title: Targeting CD9 produces stimulus-independent antiangiogenic effects predominantly in activated endothelial cells during angiogenesis: a novel antiangiogenic therapy.
abstract: The precise roles of tetraspanin CD9 are unclear. Here we show that CD9 plays a stimulus-independent role in angiogenesis and that inhibiting CD9 expression or function is a potential antiangiogenic therapy. Knocking down CD9 expression significantly inhibited in vitro endothelial cell migration and invasion induced by vascular endothelial growth factor (VEGF) or hepatocyte growth factor (HGF). Injecting CD9-specific small interfering RNA (siRNA-CD9) markedly inhibited HGF- or VEGF-induced subconjunctival angiogenesis in vivo. Both results revealed potent and stimulus-independent antiangiogenic effects of targeting CD9. Furthermore, intravitreous injections of siRNA-CD9 or anti-CD9 antibodies were therapeutically effective for laser-induced retinal and choroidal neovascularization in mice, a representative ocular angiogenic disease model. In terms of the mechanism, growth factor receptor and downstream signaling activation were not affected, whereas abnormal localization of integrins and membrane type-1 matrix metalloproteinase was observed during angiogenesis, by knocking down CD9 expression. Notably, knocking down CD9 expression did not induce death and mildly inhibited proliferation of quiescent endothelial cells under conditions without an angiogenic stimulus. Thus, CD9 does not directly affect growth factor-induced signal transduction, which is required in angiogenesis and normal vasculature, but is part of the angiogenesis machinery in endothelial cells during angiogenesis. In conclusion, targeting CD9 produced stimulus-independent antiangiogenic effects predominantly in activated endothelial cells during angiogenesis, and appears to be an effective and safe antiangiogenic approach. These results shed light on the biological roles of CD9 and may lead to novel antiangiogenic therapies.
authors.affiliation: Department of Gene Therapy and Regenerative Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Kamisasanuki
authors.forename: Saori
authors.initials: S
authors.lastname: Tokushige
authors.forename: Hiroto
authors.initials: H
authors.lastname: Terasaki
authors.forename: Ngin Cin
authors.initials: NC
authors.lastname: Khai
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Wang
authors.forename: Taiji
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Kosai
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics; D002478:Cells, Cultured; D020256:Choroidal Neovascularization / Q000188:drug therapy / Q000235:genetics / Q000628:therapy*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D034741:RNA, Small Interfering / Q000008:administration & dosage; D051381:Rats; D015861:Retinal Neovascularization / Q000188:drug therapy / Q000235:genetics / Q000628:therapy*; D060245:Tetraspanin 29; D014161:Transduction, Genetic
chemical_list: D000906:Antibodies; D015703:Antigens, CD; C554869:CD9 protein, human; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D034741:RNA, Small Interfering; D060245:Tetraspanin 29; D053511:Matrix Metalloproteinase 14