title: Nitric oxide-induced epidermal growth factor-dependent phosphorylations in A431 tumour cells.
abstract: Nitric oxide (NO*) strongly inhibits the proliferation of human A431 tumour cells. It also inhibits tyrosine phosphorylation of a 170-kDa band corresponding to the epidermal growth factor receptor (EGFR) and induces the phosphorylation at tyrosine residue(s) of a 58-kDa protein which we have denoted NOIPP-58 (nitric oxide-induced 58-kDa phosphoprotein). The NO*-induced phosphorylation of NOIPP-58 is strictly dependent on the presence of EGF. Phosphorylation of NOIPP-58 and inhibition of the phosphorylation of the band corresponding to EGFR are both cGMP-independent processes. We also demonstrate that the p38 mitogen-activated protein kinase (p38MAPK) pathway is activated by NO* in the absence and presence of EGF, whereas the activity of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and the c-Jun N-terminal kinase 1/2 (JNK1/2) pathways are not significantly affected or are slightly decreased, respectively, on addition of this agent. Moreover, we show that the p38MAPK inhibitor, SB202190, induces rapid vanadate/peroxovanadate-sensitive dephosphorylation of prephosphorylated EGFR and NOIPP-58. We propose that the dephosphorylation of both NOIPP-58 and EGFR are mediated by a p38MAPK-controlled phosphotyrosine-protein phosphatase (PYPP). Activation of the p38MAPK pathway during nitrosative stress probably prevents the operation of this PYPP, allowing NOIPP-58, and in part EGFR, to remain phosphorylated and therefore capable of generating signalling events.
authors.affiliation: Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Ruano
authors.forename: Silvia
authors.initials: S
authors.lastname: Hernández-Hernando
authors.forename: Amparo
authors.initials: A
authors.lastname: Jiménez
authors.forename: Carmen
authors.initials: C
authors.lastname: Estrada
authors.forename: Antonio
authors.initials: A
authors.lastname: Villalobo
mesh_terms: D002294:Carcinoma, Squamous Cell; D004273:DNA, Neoplasm / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology; D007700:Kinetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004273:DNA, Neoplasm; D006834:Hydrazines; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D019000:Phosphotyrosine; D009569:Nitric Oxide; D004815:Epidermal Growth Factor; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D066246:ErbB Receptors; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013936:Thymidine