MiR-291b-3p induces apoptosis in liver cell line NCTC1469 by reducing the level of RNA-binding protein HuR.

Background: There is increasing evidence that miRNAs are involved in cellular apoptosis. study, we investigated the effect of miR-291b-3p on NCTC1469 cell growth and apoptosis. Methods: Cell viability and apoptosis were examined in NCTC1469 cells transfected with miR-291b-3p mimics, inhibitor miRNA or negative control. Using computational miRNA target prediction databases, HuR was predicted as a target of miR-291b-3p. Luciferase assay, on HuR expression. In addition, the effect of HuR on cell apoptosis was evaluated using a HuR-specific siRNA Results: TNF-alpha-induced hepatocyte apoptosis was accompanied by enhanced expression of miR-291b-3p, suggesting that miR-291b-3p might contribute to the apoptotic process. Follow-up experiments showed that upregulation of miR-291b-3p decreased cell viability and induced NCTC1469 cell apoptosis. Additionally, similar to the activity of miR-519, which is another member of the same miRNA family, miR-291b-3p suppressed HuR translation through binding to the HuR coding region (CR). We further showed that the downregulation of HuR expression by miR-291b-3p was accompanied by reduced Bcl-2 expression. Moreover, knockdown of HuR also impaired Bcl-2 expression and increased the ratio of Bax/Bcl-2. More cells that were co-transfected with siRNA-HuR. Finally, inhibition of miR-291b-3p led to reduced apoptosis, while knockdown of HuR by siRNA promoted apoptosis, even in NCTC1469 cells that were co-transfected with the miR-291b-3p inhibitor. Conclusion: The current data suggested that miR-291b-3p contributed to NCTC1469 cell apoptosis by regulating the expression of HuR, which in turn increased Bcl-2 stability. Copyright (c) 2014 S. Karger AG, Basel