Oxymatrine (OM), a natural quinolizidine alkaloid extracted from the traditional Chinese herb Sophora flavescens, has been revealed to produce antitumor activities in various cancer cell lines, including glioblastoma lines, in vitro. However, the mechanisms by which OM exerts its antitumor effect against glioma are poorly understood. The aim of this study was to investigate the role of OM in the proliferation, apoptosis and invasion of glioma cells and to reveal the underlying mechanisms. The effects of OM on U251MG cells in vitro were determined using a Cell Counting Kit‑8 (CCK‑8) assay, flow cytometric analysis, Annexin V‑FITC/PI staining, DAPI staining, a terminal deoxynucleotidyl transferase‑mediated dUTP nick end‑labeling (TUNEL) assay, a Transwell assay and western blotting. Our data indicated that OM inhibited proliferation, arrested the cell cycle at the G0/G1 phase, decreased the expression levels of G1 cell cycle regulatory proteins (cyclin D1, CDK4 and CDK6), inhibited invasion and induced apoptosis in glioma cells. Additional investigations revealed that the expression levels of p‑STAT3 and key proteins in the EGFR/PI3K/Akt/mTOR signaling pathway, such as p‑EGFR, p‑Akt and p‑mTOR, were markedly decreased after OM treatment, while the total STAT3, EGFR, Akt and mTOR levels were not affected. These findings indicated that the EGFR/PI3K/Akt/mTOR signaling pathway and STAT3 suppression may be a potential mechanism of the OM‑mediated antitumor effect in glioblastoma cells and that EGFR may be a target of OM. Hence, OM may be a promising drug and may offer a novel therapeutic strategy for malignant gliomas in the future.
BackgroundArsenic trioxide (As2O3) has a dramatic therapeutic effect on acute promyelocytic leukemia (APL) patients. It can also cause apoptosis in various tumor cells. This study investigated whether As2O3 has an antitumor effect on glioma and explored the underlying mechanism.ResultsMTT and trypan blue assays showed that As2O3 remarkably inhibited growth of C6 and 9 L glioma cells. Cell viability decreased in glioma cells to a greater extent than in normal glia cells. The annexin V-FITC/PI and Hoechest/PI staining assays revealed a significant increase in apoptosis that correlated with the duration of As2O3 treatment and occurred in glioma cells to a greater extent than in normal glial cells. As2O3 treatment induced reactive oxygen species (ROS) production in C6 and 9 L cells in a time-dependent manner. Cells pretreated with the antioxidant N-acetylcysteine (NAC) showed significantly lower As2O3-induced ROS generation. As2O3 significantly inhibited the expression of the anti-apoptotic gene Bcl-2, and upregulated the proapoptotic gene Bax in both C6 and 9 L glioma cells in a time-dependent manner.ConclusionsAs2O3 can significantly inhibit the growth of glioma cells and it can induce cell apoptosis in a time- and concentration-dependent manner. ROS were found to be responsible for apoptosis in glioma cells induced by As2O3. These results suggest As2O3 is a promising agent for the treatment of glioma.
Background/Aims: Kaiso (ZBTB33) expression is closely associated with the progression of many cancers and microRNA (miRNA) processing. MiR-181a plays critical roles in multiple cancers; however, its precise mechanisms in glioma have not been well clarified. The goal of this study was to evaluate the interaction between Kaiso and miR-181a in glioma. Methods: Quantitative real-time PCR (qRT-PCR) was performed to detect the levels of Kaiso and miR-181a in glioma tissues and cell lines. Cell proliferation, invasion, and the epithelial–mesenchymal transition (EMT) were evaluated to analyze the biological functions of miR-181a and Kaiso in glioma cells. The mRNA and protein levels of Kaiso were measured by qRT-PCR and western blotting, respectively. Meanwhile, luciferase assays were performed to validate Kaiso as a miR-181a target in glioma cells. Results: We found that the level of miR-181a was the lowest among miR-181a–d in glioma tissues and cell lines, and the low level of miR-181a was closely associated with the increased expression of Kaiso in glioma tissues. Moreover, transfection of miR-181a significantly inhibited the proliferation, invasion, and EMT of glioma cells, whereas knockdown of miR-181a had the opposite effect. Bioinformatics analysis predicted that Kaiso was a potential target gene of miR-181a, and the luciferase reporter assay demonstrated that miR-181a could directly target Kaiso. In addition, Kaiso silencing had similar effects as miR-181a overexpression in glioma cells, whereas overexpression of Kaiso in glioma cells partially reversed the inhibitory effects of the miR-181a mimic. Conclusionss: miR-181a inhibited the proliferation, invasion, and EMT of glioma cells by directly targeting and downregulating Kaiso expression.
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