Glycobiology Advance Access originally published online on October 16, 2006
Glycobiology 2007 17(2):185-196; doi:10.1093/glycob/cwl059
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P-selectin mediates metastatic progression through binding to sulfatides on tumor cells
3 Center for Integrative Human Physiology
4 Institute of Physiology, University of Zürich, 8057 Zürich, Switzerland
5 GlycoInit ETH, Swiss Federal Institute of Technology Zurich, Wolfgang Paulistrasse 10, CH-8093 Zürich, Switzerland
1 To whom correspondence should be addressed; Tel: +41 44 635 5134; Fax: +41 44 635 6814; e-mail: lborsig{at}access.unizh.ch
Received on June 21, 2006; revised on October 4, 2006; accepted on October 6, 2006
Hematogenous carcinoma metastasis is associated with tumor cell emboli formation, which is now known to be facilitated by selectins. P-selectin-mediated interactions of platelets with cancer cells are based mostly on mucin- and glycosaminoglycan-type selectin ligands. We previously showed that mouse colon carcinoma cells (MC-38) carry P-selectin ligands of nonmucin origin, which were not identified. Here we show that P-selectin ligands recognized on MC-38 cells are sulfated glycolipids, thereby facilitating experimental metastasis in a syngeneic mouse model. Metabolic inhibition of sulfation by incubation of cells with sodium chlorate almost completely abrogated P-selectin binding. Metabolic labeling of MC-38 cells with 35S sulfate revealed only a single band as detected by high-performance thin layer chromatography analysis of a total lipid extract. Matrix-assisted laser desorption/ionization tandem time-of-flight/time-of-flight analysis (MALDI-TOF-TOF) analysis of the purified sulfate-containing lipid fraction identified the selectin ligand to be a sulfated galactosylceramide SM4 (HSO3-3Galß-1Cer). Modulation of glycolipid biosynthesis in MC-38 cells altered P-selectin binding, thereby confirming sulfoglycolipids to be major P-selectin ligands. In addition, P-selectin was also found to recognize lactosylceramide sulfate SM3 (HSO3-3Galß-4Glcß-1Cer) and gangliotriaosylceramide sulfate SM2 [GalNAcß-4(HSO3-3)Galß-4Glcß-1Cer] in human hepatoma cells. Finally, the enzymatic removal of sulfation from the cell surface of MC-38 cells resulted in decreased P-selectin binding and led to attenuation of metastasis. Thus, SM4 sulfatide serves as a native ligand for P-selectin contributing to cell–cell interactions and to facilitation of metastasis.
Key words: carbohydrate sulfation / glycolipids / MALDI-TOF / metastasis / selectin
2 Present address: Unit for Molecular Glycobiology, Department for Molecular Biomedical Research, Ghent University and VIB, Technologiepark 927, B-9052 Ghent-Zwijnaarde, Belgium