Sialyl-di-Lewis a antigen

Sialyl-di-Lewis a antigen is a complex branched tetrasaccharide glycan structure characterized by the presence of sialic acid linked α(2→3) to galactose, which is β(1→3) linked to N-acetylglucosamine that also carries an α(1→4) fucose residue. It is best known as the epitope recognized by CA19.9 assays and serves as an important tumor-associated carbohydrate antigen overexpressed in many adenocarcinomas—especially those of the pancreas, hepato-biliary system, and digestive tract[1][2][3]. Functionally, it acts as a ligand for E-selectin on endothelial cells facilitating leukocyte adhesion and cancer cell extravasation during metastasis[3]. Its biosynthesis involves specific sialyltransferases and fucosyltransferases acting on type 1 lactosaminic chains[2]. The clinical significance of this molecule lies primarily in its use as a diagnostic biomarker for certain cancers rather than as an established direct therapeutic target at present.

Other names

Sialyl Lewis a antigensLeaCA19.9 antigen (when referring to the epitope)NeuAcalpha2,3Galbeta1-3[Fucalpha1-4]GlcNAcalpha-Neu5Ac-(2->3)-beta-D-Gal-(1->3)-[alpha-L-Fuc-(1->4)]-D-GlcNAc[1][2]

generally, inhibition of this glycan would block tumor cell adhesion/migration via E-selectin.