title: Inhibition of angiogenesis by blockers of volume-regulated anion channels.
abstract: Osmotic cell swelling activates an outwardly rectifying Cl(-) current in endothelial cells that is mediated by volume-regulated anion channels (VRACs). In the past, we have shown that serum-induced proliferation of endothelial cells is arrested in the presence of compounds that potently block the endothelial VRACs. Here we report on the effects of four chemically distinct VRAC blockers [5-nitro-2-(3-phenylpropylamino)benzoic acid] (NPPB), mibefradil, tamoxifen, and clomiphene-on several models of experimental angiogenesis. Mibefradil (20 microM), NPPB (100 microM), tamoxifen (20 microM), and clomiphene (20 microM) inhibited tube formation by rat microvascular endothelial cells plated on matrigel by 42.9 +/- 8.8%, 25.3 +/- 10.4%, 32.2 +/- 4.5%, and 20 +/- 5.8%, respectively (p < 0.05). Additionally, NPPB (50-100 microM) and mibefradil (10-30 microM) significantly inhibited bFGF (10 ng/ml) + TNFalpha (2.5 ng/ml)-stimulated microvessel formation by human microvascular endothelial cells plated on fibrin by 30-70%. Furthermore, NPPB, mibefradil, and clomiphene concentration dependently inhibited spontaneous microvessel formation in the rat aorta-ring assay and vessel development in the chick chorioallantoic membrane assay. These results suggest that VRAC blockers are potent inhibitors of angiogenesis and thus might serve as therapeutic tools in tumor growth and other angiogenesis-dependent diseases.
authors.affiliation: Laboratory of Pharmacology, University of Thrace Medical School, I. Kaviri 6, 68100, Alexandroupolis, Greece. manolopoulos@users.duth.gr
authors.forename: V G
authors.initials: VG
authors.lastname: Manolopoulos
authors.forename: S
authors.initials: S
authors.lastname: Liekens
authors.forename: P
authors.initials: P
authors.lastname: Koolwijk
authors.forename: T
authors.initials: T
authors.lastname: Voets
authors.forename: E
authors.initials: E
authors.lastname: Peters
authors.forename: G
authors.initials: G
authors.lastname: Droogmans
authors.forename: P I
authors.initials: PI
authors.lastname: Lelkes
authors.forename: E
authors.initials: E
authors.lastname: De Clercq
authors.forename: B
authors.initials: B
authors.lastname: Nilius
mesh_terms: D000482:Allantois / Q000098:blood supply / Q000187:drug effects; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000254:growth & development; D002417:Cattle; D002478:Cells, Cultured; D002642:Chick Embryo; D002823:Chorion / Q000098:blood supply / Q000187:drug effects; D002996:Clomiphene / Q000494:pharmacology; D003094:Collagen; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D005337:Fibrin; D006801:Humans; D066298:In Vitro Techniques; D007473:Ion Channels / Q000037:antagonists & inhibitors*; D007797:Laminin; D008297:Male; D020748:Mibefradil / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D009579:Nitrobenzoates / Q000494:pharmacology; D011509:Proteoglycans; D051381:Rats; D017208:Rats, Wistar; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D020533:Angiogenesis Inhibitors; D004338:Drug Combinations; D007473:Ion Channels; D007797:Laminin; D009579:Nitrobenzoates; D011509:Proteoglycans; D013629:Tamoxifen; C059485:matrigel; D002996:Clomiphene; D020748:Mibefradil; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D005337:Fibrin; D003094:Collagen