B7-H3蛋白在脑胶质瘤中的表达及与疾病发展、预后的关系

为了探讨共刺激分子B7-H7蛋白在脑胶质瘤组织中的表达及与肿瘤发生发展及预后的关系。本研究选取我院病理科收集的100例脑胶质瘤组织作为脑胶质瘤组、40例因外伤等原因进行脑部手术切除的脑组织作为对照组,收集时间为2011年3月至2013年5月,采用免疫组化染色检测两组标本中的B7-H7蛋白表达情况,并分析其与患者临床病理特征、预后的关系。结果显示,脑胶质瘤组织中的B7-H7蛋白阳性表达率(69.00%)显著高于对照组(5.00%)(p0.05);脑胶质瘤组织中的B7-H7蛋白阳性表达与患者肿瘤分级具有显著相关性,随着肿瘤分级增高,阳性表达率增高(p0.05);脑胶质瘤组织中的B7-H7蛋白阳性表达与患者的年龄、性别、病理学类型无关(p0.05);B7-H7蛋白阳性表达的胶质瘤患者的3年生存率(27.87%)低于阴性表达患者(44.83%),但差异无统计学意义(p0.05);B7-H7蛋白阳性表达的胶质瘤患者的生存时间(20.0个月)低于阴性表达患者(28.0个月)(Log Rank(Mantel-Cox)=3.829,p0.05)。本研究表明,B7-H7蛋白在脑胶质瘤组织中表达上调,并且与肿瘤分级、不良预后显著相关。     

脑胶质瘤神经干细胞治疗研究进展

脑胶质瘤是神经外科最常见的恶性肿瘤, 发病率约占全身肿瘤的5％,占儿童肿瘤的70％,且呈逐年上升的趋势。脑胶质瘤恶性程度高,生长迅速,５ 年生存率很低,其中高级别胶质瘤具有极强的侵袭能力,目前尚缺乏很有效的根治方法。手术切除肿瘤的难度很大,术后极易复发,预后比较差,对人类健康乃至生命的危害极大。随着分子生物学的发展以及相关生物技术的应用,从基因水平揭示脑胶质瘤的发生发展机制,并寻求有效的基因治疗方法成为人类研究肿瘤治疗新的研究方向。Reynolds 和Richards等先后从成年小鼠的纹状体中分离出能够不断增殖且具有多向分化潜能的细胞群,并提出了神经干细胞（neural stem cell, NSC）的概念。NSC具有高度增殖和自我更新的能力,且有迁移功能以及与正常脑组织良好融合的特性,这为基因治疗胶质瘤提供了良好的基础。     

脑胶质瘤神经干细胞治疗研究进展

脑胶质瘤是神经外科最常见的恶性肿瘤,发病率约占全身肿瘤的5%,占儿童肿瘤的70%,且呈逐年上升的趋势。脑胶质瘤恶性程度高,生长迅速,5年生存率很低,其中高级别胶质瘤具有极强的侵袭能力,目前尚缺乏很有效的根治方法。手术切除肿瘤的难度很大,术后极易复发,预后比较差,对人类健康乃至生命的危害极大。随着分子生物学的发展以及相关生物技术的应用,从基因水平揭示脑胶质瘤的发生发展机制,并寻求有效的基因治疗方法成为人类研究肿瘤治疗新的研究方向。Reynolds和Richards等先后从成年小鼠的纹状体中分离出能够不断增殖且具有多向分化潜能的细胞群,并提出了神经干细胞(neural stem cell,NSC)的概念。NSC具有高度增殖和自我更新的能力,且有迁移功能以及与正常脑组织良好融合的特性,这为基因治疗胶质瘤提供了良好的基础。     

shRNA干扰eIF4A1基因对胶质瘤细胞体内外生物学特征的影响

胶质瘤是颅内常见的肿瘤,其中恶性脑胶质瘤成弥漫性生长,尽管给予手术、放疗或化疗等综合治疗,仍极易复发,迫切需要探索新的治疗方法.但是胶质瘤的治疗靶点匮乏,因此探索有效的靶点对其治疗具有重要的意义.本研究中首先利用中国脑胶质瘤基因组图谱计划数据库(Chinese glioma genome altas, CGGA)分析了真核生物翻译起始因子中eIF4A1与脑胶质瘤的关系.生物信息学分析显示, eIF4A与胶质瘤病理分级相关并且在胶质瘤细胞中高表达. eIF4A1的抑制剂Silvestrol明显抑制胶质瘤细胞的增殖能力.利用慢病毒感染胶质瘤细胞建立shRNA干扰eIF4A1基因的胶质瘤细胞株,进行了一系列体内外生物学特征的实验,研究结果发现, shRNA干扰eIF4A1基因后能够有效抑制胶质瘤细胞的增殖、克隆形成、细胞侵袭和迁移.因此,本实验研究证实eIF4A1是胶质瘤治疗的有效靶点,为胶质瘤的临床治疗提供可靠的理论基础.     

