574444

MIR491

microRNA 491;MIR491;microRNA 491

-

9p21.3

ncRNA

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide; the prognosis of HCC patient remains poor owing to intrahepatic and extrahepatic metastasis and postsurgical recurrence. The aim of the present study is to determine the molecular mechanisms underlying the metastasis of HCC. METHODS: HCC patients and treated HCC cells were molecularly characterized by miRNA microarray analysis, qRT-PCR, Western blots, transwell assay, and immunohistochemistry. RESULTS: Here, by employing a miRNAs microarray analysis, we found that miR-491 level was the most significant down-regulation in poorly differentiated HCC tissue compared with well-differentiated HCC tissue. We then selected HepG2 (very low migratory capacity), MHCC97L (low migratory capacity) and MHCC97H (high migratory capacity), as well as HCC tissues with different status to further investigate the effects of miR-491 on the metastasis of HCC. Our data showed that miR-491 levels were inversely correlated with different status of differentiation in HCC tissues and with migratory potential in HCC cell lines. In HepG2 cells, inhibition of miR-491 increased the expression of matrix metalloproteinase 2/9 (MMP-2/9) and the migratory potential; however, in MHCC97H cells, overexpression of miR-491 level decreased the expression of MMP-2/9 and the migratory capacity. Moreover, miR-491 had a positive relationship with E-cadherin level; however, it had a negative relationship with vimentin level both in cell lines and tissue samples of HCC. MiR-491 levels of non-metastasis HCC tissue are higher than that of metastasis HCC tissue. CONCLUSION: Our results suggest that miR-491 is involved in metastasis of HCC by blocking EMT and decreasing MMP-9 levels, which may provide a new clue for preventing tumour metastasis of HCC.

MicroRNAs offer tools to identify and treat invasive cancers. Using highly invasive isogenic oral squamous cell carcinoma (OSCC) cells, established using in vitro and in vivo selection protocols from poorly invasive parental cell populations, we used microarray expression analysis to identify a relative and specific decrease in miR-491-5p in invasive cells. Lower expression of miR-491-5p correlated with poor overall survival of patients with OSCCs. miR-491-5p overexpression in invasive OSCC cells suppressed their migratory behavior in vitro and lung metastatic behavior in vivo. We defined the G-protein-coupled receptor kinase-interacting protein 1 (GIT1)-as a direct target gene for miR-491-5p control. GIT1 overexpression was sufficient to rescue miR-491-5p-mediated inhibition of migration/invasion and lung metastasis. Conversely, GIT1 silencing phenocopied the ability of miR-491-5p to inhibit migration/invasion and metastasis of OSCC cells. Mechanistic investigations indicated that miR-491-5p overexpression or GIT1 attenuation reduced focal adhesions, with a concurrent decrease in steady-state levels of paxillin, phospho-paxillin, phospho-FAK, EGF/EGFR-mediated extracellular signal-regulated kinase (ERK1/2) activation, and MMP2/9 levels and activities. In clinical specimens of OSCCs, GIT1 levels were elevated relative to paired normal tissues and were correlated with lymph node metastasis, with expression levels of miR-491-5p and GIT1 correlated inversely in OSCCs, where they informed tumor grade. Together, our findings identify a functional axis for OSCC invasion that suggests miR-491-5p and GIT1 as biomarkers for prognosis in this cancer.