Triphlorethol-A attenuates U251 human glioma cancer cell proliferation and ameliorates apoptosis through JAK2/STAT3 and p38 MAPK/ERK signaling pathways.

Glioma is the foremost recurrent type of brain tumor in humans; in particular, glioblastoma (GBM) is the main form of brain tumor (GBM) that is highly proliferative and impervious to apoptosis. Triphlorethol-A (TA), a phlorotannin isolated from Ecklonia cava, exhibited cytoprotective, antioxidant, and anticancer properties. However, the exact molecular action of TA in the U251 human GBM cells remains unknown. This may be the first report on the antiproliferative and apoptotic mechanisms of TA on GBM. The cytotoxicity, intracellular reactive oxygen species (ROS), matrix metalloproteinase (MMP), and cell apoptosis activity of TA have been evaluated by the MTT assay and by DCFH-DA, Rh-123, AO/EB, and western blot analysis. The results obtained showed that TA abridged the viability of U251 cells, while MMP increased apoptosis by increasing the ROS levels in a time-dependent manner. The results showed that a reduction in U251 cell proliferation was associated with the regulation of JAK2/STAT3 and p38 MAPK/ERK signaling pathways. TA was found to suppress pJAK, pSTAT3, p38 MAPK, and pERK phosphorylation, thereby causing Bax/Bcl-2 imbalance, activating the caspase cascade and cytochrome c, and inducing apoptosis. Our findings showed that the suppression of JAK2/STAT3 and p38 MAPK/ERK signaling by TA results in cell growth arrest and stimulation of apoptosis in GBM cells. These studies justify the protective remedy of TA against GBM.

Long non-coding RNA MEG3 regulates proliferation, apoptosis, and autophagy and is associated with prognosis in glioma.

PURPOSE: Accumulating evidence indicates that dysregulated long noncoding RNAs (lncRNAs) play critical roles in tumorigenesis and cancer progression. LncRNA-maternally expressed gene 3 (MEG3) has been shown to be involved in the initiation and development of several cancers, including glioma. However, the clinical prognostic value of MEG3 in glioma has not yet been fully elucidated. METHODS: The expression levels of MEG3 were detected in 79 glioma tissues and adjacent normal brain tissues, as well as, glioma cells and normal human astrocytes by qRT-PCR. Kaplan-Meier and Cox regression methods were utilized for the survival analysis. MTT assay, flow cytometry, and immunofluorescence assay were carried out to detect the impact of MEG3 on glioma cell proliferation, apoptosis, and autophagy. RESULT: The current results showed that MEG3 expression was significantly downregulated in glioma tissues and cell line and negatively correlated with WHO grade in glioma patients. Low MEG3 expression was significantly associated with the advanced WHO grade, low Karnofsky performance score (KPS), IDH wild-type, and tumor recurrence. Patients displaying a low expression of MEG3 contributed to poor overall survival. The downregulated level of MEG3, advanced WHO grade, low KPS, IDH wild-type, and tumor recurrence were independent poor prognostic indicators in glioma patients. The in vitro experiments demonstrated that the MEG3 overexpression remarkably suppressed the proliferation while facilitating apoptosis and autophagy in glioma cells. CONCLUSIONS: These findings indicated a critical role of MEG3 in glioma cell proliferation, apoptosis, and autophagy. Also, the gene was found to be significantly associated with the prognosis in glioma patients. Thus, it might provide a new target for predicting prognosis and therapeutic intervention in glioma.

Arbutin effectively ameliorates the symptoms of Parkinson's disease: the role of adenosine receptors and cyclic adenosine monophosphate.

An antagonistic communication exists between adenosinergic and dopaminergic signaling in the basal ganglia, which suggests that the suppression of adenosine A2A receptors-cyclic adenosine monophosphate pathway may be able to restore the disrupted dopamine transmission that results in motor symptoms in Parkinson's disease (PD). Arbutin is a natural glycoside that possesses antioxidant, anti-inflammatory, and neuroprotective properties. The purpose of this study was to investigate whether arbutin could ameliorate the symptoms of PD and to examine the underlying mechanism. In this study, Swiss albino mouse models of PD were established by the intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine for 4 successive days, with the concurrent intraperitoneal administration of arbutin (50 and 100 mg/kg) for 7 days. The results showed that arbutin significantly reduced lipid peroxidation, total nitrite levels, and inflammation in the substantia nigra and striatum of PD mouse models. In addition, arbutin decreased the activity of endogenous antioxidants, reduced the levels of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and γ-aminobutyric acid, and minimized neurodegeneration in the striatum. Arbutin also reduced the abnormal performance of PD mouse models in the open field test, bar test, pole test, and rotarod test. The therapeutic efficacy of arbutin was similar to that of madopar. The intraperitoneal injection of the A2AR agonist CGS21680 (0.5 mg/kg) attenuated the therapeutic effects of arbutin, whereas the intraperitoneal injection of forskolin (3 mg/kg) enhanced arbutin-mediated improvements. These findings suggest that arbutin can improve the performance of PD mouse models by inhibiting the function of the A2AR and enhancing the effects of cyclic adenosine monophosphate. This study was approved by the Institutional Animal Ethics Committee (1616/PO/Re/S/12/CPCSEA) on November 17, 2019 (approval No. IAEC/2019/010).

Exosome-Mediated Transfer of Long Noncoding RNA HOTAIR Regulates Temozolomide Resistance by miR-519a-3p/RRM1 Axis in Glioblastoma.

