Difference in the Inhibitory Effect of Temozolomide on TJ905 Glioma Cells and Stem Cells.

This study aims to determine the difference in the inhibitory effect of temozolomide (TMZ) on TJ905 glioma cells and stem cells. TJ905 cancer stem cells were isolated. Livin is a member of the inhibitor of apoptosis protein family. The TJ905 cells and cancer stem cells were transfected with a Livin-shRNA and negative-shRNA, respectively, and then treated with TMZ. At 48 h post-transfection, a cell counting kit 8 assay, flow cytometry, and real-time qPCR were performed to detect cell proliferation, the cell cycle, and the expression of the Caspase-3, -7, and -9 mRNAs, respectively. As a result, the suppressive effect of TMZ on TJ905 cells was more significant than its effect on TJ905 cancer stem cells. TMZ exerted an inhibitory effect on the growth of TJ905 glioma cells by arresting them at G0/G1 phase and arresting cancer stem cells at S phase in a dose-dependent manner. TMZ inhibited Livin mRNA expression and increased the expression of the Caspase-3, -7, and -9 mRNAs. Low Livin mRNA expression induced high levels of Caspase-3, -7, and -9 expressions, thus promoting the apoptosis of both TJ905 cells and cancer stem cells in response to TMZ treatment. The TJ905 cells transfected with the Livin-shRNA were more sensitive to TMZ, whereas the TJ905 glioma stem cells transfected with the Livin-shRNA showed no significant changes in their sensitivity to TMZ. In conclusion, the Livin gene may play an important role in the resistance mechanisms of TJ905 glioma cells and cancer stem cells. However, Livin had a more distinct role in TMZ resistance, cell proliferation, and the cell cycle in TJ905 glioma cells than in cancer stem cells.

Effect of Corilagin on the Proliferation and NF-κB in U251 Glioblastoma Cells and U251 Glioblastoma Stem-Like Cells.

Background. This study is to explore the effect of corilagin on the proliferation and NF-κB signaling pathway in U251 glioblastoma cells and U251 glioblastoma stem-like cells. Methods. CD133 positive U251 glioblastoma cells were separated by immunomagnetic beads to isolate glioblastoma stem-like cells. U251 cells and stem-like cells were intervened by different corilagin concentrations (0, 25, 50, and 100 µg/mL) for 48 h, respectively. Cell morphology, cell counting kit-8 assay, flow cytometry, dual luciferase reporter assay, and a western blot were used to detect and analyze the cell proliferation and cell cycle and investigate the expression of IKBα protein in cytoplasm and NF-κB/p65 in nucleus. Results. Corilagin inhibited the cell proliferation of U251 cells and their stem-like cells and the inhibition role was stronger in U251 stem-like cells (P < 0.05). The cell cycle was arrested at G2/M phase in the U251 cells following corilagin intervention; the proportion of cells in G2/M phase increased as the concentration of corilagin increased (P < 0.05). The U251 stem-like cells were arrested at the S phase following treatment with corilagin; the proportion of cells in the S phase increased as the concentration of corilagin increased (P < 0.05). The ratio of dual luciferase activities of U251 stem-like cells was lower than that of U251 cells in the same corilagin concentration. With increasing concentrations of corilagin, the IKBα expression in cytoplasm of U251 cells and U251 stem-like cells was increased, but the p65 expression in nucleus of U251 cells and U251 stem-like cells was decreased (P < 0.05). Conclusion. Corilagin can inhibit the proliferation of glioblastoma cells and glioblastoma stem-like cells; the inhibition on glioblastoma stem-like cell proliferation is stronger than glioblastoma cells. This different result indicates that the effect of corilagin on U251 cells and U251 stem-like cells may have close relationships with mechanism of cell cycle and NF-κB signaling pathway; however, the real antitumor mechanism of corilagin is not yet clear and requires further study.

IDH1R¹³²H decreases the proliferation of U87 glioma cells through upregulation of microRNA-128a.

Mutations in isocitrate dehydrogenase 1 (IDH1) are found in >70% of secondary glioblastomas and lower-grade gliomas (grades II-III). Among the numerous phenotypic differences between IDH1 mutant and wild-type glioma patients, the most salient is an improved survival rate for patients with a mutation. MicroRNAs (miRNAs) are a class of small, non­coding, single­stranded RNAs that can negatively regulate gene expression at the post­transcriptional level, predominantly by binding to the 3'­untranslated region of their target mRNAs. The dysregulated expression of several miRNAs has been reported to modulate glioma progression; however, it is unclear whether mutations in IDH1 regulate glioma cell proliferation through miRNA dysregulation. In the present study, stable overexpression of IDH1WT or IDH1R132H was established in the U87 glioma cell line. It was found that IDH1R132H decreased cell proliferation of U87 glioma cells by inducing the expression of the miRNA miR­128a. This process was dependent on the transcription factor hypoxia inducible factor­1α (HIF­1α), which binds to a hypoxia response element in the promoter of miR­128a. Furthermore, miR­128a negatively regulated the expression of B­cell­specific Moloney murine leukemia virus integration site 1 protein (Bmi­1), which is involved in suppressing cell proliferation. These findings suggest that the IDH1R132H­HIF­1α­miR­128a­Bmi­1 pathway is involved in glioma cell proliferation.