title: Thrombospondin-1-induced apoptosis of brain microvascular endothelial cells can be mediated by TNF-R1.
abstract: Thrombospondin-1 (TSP-1) treatment of dermal microvascular endothelial cells (MvEC) has been shown to upregulate Fas ligand (FasL) and to induce apoptosis by a mechanism that requires caspase-8 activity. We have examined the potential anti-angiogenic effects of TSP-1 on primary human brain MvEC. The addition of TSP-1 to primary human brain MvEC cultured as monolayers on type 1 collagen, induced cell death and apoptosis (evidenced by caspase-3 cleavage) in a dose- (5-30 nM) and time-dependent (maximal at 17 h) manner. TSP-1 treatment for 17 h induced caspase-3 cleavage that required caspase-8 activity and the tumor necrosis factor receptor 1 (TNF-R1). We did not find a requirement for Fas, or the tumor necrosis-related apoptosis-inducing ligand receptors (TRAIL-R) 1 and 2. We confirmed the findings using caspase inhibitors, blocking antibodies and small interfering RNA (siRNA). Further analysis indicated that the TSP-1 induction of caspase-3 cleavage of primary human brain MvEC adherent to collagen required the synthesis of new message and protein, and that TSP-1 induced the expression of TNFalpha mRNA and protein. Consistent with these findings, when the primary human brain MvEC were propagated on collagen gels mAb anti-TNF-R1 reversed the inhibitory effect, in part, of TSP-1 on tube formation and branching. These data identify a novel mechanism whereby TSP-1 can inhibit angiogenesis-through induction of apoptosis in a process mediated by TNF-R1.
authors: Division of Neuropathology, Department of Pathology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors: Tanya A
authors: TA
authors: Rege
authors: Jerry
authors: J
authors: Stewart
authors: Brian
authors: B
authors: Dranka
authors: Etty N
authors: EN
authors: Benveniste
authors: Roy L
authors: RL
authors: Silverstein
authors: Candece L
authors: CL
authors: Gladson
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D001921:Brain / Q000166:cytology* / Q000378:metabolism*; D018955:CD36 Antigens / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008833:Microcirculation / Q000187:drug effects; D018919:Neovascularization, Physiologic / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019700:Thrombospondin 1 / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D018955:CD36 Antigens; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D047888:Receptors, Tumor Necrosis Factor, Type I; D019700:Thrombospondin 1; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; D053148:Caspase 3