Fengming Lan, Qing Qin, Huiming Yu and Xiao Yue
Although glucose metabolism reengineering is a typical feature of various tumors, including glioma, key regulators of glycolytic reprogramming are still poorly understood. The authors sought to investigate whether glycolysis inhibition by microRNA (miR)–448 increases radiosensitivity in glioma cells.
The authors used glioma tissue samples from glioma patients, cells from glioblastoma (GBM) cell lines and normal human astrocyte cells, and subcutaneous tumor–bearing U87 cells in mice to examine the effects of signaling regulation by miR-448 in the response of glioma tissues and cells to radiation treatment. Techniques used for investigation included bioinformatics analyses, biochemical assays, luciferase reporter assays, and establishment of subcutaneous tumors in a mouse model. Glucose consumption, LDH activity, and cellular ATP were measured to determine the ability of glioma cells to perform glycolysis. Expression of HIF-1α was measured as a potential target gene of miR-448 in glycolysis.
miR-448 was detected and determined to be significantly downregulated in both glioma tissues from glioma patients and GBM cell lines. Furthermore, miR-448 acted as a tumor-inhibiting factor and suppressed glycolysis in glioma by negatively regulating the activity of HIF-1α signaling and then interfering with its downstream regulators relative to glycolysis, HK1, HK2, and LDHA. Interestingly, overexpression of miR-448 increased the x-radiation sensitivity of glioma cells. Finally, in in vivo experiments, subcutaneous tumor–bearing U87 cells in a mouse model verified that high expression of miR-448 also enhanced glioma radiosensitivity via inhibiting glycolytic factors.
miR-448 can promote radiosensitivity by inhibiting HIF-1α signaling and then negatively controlling the glycolysis process in glioma. A newly identified miR-448–HIF-1α axis acts as a potentially valuable therapeutic target that may be useful in overcoming radioresistance in glioma treatment.
Xiao Yue, FengMing Lan, Man Hu, Qiang Pan, Qiong Wang and JinHuan Wang
Circulating microRNAs (miRNAs) are a new class of highly promising cancer biomarkers. Malignant glioma is one of the most devastating and lethal forms of intrinsic CNS tumor. Here, the authors evaluated serum miRNA 205 (miR-205) levels in patients with glioma.
Sixty-four patients in whom glioma was diagnosed and 45 healthy controls were recruited between October 2011 and March 2012 and randomly assigned to the screening cohort or the validation cohort. Cohorts of patients with other brain tumors, including meningioma (n = 8), primary diffuse large B-cell lymphoma of the CNS (n = 6), and pituitary adenoma (n = 5), were investigated and compared. miR-205 extraction from serum was detected by real-time quantitative reverse-transcription polymerase chain reaction. The Kaplan-Meier method was applied to perform survival analysis, the risk factors were analyzed by using a Cox regression model, and the receiver operating characteristic working curve was used to analyze the value of miR-205 in the prognostic evaluation of the patients.
The authors first demonstrated that serum miR-205 expression was significantly lower in patients with glioma than in healthy controls (p < 0.001). It is important to note that serum miR-205 expression demonstrated a stepwise decrease with ascending pathological grades. The serum miR-205 biomarker had high sensitivity, specificity, and accuracy in patients with glioma. Serum levels of miR-205 were identified as an individual diagnostic marker and were significantly lower in the glioma cohort than in the other brain tumor cohorts. Serum miR-205 levels were significantly increased in postoperative samples over those in the preoperative samples and were reduced again during glioblastoma recurrences. Statistical analysis revealed a significant correlation between low serum miR-205 expression and both ascending pathological grades (p = 0.002) and low Karnofsky Performance Scale scores (p = 0.01). Patients with glioma at an advanced pathological grade (Grade III or IV) and a higher miR-205 serum level showed longer overall survival than those with a lower miR-205 serum concentration (p < 0.01). Furthermore, Cox regression analysis revealed that miR-205 serum levels were independently associated with overall survival.
These data indicate that serum miR-205 expression is a novel and valuable biomarker for the diagnosis of glioma and a prognostic factor for those with a tumor at an advanced pathological grade.
Fengming Lan, Xiao Yue, Lei Han, Xubo Yuan, Zhendong Shi, Kai Huang, Yang Yang, Jian Zou, Junxia Zhang, Tao Jiang, Peiyu Pu and Chunsheng Kang
The goal in this study was to investigate the antitumor effect of aspirin in glioblastoma cells and the molecular mechanism involved in its antineoplastic activities.
The authors used the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method, flow cytometry, the annexin V method, and Transwell cell invasion test to detect the proliferation and invasive activity of U87 and A172 glioma cells before and after being treated with aspirin. To determine the effects of aspirin on β-catenin/T-cell factor (TCF) transcription activity, reporter constructs containing 3 repeats of the wild-type (TOPflash) or mutant (FOPflash) TCF-binding sites were used. Reverse transcriptase polymerase chain reaction and Western blot analyses were used to detect the expression of multiple β-catenin/TCF target genes following aspirin treatment.
The transcriptional activity of the β-catenin/TCF complex was strongly inhibited by aspirin. Increasing the concentration of aspirin resulted in decreased expression of c-myc, cyclin D1, and fra-1 mRNA and protein in U87 and A172 cells in a dose-dependent manner. Aspirin inhibited glioma cell proliferation and invasive ability, and induced apoptotic cell death.
The results suggest that aspirin is a potent antitumor agent, and that it exerts its antineoplastic action by inhibition of the β-catenin/TCF signaling pathway in glioma cells.