Tenascin-C (Fibronectin type III domain D) (TNC-D)

Tenascin-C is a large, hexameric extracellular matrix (ECM) glycoprotein that is highly expressed during embryogenesis but largely absent in healthy adult tissues, except for specific niches like tendons and lymphoid organs [UniProt P24821]. The FNIII-D domain is one of the extra domains included in the protein through alternative splicing of the fibronectin type III repeats, specifically characterizing the "large" isoforms of Tenascin-C [PubMed: 19435940]. These large isoforms are prominently upregulated in the tumor stroma of various cancers, including glioblastoma, breast, and lung carcinoma, as well as in inflammatory conditions like rheumatoid arthritis [PubMed: 20603601]. Because of its high tumor-to-normal tissue ratio, the FNIII-D domain serves as a specific target for antibody-based therapies designed to deliver payloads directly to the disease site. The most prominent targeting agent is the F16 human monoclonal antibody, which has been developed into various fusion proteins such as F16-IL2 (Teleukin) and F16-TNF (Fibromun) to stimulate localized immune responses [PubMed: 25605114]. These therapeutic strategies leverage the stable presence of the FNIII-D domain in the ECM to achieve high local concentrations of cytokines, thereby enhancing anti-tumor efficacy while reducing systemic side effects. Beyond oncology, the domain is also explored as a target for imaging and treating chronic inflammatory diseases where ECM remodeling is active. The domain's role in the ECM involves modulating cell-matrix interactions, often promoting a "pro-migratory" environment that facilitates tumor invasion and metastasis.

Other names

TNCCytotactinNeuronectinGMEMJIGP 150-225Tenascin-C large isoformFNIII-DTenascin-C domain D

Targeted delivery of immunomodulatory cytokines or radionuclides to the extracellular matrix of diseased tissues via high-affinity antibody binding to the FNIII-D splice domain, facilitating localized therapeutic action.