Lysophosphatidic acid-induced squamous cell carcinoma cell proliferation and motility involves epidermal growth factor receptor signal transactivation.
Transactivation of the epidermal growth factor receptor (EGFR) represents the paradigm for cross-talk between G protein-coupled receptors (GPCRs) and receptor tyrosine kinase signaling pathways. In a variety of squamous cell carcinoma cell lines of the head and neck (HNSCCs), we found that treatment with the GPCR agonists lysophosphatidic acid (LPA), bradykinin, thrombin, and carbachol results in rapid tyrosine phosphorylation of the EGFR. In these tumor cells, signal transactivation of the EGFR and the oncoprotein HER2/neu is critically dependent on metalloprotease activity. Using the metalloprotease inhibitor batimastat, the EGFR-specific tyrphostin AG1478, and a dominant-negative EGFR mutant, we show that in HNSCC cell lines, EGFR tyrosine phosphorylation, recruitment of the adaptor proteins SHC and Gab1, and activation of the ERK/mitogen-activated protein kinase pathway in response to LPA depend both on metalloprotease function and EGFR tyrosine kinase activity. Most importantly, critical characteristics of HNSCC cell lines such as DNA synthesis, cell cycle progression and tumor cell migration are stimulated by LPA and can be abrogated by interfering with EGFR signal transmission. Together, our results demonstrate the importance of a mechanism that promotes head and neck cancer cell proliferation and motility by GPCR ligands involving EGFR transactivation. Our findings suggest that highly abundant GPCR ligands such as LPA may function as tumor promoters and determinants of HNSCC progression.
Gschwind
Andreas
A
Department of Molecular Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany.
Prenzel
Norbert
N
Ullrich
Axel
A
D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D004273:DNA, Neoplasm / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000201:enzymology / Q000473:pathology*; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008666:Metalloendopeptidases / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000502:physiology; D016196:S Phase / Q000502:physiology; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured; D020032:Tyrphostins / Q000494:pharmacology
D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D019204:GTP-Binding Proteins; D008246:Lysophospholipids; D008666:Metalloendopeptidases; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D020032:Tyrphostins; C101044:RTKI cpd