Expression Profile and Diagnostic Significance of MicroRNAs in Papillary Thyroid Cancer

SIMPLE SUMMARY: In recent years, the incidence of papillary thyroid cancer (PTC) has increased in many countries worldwide. MicroRNAs appear to be important regulators of PTC, but a better understanding of their role is needed to develop novel diagnostic tools and identify potential vulnerabilities. In this study, we aimed to gain insight into the microRNA profile of PTC tissue. Consequently, crucial pathways in PTC were highlighted. A panel of four microRNAs (miR-152-3p, miR-221-3p, miR-551b-3p, and miR-7-5p) was proposed as a PTC diagnostic biomarker. Our analysis indicated that microRNAs are a potential diagnostic tool for PTC patients. ABSTRACT: The incidence of papillary thyroid cancer (PTC) has increased in recent years. To improve the diagnostic management of PTC, we propose the use of microRNAs (miRNAs) as a biomarker. Our aim in this study was to evaluate the miRNA expression pattern in PTC using NanoString technology. We identified ten miRNAs deregulated in PTC compared with reference tissue: miR-146b-5p, miR-221-3p, miR-221-5p, miR-34-5p, miR-551b-3p, miR-152-3p, miR-15a-5p, miR-31-5p, and miR-7-5p (FDR < 0.05; |fold change (FC)| ≥ 1.5). The gene ontology (GO) analysis of differentially expressed miRNA (DEM) target genes identified the predominant involvement of epidermal growth factor receptor (EGFR), tyrosine kinase inhibitor resistance, and pathways in cancer in PTC. The highest area under the receiver operating characteristic (ROC) curve (AUC) for DEMs was found for miR-146-5p (AUC = 0.770) expression, indicating possible clinical applicability in PTC diagnosis. The combination of four miRNAs (miR-152-3p, miR-221-3p, miR-551b-3p, and miR-7-5p) showed an AUC of 0.841. Validation by real-time quantitative polymerase chain reactions (qRT-PCRs) confirmed our findings. The introduction of an miRNA diagnostic panel based on the results of our study may help to improve therapeutic decision making for questionable cases. The use of miRNAs as biomarkers of PTC may become an aspect of personalized medicine.