全反式维甲酸抑制MDM2基因在胶质瘤细胞SHG-44中的表达

目的 探讨全反式维甲酸对胶质瘤细胞SHG-44中MDM2基因表达的影响,为进一步研究脑胶质瘤的进展机制及基因治疗提供依据.方法 分别利用cDNA微阵列与Western blot技术分析在10μmol/L全反式维甲酸(all-transretinoic acid,ATRA)处理前后的胶质瘤SHG-44细胞MDM2基因和蛋白的差异表达应用免疫组化链霉菌抗生物素蛋白-过氧化酶(Streptavidin-Peroxidase,SP)法检测Ⅱ级与Ⅳ级胶质瘤标本MDM2蛋白的表达.随机选择数个差异基因进行Northern杂交实验,以验证cDNA微阵列的结果.结果 应用cDNA微阵列检测发现,MDM2基因在ATRA处理与未处理的SHG-44细胞之间表达量的比值为0.37,提示ATRA可抑制MDM2基因在SHG-44中的表达.该结果进一步得Northern杂交实验结果的支持.Western blot分析结果显示10μmol/L ATRA处理前后胶质瘤SHG-44细胞之间MDM2蛋白的相对表达量分别为21.40±0.58和14.02±0.35(t=24.728,P=0.000),提示MDM2蛋白在SHG-44中的表达受到ATRA抑制.Ⅱ级和Ⅳ级胶质瘤标本MDM2蛋白的阳性表达率分别为24.00%(6/25)和56.52%(13/23)(X2=5.298,P=0.021),MDM2蛋白的表达随胶质瘤恶性程度的增高而增加.结论 ATRA可抑制SHG-44胶质瘤细胞中MDM2基因的表达,MDM2基因的表达水平与胶质瘤的演进有关.     

他莫昔芬对SHG-44胶质瘤细胞氯通道的抑制作用

目的研究氯通道阻断剂他莫昔芬（tamoxifen）对SHG-44胶质瘤细胞电压依赖性氯通道电流的作用。方法采用全细胞膜片钳方法记录SHG-44细胞的电压依赖性氯通道电流，并观察施用不同浓度的他莫昔芬后电流的变化。结果该电流特性为外向整流、不失活，他莫昔芬能够明显阻断该电流，该阻断具有剂量依赖性及电压依赖性。在＋100mV时，1μM及5μM他莫昔芬对氯电流抑制率分别为48％及89％。结论他莫昔芬可明显阻断SHG-44胶质瘤细胞上的电压依赖性氯通道。     

九节龙皂苷诱导胶质瘤SHG-44细胞凋亡及其机制研究

目的研究九节龙皂苷对胶质瘤SHG-44细胞潜在的治疗作用及其机制。方法用四甲基偶氨唑蓝（MTT）法检测不同剂量九节龙皂苷于不同时间（6、12、24、72h）对人胶质瘤SHG-d4细胞活性的影响和细胞流式术检测SGH-44细胞调亡情况;Western—blot检测caspase-3和Bcl-2在SHG-44细胞中的表达情况。结果流式细胞仪检测显示,随着九节龙皂苷浓度的增大和时间延长,SHG-44细胞的凋亡率明显上升,Western—blot结果提示九节龙皂苷下调了凋亡抑制蛋白Bcl-2的表达并激活了凋亡蛋白caspase-3,九节龙皂苷明显抑制SHG-44细胞的生长与增殖。结论九节龙皂苷引起胶质瘤细胞大量凋亡,具有显著的抗肿瘤作用,通过调控caspase-3和Bcl-2诱导胶质瘤SHG-44细胞凋亡。     

针对MAGE-1基因RNAi在恶性胶质瘤SHG-44细胞中的作用研究

目的构建抑制黑色素瘤抗原-1(MAGE-1)的siRNA表达载体,鉴定其在人恶性胶质瘤细胞系SHG-44细胞中对MAGE-1基因表达的干涉作用。方法化学合成2对编码短发夹RNA序列的靶向MAGE-1基因寡核苷酸链,克隆到经BglⅡ、HindⅢ双酶切的pSUPER载体上,重组构建RNA干涉(RNAi)质粒载体。利用逆转录多聚酶链反应(RT-PCR)、流式细胞术和荧光显微镜,检测经稳定转染后SHG-44细胞中MAGE-1的表达,以了解siRNA的干扰效果。结果重组构建的pSUPER-MAGE-1载体经双酶切电泳及插入基因片段序列分析,表明寡核苷酸链成功插入到预计位点,并且序列与预期完全一致。稳定转染后G418筛选出的SHG-44多克隆细胞MAGE-1的表达经RT-PCR、流式细胞术和荧光显微镜检测,2对siRNA均有较明显的干涉作用。结论成功构建了针对MAGE-1基因的siRNA表达载体,抑制SHG-44细胞中的MAGE-1分子的表达。     

