Sialyl Tn antigen is a tumor-associated carbohydrate antigen (TACA) that is overexpressed in a variety of carcinomas such as breast, ovarian, and colon cancer. CD BioGlyco has accumulated rich experience in chemoenzymatic synthesis of sialyl Tn, which is considered a specific tumor-associated antigen for vaccination.
Sialyl Tn is a disaccharide formed of one residue of N-acetyl-galactosamine (GalNAc) alpha-O-linked to a serine or a threonine residue and substituted by a sialic acid (Neu5Ac in humans) on carbon 6, also referred to as CD175s by the “cluster of differentiation” nomenclature. The activation of an abnormal glycosylation pathway in cancer cells leads to the formation of the sialyl Tn. Therefore, sialyl Tn is absent in normal healthy tissues but can be detected at various frequencies in almost all kinds of carcinomas. Early studies identified the sialyl Tn as a marker for diagnosis and subsequent prognosis in cancer, and later work focused on using sialyl Tn as a potential therapeutic target to treat cancers, notably breast cancer.
Fig.1 Structure of sialyl Tn antigen. (Martinez-Duncker, 2011)
The biosynthesis of sialyl Tn is mediated by a specific sialyltransferase termed ST6GalNAc I, which competes with O-glycans elongating glycosyltransferases and prevents cancer cells from exhibiting longer O-glycans. Especially, the biosynthesis of sialyl Tn is mediated in vitro by the specific sialyltransferases ST6GalNAc1 and ST6GalNAc2. However, in a cellular context, only ST6GalNAc1 synthesizes STn.
Fig.2 Biosynthesis of sialyl Tn antigen in cancer cells. (Munkley, 2016)
At CD BioGlyco, custom STn antigen production services include but are not limited to:
The chemical sialylation step often leads to low yields due to difficulties in controlling the stereospecificity of a-sialyl linkage. Our chemoenzymatic synthesis of STn and its derivatives provides higher regio- and stereo-selectivity of α-sialyl linkage than the chemical synthesis of STn. For example, we prepare STn-polysaccharide A1 conjugate which invokes a robust cellular immunity.
For example, the STn expression level is evaluated by an immunoradiometric competitive inhibition assay and flow cytometric analysis. Moreover, we provide the analysis of STn using western blotting.
CD BioGlyco has been working on sialic acid research for many years and providing clients with high-quality Sialic Acid Analysis Services. We have a wide variety of synthetic stratrgies to provide high-quality STn antigens. If you are interested in our services, please contact us for more detailed information.
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