Circular RNA TTBK2 promotes the development of human glioma cells via miR-520b/EZH2 axis.

OBJECTIVE: Glioma is a highly malignant human disease characterized by limited response to clinical therapy. Evidence indicated that circular RNA Tau tubulin kinase 2 circular RNAs (circ-TTBK2) participated in glioma pathogenesis. However, the precise effect of circ-TTBK2 on glioma progression is needed to be highlighted. MATERIALS AND METHODS: The levels of circ-TTBK2, microRNA-520b (miR-520b), and enhancer of zeste homologue 2 (EZH2) were detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) or Western blot. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was performed to determine cell proliferation in vitro. Besides, a flow cytometry assay was conducted to examine apoptosis of A172 and U251 cells. Cell invasion was identified using the transwell assay. Moreover, Dual-Luciferase reporter assay was used to confirm the interaction between miR-520b and circ-TTBK2 or EZH2. The role of circ-TTBK2 in glioma progression was exposed using xenograft tumor experiments. RESULTS: The levels of circ-TTBK2 and EZH2 were markedly augmented, whereas miR-520b expression level was notably reduced in glioma tissues and cell lines. Either circ-TTBK2 or EZH2 detection could clearly facilitate cell apoptosis and block proliferation and invasion in A172 and U251 cells, while the effect of circ-TTBK2 or EZH2 deficiency was reverted by co-transfecting with miR-520 inhibitor. Moreover, circ-TTBK2 exerted its roles via miR-520b/EZH2 axis in glioma cells, and the knockdown of circ-TTBK2 could hinder the progression of glioma. CONCLUSIONS: Circ-TTBK2/miR-520b/EZH2 axis modulated cell proliferation, apoptosis, and invasion in glioma cell lines, and might serve as potential targets for glioma diagnosis and therapy.

The ECRIS charge state breeding project at TRIUMF.

The performance of charge state breeding with an electron cyclotron resonance (ECR) ion source intended to increase the charge state of online produced radioactive ions at the ISAC facility at TRIUMF has been investigated. A 14 GHz PHOENIX from PANTECHNIK has been setup on a test bench. Singly charged ions have been produced with several ion sources typical for the on-line operation and were injected into the charge breeder. The main purpose of the tests has been the optimization of the efficiency for the charge breeding into the desired charge state. Maximum efficiencies reached so far with the standard one step deceleration of the ions in front of the plasma are up to about 6% for noble gas ions and about 3.5% for alkalines. As ion optics simulations show, the acceptance can be increased by a two step deceleration. In order to meet the velocity acceptance of the accelerator at different A/q values a similar two gap acceleration system for the highly charged ions has been installed to allow the source to run at different voltages. For the further beam transport to the accelerator, cross sections for charge exchange of the highly charged ions with the residual gas have been determined.