MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1.

Aims: MicroRNA-1 (miR-1) has been demonstrated as a tumor-suppressive miRNA, which shows a down-regulated pattern in several human malignancies including hepatocellular carcinoma (HCC). However, the pathophysiologic roles of miR-1 and their mechanisms in HCC tumorigenesis are still not totally elucidated.

Main Methods: Pre-miR-1 was cloned into pSuper plasmid to overexpress the miR-1 in hepatoma cells. Real-time PCR and Western blot were applied to detect miR-1, ET-1 mRNA and protein levels respectively. Dual luciferase reporter assay was conducted to investigate the binding site of miR-1 on 3'UTR of ET-1 mRNA. Proliferation of hepatoma cells was evaluated by MTT assay.

Key Findings: We observed that over-expression of miR-1 by miRNA-expressing plasmid transfection in HepG2 and Hep3B cells significantly reduced the proliferation of these cells. To explore the mechanism, we examined the potential target genes of miR-1 by bioinformatics. A potent mitogen, Endothelin-1 (ET-1), attracted our attention. Elevated expression of ET-1 but reduced miR-1 level was detected both in human liver cancer tissues and in hepatoma cell lines using Western Blot and miRNA real-time PCR respectively. By the over-expression and inhibition of miR-1 in HepG2 and Hep3B, we confirmed that miR-1 negatively regulated ET-1 expression in hepatoma cells. A luciferase reporter assay showed that miR-1 regulation was established by pairing to a complementary binding site within the ET-1 3'UTR. Finally, attenuated proliferation of hepatoma cells by over-expression of miR-1 could be partially restored by exogenous ET-1 treatment.

Significance: Our findings demonstrate that miR-1 could inhibit ET-1 expression to attenuate the proliferation of hepatoma cells.