Tumor-associated Tn antigen (Tn antigen)

The "Tumor-associated Tn antigen" is a truncated O-linked glycan structure defined by an N-acetylgalactosamine residue attached via an α-glycosidic linkage to serine or threonine residues on proteins—most notably mucins—on the cell surface[1][4]. It arises from abnormal O-glycosylation due to dysfunction of key enzymes such as C1GALT1 or its chaperone Cosmc. The overexpression of this glycan is observed in up to 90% of human carcinomas including breast, colon, gastric, lung and other cancers[7]. Its presence correlates with poor prognosis and increased metastatic potential due to its roles in promoting tumor growth through enhanced cell proliferation/migration and decreased apoptosis[1]. The "Tn antigen" also contributes significantly to immune evasion by modulating the tumor microenvironment. It reduces cytotoxic CD8+ T-cell infiltration while increasing myeloid-derived suppressor cells within tumors[1], fostering an immunosuppressive milieu that supports cancer progression. Additionally, it disrupts normal cell-cell adhesion structures leading to increased invasiveness via epithelial-to-mesenchymal transition pathways[2]. As a result of these properties—and because it is largely absent from healthy adult tissues—the "Tumor-associated Tn antigen" serves as both a diagnostic biomarker for various cancers and an emerging target for experimental cancer immunotherapies such as vaccines or antibody-based treatments aimed at restoring anti-tumor immunity or directly targeting malignant cells expressing this epitope[3].

Other names

Tn antigenTumor-associated carbohydrate antigen (TACA)α-GalNAc-O-Ser/Thr (N-acetylgalactosamine linked to serine or threonine)GalNAc-TnMucin-type Tn antigen