脑胶质瘤MGMT、hMLH1和hMSH2基因启动子甲基化状态研究

目的：探讨脑胶质瘤患者O6-甲基鸟嘌呤-DNA甲基转移酶基因MGMT和错配修复基因hMLH1、hMSH2启动子CpG岛甲基化状态,及其在烷化剂化疗中的意义。方法：采用甲基化特异性PCR（MSP）方法检测39例脑胶质瘤和6例正常脑组织MGMT、hMLH1和hMSH2基因启动子区的甲基化状态,免疫组化方法测定蛋白表达。结果：脑胶质瘤患者组织MGMT、hMLH1和hMSH2基因启动子区甲基化发生率分别为46.2%、10.3%和20.5%,3种基因启动子未甲基化模式与其对应蛋白表达模式相似,并与患者性别、年龄、病理类型和病理分级无明显相关性。回顾性分析患者资料,显示39例脑胶质瘤患者中,MGMT基因甲基化的患者生存期显著高于MGMT基因未甲基化患者（P〈0.05,Log-rank检验）。结论：MGMT及错配修复基因甲基化是脑胶质瘤发生过程中常见的分子事件,可能与肿瘤的发生有关;检测MGMT、hMLH1和hMSH2基因启动子甲基化状态,在判断脑胶质瘤患者预后和预测烷化剂化疗耐药性中可能具有重要意义。     

基于数据挖掘分析POLR2A基因在脑胶质瘤的表达及意义

目的:基于数据挖掘分析POLR2A基因在低级别脑胶质瘤及正常脑组织中的表达情况,进一步探讨POLR2A基因对低级别脑胶质瘤患者的预后意义。方法:利用Oncomine和GEPIA数据库对POLR2A基因mRNA在正常脑组织和低级别脑胶质瘤组织中的表达进行分析;通过cBioportal分析POLR2A基因在低级别脑胶质瘤组织中的突变情况;利用Onco Lnc数据库对POLR2A基因的表达水平与低级别脑胶质瘤患者生存率做Kaplan-Meier生存分析;使用String-DB数据库探索真核生物表达调控过程中的POLR2A相关蛋白。结果:与正常脑组织相比,低级别脑胶质瘤组织中的POLR2A基因mRNA水平呈显著高表达(P≤0.05);POLR2A基因的表达水平与低级别脑胶质瘤患者的总生存时间无明显相关性;POLR2A基因在低级别脑胶质瘤组织中存在高突变率;真核生物RNA聚合酶POLR2E、POLR2F、POLR2G、POLR2K、POLR2L等与POLR2A有明显的相互作用。结论:数据库中荟萃了POLR2A基因在低级别脑胶质瘤组织中表达的相关信息,证实POLR2A基因在低级别脑胶质瘤组织中呈高表达。     

ZEB1上调神经细胞黏附分子促进胶质瘤细胞侵袭与转移

胶质瘤是一种较为常见的颅内恶性肿瘤,其侵袭转移能力强,影响临床疗效。探讨胶质瘤发生侵袭转移的分子机制,寻找新的靶点干预胶质瘤侵袭转移是目前亟待解决的重大课题。我们前期研究中发现,神经细胞黏附分子（neuronal cell adhesion molecule, NRCAM）在各种胶质瘤细胞中的表达量均显著高于其在人正常星形胶质细胞(NHA)中的表达量（NRCAM在胶质瘤A172和T98G中的表达量分别是其在NHA中的2.15和17.63倍）;且根据人类蛋白质组学数据库信息及qRT-PCR结果证实,NRCAM在胶质瘤组织中的表达量也显著高于其在正常组织中的表达。Kaplan-Meier分析提示,高表达的NRCAM与胶质瘤患者较差的预后正相关。在此基础上,通过生物信息学预测的方法结合双荧光素酶报告基因实验证实,转录因子锌指E盒结合蛋白1(ZEB1)能够增加NRCAM启动子活性,上调NRCAM mRNA和蛋白质水平的表达量。通过Transwell实验证实,在过表达ZEB1的胶质瘤细胞A172中,沉默NRCAM将抑制该细胞的侵袭能力。而在敲低ZEB1的胶质瘤细胞T98G中,过表达NRCAM将增加该细胞的侵袭能力。总之,NRCAM在胶质瘤中显著高表达且与患者较差的预后正相关。ZEB1转录上调NRCAM来增加胶质瘤细胞侵袭能力。     

