title: P-selectin mediates metastatic progression through binding to sulfatides on tumor cells.
abstract: 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 (35)S 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 (HSO(3)-3Galbeta-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 (HSO(3)-3Galbeta-4Glcbeta-1Cer) and gangliotriaosylceramide sulfate SM2 [GalNAcbeta-4(HSO(3)-3)Galbeta-4Glcbeta-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.
authors.affiliation: Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Josep
authors.initials: J
authors.lastname: Garcia
authors.forename: Nico
authors.initials: N
authors.lastname: Callewaert
authors.forename: Lubor
authors.initials: L
authors.lastname: Borsig
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D002450:Cell Communication; D018450:Disease Progression; D006801:Humans; D008024:Ligands; D051379:Mice; D009362:Neoplasm Metastasis; D019007:P-Selectin / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013433:Sulfoglycosphingolipids / Q000032:analysis / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D008024:Ligands; D019007:P-Selectin; D013433:Sulfoglycosphingolipids