Analysis of Let-7 Family miRNA in Plasma as Potential Predictive Biomarkers of Diagnosis for Papillary Thyroid Cancer

Abstract

The most common histological type of thyroid cancer is papillary thyroid carcinoma (PTC). Radical resection of the thyroid gland is currently the recommended method of treatment. Almost 75% of thyroidectomies performed just for diagnostic purposes are benign. Thus, the confirmation of innovative and more precise noninvasive biomarkers holds promise for the detection of PTC, which may decrease the number of unnecessary thyroid lobectomies. In this work, using the droplet digital PCR (ddPCR) method, we have analyzed the level of five miRNAs (let-7a, let-7c, let-7d, let-7f, and let-7i) in the plasma of patients with PTC and compared them with those of a healthy control group to investigate whether miRNAs also have value in the management of PTC. Levels of four miRNAs, namely let-7a, let-7c, let-7d, and let-7f, were significantly higher in PTC patients than healthy controls. Thus, the analysis of circulating let-7 can be a useful tool and support the currently used methods for PTC diagnosis. However, our observation requires further research on a larger patient group.

Opportunities and Challenges of Liquid Biopsy in Thyroid Cancer

“…Comprehensively, a set of mi-RNAs (mi-RNA-375, 34a, 145b, 221, 222, 155, Let-7, and 181b) can be designated as a diagnostic biomarker to distinguish PTCs from benign nodules and identify cancer at an early stage [ 45 ]. Additional evidence suggests that plasma-derived mi-RNA-222 and another set of circulating mi-RNAs (let-7a, let-7c, let-7d, and let-7f) can be significantly increased in PTC patients compared to subjects with goiter or healthy controls [ 46 , 47 ]. In a prospective observational study, the serum levels of 754 mi-RNAs were measured in 11 PTC patients before and after surgery.…”

The Importance of miRNA in the Diagnosis and Prognosis of Papillary Thyroid Cancer

“…Furthermore, the study performed by Perdas et al suggested that the screening panel, consisting of four miRNAs, such as let-7a, let-7c, let-7d, and let-7f, whose levels were elevated in plasma, have a higher PTC screening utility [ 72 ]. Accordingly, Ricarte-Filho et al showed that the let-7 family affects growth and differentiation of PTCs.…”

MiRNA let-7 from TPO(+) Extracellular Vesicles is a Potential Marker for a Differential Diagnosis of Follicular Thyroid Nodules

“…The involvement of Let-7 in thyroid carcinogenesis has been described in a number of studies [ 18 ], however, all reports published thus far have focused on papillary thyroid cancer. For example, the elevated level of Let-7a, Let-7c, Let-7d, and Let-7f in the plasma of papillary thyroid cancer patients has been reported recently [ 19 ]. Moreover, Let-7 is being discussed as a promising serum for miRNA markers for the diagnosis and prognosis of thyroid cancer [ 20 ].…”

“…In addition to the Let-7 miRNA family, FTC-relevant miRNAs, other types of vesicular RNA, or other vesicular components can serve as a marker of follicular cell malignancy. Moreover, an increase in the plasma level of Let-7 miRNAs was also associated with papillary thyroid cancer [ 19 ]. These data and the design of our study do not allow us to argue about the diagnostic specificity of Let-7, even isolated from TPO(+)EV.…”