胶质瘤干细胞放射抗拒和放射增敏蛋白质组学研究进展

经过包括放疗在内的多学科治疗,多形性胶质母细胞瘤中位生存期始终停留在1年左右。胶质瘤干细胞基因组和蛋白质组的异质性是影响预后的根本原因,依据蛋白质组学制定针对关键放射抗拒蛋白的增敏研究有望改善多形性胶质母细胞瘤预后。本文通过Pubmed等数据库查阅了近十年来的相关文献,系统地讨论了各种常用蛋白质定量技术、用于数据处理的工具及其在胶质瘤干细胞放射抗拒和放射增敏中的进展。     

胶质瘤放射增敏治疗分子生物学研究进展

胶质瘤是最常见的中枢神经系统肿瘤,进展迅速,预后不佳,死亡率高.放疗是治疗高级别胶质瘤的常规手段,放射增敏剂能够增强胶质瘤的放疗效果.本文拟对胶质瘤放射增敏剂研究进展作一概述.     

NF-κB和EGFR在不同放射敏感性胶质瘤中的表达

 目的 探讨NF-κB和EGFR的表达水平与胶质瘤放射敏感性的关系。方法 应用免疫组织化学SABC法检测NF-κB p50、p65及EGFR在5例正常脑组织和82例不同放射敏感性胶质瘤中的表达。结果 NF-κBB p50、p65和EGFR在正常脑组织中均未见表达。髓母细胞瘤、室管膜瘤、少枝胶质细胞瘤、低(Ⅰ～Ⅱ级)及高级别(Ⅲ～Ⅳ级)星形细胞瘤、多形性胶质母细胞瘤的NF-κB和EGFR表达率呈依次上升趋势。对放疗最敏感的髓母细胞瘤表达率与其他各组均有显著性差异(P<0．05)。结论 NF-κB和EGFR表达水平与胶质瘤的不同放射敏感性可能相关。     

塞来昔布对脑胶质瘤细胞放射增敏效应的研究

[目的]观察COX-2选择性抑制剂塞来昔布（Celecoxib）对三种脑胶质瘤细胞放射增敏作用。[方法]选择适当浓度的COX-2选择性抑制剂Celecoxib进行放射增敏实验，设置单纯放射（R）组和放射＋药物（R＋D）组，采用集落形成法分别检测Celecoxib对脑胶质瘤SHG-44细胞株，767细胞以及大鼠脑胶质瘤C6细胞株的放射增敏效应，并绘制细胞存活曲线。[结果]Celecoxib对3种胶质瘤细胞株均显示出放射增敏效应，R＋D组与R组相比较，反映放射敏感性指标的SF2、D0.01、D0、Dq均出现下降。其中tSF2=8．315，P=0．014；tD0.01=9．28，P=0．011；tD0=3．985，P=0．058；tDq=3．348，P=O．075。[结论]Celecoxib在体外实验中可以提高脑胶质瘤的放射敏感性。Celecoxib有可能成为治疗胶质瘤的放射增敏剂。     

不同类型恶性胶质瘤离体细胞系放射敏感性的比较

利用集落形成法测绘5个恶性胶质瘤离体细胞系的剂量存活曲线,计算与肿瘤细胞固有放射敏感性有关的参数。结果表明胶质母细胞瘤的放射敏感性较低,髓母细胞瘤的放射敏感性较高,复发恶性星形细胞的放射敏感性明显低于初发瘤。进一步证实肿瘤的组织病理学类型与放射敏感性有关。     

联合用药靶向胶质母细胞瘤样干细胞的治疗进展

胶质母细胞瘤作为常见的恶性胶质瘤,其等级系数高,致死性强.随着肿瘤干细胞理论的提出,为肿瘤靶向治疗提供了新的途径.通过联合用药抑制生长机制,阻止胶质母细胞瘤样干细胞的增殖,从而为靶向治疗恶性胶质瘤提供了可能.本文就联合用药靶向胶质母细胞瘤样干细胞进行简要综述.     

