MiRNAs in Extracellular Vesicles as Biomarkers in Plasma of Papillary Thyroid Cancer Patients: A Proof-of-Concept Study

Simple Summary Cancer diagnoses, including papillary thyroid carcinoma (PTC), are increasing, and early detection is critical for successful treatment. To help address this, our study focuses on identifying reliable biomarkers-specific molecules indicating the presence of disease-that can be detected through non-invasive methods like liquid biopsies. We examined small RNA molecules, known as microRNAs (miRNAs), found in microparticles called extracellular vesicles (EVs) in blood samples from PTC patients, which are linked to the development of PTC. Our results showed these miRNAs were present at higher levels in PTC patients and returned to normal after surgery, suggesting their potential as reliable indicators of PTC. The use of these biomarkers in EVs could allow easier, less invasive, and more frequent testing compared to current methods, improving early detection and monitoring of thyroid cancer, thus benefiting patients and healthcare systems.Abstract Background: The incidence of various types of cancer, for example, papillary thyroid carcinoma (PTC), is on the rise. Since therapeutic success depends greatly on early diagnosis, reliable diagnostic biomarkers must be identified, and easy-to-apply tools for detecting them must urgently be standardized. Here, we contribute to solving this medical challenge by assessing miRNAs suspected of promoting carcinogenesis in extracellular vesicles (EVs) that can be routinely obtained via liquid biopsy. We profit from current progress in cancerology that provides innovations in liquid biopsy and EVs analysis, along with the identification of miRNAs and chaperone system (CS) components implicated in carcinogenesis. Methods: We measured in EVs obtained from circulating blood plasma from PTC patients the levels of three miRNAs implicated in thyroid cancer, hsa-miR-1-3p, hsa-miR-206, and hsa-miR-221-3p, and most likely involved in the regulation of two members of the CS, Hsp60 and CCT. EVs were isolated from the plasma of patients with PTC and controls with benign goiter (BG) and from the culture medium of a PTC cell line (MDAT32) and were appropriately characterized. Results: The levels of miRNAs determined by RT-qPCR were consistently higher in PTC patients and decreased down to control levels after thyroidectomy. Bioinformatics showed that the miRNAs target genes are associated with the molecular pathogenesis of PTC. Conclusions: Our exploratory study reaffirms the potential in clinics of the selected miRNAs in EVs as useful biomarkers of PTC easily accessible via liquid biopsy, which is minimally invasive and amenable to periodic repetition, an improvement compared to the established fine-needle aspirate biopsy.