title: Novel antiangiogenic pathway of thrombospondin-1 mediated by suppression of the cell cycle.
abstract: We have recently reported that keratin 14-promoter-driven vascular endothelial growth factor (VEGF)-E(NZ-7) transgenic mice have a significant number of capillary vessels in subcutaneous tissue. However, these vessels are generated in a layer some distance from the epithelial basal cells that express VEGF-E(NZ-7), suggesting that one or more antiangiogenenic molecules may exist very near the basal cell layer. By screening keratinocyte-conditioned medium, we found that thrombospondin-1 (TSP-1) is produced from keratinocytes and suppresses human umbilical vein endothelial cells (HUVEC) growth as well as tubular formation in a HUVEC-fibroblast coculture system. Different to the known mechanism of CD36-dependent endothelial cell apoptosis, the HUVEC we used did not express CD36 at detectable levels, indicating a new mechanism for TSP-1-induced antiangiogenesis. We found that TSP-1 induces little apoptosis of endothelial cells but causes cell-cycle arrest, increasing the amounts of p21(CIP/WAF-1) and unphosphorylated retinoblastoma (Rb) in HUVEC. CD36-binding peptide in TSP-1 and CD36-neutralizing antibody did not block the TSP-1-induced cell-cycle arrest. Our results strongly suggest that TSP-1 utilizes a novel pathway for its antiangiogenic effect independent of CD36, and suppresses the cell cycle.
authors.affiliation: Departement of Genetics, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Yamauchi
authors.forename: Shinobu
authors.initials: S
authors.lastname: Imajoh-Ohmi
authors.forename: Masabumi
authors.initials: M
authors.lastname: Shibuya
mesh_terms: D000595:Amino Acid Sequence; D020533:Angiogenesis Inhibitors / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D006131:Growth Inhibitors / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D015398:Signal Transduction / Q000502:physiology*; D019700:Thrombospondin 1 / Q000378:metabolism / Q000502:physiology*; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism / Q000502:physiology
chemical_list: D020533:Angiogenesis Inhibitors; D006131:Growth Inhibitors; D019700:Thrombospondin 1