Lysophosphatidic acid decreases epidermal growth factor receptor binding in airway epithelial cells

Karen M. Kassel, Nancy A. Schulte, Stacey M. Parker, Aaron D. Lanik, Myron L. Toews

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

We showed previously that treatment of human airway smooth muscle cells and lung fibroblasts with lysophosphatidic acid (LPA) increases the binding of epidermal growth factor (EGF) to EGF receptors (EGFRs). The purpose of this study was to determine whether LPA also regulates EGFR binding in airway epithelial cells. Airway epithelial cells were incubated in the absence or presence of 10 μM LPA for increasing times, and binding of 125I-EGF to intact cells on ice was measured. Exposure to LPA for only 15 min caused a 30 to 70% decrease in EGFR binding in a dose-dependent manner, depending on the cell line. This decrease in binding was sustained to at least 18 h in BEAS-2B and primary human bronchial epithelial cells. In contrast, the LPA-induced decrease in binding reversed rapidly in two lung cancer epithelial cell lines, H292 and A549, returning to control levels within 3 h. LPA increased phosphorylation of the EGFR in BEAS-2B cells, and this phosphorylation was inhibited by both 4-(3′-chloroanilino)-6,7-dimethoxy- quinazoline (AG1478; EGFR tyrosine kinase inhibitor) and N-[(2R)-2- (hydroxamidocarbonylmethyl)-4-methylpentanoyl]-L-tryptophan methylamide (GM6001; matrix metalloproteinase inhibitor) but not by CRM197 (heparin-binding EGF inhibitor). AG-1478 and GM6001 also inhibited the LPA-induced decrease in EGFR binding but only by 50%, suggesting only partial involvement of EGFR transactivation in the decrease in EGFR binding. In summary, LPA stimulates a decrease in EGFR binding in airway epithelial cells that is sustained in normal cells but that rapidly reverses in cancer cells. LPA-induced transactivation of EGFRs occurs and contributes to the decrease in EGFR binding, but additional pathway(s) may also be involved.

Original languageEnglish (US)
Pages (from-to)109-118
Number of pages10
JournalJournal of Pharmacology and Experimental Therapeutics
Volume323
Issue number1
DOIs
StatePublished - Oct 2007

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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