Mucin 1, tumor-associated glycoform (TA-MUC1)

Mucin 1, tumor-associated glycoform (TA-MUC1) is a transmembrane glycoprotein that is aberrantly expressed and glycosylated in over 90% of breast, pancreatic, and ovarian adenocarcinomas (PMID: 29158515). Unlike the MUC1 found on healthy epithelial cells, which is heavily glycosylated with long, branched carbohydrate chains, TA-MUC1 features truncated O-glycans such as the Tn and Sialyl-Tn antigens (PMID: 30333295). This hypoglycosylation exposes the protein backbone, specifically the tandem repeat domain, creating unique neoepitopes that are highly specific to malignant cells (UniProt P15941). Biologically, TA-MUC1 acts as an oncoprotein by interacting with signaling molecules like EGFR and beta-catenin to promote cell proliferation, survival, and metastasis (PMID: 24523238). It also plays a role in immune evasion by binding to Siglec-9 on myeloid cells, thereby inducing an immunosuppressive environment (PMID: 27105311). Because of its high tumor specificity and role in disease progression, TA-MUC1 is a primary target for various immunotherapies, including monoclonal antibodies, CAR-T cells, and vaccine platforms (ClinicalTrials.gov).

Other names

tMUC1Tumor-associated MUC1MUC1-TnMUC1-STnCD227Epithelial membrane antigenPolymorphic epithelial mucinPEMKL-6CA 15-3

The primary mechanism of action for drugs targeting TA-MUC1 involves the induction of immune-mediated cytotoxicity. Monoclonal antibodies like gatipotuzumab bind to tumor-specific glycopeptide epitopes to trigger antibody-dependent cellular cytotoxicity (ADCC) (PMID: 21938615). Therapeutic vaccines, such as tecemotide, stimulate the production of cytotoxic T-lymphocytes (CTLs) that recognize MUC1-derived peptides presented on MHC class I molecules (PMID: 24333119). CAR-T cell therapies, such as P-MUC1C-ALLO1, utilize chimeric antigen receptors to directly recognize and kill cells expressing the MUC1-C or Tn-MUC1 glycoforms (PMID: 26901400). Additionally, peptide inhibitors like GO-203 target the MUC1-C cytoplasmic domain to block its oncogenic signaling and dimerization (PMID: 19651621).