sphingosine-1-phosphate and Fibrosarcoma

Sphingolipid metabolites including ceramide, sphingosine, and their phosphorylated products [sphingosine-1-phosphate (S1P) and ceramide-1-phosphate] regulate cell functions including arachidonic acid (AA) metabolism and cell death. The development of analogs of S1P may be useful for regulating these mediator-induced cellular responses. We synthesized new analogs of S1P and examined their effects on the release of AA and cell death in L929 mouse fibrosarcoma cells. Among the analogs tested, several compounds including DMB-mC11S [dimethyl (2S,3R)-2-tert-butoxycarbonylamino-3-hydroxy-3-(3'-undecyl)phenylpropyl phosphate] and DMB-mC9S [dimethyl (2S,3R)-2-tert-butoxycarbonylamino-3-hydroxy-3-(3'-nonyl)phenylpropyl phosphate] released AA within 1 h and caused cell death 6 h after treatment. The release of AA was observed in C12 cells [a L929 variant lacking a type alpha cytosolic phospholipase A(2) (cPLA(2)alpha)] and L929-cPLAalpha-siRNA cells (L929 cells treated with small interference RNA for cPLA(2)alpha). Treatment with pharmacological inhibitors of secretory and Ca(2+)-independent PLA(2)s decreased the DMB-mC11S-induced release of AA. The effect of the S1P analogs tested on the release of AA was comparable to that on cell death in L929 cells, and a high correlation coefficient was observed. Two analogs lacking a butoxycarbonyl moiety [DMAc-mC11S (dimethyl (2S,3R)-2-acetamino-3-hydroxy-3-(3'-undecyl)phenylpropyl phosphate] and DMAm-mC11S [dimethyl (2S,3R)-2-amino-3-hydroxy-3-(3'-undecyl)phenylpropyl phosphate)] had inhibitory effects on the release of AA and cell toxicity induced by DMB-mC11S. Synthetic phosphorylated lipid analogs may be useful for studying PLA(2) activity and its toxicity in cells. [Supplementary Fig. 1: available only at http://dx.doi.org/10.1254/jphs.08284FP].

Topics: Animals; Arachidonic Acid; Cell Death; Cell Line, Tumor; Fibrosarcoma; Group IV Phospholipases A2; Lysophospholipids; Mice; RNA, Small Interfering; Sphingosine; Structure-Activity Relationship; Time Factors

Vascular endothelial growth factor (VEGF) and platelet-derived lipid sphingosine-1-phosphate (S1P) are two proinflammatory mediators which contribute to angiogenesis, in part through the synthesis of platelet-activating factor (PAF). The red grape skin polyphenolic extract (SGE) both prevents and inhibits angiogenesis in the Matrigel model, decreases the basal motility of endothelial and cancer cells, and reverses the chemotactic effect of S1P and VEGF on bovine aortic endothelial cells (BAECs) as well as the chemotactic effect of conditioned medium on human HT-1080 fibrosarcoma, human U-87 glioblastoma, and human DAOY medulloblastoma cells. Inhibition of VEGF- and S1P-mediated chemotaxis by SGE is associated with a down-regulation of ERK and p38/MAPK phosphorylation and a decreased in acute PAF synthesis. Notably, as do extracellular inhibitors of PAF receptor, SGE prevents S1P-induced PAF synthesis and the resulting activation of the S1P/endothelial differentiation gene-1 cascade. Given the key role of VEGF and S1P in inflammation, angiogenesis, and tumor invasion, SGE may therefore contribute to prevent (or to delay) the development of diseases associated with angiogenesis dysregulation, including cancer. The dual inhibition of S1P- and VEGF-mediated migration of endothelial cell and of serum-stimulated migration of U-87 cells suggests a usefulness of SGE against highly invasive human glioblastoma.

Topics: Animals; Aorta; Cattle; Cell Movement; Cells, Cultured; Chemotaxis; Endothelium, Vascular; Fibrosarcoma; Flavonoids; Glioblastoma; Humans; Lysophospholipids; Medulloblastoma; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neovascularization, Pathologic; Neovascularization, Physiologic; p38 Mitogen-Activated Protein Kinases; Phenols; Phosphorylation; Platelet Activating Factor; Platelet Membrane Glycoproteins; Polyphenols; Receptors, G-Protein-Coupled; Sphingosine; Vascular Endothelial Growth Factor A; Vitis