EphA2对神经胶质瘤细胞系U251的凋亡﹑增殖﹑迁移和侵袭的研究

为了研究EphA2对神经胶质瘤细胞系U251在增殖、凋亡、迁移和侵袭方面所起的作用,用RT-PCR方法检测正常脑组织标本与两种恶性胶质瘤细胞系中EphA2 mRNA表达水平,然后用化学合成的针对EphA2基因的小干扰RNA(siRNA)下调该基因的表达,以检测其在U251中的生物学功能．证实了EphA2基因在正常脑组织标本中的表达水平远低于两种恶性胶质瘤细胞系．把体外化学合成针对EphA2基因的小干扰RNA(siRNA- EphA2)转染入U251细胞后,Western blot, 实时定量 RT-PCR检测到U251细胞中EphA2蛋白及mRNA表达水平都明显降低,并且细胞增殖受到显著抑制,同时出现了明显的细胞凋亡．伤口愈合实验(检测细胞迁移能力),Transwell小室实验(检测细胞侵袭能力)均表明,下调EphA2的表达后,细胞的迁移和侵袭能力较阴性对照组显著减弱．上述结果表明,在神经胶质瘤U251细胞中,EphA2与其恶性增殖及高度侵染性相关,可作为分子治疗的有效靶点．     

基于单细胞转录组的多级别胶质瘤异质性及免疫微环境分析揭示了潜在的预后生物标志物

脑胶质瘤（glioma）是中枢神经系统最常见的内在肿瘤,具有发病率高、预后较差等特点。本研究旨在鉴定多形性胶质母细胞瘤（glioblastoma multiforme,GBM）和低级别胶质瘤（lower-grade gliomas,LGG）之间的差异表达基因（differentially expressed genes,DEGs）,以探讨不同级别胶质瘤的预后影响因素。从NCBI基因表达综合数据库中收集了胶质瘤的单细胞转录组测序数据,其中包括来自3个数据集的共29 097个细胞样本。对于不同分级的人脑胶质瘤进行分析,经过滤得到21 071个细胞,通过基因本体分析、京都基因与基因组百科全书途径分析,从差异表达基因中筛选出70个基因,我们通过查阅文献,聚焦到delta样典型Notch配体3（delta like canonical Notch ligand 3,DLL3）这个基因。基于TCGA的基因表达谱交互分析（gene expression profiling interactive analysis,GEPIA）数据库用于探索LGG和GBM中DLL3基因的表达差异,采用基因表达谱交互式分析和肿瘤免疫学估计资源（tumor immune estimation resource,TIMER）数据库,研究关键基因在不同分级的脑胶质瘤中的表达,预测了与免疫治疗密切相关的生物标志物。cBioPortal数据库用于探索DLL3表达与25个免疫检查点之间的关系。基因集富集分析（gene set enrichment analysis,GSEA）进一步确定了与中心基因相关的途径。最后,在中国胶质瘤基因组图谱（Chinese glioma genome atlas,CGGA）中验证了生物标志物在预后和预测中的疗效。这些结果发现,预后基因与肿瘤增殖和进展有关,通过生物学信息和生存分析,表明这些基因可能作为一种有前途的预后生物标志物,并作为选择治疗策略的新靶点。     

