Downregulation of miR-519d-3p is Associated with Poor Outcomes and Facilitates Tumor Progression in Papillary Thyroid Cancer by Regulating FOXQ1.

MicroRNA-519d-3p (miR-519d-3p) has emerged as a tumor suppressor in several human cancers. But whether miR-519d-3p is involved in papillary thyroid cancer (PTC) remains elusive. In this study, we investigated the potential relevance of miR-miR-519d-3p in PTC. A retrospective study of 119 PTCs was carried out. The RT-qPCR analysis was used to measure the expression of miR-519d-3p and FOXQ1 in PTC tissues and cells. Chi-square test, Kaplan-Meier curve analysis, and multivariate Cox regression analyses were performed to assess the clinical and prognostic value of miR-519d-3p in PTC. Then cellular experiments were used to explore its biological effects on PTC cells. Finally, the Pearson correlation coefficient, dual-luciferase reporter assay, and rescue experiments were used to analyze the association between miR-519d-3p and FOXQ1. miR-519d-3p was significantly downregulated in PTC tissues and cell lines. The decreased expression of miR-519d-3p was associated with reduced overall survival and progression-free survival of patients. The proliferative, migratory, and invasive abilities of cells were blocked or elevated after upregulation or downregulation of miR-519d-3p, while FOXQ1 reversed these cellular behaviors caused after upregulation or knockdown of miR-519d-3p. In conclusion, miR-519d-3p was downregulated in PTC and associated with OS and PFS of patients. MiR-519d-3p may be a tumor-inhibiting miRNA in PTC, and that miR-519d-3p/FOXQ1 axis mediated PTC tumor progression from cell proliferation, migration, and invasion in PTC cells.