title: Eicosanoid activation of extracellular signal-regulated kinase1/2 in human epidermoid carcinoma cells.
abstract: 12(S)-Hydroxyeicosatetraenoic acid (12(S)-HETE), a 12-lipoxygenase metabolite of arachidonic acid, has multiple effects on tumor and endothelial cells, including stimulation of invasion and angiogenesis. However, the signaling mechanisms controlling these physiological processes are poorly understood. In a human epidermoid carcinoma cell line (i.e. A431), 12(S)-HETE activates extracellular signal-regulated kinases 1/2 (ERK1/2), which is mediated by upstream kinases MEK and Raf. 12(S)-HETE stimulates phosphorylation of phospholipase Cgamma1 and activity of protein kinase Calpha (PKCalpha). In addition, independent of PKC 12(S)-HETE increases tyrosine phosphorylation of Shc, and Grb2, stimulates association between Shc and Src, and increases the activity of Ras, via Src family kinases. Furthermore, at low (10-100 nm) concentrations 12(S)-HETE counteracts epidermal growth factor-stimulated activation of ERK1/2 via stimulating protein tyrosine phosphatases. We also present evidence that 12(S)-HETE stimulates ERK1/2 via G proteins and that A431 cells have multiple binding sites for 12(S)-HETE. Finally, inhibition of 12-lipoxygenase induced apoptosis of A431 cells, which was reversed by addition of exogenous 12(S)-HETE. Collectively we demonstrate that the activation of ERK1/2 by 12(S)-HETE may be regulated by multiple receptors triggering PKC-dependent and PKC-independent pathways in A431 cells.
authors.affiliation: Department of Radiation Oncology and the Departments of Pathology and Chemistry, Wayne State University, Detroit Michigan 48202, USA.
authors.forename: C K
authors.initials: CK
authors.lastname: Szekeres
authors.forename: K
authors.initials: K
authors.lastname: Tang
authors.forename: M
authors.initials: M
authors.lastname: Trikha
authors.forename: K V
authors.initials: KV
authors.lastname: Honn
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000494:pharmacology*; D001092:Arachidonate 12-Lipoxygenase / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000201:enzymology*; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D016859:Lipoxygenase Inhibitors; D048728:MAP Kinase Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D051966:Phospholipase C gamma; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D016859:Lipoxygenase Inhibitors; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D004815:Epidermal Growth Factor; D001092:Arachidonate 12-Lipoxygenase; D017346:Protein Serine-Threonine Kinases; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma