406950

MIR16-1

MicroRNAs (miRNAs or miRs), a class of non-coding RNAs 18-25 nucleotides in length, act as key regulators in the development and malignant progression of various human cancers by modulating the expression of their target genes. Recently, miR16 has been demonstrated to be play a role in glioma. However, the regulatory mechanisms of miR16 in glioma growth and metastasis remain largely unclear. In the present study, qRT-PCR revealed that miR16 was significantly downregulated in 23 glioma tissue specimens compared to 7 normal brain tissue specimens. Moreover, its levels were markedly lower in the glioma samples at stages T2-T4 compared to those at stage T1. The overexpression of miR-16 significantly suppressed the proliferation, migration and invasion of U251 and U87 glioma cells. Luciferase reporter assay identified Sal-like protein 4 (SALL4) as a target gene of miR16, and its protein levels were found to be decreased in miR16-overexpressing U251 and U87 cells. Furthermore, the overexpression of SALL4 significantly reversed the suppressive effects of miR16 on the proliferation, migration and invasion of U251 and U87 cells, suggesting that miR16 playsa tumor suppressor role in glioma by inhibiting cell proliferation and invasion through the targeting of SALL4. Finally, we found that SALL4 was significantly upregulated in glioma tissues compared to normal brain tissues, and its levels were markedly higher in the glioma tissues at stages T2-T4 compared to those at stage T1. In addition, the expression levels of SALL4 inversely correlated with the miR16 levels in glioma tissues, suggesting that the downregulation of miR16 contributes to the upregulation of SALL4 in glioma. On the whole, the findings of this study indicate a role for the miR16/SALL4 axis in glioma. Our data may also provide a potential therapeutic target for the treatment of glioma.

Autophagy is critical for the metastasis of cancer cells through induction of epithelial-to-mesenchymal transition (EMT). Activation of TGF-beta signaling plays a key role in regulating autophagy. miR-16 may be associated with non-small cell lung carcinoma (NSCLC) progression. However, the role of miR-16 in NSCLC cell autophagy in the presence of TGF-beta and the underlying mechanism are still unclear. To test whether miR-16 targets ATG3 which is involved in autophagy of NSCLC cells, we studied the expression levels of miR-16 and ATG3 in NSCLC patients, verified the targeting of ATG3 by miR-16 by luciferase reporter gene system, and investigated the role of miR-16 in the autophagy of NSCLC cells. Results revealed that miR-16 was significantly downregulated, and ATG3 was significantly upregulated in NSCLC patient tissue samples. ATG3 was found to be a direct target of miR-16. TGF-beta1 significantly downregulated the expression of miR-16 and ATG3 mRNA. Using transmission electron microscopy, we observed that TGF-beta1 treatment reduced autophagosomes in the A549 cells, and miR-16 mimics increased the autophagosomes in the presence of TGF-beta1. Acridine orange (AO) staining and expression of LC3B II/I and p62 confirmed the inhibition of autophagy by TGF-beta1, and the recovery of TGF-beta1-mediated inhibition of autophagy by miR-16 mimics. Finally, miR-16 mimics inhibited TGF-beta1-induced EMT, and this effect was attenuated by autophagy inhibitor 3-MA. Taken together, miR-16 mimics inhibited TGF-beta1-induced EMT via activation of autophagy.