脑胶质瘤组织中p16基因启动子区CpG岛甲基化检测及其临床意义研究

目的：研究脑胶质瘤中p16基因启动子区甲基化情况及其临床意义。方法：用甲基化特异性PCR技术检测42例脑胶质瘤组织和癌旁正常脑组织中p16基因启动子甲基化,并分析该基因启动子甲基化与临床病理特征之间的关系。结果：脑胶质瘤组织中p16基因异常甲基化率（38.27%）显著高于癌旁正常脑组织中p16基因的异常甲基化率（8.8%,P=0.000）。发生甲基化的肿瘤组织或者正常脑组织中p16基因mRNA和蛋白表达显著降低。此外,p16基因异常甲基化和肿瘤病理分级有相关性（P=0.007）,而与患者性别、年龄及肿瘤类型等临床特征无关（P=0.669,0.869和0.944）。结论：p16基因启动子区CpG岛高甲基化与p16表达下调相关,推测p16启动子区CpG岛高甲基化是导致p16基因在脑胶质瘤中表达下调的重要因素,有望成为脑胶质瘤早期辅助诊断的分子标志物之一。     

The Ubiquitin Ligase COP1 Promotes Glioma Cell Proliferation by Preferentially Downregulating Tumor Suppressor p53

Human glioma causes substantial morbidity and mortality worldwide. However, the molecular mechanisms underlying glioma progression are still largely unknown. COP1 (constitutively photomorphogenic 1), an E3 ubiquitin ligase, is important in cell survival, development, cell growth, and cancer biology by regulating different substrates. As is well known, both tumor suppressor p53 and oncogenic protein c-JUN could be ubiquitinated and degraded by ubiquitin ligase COP1, which may be the reason that COP1 serves as an oncogene or a tumor suppressor in different cancer types. Up to now, the possible role of COP1 in human glioma is still unclear. In the present study, we found that the expression of COP1 was upregulated in human glioma tissues. The role of COP1 in glioma cell proliferation was investigated using COP1 loss- and gain-of-function. The results showed that downregulation of COP1 by short hairpin RNA (shRNA) inhibited glioma cell proliferation, while overexpression of COP1 significantly promoted it. Furthermore, we demonstrated that COP1 only interacted with and regulated p53, but not c-JUN. Taken together, these results indicate that COP1 may play a role in promoting glioma cell proliferation by interacting with and downregulating tumor suppressor p53 rather than oncogenic protein c-JUN.     

Matrix Metalloproteinase-13 (MMP-13) Directly and Indirectly Promotes Tumor Angiogenesis

Matrix metalloproteinases (MMPs) are extracellular zinc-dependent endopeptidases involved in the degradation and remodeling of extracellular matrix in physiological and pathological processes. MMPs also have a role in cell proliferation, migration, differentiation, angiogenesis, and apoptosis. We previously identified cancer invasion-related factors by comparing the gene expression profiles between parent and the highly invasive clone of cancer cells. Matrix metalloproteinase-13 (MMP-13) was identified as a common up-regulated gene by cancer invasion-related factors. Although MMP-13 slightly promoted tumor invasion, we found that MMP-13 was involved in tumor angiogenesis. Conditioned medium from MMP-13-overexpressing cells promoted capillary formation of immortalized human umbilical vein endothelial cells. Furthermore, treatment with recombinant MMP-13 protein enhanced capillary tube formation both in vitro and in vivo. MMP-13-promoted capillary tube formation was mediated by activation of focal adhesion kinase and ERK. Interestingly, MMP-13 promoted the secretion of VEGF-A from fibroblasts and endothelial cells. By immunohistochemical analysis, we found a possible correlation between MMP-13 expression and the number of blood vessels in human cancer cases. In summary, these findings suggest that MMP-13 may directly and indirectly promote tumor angiogenesis.     

A role for the NG2 proteoglycan in glioma progression

Many human gliomas carry markers characteristic of oligodendrocyte progenitor cells (such as Olig-2, PDGF alpha receptor and NG2 proteoglycan), suggesting these progenitors as the cells of origin for glioma initiation. This review considers the potential roles of the NG2 proteoglycan in glioma progression. NG2 is expressed not only by glioma cells and by oligodendrocyte progenitors, but also by pericytes associated with the tumor microvasculature. The proteoglycan may therefore promote tumor vascularization and recruitment of normal progenitors to the tumor mass, in addition to mediating expansion of the transformed cell population. Along with potentiating growth factor signaling and serving as a cell surface receptor for extracellular matrix components, NG2 also has the ability to mediate activation of β-1 integrins. These molecular interactions allow the proteoglycan to contribute to critical processes such as cell proliferation, cell motility and cell survival.Key words: NG2 proteoglycan, glioma progression, cell motility, cell proliferation, cell survival, tumor vascularization     

