Glioblastoma multiforme (GBM) is lethal brain tumor thought to arise from GBM stem cells (GBM-SCs). MicroRNAs carry out post-transcriptional regulation of various cellular processes that modulate the stemness properties of GBM-SCs. Here, we investigated the critical role of miR-153 in GBM-SCs. First, GBM-SCs were isolated from six GBM specimens. These GBM-SCs formed GBM spheres, expressed markers associated with neural stem cells, and possessed the capacity for self-renewal and multilineage differentiation. Then qRT-PCR analysis showed that miR-153 expression was down-regulated in GBM tissues relative to normal brain tissues, and in CD133 positive cells relative to CD133 negative cells. This project demonstrates for the first time that transient transfection of miR-153 into GBM-SCs can inhibit their stemness properties, such as impairing self-renewal ability and inducing differentiation. Meanwhile, miR-153 can also repress GBM-SCs growth and induce apoptosis. Altogether, these results indicate that reactivation of miR-153 expression suggests novel therapeutic strategies for GBM-SCs.

Background Celastrol is a potential anti-tumor agent in hepatocellular carcinoma (HCC). Identifying the molecular determinants of the anti-HCC effect of celastrol is still challenging. In this study, we undertook to associate circular RNAs (circRNAs) with the anti-HCC molecular determinants of celastrol. Methods Cell colony formation, proliferation, migration, invasion and apoptosis were determined using the colony formation, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide (MTS), transwell and flow cytometry assays, respectively. The levels of circRNA slit guidance ligand 3 (circ_SLIT3), miR-223-3p and C-X-C motif chemokine receptor 4 (CXCR4) were gauged by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Ribonuclease R (RNase R) and actinomycin D assays were performed to assess the stability of circ_SLIT3. Targeted relationships among circ_SLIT3, miR-223-3p and CXCR4 were confirmed by the dual-luciferase reporter assay. In vivo assays were performed to detect the roles of celastrol and circ_SLIT3 on tumor growth in vivo. Results Celastrol repressed HCC cell proliferation, migration, invasion, and enhanced apoptosis in vitro and suppressed tumor growth in vivo. Celastrol down-regulated circ_SLIT3 expression in HCC cells, and celastrol exerted an anti-tumor effect on HCC in vitro and in vivo by down-regulating circ_SLIT3. Mechanistically, circ_SLIT3 directly interacted with miR-223-3p, and circ_SLIT3 controlled CXCR4 expression by sponging miR-223-3p. Moreover, miR-223-3p was involved in the celastrol/circ_SLIT3-mediated regulation on HCC progression. Furthermore, celastrol exerted the anti-HCC effect in vitro through the miR-223-3p/CXCR4 axis. Conclusion Our present work first identified the circ_SLIT3/miR-223-3p/CXCR4 axis as a novel mechanism of the anti-HCC effect of celastrol, providing a new insight into the involvement of circRNAs in the anti-tumor molecular determinants of celastrol.

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