title: Novel role of lactosylceramide in vascular endothelial growth factor-mediated angiogenesis in human endothelial cells.
abstract: Vascular endothelial growth factor (VEGF) has been implicated in angiogenesis associated with coronary heart disease, vascular complications in diabetes, inflammatory vascular diseases, and tumor metastasis. The mechanism of VEGF-driven angiogenesis involving glycosphingolipids such as lactosylceramide (LacCer), however, is not known. To demonstrate the involvement of LacCer in VEGF-induced angiogenesis, we used small interfering RNA (siRNA)-mediated silencing of LacCer synthase expression (GalT-V) in human umbilical vein endothelial cells. This gene silencing markedly inhibited VEGF-induced platelet endothelial cell adhesion molecule-1 (PECAM-1) expression and angiogenesis. Second, we used D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), an inhibitor of LacCer synthase and glucosylceramide synthase, that significantly mitigated VEGF-induced PECAM-1 expression and angiogenesis. Interestingly, these phenotypic changes were reversed by LacCer but not by structurally related compounds such as glucosylceramide, digalactosylceramide, and ceramide. In a human mesothelioma cell line (REN) that lacks the endogenous expression of PECAM-1, VEGF/LacCer failed to stimulate PECAM-1 expression and tube formation/angiogenesis. In REN cells expressing human PECAM-1 gene/protein, however, both VEGF and LacCer-induced PECAM-1 protein expression and tube formation/angiogenesis. In fact, VEGF-induced but not LacCer-induced angiogenesis was mitigated by SU-1498, a VEGF receptor tyrosine kinase inhibitor. Also, VEGF/LacCer-induced PECAM-1 expression and angiogenesis was mitigated by protein kinase C and phospholipase A2 inhibitors. These results indicate that LacCer generated in VEGF-treated endothelial cells may serve as an important signaling molecule for PECAM-1 expression and in angiogenesis. This finding and the reagents developed in our report may be useful as anti-angiogenic drugs for further studies in vitro and in vivo.
authors.affiliation: Johns Hopkins Singapore.
authors.forename: Mohanraj
authors.initials: M
authors.lastname: Rajesh
authors.forename: Antonina
authors.initials: A
authors.lastname: Kolmakova
authors.forename: Subroto
authors.initials: S
authors.lastname: Chatterjee
mesh_terms: D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D005700:Galactosyltransferases / Q000502:physiology; D006801:Humans; D007790:Lactosylceramides / Q000502:physiology*; D009025:Morpholines / Q000494:pharmacology; D018919:Neovascularization, Physiologic; D010741:Phospholipases A / Q000502:physiology; D054467:Phospholipases A2; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics; D011493:Protein Kinase C / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D007790:Lactosylceramides; D009025:Morpholines; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C033110:RV 538; D005700:Galactosyltransferases; C039090:UDPgalactose-glucosylceramide galactosyltransferase; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2