Interfering with hyaluronic acid metabolism suppresses glioma cell proliferation by regulating autophagy

The tumor microenvironment plays an important role in tumor progression. Hyaluronic acid (HA), an important component of the extracellular matrix in the tumor microenvironment, abnormally accumulates in a variety of tumors. However, the role of abnormal HA accumulation in glioma remains unclear. The present study indicated that HA, hyaluronic acid synthase 3 (HAS3), and a receptor of HA named CD44 were expressed at high levels in human glioma tissues and negatively correlated with the prognosis of patients with glioma. Silencing HAS3 expression or blocking CD44 inhibited glioma cell proliferation in vitro and in vivo. The underlying mechanism was attributed to the inhibition of autophagy flux and maintaining glioma cell cycle arrest in G1 phase. More importantly, 4-methylumbelliferone (4-MU), a small competitive inhibitor of Uridine diphosphate (UDP) with the ability to penetrate the blood-brain barrier (BBB), also inhibited glioma cell proliferation in vitro and in vivo. Thus, approaches that interfere with HA metabolism by altering the expression of HAS3 and CD44 and the administration of 4-MU potentially represent effective strategies for glioma treatment.Subject terms: Cancer metabolism, Drug development, Cancer genomics     

Roles of sphingosine-1-phosphate (S1P) receptors in malignant behavior of glioma cells. Differential effects of S1P2 on cell migration and invasiveness

Sphingosine-1-phosphate (S1P) is a bioactive lipid that signals through a family of five G-protein-coupled receptors, termed S1P(1-5). S1P stimulates growth and invasiveness of glioma cells, and high expression levels of the enzyme that forms S1P, sphingosine kinase-1, correlate with short survival of glioma patients. In this study we examined the mechanism of S1P stimulation of glioma cell proliferation and invasion by either overexpressing or knocking down, by RNA interference, S1P receptor expression in glioma cell lines. S1P(1), S1P(2) and S1P(3) all contribute positively to S1P-stimulated glioma cell proliferation, with S1P(1) being the major contributor. Stimulation of glioma cell proliferation by these receptors correlated with activation of ERK MAP kinase. S1P(5) blocks glioma cell proliferation, and inhibits ERK activation. S1P(1) and S1P(3) enhance glioma cell migration and invasion. S1P(2) inhibits migration through Rho activation, Rho kinase signaling and stress fiber formation, but unexpectedly, enhances glioma cell invasiveness by stimulating cell adhesion. S1P(2) also potently enhances expression of the matricellular protein CCN1/Cyr61, which has been implicated in tumor cell adhesion, and invasion as well as tumor angiogenesis. A neutralizing antibody to CCN1 blocked S1P(2)-stimulated glioma invasion. Thus, while S1P(2) decreases glioma cell motility, it may enhance invasion through induction of proteins that modulate glioma cell interaction with the extracellular matrix.     

Long noncoding RNA FOXD2-AS1 promotes glioma malignancy and tumorigenesis via targeting miR-185-5p/CCND2 axis

Glioma is the most aggressive malignant tumor in the adult central nervous system. Abnormal long noncoding RNA (lncRNA) FOXD2-AS1 expression was associated with tumor development. However, the possible role of FOXD2-AS1 in the progression of glioma is not known. In the present study, we used in vitro and in vivo assays to investigate the effect of abnormal expression of FOXD2-AS1 on glioma progression and to explore the mechanisms. FOXD2-AS1 was upregulated in glioma tissue, cells, and sphere subpopulation. Upregulation of FOXD2-AS1 was correlated with poor prognosis of glioma. Downregulation of FOXD2-AS1 decreased cell proliferation, migration, invasion, stemness, and epithelial-mesenchymal transition (EMT) in glioma cells and inhibited tumor growth in transplanted tumor. We also revealed that FOXD2-AS1 was mainly located in cytoplasm and microRNA (miR)-185-5p both targeted FOXD2-AS1 and CCND2 messenger RNA (mRNA) 3′-untranslated region (3′-UTR). miR-185-5p was downregulated in glioma tissue, cells, and sphere subpopulation. Downregulation of miR-185-5p was closely correlated with poor prognosis of glioma patients. In addition, miR-185-5p mimics decreased cell proliferation, migration, invasion, stemness, and EMT in glioma cells. CCND2 was upregulated in glioma tissue, cells, and sphere subpopulation. Upregulation of CCND2 was closely correlated with poor prognosis of glioma patients. CCND2 knockdown decreased cell proliferation, migration, invasion, and EMT in glioma cells. In glioma tissues, CCND2 expression was negatively associated with miR-185-5p, but positively correlated with FOXD2-AS1. FOXD2-AS1 knockdown and miR-185-5p mimics decreased CCND2 expression. Inhibition of miR-185-5p suppressed FOXD2-AS1 knockdown-induced decrease of CCND2 expression. Overexpression of CCND2 suppressed FOXD2-AS1 knockdown-induced inhibition of glioma malignancy. Taken together, our findings highlight the FOXD2-AS1/miR-185-5p/CCND2 axis in the glioma development.     

