Thyroid-Originating Extracellular Vesicles Harbor Thyroid-Specific Biomarkers with Potential Relevance for Thyroid Cancer Recurrence Detection

Thyroid cancer (TC) is the most common endocrine malignancy, and challenges persist in preoperative diagnosis of indeterminate nodules and postoperative monitoring when thyroglobulin (Tg) assays are compromised by interfering anti-Tg antibodies (Tg-Ab). Extracellular vesicles (EVs) carry molecular cargo reflective of cells of origin and are increasingly explored as biomarker sources. In this study, we investigated whether thyroid-derived EVs retain the expression of thyroid-specific thyrotropin-receptor (TSHR), a suitable target in immunoaffinity-based EV isolation, and explored the presence of Tg in EV cargo as potential surrogate for serum Tg. EVs from thyroid cell lines (Nthy-Ori 3-1, TPC-1, OCUT2) and plasma of patients with benign, malignant tumors and recurrent TC were isolated by differential ultracentrifugation and characterized via nanoparticle tracking and Dot and Western blot analyses. EVs derived from Nthy-Ori 3-1 and TPC-1 cell lines were positive for surface TSHR and vesicular Tg, but not OCUT2. All plasma-derived EVs were positive for TSHR and Tg, while their electrophoretic profiles from vesicles differed compared to tissue lysate. Tg was detectable in EVs isolated from recurrent TC samples, even in Tg-Ab positive cases. Together, these results support the use of TSHR for targeted EV isolation and point to vesicular Tg as a potential recurrence marker.