title: Inhibition of L- and P-selectin by a rationally synthesized novel core 2-like branched structure containing GalNAc-Lewisx and Neu5Acalpha2-3Galbeta1-3GalNAc sequences.
abstract: The selectins interact in important normal and pathological situations with certain sialylated, fucosylated glycoconjugate ligands containing sialyl Lewisx(Neu5Acalpha2-3Galbeta1-4(Fucalpha1-3)GlcN Ac). Much effort has gone into the synthesis of sialylated and sulfated Lewisxanalogs as competitive ligands for the selectins. Since the natural selectin ligands GlyCAM-1 and PSGL-1 carry sialyl Lewisxas part of a branched Core 2 O-linked structure, we recently synthesized Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-6(SE-3Galbeta1++ +-3)GalNAc1alphaOMe and found it to be a moderately superior ligand for L and P-selectin (Koenig et al. , Glycobiology 7, 79-93, 1997). Other studies have shown that sulfate esters can replace sialic acid in some selectin ligands (Yeun et al. , Biochemistry, 31, 9126-9131, 1992; Imai et al. , Nature, 361, 555, 1993). Based upon these observations, we hypothesized that Neu5Acalpha2-3Galbeta1-3GalNAc might have the capability of interacting with L- and P-selectin. To examine this hypothesis, we synthesized Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-6(Neu5Acalpha2++ +-3Galbeta1-3)-GalNAc alpha1-OB, which was found to be 2- to 3-fold better than sialyl Lexfor P and L selectin, respectively. We also report the synthesis of an unusual structure GalNAcbeta1-4(Fucalpha1- 3)GlcNAcbeta1-OMe (GalNAc-Lewisx-O-methyl glycoside), which also proved to be a better inhibitor of L- and P-selectin than sialyl Lewisx-OMe. Combining this with our knowledge of Core 2 branched structures, we have synthesized a molecule that is 5- to 6-fold better at inhibiting L- and P-selectin than sialyl Lewisx-OMe, By contrast to unbranched structures, substitution of a sulfate ester group for a sialic acid residue in such a molecule resulted in a considerable loss of inhibition ability. Thus, the combination of a sialic acid residue on the primary (beta1-3) arm, and a modified Lexunit on the branched (beta1-6) arm on an O-linked Core 2 structure generated a monovalent synthetic oliogosaccharide inhibitor superior to SLexfor both L- and P-selectin.
authors.affiliation: Department of Gynecologic Oncology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Jain
authors.forename: C F
authors.initials: CF
authors.lastname: Piskorz
authors.forename: B G
authors.initials: BG
authors.lastname: Huang
authors.forename: R D
authors.initials: RD
authors.lastname: Locke
authors.forename: H L
authors.initials: HL
authors.lastname: Han
authors.forename: A
authors.initials: A
authors.lastname: Koenig
authors.forename: A
authors.initials: A
authors.lastname: Varki
authors.forename: K L
authors.initials: KL
authors.lastname: Matta
mesh_terms: D001667:Binding, Competitive; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D007700:Kinetics; D019041:L-Selectin / Q000187:drug effects / Q000502:physiology*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D009904:Optical Rotation; D019007:P-Selectin / Q000187:drug effects / Q000502:physiology*; D000080506:Sialyl Lewis X Antigen; D013329:Structure-Activity Relationship
chemical_list: D007074:Immunoglobulin G; D007202:Indicators and Reagents; D008024:Ligands; D009844:Oligosaccharides; D019007:P-Selectin; D000080506:Sialyl Lewis X Antigen; D019041:L-Selectin