Autophagy induced by valproic acid is associated with oxidative stress in glioma cell lines

Autophagy represents an alternative tumor-suppressing mechanism that overcomes the dramatic resistance of malignant gliomas to radiotherapy and proapoptotic-related chemotherapy. This study reports that valproic acid (VPA), a widely used anti-epilepsy drug, induces autophagy in glioma cells. Autophagy, crucial for VPA-induced cell death, is independent of apoptosis, even though apoptotic machinery is proficient. Oxidative stress induced by VPA occurs upstream of autophagy. Oxidative stress also activates the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, whereas blocking this pathway inhibits autophagy and induces apoptosis. VPA-induced autophagy cannot be alleviated by inositol, suggesting a mechanism different from that for lithium. Moreover, VPA potentiates autophagic cell death, but not apoptosis, when combined with other autophagy inducers such as rapamycin, {"type":"entrez-nucleotide","attrs":{"text":"Ly294002","term_id":"1257998346","term_text":"LY294002"}}Ly294002, and temozolomide in glioma cells both in vitro and in vivo, which may warrant further investigation toward possible clinical application in patients with malignant gliomas.     

Clinical significance of vasculogenic mimicry in human gliomas

Vasculogenic mimicry (VM) is known as non-endothelial tumor cell-lined microvascular channels in aggressive tumors. We have previously found the presence of VM in high-grade gliomas. In this study, we aimed to identify VM patterns in gliomas and to explore their clinical significance. Tumor samples as well as their detailed clinical/prognostic data were collected from 101 patients. Vasculogenic mimicry in the glioma samples was determined by dual staining for endothelial marker CD34 and periodic acid–Schiff (PAS). Tumor samples were also immunohistochemically stained for Ki-67, VEGF, COX-2 and MMP-9. The association between VM and the clinical characteristics of the patients were analyzed. A Kaplan–Meier survival analysis and log-rank tests were performed to compare survival times of the patients. Vasculogenic mimicry was present in 13 out of 101 samples. The higher grade gliomas had a higher incidence of VM than that of lower grade gliomas (P = 0.006). Vasculogenic mimicry channels were associated with the expression of COX-2 and MMP-9 (P < 0.05). While there was no association between the existence of VM and the sex, age and preoperative epilepsy of the patients, or expression of Ki-67 and VEGF. However, patients with VM-positive gliomas survived a shorter period of time than those with VM negative gliomas (P = 0.027). Interestingly, in high-grade gliomas, the level of microvascular density was lower in VM positive tumors than those VM negative tumors (P = 0.039). Our results suggest that VM channels in gliomas correlate with increasing malignancy and higher aggressiveness, and may provide a complementation to the tumor’s blood supply, especially in less vascularized regions, which may aid in the identification of glioma patients with a poorer prognosis.     

Overexpression of IL-7 enhances cisplatin resistance in glioma

Cisplatin is one of the most commonly used chemotherapeutic agents for glioma patients. In this study, array comparative genomic hybridization (aCGH) was used to identify genes associated with cisplatin resistance in a human glioma cell line. The cisplatin-resistant U251/CP2 cell line was derived by stepwise selection using cisplatin. The genetic aberrations of the U251 parental cell line and the U251/CP2 cells were analyzed using aCGH. RT-PCR was used to detect the expression of the altered genes revealed by aCGH. The sensitivity of glioma cells to cisplatin was determined by using the MTT assay. Apoptosis was detected using flow cytometry and western blot analysis. The IC 50 value of cisplatin in U251/CP2 cells was five times higher than its IC 50 in U251 cells. The U251 cells lost at least one copy each of the CFHR1 and CFHR3 genes, and both CFHR1 and CFHR3 were homozygously deleted in U251/CP2 cells. The U251/CP2 cells gained two to three copies of C8orf70 and IL-7 genes. IL-7 mRNA expression was studied in 12 glioma cell lines, and expression was positively correlated with the IC 50 of cisplatin. Furthermore, IL-7 mRNA expression was also positively correlated with the IC 50 of cisplatin in 91 clinical glioma specimens. Additionally, treatment with recombinant human IL-7 (rhIL-7) enhanced cisplatin resistance and increased the relative growth rate of the glioma cells. Moreover, the apoptosis induced by cisplatin could be inhibited by IL-7. In conclusion, our results suggest that IL-7 may play an important role in cisplatin resistance in glioma.     

脑胶质瘤细胞顺铂耐药分子标志物筛选

背景与目的：顺铂是神经肿瘤化疗常用药物之一,耐药是疗效不佳原因之一。遗传学改变可以影响肿瘤细胞对化疗的敏感性。本研究旨在利用芯片-基因组杂交技术筛选胶质瘤细胞中与顺铂耐药相关的分子标志物。方法：用芯片-基因组杂交技术对我们先前采用顺铂剂量梯度爬升诱导的对顺铂高度耐药的U251/CP2细胞（IC50为76.5μg/mL）和亲代细胞U251细胞（IC50为1.2μg/ml）筛选与顺铂耐药相关的分子标志物。RT-PCR和实时荧光定量PCR用来对结果进行验证。结果：补体因子H相关蛋白1基因（CFHR1）和补体因子H相关蛋白3基因（CFHR3）在U251细胞中至少各自缺失了一个拷贝,在U251/CP2细胞中完全缺失。IL-7基因在U251/CP2细胞中的拷贝数为U251细胞的2～3倍。结论：CFHR1、CFHR3和IL-7基因可能与胶质瘤对顺铂耐药有关。     

髓母细胞瘤与幕上原始神经外胚叶肿瘤中RASSF1A基因的甲基化差异

目的通过研究髓母细胞瘤与幕上原始神经外胚叶肿瘤（SPNET）中RASSF1A基因的甲基化改变,探讨颅内原始神经外胚叶肿瘤（PNET）的不同亚型中该基因的表遗传学差异及其意义。方法收集25例原发髓母细胞瘤,9例原发SPNET,3株髓母细胞瘤细胞系和2株SPNET细胞系。采用甲基化特异性聚合酶链反应（MSP）检测RASSF1A基因启动子区的甲基化状态。应用去甲基化试剂5-aza-2’deoxycytidine处理存在基因表达缺失的细胞系,探讨基因表达与甲基化之间的关系。结果100％（25／25）的原发髓母细胞瘤、6／9的原发SPNET及全部PNET细胞系中均检测到RASSFIA基因的甲基化。相反,该基因甲基化在全部正常组织（包括2例小脑,5例大脑）中均未检测到。并且,RASSF1A在SPNET中的甲基化率明显低于髓母细胞瘤（Fisher精确检验,P=0．014）。在经去甲基化试剂处理的PNET细胞中,该基因表达得以恢复,证明甲基化与该基因沉默相关。结论RASSF1A甲基化是肿瘤特异性的,RASSF1A甲基化与PNET的发生有一定关联,不同亚型的PNET之间RASSF1A基因的不同甲基化状态提示髓母细胞瘤和SPNET是表遗传学上存在差异的两类肿瘤。     

Lumbosacral clear-cell meningioma treated with subtotal resection and radiotherapy.

We wish to report a rare case of clear-cell meningioma in the lumbosacral region in a 34-year-old male patient who presented to us with lower back pain and leg pain. The management of the patient will be reported and histological appearance discussed. This rare tumour in a difficult anatomical position presents a challenge that requires management in a multidisciplinary fashion.