MicroRNAs in Papillary Thyroid Cancer: What Is New in Diagnosis and Treatment

Abstract

IntroductionPapillary thyroid cancer (PTC) accounts for up to 80% of thyroid malignancies. New diagnostic and therapeutic options are suggested including innovative molecular methods. MicroRNAs (miRNAs) are nonprotein coding single-stranded RNAs that regulate many cell processes. The aim of the present study is to review the deregulated miRNAs associated with PTCs.MethodsA bibliographic research was conducted, resulting in 272 articles referred to miRNAs and PTC. Regarding our exclusion criteria, 183 articles were finally included in our review.ResultsA remarkably large number of miRNAs have been found to be deregulated during PTC manifestation in the literature. The deregulated miRNAs are detected in tissue samples, serum/plasma, and FNA samples of patients with PTC. These miRNAs are related to several molecular pathways, involving genes and proteins responsible for important biological processes. MiRNA deregulation is associated with tumor aggressiveness, including larger tumor size, multifocality, extrathyroidal extension, lymphovascular invasion, lymph node and distant metastasis, and advanced tumor node metastasis stage.ConclusionMiRNAs are proposed as new diagnostic and therapeutic tools regarding PTC. They could be essential biomarkers for PTC diagnosis applied in serum and FNA samples, while their contribution to prognosis is of great importance.

Expression Profile and Diagnostic Significance of MicroRNAs in Papillary Thyroid Cancer

“…To increase the diagnostic accuracy of using miRNAs, we assessed a combination of four miRNAs (miR-152-3p, miR-221-3p, miR-551b-3p, and miR-7-5p) with a calculated AUC of 0.841. Moreover, the AUC values obtained in our study are comparable to those previously published in the literature [ 16 , 36 , 47 ]. Other authors also proposed miR-221 measurement as a potential biomarker of PTC recurrence [ 18 ].…”

“…Thus, the improved standardization of methods used to evaluate miRNAs expression may support their introduction in the personalized medicine approach in PTC patients. Significant literature data have already been accumulated on the particular miRNA expression in a specific type of specimens in PTC [ 33 , 34 , 35 , 36 ], however, miRNA expression pattern using large-scale methods with subsequent data validation are still needed to fill in the data gap. Our miRNA combination distinguishes between early PTC and normal tissue, thus additional studies including benign tissues should be performed to confirm the diagnostic usefulness of the miRNA panel.…”

“…Notably, miRNA deregulation has been implicated in the development of many different cancers, including thyroid cancer [ 20 , 39 ]. Literature data show a relationship between the expression of various miRNAs in thyroid cancer and the TNM classification [ 17 , 36 ]. The evaluation of PTC pathogenesis particularly emphasizes the deregulation of miR-146b, miR-221, miR-222, miR-181b, and miR-21 [ 40 ].…”

“…The evaluation of PTC pathogenesis particularly emphasizes the deregulation of miR-146b, miR-221, miR-222, miR-181b, and miR-21 [ 40 ]. Deregulation of miR-146b affects the MAPK/ERK and TGF-β pathways, thus increasing the risk of vascular invasion and metastasis to lymph nodes and distant organs [ 36 ]. Another miRNA implicated in the pathogenesis of PTC is miR-181b whose upregulation affects the inhibition of apoptosis and promotion of cell division [ 41 ].…”

“…This promotes the migration of PTC cells [ 48 ]. Another biomarker that could differentiate PTC from benign lesions is miR-155 [ 36 ]. Moreover, the let-7 family, which downregulates RAS expression, has the potential to be a biomarker of PTC [ 49 ].…”