Abstract
MicroRNA-219-5p (miR-219-5p) is a key post-transcriptional regulator of gene expression that is known to regulate cancer progression, but its role in the context of hepatocellular carcinoma (HCC) remains to be fully elucidated. Herein, it was found that this miRNA functions as a tumor suppressor. Specifically, significant decreases in miR-219-5p expression were detected in HCC cells and patient serum samples relative to that found in the serum of 15 healthy people, and it was concluded that miR-219-5p overexpression was sufficient to impair HCC cell proliferation in vitro and vivo and migration in vitro. At the mechanistic level, it was found that miR-219-5p was able to suppress the expression of NEK6 (never in mitosis gene a-related kinase 6), thereby resulting in dysregulated β-catenin/c-Myc-regulated gene expression. When NEK6 was overexpressed in HCC cells, this was sufficient to reverse the inhibitory impact of miR-219-5p on HCC cell proliferation both in vitro and vivo and metastasis in vitro. Bioinformatics analyses were also conducted, and both miR-219-5p and Nek6 were linked to disease progression in HCC patients with advanced disease. More importantly, the serum specimen data showed that reduced perioperative plasma miR-219-5p correlated significantly with increased risk of early recurrence after curative hepatectomy, whereas it was opposed to NEK6. Together, these findings highlight miR-219-5p as a potentially valuable diagnostic biomarker that can potentially be leveraged to improve clinical outcomes in HCC patients.