Background: Chemoresistance obstructs the treatment of glioblastoma (GB). Exosome-mediated transfer of long noncoding RNAs (lncRNAs) was reported to regulate chemoresistance in diverse cancers. The authors aimed to investigate the underlying mechanism of lncRNA HOX transcript antisense intergenic RNA (HOTAIR) in regulating temozolomide (TMZ) resistance in GB. Materials and Methods: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was utilized to check TMZ resistance and cell proliferation. The abilities of cell migration and invasion were evaluated by transwell assay. The protein levels of E-cadherin, N-cadherin, Vimentin, CD63, CD81, and ribonucleoside-diphosphate reductase subunit M1 (RRM1) were measured by western blot. Quantitative real-time polymerase chain reaction was conducted to detect the levels of HOTAIR, microRNA (miR)-519a-3p, and RRM1. The starBase was hired to predict the target sites between miR-519a-3p and HOTAIR or RRM1 and the dual-luciferase reporter assay was performed to verify the interaction. Xenograft tumor model was established to investigate the biological role of HOTAIR in vivo. Results: The high abilities of cell viability and metastasis were observed in TMZ-resistant GB cells. LncRNA HOTAIR was significantly upregulated in TMZ-resistant GB cells and its downregulation inhibited proliferation, migration, invasion, and epithelial/mesenchymal transition in TMZ-resistant GB cells. Further analysis indicated that exosomal lncRNA HOTAIR induced TMZ resistance and modulated TMZ resistance through miR-519a-3p/RRM1 axis. Besides, serum exosomal lncRNA HOTAIR was stable and had diagnostic value. Moreover, knockdown of lncRNA HOTAIR reduced TMZ resistance in vivo. Conclusions: Exosomal lncRNA HOTAIR mediated TMZ resistance through miR-519a-3p/RRM1 axis in GB.

NCK1-AS1 Increases Drug Resistance of Glioma Cells to Temozolomide by Modulating miR-137/TRIM24.

Background: Glioma is a common malignant tumor. The purpose of this study was to investigate the effect and molecular mechanism of long noncoding RNA (lncRNA) NCK1-AS1 on the drug resistance of temozolomide (TMZ) in glioma cells. Methods: The fresh and recurrent glioma tissues and peritumoral brain edema (PTBE) were collected from the same patient. U251 and A172 cells were treated with TMZ to screen TMZ-resistant cells. The expression levels of NCK1-AS1, miR-137, or TRIM24 were detected by quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, in situ hybridization (ISH), or RNA pull-down assay. Cell viability was measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazoliumbromide (MTT) assay. In addition, the relationship between NCK1-AS1 and miR-137 or TRIM24 and miR-137 was confirmed by dual luciferase activity assay. Results: NCK1-AS1 expression was increased in regular and recurrent glioma tissues and TMZ-resistant cells. Cell viability was increased in TMZ-resistant cells, and the IC50 of TMZ also increased in TMZ resistant cells. However, knockdown of NCK1-AS1 inhibited these increases. Moreover, suppression of NCK1-AS1 increased miR-137 expression, whereas overexpression of miR-137 decreased TRIM24 expression. Then, expression of miR-137 alleviated the NCK1-AS1 overexpression-induced increased expression of TRIM24. In addition, the decreases of cell viability and IC50 induced by NCK1-AS1 knockdown were reversed after adding TRIM24 in U251/TMZ and A172/TMZ cells. Conclusion: NCK1-AS1 could increase drug resistance of glioma cells to TMZ by modulating miR-137/TRIM24 pathway.

[Toxic effects of Vitamin C combined with temozolomide on glioma cells and its mechanism].

Objective: To investigate the toxic effects of vitamin C (VC) combined with temozolomide (TMZ) on gliomas and its mechanism. Methods: Human glioma cells BMG-1 and SHG44 cells were cultured in vitro, specifically divided into control group (without VC and TMZ), TMZ group (0.2 mmol/L), VC (0.5 mmol/L)+TMZ(0.2 mmol/L) group and TMZ(0.2 mmol/L TMZ)+U0126(10 µmol/L)group, each experiment was repeated three times. Cell survival rate was detected by MTT assay; Cell apoptosis was detected by flow cytometry and Annexin V-FITC/PI staining; Reactive oxygen species (ROS) levels were detected by ROS detection kit, and Western blot was used to detect the expression levels of proteins related to apoptosis, autophagy and ERK pathway. Results: Compared with the control group, the survival rate of glioma cells in the TMZ group was decreased significantly(P＜0.05). Compared with the TMZ group, the survival rate of glioma cells in the VC+TMZ group was decreased significantly(P＜0.01), the cell apoptosis rate was increased, and the expressions of Bax, Cleaved caspase-3 and Cleaved PARP protein were increased, while the expression of Bcl-2 was decreased. The ROS level and autophagy rate were decreased, while the expression of LC3-II/LC3-1 was decreased, and the expression of p62 was increased in the VC+TMZ group (all P＜0.05). At the same time, VC combined with TMZ decreased the expression level of p-ERK1/2-related protein in BMG-1 and SHG44 cells, and increased the apoptosis rate (P＜0.05). Conclusion: VC combined with temozolomide can enhance the toxicity of glioma cells. This effect is to promote apoptosis and inhibit temozolomide-mediated autophagy through the regulation of the ERK signaling pathway.