title: The EGF receptor and HER2 participate in TNF-α-dependent MAPK activation and IL-8 secretion in intestinal epithelial cells.
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.
authors.affiliation: Gastrointestinal Research Group, Health Sciences Centre, University of Calgary, Calgary, AB T2N 1N4, Canada.
authors.forename: Humberto B
authors.initials: HB
authors.lastname: Jijon
authors.forename: Andre
authors.initials: A
authors.lastname: Buret
authors.forename: Christina L
authors.initials: CL
authors.lastname: Hirota
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Paul L
authors.initials: PL
authors.lastname: Beck
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D019073:HT29 Cells; D006801:Humans; D047468:Immunoprecipitation; D016209:Interleukin-8 / Q000378:metabolism*; D007422:Intestines / Q000166:cytology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011799:Quinazolines / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D066246:ErbB Receptors; D016209:Interleukin-8; D020928:Mitogen-Activated Protein Kinases; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C101044:RTKI cpd