lncRNA TUG1 inhibits the cancer stem cell­like properties of temozolomide­resistant glioma cells by interacting with EZH2.

Temozolomide (TMZ) is currently one of the first­line drugs used for the treatment of high­grade gliomas. However, TMZ resistance results in unsatisfactory therapeutic effects in gliomas. Cancer stem cells (CSCs) have recently been determined to serve a pivotal regulatory role in tumor metastasis, recurrence and chemoresistance. In addition, numerous reports have shown that long non­coding RNAs (lncRNAs) exert an essential role in the occurrence and development of tumors, and can be used as biomarkers for tumor diagnosis and treatment. Among them, studies have revealed that taurine upregulated gene 1 (TUG1) exhibits an important regulatory effect on the malignant biological behavior of glioma cells. Moreover, it has been reported that enhancer of Zeste homolog 2 polycomb repressive complex subunit 2 (EZH2) promotes tumorigenesis, including in glioma. However, the underlying mechanism of the interaction of TUG1 and EZH2 with CSCs of glioma remains elusive, and thus requires further clarification. The present study aimed to explore the role of TUG1 and EZH2 in TMZ resistance in glioma. Cell Counting Kit­8, colony formation,sphere formation and Annexin V­FITC/PI assays were used to detect the proliferation, clone formation efficiency, stemness and apoptosis of TMZ­resistant glioma cells. Xenograft tumor assay was used to detect the effect of TUG1 on the tumorigenesis of TMZ­resistant glioma cells. The present findings demonstrated that TUG1 exhibited a low expression in glioma cells, while EZH2 expression was the opposite. Moreover, it was observed that A172/TMZ cells possessed higher CSCs­like properties compared with parent cells, and that TUG1 and EZH2 were abnormally expressed in A172/TMZ cells. Knockdown of TUG1 or overexpression of EZH2 promoted A172/TMZ cell proliferation and CSCs­like properties, as well as inhibited their apoptosis, thereby enhancing the TMZ resistance of A172/TMZ cells. Furthermore, it was found that TUG1 alleviated the TMZ resistance of A172/TMZ cells by inhibiting EZH2 expression. Of note, overexpression of TUG1 inhibited the tumorigenicity of A172/TMZ cells by downregulating EZH2 expression in vivo. Collectively, the present study demonstrated that TUG1 served an essential regulatory role in TMZ resistance of gliomas.

Hyperbaric oxygen inhibits production of CD3+ T cells in the thymus and facilitates malignant glioma cell growth.

Objective Hyperbaric oxygen (HBO) is an emerging complementary alternative medical approach in glioma treatment. However, its mode of action is unknown, so this was investigated in the present study. Methods We constructed an intracranial glioma model of congenic C57BL/6J mice. Glioma growth under HBO stimulation was assessed by bioluminescent imaging and magnetic resonance imaging. Flow cytometry assessed direct effects of HBO on reactive oxygen species (ROS) signaling of transplanted glioma cells and organs, and quantified mature T cells and subgroups in tumors, the brain, and blood. Results HBO promoted the growth of transplanted GL261-Luc glioma in the intracranial glioma mouse model. ROS signaling of glioma cells and brain cells was significantly downregulated under HBO stimulation, but thymus ROS levels were significantly upregulated. CD3+ T cells were significantly downregulated, while both Ti/Th cells (CD3+CD4+) and Ts/Tc cells (CD3+CD8+) were inhibited in tumors of the HBO group. The percentage of regulatory T cells in Ti/Th (CD3+CD4+) cells was elevated in the tumors and thymuses of the HBO group. Conclusion HBO induced ROS signaling in the thymus, inhibited CD3+ T cell generation, and facilitated malignant glioma cell growth in vivo in the intracranial glioma mouse model.