丁酸钠对胶质瘤细胞放射敏感度的影响

目的研究丁酸钠（sodium butyrate,NaB）对胶质瘤细胞U-251的放射增敏作用及其机制。方法采用克隆形成实验分析NaB对U-251细胞的放射增敏作用;采用反转录PCR以及Western blot的方法评价NaB对DNA损伤修复相关基因Ku70的mRNA及蛋白表达水平的影响。结果NaB作用组细胞放疗后存活率明显降低,放射增敏比值（SER）为1.23;而且其在mRNA及蛋白水平降低了DNA损伤修复基因Ku70的表达（P<0.05）。结论丁酸钠能增加胶质瘤细胞的放射敏感度,这可能与丁酸钠能下调Ku70蛋白表达有关。     

COX-2表达对脑胶质瘤的放射敏感性和细胞周期的影响

背景与目的COX-2在胶质瘤的发生发展过程中发挥重要作用,近年来发现COX-2抑制剂对一些胶质瘤细胞有增强放射敏感性的作用.本研究的目的在于观察人恶性脑胶质瘤细胞的COX-2蛋白表达和COX-1/COX-2双重抑制剂对乙酰氨基酚(acetaminophen,ACE)对细胞COX-2 mRNA表达、克隆形成率和细胞周期的影响,并探讨ACE提高胶质瘤细胞放射敏感性的机制.方法选用人恶性脑胶质瘤细胞株SHG-44作为研究对象.免疫细胞化学和RT-PCR检测细胞COX-2表达,成克隆分析法测定对乙酰氨基酚对细胞的放射增敏作用,流式细胞仪检测细胞周期分布.结果免疫细胞化学染色SHG-44细胞的胞膜和胞质均有COX-2蛋白表达.RT-PCR检测对乙酰氨基酚作用后细胞中COX-2mRNA表达降低.对乙酰氨基酚联合放疗作用于SHG-44细胞与单纯照射组相比,显示了放射增敏作用,增敏比为1.23(D0值水平)或1.43(Dq值水平).细胞周期检测发现,不同时间各组细胞都出现了不同的周期分布,照射后12 h单纯照射组和放射加药组G2/M期细胞明显多于对照组,24 h后单纯照射组迅速下降到与对照组相等的水平,而放射加药组仍维持较高比例(P＜0.01),同时对放射抗拒的S期细胞比例最低.结论人恶性脑胶质瘤细胞株SHG-44的胞膜和胞质均有COX-2蛋白表达,对乙酰氨基酚能增加该细胞株的放射敏感性,其机制可能与抑制COX-2表达、改变细胞周期分布有关.     

高分级胶质瘤的放疗

脑胶质瘤的分类,一是kernohan按恶性度分类,数字分级表示。恶性度最低为星形细胞瘤Ⅰ级,神经胶质母细胞瘤和有分化差倾向的显形细胞瘤为Ⅱ级,星形细胞瘤Ⅲ和Ⅳ级为有低、高度恶性的多形性胶质母细胞瘤。也有作者只将星形细胞瘤Ⅳ级归为多形性胶质母细胞瘤。     

鼻咽癌放射敏感性的分子生物学研究进展

鼻咽癌是我国南方地区常见的恶性肿瘤之一, 由于其解剖位置的特殊性以及对放射线敏感的特性, 放射治疗是首选的治疗手段。鼻咽癌治疗失败的原因之一为放射抗拒, 研究其抗拒机制、寻找放射增敏途径是提高治愈率的途径之一。通过预测肿瘤细胞内在放射敏感性来推测个体肿瘤放射治愈的可能性是当前的研究热点。本文将对国内外在鼻咽癌放射敏感性分子生物学方面的研究近况进行综述。      

ILKAP,ILK and PINCH1 control cell survival of p53-wildtype glioblastoma cells after irradiation

