Downregulation of miR‑486‑5p in papillary thyroid carcinoma tissue: A study based on microarray and miRNA sequencing.

Abnormal expression of microRNA (miR) is associated with the occurrence and progression of various types of cancers, including papillary thyroid carcinoma (PTC). In the present study, the aim was to explore miR‑486‑5p expression and its role in PTC, as well as to investigate the biological function of its potential target genes. The expression levels of miR‑486‑5p and its clinicopathological significance were examined in 507 PTC and 59 normal thyroid samples via The Cancer Genome Atlas (TCGA). Subsequently, the results were validated using data from Gene Expression Omnibus (GEO) and ArrayExpress. Receiver operating characteristic and summary receiver operating characteristic curves were used to assess the ability of miR‑486‑5p in distinguishing PTC from normal tissue. Furthermore, potential miR‑486‑5p mRNA targets were identified using 12 prediction tools and enrichment analysis was performed on the encoding genes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. The expression levels of miR‑486‑5p were consistently downregulated in PTC compared with in normal tissue across datasets from TCGA, GEO (GSE40807, GSE62054 and GSE73182) and ArrayExpress (E‑MTAB‑736). The results also demonstrated that miR‑486‑5p expression was associated with cancer stage (P=0.003), pathologic lymph node (P=0.047), metastasis (P=0.042), neoplasm (P=0.012) and recurrence (P=0.016) in patients with PTC. In addition, low expression of miR‑486‑5p in patients with PTC was associated with a worse overall survival. A total of 80 miR‑486‑5p‑related genes were observed from at least 9 of 12 prediction platforms, and these were involved in 'hsa05200: Pathways in cancer' and 'hsa05206: MicroRNAs in cancer'. Finally, three hub genes, CRK like proto‑oncogene, phosphatase and tensin homolog and tropomyosin 3, were identified as important candidates in tumorigenesis and progression of PTC. In conclusion, it may be hypothesized that miR‑486‑5p contributes towards PTC onset and progression, and may act as a clinical target. However, in vitro and in vivo experiments are required to validate the findings of the present study.