kappa B (NF-κB) is aberrantly expressed in GBM tumors and primary cell lines derived from tumor tissue. Here we show that IL-8, a chemokine is also aberrantly expressed by GBM cell lines and expression of IL-8 is in large part, attributable to the aberrant activation of NF-κB. We hypothesized that invasiveness of GBM cells is driven at least in part by aberrantly expressed IL-8. In support of the hypothesis we found that treatment of glioma cells with an IL-8 neutralizing antibody markedly decreased their invasiveness compared to cells treated with control IgG or left untreated. Furthermore, downregulation of IL-8 protein production with use of IL-8 targeted siRNA also resulted in decreased invasion in matrigel. We next investigated the presence of IL-8 receptors by FACS analysis and found that GBM cells (U87, U251, D54 and LN229) only express CXCR1 but not CXCR2. Treatment of U87 cells with a blocking CXCR1 antibody reduced their invasion through matrigel. Finally, we found that addition of exogenous IL-8, following downregulation of NF-κB which results in loss of endogenous IL-8 production, incompletely restored tumor cell invasion. Our data indicate that IL-8 is necessary but not solely responsible for glioma cell invasion and mediates its effect in an autocrine manner.

MeSH terms

  • Antibodies / pharmacology
  • Cell Line, Tumor
  • Enzyme-Linked Immunosorbent Assay / methods
  • Flow Cytometry / methods
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / physiology*
  • Gene Transfer Techniques
  • Glioblastoma / pathology
  • Humans
  • Interleukin-8 / immunology
  • Interleukin-8 / metabolism*
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Neoplasm Invasiveness
  • RNA, Small Interfering / pharmacology
  • Receptors, Interleukin-8A / immunology
  • Receptors, Interleukin-8A / metabolism
  • Receptors, Interleukin-8B / immunology
  • Receptors, Interleukin-8B / metabolism
  • Time Factors

Substances

  • Antibodies
  • Interleukin-8
  • NF-kappa B
  • RNA, Small Interfering
  • Receptors, Interleukin-8A
  • Receptors, Interleukin-8B