Two miRNAs enriched in plasma extracellular vesicles are potential biomarkers for thyroid cancer

Abstract

Differential diagnosis of thyroid cancer and benign nodules is still one of the most challenging issues in the field of endocrinology. To overcome overdiagnosis of papillary thyroid carcinomas (PTC) and the consecutive overtreatment of multinodular diseases, the search for easily accessible, sensitive and accurate biomarkers is critical. Several micro-RNAs (miRNAs) freely circulating in peripheral blood or enclosed in extracellular vesicles (EVs) have been proposed as potential biomarkers from non-invasive liquid biopsies. However, protocols are rarely comparable and conflicting data exists in the literature. In this work, we aimed to assess the diagnostic value of 6 micro-RNAs by comparing their expression in thyroid tissue to their abundance in bulk plasma and in plasma-EVs, before and after thyroid surgery. Plasma-EVs were isolated using a sequential density- and size-based fractionation, followed by in-depth characterization, confirming EV purity. Micro-RNA levels were measured by RT-qPCR in thyroid tissue, plasma and plasma-EVs. Among the 6 candidates, only miR-146b-5p and miR-21a-5p displayed a significant differential abundance in purified plasma-derived EVs from patients with PTC and benign disease. However, no difference could be demonstrated in bulk plasma through our cohort of patients. Overall, our work supports the use of a well-defined protocol of plasma-EV miRNAs purification for biomarker discovery, rather than the use of freely-circulating miRNAs in bulk plasma. Our work also demonstrates that standardized pre-analytical and analytical procedures as well as optimized EV-miRNAs detection methods are essential.

Role of Extracellular Vesicles in Thyroid Physiology and Diseases: Implications for Diagnosis and Treatment

“…Only miR-146b-5p and miR-21a-5p displayed a significant differential abundance in EVs purified from the plasma of patients with PTC as compared to benign disease. No difference could be demonstrated in bulk plasma, and no correlation could be highlighted between abundance in EVs and expression in tissue [ 54 ]. The absence of a relationship between the abundance of most free and encapsulated miRNA in the serum of a patient with thyroid diseases was also reported [ 55 ].…”

BRAFV600E expression in thyrocytes causes recruitment of immunosuppressive STABILIN-1 macrophages

“…Total RNA was extracted from mice thyroid tissues using TRIzol Reagent (Thermo Scientific), as described in [25] followed by an additional phenol/chloroform purification step. Total RNA was extracted from human thyroid tissues using miRNeasy Mini kit (Qiagen) according to the manufacturer's instructions and as described [26]. Tissue-RNA concentration was measured by spectrophotometry (Thermo Scientific, NanoDrop 8000).…”

The diagnostic performance of microRNAs expression levels in cellular aspirate of solitary thyroid nodule overrides that of cytology

“…7 The widespread use of diagnostic imaging and more sensitive diagnostic tools resulted in great increase in incidence of small and localized thyroid tumors; however, this may result in over-diagnosis of STN, and needs to be refined to guard against faulty surgicaldecision making. 8 The preliminary diagnosis of STN depending on the cytological examination of fine needle aspirate (FNA) had certain fallacies especially for the nodules diagnosed cytologically as indeterminate nodules. 9…”