title: Endothelin-1 and endothelin-3 promote invasive behavior via hypoxia-inducible factor-1alpha in human melanoma cells.
abstract: Endothelin (ET) B receptor (ET(B)R), which is overexpressed in human cutaneous melanomas, promotes tumorigenesis upon activation by ET-1 or ET-3, thus representing a potential novel therapeutic target. Hypoxia-inducible factor-1alpha (HIF-1alpha) is the transcriptional factor that conveys signaling elicited by hypoxia and growth factor receptors. Here, we investigated the interplay between ET axis and hypoxia in primary and metastatic melanoma cell lines. We report that under normoxic conditions, ET(B)R activation by ET-1/ET-3 enhances vascular endothelial growth factor (VEGF) up-regulation, cyclooxygenase (COX)-1/COX-2 protein expression and COX-2 promoter activity, prostaglandin E(2) (PGE(2)) production, and do so to a greater extent under hypoxia. Moreover, COX-1/COX-2 inhibitors block ET-induced PGE(2) and VEGF secretion, matrix metalloproteinase (MMP) activation, and cell invasion, indicating that both enzymes function as downstream mediators of ET-induced invasive properties. The ET(B)R selective antagonist BQ788 or transfection with ET(B)R small interfering RNA (siRNA) block the ET-mediated effects. ETs also increase HIF-1alpha expression under both normoxic and hypoxic conditions and its silencing by siRNA desensitizes COX-2 transcriptional activity, PGE(2) and VEGF production, and MMP activation in response to ET-3, implicating, for the first time, HIF-1alpha/COX as downstream targets of ET(B)R signaling leading to invasiveness. In melanoma xenografts, specific ET(B)R antagonist suppresses tumor growth, neovascularization, and invasiveness-related factors. Collectively, these results identify a new mechanism whereby ET-1/ET-3/ET(B)R axis can promote and interact with the HIF-1alpha-dependent machinery to amplify the COX-mediated invasive behavior of melanoma. New therapeutic strategies using specific ET(B)R antagonist could provide an improved approach to the treatment of melanoma by inhibiting tumor growth and progression.
authors.affiliation: Laboratory of Molecular Pathology and Ultrastructure, Rome Oncogenomic Center, and Laboratory of Immunology, Regina Elena Cancer Institute, Via delle Messi d'Oro 156, 00158 Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Spinella
authors.forename: Laura
authors.initials: L
authors.lastname: Rosanò
authors.forename: Valeriana
authors.initials: V
authors.lastname: Di Castro
authors.forename: Samantha
authors.initials: S
authors.lastname: Decandia
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Nicotra
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Natali
authors.forename: Anna
authors.initials: A
authors.lastname: Bagnato
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1 / Q000096:biosynthesis; D051546:Cyclooxygenase 2 / Q000096:biosynthesis / Q000235:genetics; D015232:Dinoprostone / Q000096:biosynthesis; D019332:Endothelin-1 / Q000494:pharmacology*; D019334:Endothelin-3 / Q000494:pharmacology*; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008545:Melanoma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D044023:Receptor, Endothelin B / Q000378:metabolism; D012878:Skin Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D019332:Endothelin-1; D019334:Endothelin-3; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D044023:Receptor, Endothelin B; D042461:Vascular Endothelial Growth Factor A; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D020782:Matrix Metalloproteinases; D015232:Dinoprostone