The prognosis is generally poor for patients suffering from glioblastoma multiforme (GBM) due to radiation and drug resistance. Prosurvival signaling originating from focal adhesion hubs essentially contributes to therapy resistance and tumor aggressiveness. As the underlying molecular mechanisms remain largely elusive, we addressed whether targeting of the focal adhesion proteins particularly interesting new cysteine-histidine-rich 1 (PINCH1), integrin-linked kinase (ILK) and ILK associated phosphatase (ILKAP) modulates GBM cell radioresistance. Intriguingly, PINCH1, ILK and ILKAP depletion sensitized p53-wildtype, but not p53-mutant, GBM cells to radiotherapy. Concomitantly, these cells showed inactivated Glycogen synthase kinase-3β (GSK3β) and reduced proliferation. For PINCH1 and ILKAP knockdown, elevated levels of radiation-induced γH2AX/53BP1-positive foci, as a marker for DNA double strand breaks, were observed. Mechanistically, we identified radiation-induced phosphorylation of DNA protein kinase (DNAPK), an important DNA repair protein, to be dependent on ILKAP. This interaction was fundamental to radiation survival of p53-wildtype GBM cells. Conclusively, our data suggest an essential role of PINCH1, ILK and ILKAP for the radioresistance of p53-wildtype GBM cells and provide evidence for DNAPK functioning as a central mediator of ILKAP signaling. Strategies for targeting focal adhesion proteins in combination with radiotherapy might be a promising approach for patients with GBM.     

Abrogation of radioresistance in glioblastoma stem‐like cells by inhibition of ATM kinase

Resistance to radiotherapy in glioblastoma (GBM) is an important clinical problem and several authors have attributed this to a subpopulation of GBM cancer stem cells (CSCs) which may be responsible for tumour recurrence following treatment. It is hypothesised that GBM CSCs exhibit upregulated DNA damage responses and are resistant to radiation but the current literature is conflicting. We investigated radioresistance of primary GBM cells grown in stem cell conditions (CSC) compared to paired differentiated tumour cell populations and explored the radiosensitising effects of the ATM inhibitor KU‐55933.We report that GBM CSCs are radioresistant compared to paired differentiated tumour cells as measured by clonogenic assay. GBM CSC''s display upregulated phosphorylated DNA damage response proteins and enhanced activation of the G2/M checkpoint following irradiation and repair DNA double strand breaks (DSBs) more efficiently than their differentiated tumour cell counterparts following radiation.Inhibition of ATM kinase by KU‐55933 produced potent radiosensitisation of GBM CSCs (sensitiser enhancement ratios 2.6–3.5) and effectively abrogated the enhanced DSB repair proficiency observed in GBM CSCs at 24 h post irradiation. G2/M checkpoint activation was reduced but not abolished by KU‐55933 in GBM CSCs.ATM kinase inhibition overcomes radioresistance of GBM CSCs and, in combination with conventional therapy, has potential to improve outcomes for patients with GBM.     

Gliosarcoma: distinct molecular pathways and genomic alterations identified by DNA copy number/SNP microarray analysis

Journal of Neuro-Oncology - Gliosarcoma is a histologic variant of glioblastoma (GBM), and like GBM carries a poor prognosis. Median survival is less than one (1) year with less than 5% of patients...     

Inhibition of Cathepsin D (CTSD) enhances radiosensitivity of glioblastoma cells by attenuating autophagy

Postoperative radiotherapy combined with chemotherapy is a commonly used treatment for glioblastoma (GBM) but radiotherapy often fails to achieve the expected results mainly due to tumor radioresistance. In this study, we established a radioresistant subline from human glioma cell line U251 and found that Cathepsin D (CTSD), a gene closely related to the clinical malignancy and prognosis in glioma, had higher expression level in radioresistant clones than that in parental cells, and knocking down CTSD by small interfering RNA (siRNA) or its inhibitor Pepstatin-A increased the radiosensitivity. The level of autophagy was enhanced in the radioresistant GBM cells compared with its parent cells, and silencing autophagy by light chain 3 (LC3) siRNA significantly sensitized GBM cells to ionizing radiation (IR). Moreover, the protein expression level of CTSD was positively correlated with the autophagy marker LC3 II/I and negatively correlated with P62 after IR in radioresistant cells. As expected, through the combination of Western blot and immunofluorescence assays, inhibition of CTSD increased the formation of autophagosomes, while decreased the formation of autolysosomes, which indicating an attenuated autophagy level, leading to radiosensitization ultimately. Our results revealed for the first time that CTSD regulated the radiosensitivity of glioblastoma by affecting the fusion of autophagosomes and lysosomes. In significance, CTSD might be a potential molecular biomarker and a new therapeutic target in glioblastoma.     

