The EGF receptor and HER2 participate in TNF-α-dependent MAPK activation and IL-8 secretion in intestinal epithelial cells

Mediators Inflamm. 2012;2012:207398. doi: 10.1155/2012/207398. Epub 2012 Sep 5.

Abstract

TNF-α activates multiple mitogen-activated protein kinase (MAPK) cascades in intestinal epithelial cells (IECs) leading to the secretion of interleukin 8 (IL-8), a neutrophil chemoattractant and an angiogenic factor with tumor promoting properties. As the epidermal growth factor receptor (EGFR) is a known transducer of proliferative signals and a potent activator of MAPKs, we hypothesized that the EGFR participates in TNF-dependent MAPK activation and IL-8 secretion by intestinal epithelial cells (IECs). We show that the EGFR is tyrosine-phosphorylated following treatment of IECs (HT-29 and IEC-6) with TNF-α. This requires EGFR autophosphorylation as it was blocked by the EGFR kinase inhibitor AG1478. Autophosphorylation was also inhibited by both a Src-kinase inhibitor and the metalloproteinase inhibitor batimastat. TNF treatment of IECs resulted in the accumulation of soluble TGF-α; treatment of IECs with batimastat suppressed TGF-α release and immunoneutralization of TGF-α resulted in decreased EGFR and ERK phosphorylations. TNF-α treatment of IECs resulted in an association between EGFR and HER2 and inhibition of HER2 using a specific inhibitor AG879 in combination with AG1478-suppressed TNF-α-dependent ERK phosphorylation and IL-8 release. Downregulation of HER2 via siRNA resulted in a significant decrease in ERK phosphorylation and a 50% reduction in IL-8 secretion.

MeSH terms

  • Blotting, Western
  • Cell Line
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • HT29 Cells
  • Humans
  • Immunoprecipitation
  • Interleukin-8 / metabolism*
  • Intestines / cytology*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphorylation / drug effects
  • Quinazolines / pharmacology
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism*
  • Tumor Necrosis Factor-alpha / pharmacology
  • Tyrphostins / pharmacology

Substances

  • Interleukin-8
  • Quinazolines
  • Tumor Necrosis Factor-alpha
  • Tyrphostins
  • RTKI cpd
  • ErbB Receptors
  • Receptor, ErbB-2
  • Mitogen-Activated Protein Kinases