Overexpression of Annexin A2 promotes proliferation by forming a Glypican 1/c-Myc positive feedback loop: prognostic significance in human glioma

In order to set up a reliable prediction system for the tumor grade and prognosis in glioma patients, we clarify the complicated crosstalk of Annexin A2 (ANXA2) with Glypican 1 (GPC1) and demonstrate whether combined indexes of ANXA2 and GPC1 could improve the prognostic evaluation for glioma patients. We found that ANXA2-induced glioma cell proliferation in a c-Myc-dependent manner. ANXA2 increased the expression of GPC1 via c-Myc and the upregulated GPC1 further promoted the c-Myc level, forming a positive feedback loop, which eventually led to enhanced proliferation of glioma cells. Both mRNA and protein levels of ANXA2 were upregulated in glioma tissues and coincided with the overexpression of GPC1. Besides, we utilized tissue microarrays (TMAs) and immunohistochemistry to demonstrate that glioma patients with both high expression of ANXA2 and GPC1 tended to have higher rate of tumor recurrence and shorter overall survival (OS). In conclusion, the overexpression of ANXA2 promotes proliferation of glioma cells by forming a GPC1/c-Myc positive feedback loop, and ANXA2 together with its downstream target GPC1 could be a potential “combination biomarker” for predicting prognosis of glioma patients.Subject terms: CNS cancer, Prognostic markers     

Enolase‐phosphatase 1 acts as an oncogenic driver in glioma

Enolase‐phosphatase 1 (ENOPH1), a newly identified enzyme involved in l ‐methionine biosynthesis, is associated with anxiety and depression. In this study, ENOPH1 was found to play a crucial role in promoting the proliferation and migration of glioma cells. Among high‐grade glioma patients, the overall survival of the group showing high ENOPH1 expression was shorter than that of the group showing low ENOPH1 expression. ENOPH1 knockdown inhibited glioma cell proliferation and migration. In parallel, ENOPH1 knockdown suppressed tumor growth capacity and prolonged survival in an orthotopic glioma model. Mechanistically, we found that ENOPH1 activates the PI3K/AKT/mTOR signaling pathway by regulating THEM4. In conclusion, ENOPH1 is an important mediator that promotes glioma cell proliferation and migration.     

pERK, pAkt and pBad: A Possible Role in Cell Proliferation and Sustained Cellular Survival During Tumorigenesis and Tumor Progression in ENU Induced Transplacental Glioma Rat Model

Gliomas remain to be an unresolved medical problem. Better understanding of complex regulation and key molecules involved in glioma pathology are needed for designing new and effective treatment modalities. Activation of mitogen-activated protein kinase/extracellular signal regulated kinase (ERK) pathway is known to be having a critical role in cell proliferation and differentiation during the invasion and metastasis of the tumor cells. In the present study, N-ethyl N-nitrosourea induced glioma rat model was used to understand the role of ERK1/2 and Akt pathways in the progression of tumor malignancy. Twenty-four glioma rat brains of early (P90) and progressive (P180) stages were used for histological and immunoblot analysis. Results have shown increased levels of activated ERK1/2, activated Akt or protein kinase B, Bcl-2 and pBad in the glioma rats. This study may indicate increased cell proliferation and angiogenesis, mediated through activation of both ERK and Akt pathways along with increased levels of pBad. Further, pAkt and Bcl-2 levels in the progressive stage glioma rats may indicate existence of sustained tumor cell survival signals. Moreover, enhanced pBad levels in tumor may indicate that there are anti-apoptotic mechanisms, further making the malignant cells resistant to apoptosis.