title: Muscarinic regulation of SCA-9 cell proliferation via nitric oxide synthases, arginases and cyclooxygenases. Role of the nuclear translocation factor-κB.
abstract: The submandibular gland-derived tumor cell line SCA-9 is considered a useful tool to study the signaling pathways involved in proliferation, and their regulation, triggered by different stimuli. It is proposed that the non neuronal cholinergic system: acethylcholine, the enzymes that synthesize and degrade it, and the nicotinic and muscarinic receptors, play a key role in tumorigenesis. Here, we investigate the role of muscarinic receptors in SCA-9 cell proliferation, and the modulation of cholinergic signaling pathways exerted by the nuclear transcription factor κB (NF-κB). The activation of cholinergic receptors by carbachol (10⁻⁹M) increased cell proliferation (P<0.001). This was prevented by preincubating cells with the muscarinic antagonist atropine but not by mecamylamine, a nicotinic receptor blocker. Phospholipase C (PLC)/nitric oxide synthase (NOS)/arginase pathway is involved in this effect, since carbachol stimulated nitric oxide production, increased NOS2 and NOS3 expressions, urea production, and arginase II expression (P<0.001). Also, phospholipase A₂ (PLA₂)/cyclooxygenase (COX) pathway is up-regulated in carbachol-induced SCA-9 cell proliferation, because prostaglandin E₂ liberation (P<0.001) is increased and COX-1 expression is turned up (P<0.001). Interactions between PLC/NOS/arginases and PLA₂/COX pathways via its metabolites were detected. SCA-9 cells exhibit a constitutive activation of NF-κB, which regulates carbachol-induced NOS2 and 3, arginase II and COX-1 expressions. In addition, protein kinase C is involved in the up-regulation of NOS2 and arginase II enzymes induced by carbachol via NF-κB. In conclusion, the activation of cholinergic receptors in SCA-9 tumor cells promotes proliferation via muscarinic effector enzymes, and reveals the participation of NF-κB at this step of tumorigenesis.
authors.affiliation: Centro de Estudios Farmacológicos y Botánicos (CEFYBO)-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155 piso 16, CP1 121 Buenos Aires, Argentina.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Español
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Dasso
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Cella
authors.forename: Nora
authors.initials: N
authors.lastname: Goren
authors.forename: María Elena
authors.initials: ME
authors.lastname: Sales
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001119:Arginase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D018679:Cholinergic Agonists / Q000494:pharmacology; D051545:Cyclooxygenase 1 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D018727:Muscarinic Antagonists / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000737:chemistry / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013365:Submandibular Gland Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D018679:Cholinergic Agonists; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D018727:Muscarinic Antagonists; D016328:NF-kappa B; D009363:Neoplasm Proteins; D064801:Phospholipase A2 Inhibitors; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D019001:Nitric Oxide Synthase; D051545:Cyclooxygenase 1; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D054467:Phospholipases A2; C481673:Arg2 protein, mouse; D001119:Arginase