Role of miR-137 in Notch1 mediated autophagy in proliferation and migration of hepatocellular carcinoma cells

Objective To explore the role of miR-137 in the proliferation and migration of hepatocellular carcinoma (HCC) cells by regulating Notch1 and mediating autophagy. Methods The human SMMC7721 hepatoma cell line was transfected with miR-137 mimics, miR-137 inhibitor and Notch1 interfe-ring RNA (siRNA), and divided into normal control group (NC group), miR-137 mimics group, miR-137 inhibitor group, Notch1 siRNA group.The expression levels of miR-137 and Notch1 mRNA after the transfection were detected by RT-PCR in SMMC7721 cells. Transwell experiments were performed to analyze the effect of miR-137 and Notch1 on the migration and invasion of SMMC7721 cells. The expression levels of β-catenin and vimentin in SMMC7721 cells were detected by immunohistochemistry. The number of autophagosomes was detected by double labeled adenovirus. Western blot was utilized to detect the expression of Notch1, E-Cadherin, N-Cadherin, vimentin, P62, and LC3. Results The results of RT-PCR showed that the relative expression level of Notch1 in miR-137 inhibitor group (5.71±0.45) was significantly higher than that in miR-137 mimics group (0.21±0.06) with statistical significance (P<0.05). The Transwell experiments showed that there were fewer invasive metastatic hepatoma cells in miR-137 mimics group (66.00±4.55) and Notch1 siRNA group (88.00±6.78) than that in the miR-137 inhibitor group (515.00±35.12) (P<0.05). The expression levels of β-catenin in miR-137 mimics group and Notch1 siRNA group were significantly increased and the expression level of vimentin was decreased (P<0.05). The results of autophagy double labeled adenovirus test showed that the number of autophagosomes in miR-137 mimics group (5.50±3.70) was significantly fewer than that in miR-137 inhibitor group (32.75±4.11), and the difference was statistically significant (P<0.05). The expression levels of Notch1, N-cadherin, vimentin, and LC3 protein in miR-137 mimics group were much lower than that in miR-137 inhibitor group and NC group, and the expression levels of E-Cadherin and P62 protein were greatly increased. The expression level of Notch1, N-cadherin, and LC3 protein in Notch1 siRNA group were significantly lower than that in NC group, and the expression levels of E-cadherin and P62 protein were much higher than that in NC group. Conclusion MiR-137 can inhibit the proliferation, migration and invasion of HCC cells by inhibiting the expression of Notch1 and autophagy, which may become a new target for the treatment of HCC. Key words: Hepatocellular carcinoma; MiR-137; Notch1; Invasion and metastasis; Autophagy