Glioblastoma multiforme: the role of DSB repair between genotype and phenotype

Glioblastoma is the most frequent primary brain tumor in adults. The average survival time of less than 1 year did not improve notably over the last three decades. The dismal prognosis of glioblastoma patients is largely due to the striking radioresistance of this tumor. Here, we attempt a combined view on the genetics, the repair mechanisms and the radioresistance of glioblastoma. Specifically, we address the role of DNA-PKcs and the novel potential end-joining factor KUB3 in maintaining the radioresistant phenotype, the interrelationship between genetic lesions and repair mechanisms, and new perspectives that emerge from the identification of glioblastoma stem cells.     

Giant cell glioblastoma: A glioblastoma subtype with distinct epidemiology and superior prognosis

Giant cell glioblastoma (GC) is an uncommon subtype of glioblastoma multiforme (GBM). Consequently, the epidemiology, natural history, and factors associated with outcome are not well defined. Patients diagnosed with GC from 1988 through 2004 were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Outcomes were examined with Kaplan-Meier survival analysis and Cox models. For comparison, similar analyses were conducted for patients diagnosed with GBM. GC was identified in 1% of 16,430 patients diagnosed with either GC or GBM. Compared with GBM, GC showed similar gender and racial distributions. Likewise, tumor size and location were not significantly different between the two histologies. GC tended to occur in younger patients with a median age at diagnosis of 51 years, compared with 62 years for GBM. Additionally, patients with GC were more likely to undergo complete resection compared with patients with GBM. For both histologies, young age, tumor size, extent of resection, and the use of adjuvant radiation therapy (RT) were associated with improved survival. Cox modeling suggests the prognosis for GC is significantly superior to that for GBM (hazard ratio = 0.76; 95% confidence interval, 0.59–0.97) even after adjustment for factors affecting survival. GC is an uncommon GBM subtype that tends to occur in younger patients. Prospective data defining optimal treatment for GC are unavailable; however, these retrospective findings suggest that resection, as opposed to biopsy only, and adjuvant RT may improve survival. The prognosis of GC is superior to that of GBM, and long-term survival is possible, suggesting aggressive therapy is warranted.     

胶质母细胞瘤循环肿瘤细胞的研究进展

胶质母细胞瘤（glioblastoma, GBM）是恶性程度极高的肿瘤,即使在手术、放射治疗和化学治疗等多重方案联合治疗下,大部分GBM患者还是因复发死亡。胶质母细胞瘤患者预后极差不仅与肿瘤细胞侵袭和增殖相关,而且还与肿瘤监测手段尚欠成熟有关。研究发现循环肿瘤细胞（circulating tumor cells, CTCs）能够在GBM患者血液中能检测到,它在GBM的复发过程中发挥极其重要的作用。因此,胶质母细胞瘤CTCs的检测技术及其临床意义成为当下研究热点之一。     

Characterization of genomic alterations in primary central nervous system lymphomas

Glioblastoma (GBM) is a highly fatal disease with a 5 year survival rate of less than 22%. One of the most effective treatment regimens to date is the use of radiotherapy which induces lethal DNA double-strand breaks to prevent tumour growth. However, recurrence occurs in the majority of patients and is in-part a result of robust radioresistance mechanisms. In this study, we demonstrate that the multifunctional cytokine, interleukin-6 (IL-6), confers a growth advantage in GBM cells but does not have the same effect on normal neural progenitor cells. Further analysis showed IL-6 can promote radioresistance in GBM cells when exposed to ionising radiation. Ablation of the Ataxia-telangiectasia mutated serine/threonine kinase that is recruited and activated by DNA double-strand breaks reverses the effect of radioresistance and re-sensitised GBM to DNA damage thus leading to increase cell death. Our finding suggests targeting the signaling cascade of DNA damage response is a potential therapeutic approach to circumvent IL-6 from promoting radioresistance in GBM.