MicroRNA-519 suppresses cell growth and invasion by reducing HuR levels in hepatocellular carcinoma

MicroRNAs (miRNAs), which are suppressors of gene expression, participate in diverse biological functions and in carcinogenesis. Aberrant expression of miR-519 has been confirmed in various human cancer tissues and cells, and it represses HuR translation without influencing HuR mRNA level. However, the role of miR-519 in hepatocellular carcinoma (HCC) has yet to be elucidated. Here, we analyzed the miR-519 expression in HCC tissues and cell lines using qRT-PCR. We observed that miR-519 was dramatically downregulated in HCC clinical specimens and cell lines as compared to normal tissues and cells. In addition, enhanced expression of miR-519 resulted in the inhibition of cell growth through suppressing proliferation and promoting apoptosis, and repression of cell invasion. Importantly, we found that miR-519 potently repressed HuR expression through suppressing translation without affecting HuR mRNA level. Meanwhile, our results demonstrated that HuR protein level in the cancer tissues was inversely correlated with miR-519 expression in 25 HCC patients. Furthermore, overexpression of HuR abrogates the suppressive effects of miR-519 upregulation on HCC cell growth and invasion. Taken together, our findings suggested that miR-519 might functions as a tumor suppressor via inhibiting HuR expression in the development of progression of HCC, and implicated the potential application of miR-519 in HCC treatment.