thematic review Thematic Review Series: Sphingolipids Ganglioside GM3 suppresses the proangiogenic effects of vascular endothelial growth factor and ganglioside GD1a Purna Mukherjee, Anthony C. Faber, Laura M. Shelton, Rena C. Baek, Thomas C. Chiles, and Thomas N. Seyfried 1 Department of Biology, Boston College, Chestnut Hill, MA 02467 Abstract Gangliosides are sialic acid-containing glyco- sphingolipids that have long been associated with tumor malignancy and metastasis. Mounting evidence suggests that gangliosides also modulate tumor angiogenesis. Tumor cells shed gangliosides into the microenvironment, which produces both autocrine and paracrine effects on tumor cells and tumor-associated host cells. In this study, we show that the simple monosialoganglioside GM3 counteracts the proangiogenic effects of vascular endothelial growth factor (VEGF) and of the complex disialoganglioside GD1a. GM3 suppressed the action of VEGF and GD1a on the prolifer- ation of human umbilical vein endothelial cells (HUVECs) and inhibited the migration of HUVECs toward VEGF as a chemoattractant. Enrichment of added GM3 in the HUVEC membrane also reduced the phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR-2) and downstream Akt. Moreover, GM3 reduced the proan- giogenic effects of GD1a and growth factors in the in vivo Matrigel plug assay. Inhibition of GM3 biosynthesis with the glucosyl transferase inhibitor, N-butyldeoxynojirimycin (N B-DNJ), increased HUVEC proliferation and the phos- phorylation of VEGFR-2 and Akt. The effects of N B-DNJ on HUVECs were reversed with the addition of GM3. We conclude that GM3 has antiangiogenic action and may possess therapeutic potential for reducing tumor angio- genesis.—Mukherjee, P., A. C. Faber, L. M. Shelton, R. C. Baek, T. C. Chiles, and T. N. Seyfried. Ganglioside GM3 suppresses the proangiogenic effects of vascular endothelial growth factor and ganglioside GD1a. J. Lipid Res. 2008. 49: 929–938. Supplementary key words glycosphingolipid & human umbilical endothelial cell migration & matrigel plug assay & growth factor receptor & phosphorylated Akt Gangliosides are a family of sialic acid-containing glycosphingolipids that are enriched in the outer surface of plasma membranes and have long been associated with tumor malignancy and metastasis (1–3). These molecules contain an oligosaccharide head group that is attached to a lipophilic ceramide, consisting of a sphingosine base and a long-chain fatty acid. Gangliosides can be shed from the surface of tumor cells into the microenvironment, where they can influence tumor host cell interactions to include angiogenesis (1, 4–13). Ganglioside GM3, a sim- ple monosialoganglioside (NeuAca2Y3Galb1Y4Glcb1Y 1¶-ceramide), modulates cell adhesion, proliferation, and differentiation (2, 5, 12, 14). The antiproliferative and proapoptotic effects of GM3 were observed in glioma cells grown both in vivo and in vitro (15–17). In contrast to GM3, complex gangliosides like GM2, GM1, GD1a, GD1b, GT1b, and GD3, which contain longer oligosaccharide chains than that of GM3, enhance tumor cell prolifer- ation, invasion, and metastasis (1, 3, 14, 18, 19). Increased tumorigenic effects of complex gangliosides were ob- served in a variety of tumor cells, including bladder, lym- phoma, glioma, neuroblastoma, and melanoma (7, 11, 14, 20–22). Specific inhibitors of ganglioside biosynthesis also reduced tumor growth (23–25), whereas gene-linked shifts in ganglioside distribution changed tumor growth and angiogenesis in vivo (4, 8, 12). Endothelial cell signaling is important in cancer- associated vascularity (angiogenesis). The proliferation and migration of endothelial cells in response to growth factors is one of the major determinants of tumor growth and progression. Dysregulation of the balance between proangiogenic and antiangiogenic factors contributes to Manuscript received 3 January 2008 and in revised form 15 February 2008. Published, JLR Papers in Press, February 20, 2008. DOI 10.1194/jlr.R800006-JLR200 Abbreviations: bFGF, basic fibroblast growth factor; EBM, endo- thelial basal medium; EGFR, epidermal growth factor receptor; EGM- 2, endothelial growth medium; HPTLC, high-performance thin-layer chromatography; HUVEC, human umbilical vein endothelial cell; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; N B-DNJ, N-butyldeoxynojirimycin; VEGF, vascular endothelial growth factor; VEGFR-2, vascular endothelial growth factor receptor 2. 1 To whom correspondence should be addressed. e-mail: thomas.seyfried@bc.edu Copyright D 2008 by the American Society for Biochemistry and Molecular Biology, Inc. This article is available online at http://www.jlr.org Journal of Lipid Research Volume 49, 2008 929 by guest, on May 12, 2016 www.jlr.org Downloaded from