MG-132激活SHG-44细胞株自噬途径的体外实验

目的 探讨抑制蛋白酶体功能对人胶质瘤SHG-44细胞内自噬途径的激活作用.方法 采用5.0μmol/L蛋白酶体特异性抑制剂MG-132抑制人胶质瘤细胞SHG-44蛋白酶体功能.采用HE染色光镜观察细胞形态变化,AO染色荧光显微镜观察胞质内酸性囊泡细胞器的形成,锇铀铅染色透射电镜观察亚细胞结构变化.差速离心及蛋白印迹分析自噬关联蛋白Beclin及LC3的表达.结果 蛋白酶体功能被抑制后,HE染色光镜下可见SHG-44细胞的胞核呈深蓝色,大小无明显变化,部分染色质轻度浓缩,胞质内可见空泡,胞核附近胞质呈嗜酸性红染;荧光显微镜下见胞核呈黄绿色荧光,细胞核周围的胞质呈点状红色荧光;透射电镜下可见胞核无明显变化,胞质内出现自噬前体、自噬体及自噬溶酶体等亚细胞结构;蛋白印迹分析显示胞质内的Beclin、LC3-Ⅰ、LC3-Ⅱ显著增加.结论 抑制蛋白酶体功能可以有效地激活人胶质瘤SHG-44细胞内自噬途径.     

Differentially expressed genes from the glioblastoma cell line SHG-44 treated with all-trans retinoic acid in vitro

Morphology, immunocytochemistry, growth curve assay, and flow cytometry were used to investigate the effects of all-trans retinoic acid (RA) on cell proliferation, cell cycle progression and differentiation of the astrocytoma cell line SHG-44 from glioblastoma multiforme (World Health Organization grade IV). The differentially expressed genes from RA-treated and normal SHG-44 were identified by cDNA microarray after the cell line SHG-44 was treated with 10 μM RA for 3 days. Validation of some differentially expressed genes was performed by Northern Blot analysis. The expression of glial fibrillary acidic protein (GFAP) was markedly increased in RA-treated SHG-44 cells. Other changes included a short shuttle shape, small nucleus, decreased karyoplasm proportion, the formation of increased thin cytoplasmic processes, reduced cell growth and a 15% increase in G0/G1 phase cell populations. In addition, 42 known genes were identified with altered expression in our cDNA microarray. There was stable down-regulation of MDM2 and UGB as well as overexpression of SOD2, CSTB, and G3BP when RA-treated SHG-44 was compared with normal SHG-44. RA simultaneously suppressed the proliferation of SHG-44 cells significantly as well as induced differentiation and altered gene expression.     

Identification of tumor invasion-related differentially expressed genes in different grades and all-trans retinoic acid-treated astrocytoma cell lines

BACKGROUND:Although several genetic aberrations and gene expressional changes have been shown to exist in tumors and different grades of astrocytomas,as well as in normal tissues,the gene profiling and ge-netic pathways associated with malignant transformation and progression remain unclear. OBJECTIVE: To identify differentially expressed genes related to tumor invasion from various grades and all-trans retinoic acid (ATRA)-treated astrocytoma cell lines by cDNA microarray. DESIGN,TIME AND SETTING: In vitro...     

Screening of differentially expressed genes related to differentiation and proliferation by gene expression profiling of different grade astrocytoma cell lines*☆

BACKGROUND： The detection of differential gene expression in brain is possible by cDNA microarray technology, and the screening of differentially expressed genes might provide a biological basis for gene-targeted therapy for tumors. OBJECTIVE： To detect the differential expression of genes among astrocytoma SHG-44 （WHO grade Ⅳ）, CHG-5 （WHO grade Ⅱ）, and ATRA-treated SHG-44 cell lines by cDNA microarray. DESIGN： Laboratory experiments in vitro. SETTING： Department of Neurobiology, the Third Military Medical University. MATERIALS： The experiment was performed at the Department of Neurobiology in the Third Military Medical University of the Chinese PLA from January to October 2007. The SHG-44 cell line （WHO grade Ⅳ） was established by Prof. Ziwei Du, and the CHG-5 cell line （WHO grade Ⅱ） was set up by Prof. Xiuwu Bian from the Third Military Medical University of the Chinese PLA. The cDNA microarray containing 9182 known genes was prepared and provided by Dr. Yang Zhong at the City University of Hong Kong. METHODS： To screen differentially expressed genes from the gene expression profiles detected by cDNA microarray comparisons were made between CHG-5 and SHG-44 cells and between SHG-44 cells with or without treatment with 10 μmol/L ATRA. Some differentially expressed genes were selected randomly for Northern Blot analysis to confirm the results of the microarray. The determination criteria for differential gene expression were as follows. ① The ratio of Cy5 signal to Cy3 was greater than 2.0 or less than 0.5. ② The results of the triplicate microarray hybridizations showed the same trend in three experiments. ③ A gene appeared at least two times on the triplicate microarray hybridizations, and the 3^rd value did not show a contradictory trend. A normalized ratio of Cy5 intensity to Cy3 greater than 2.0 or less than 0.5 was considered to represent up-regulated or down-regulated gene expression, respectively. MAIN OUTCOME MEASURES： The identification of genes that were sim     

Growth and radiosensitivity of irradiated human glioma cell progeny

BACKGROUND： Progenitors of the immortalized human glioma cell line, SHG-44, are significantly less sensitive to irradiation. Two hypotheses regarding the mechanism of this effect exist： several studies have suggested that there is a subgroup with different radiosensitivities in identical cell group, and the progenitors of irradiate is a adaptive response subgroup, so its radiosensitivity is descend. A second hypothesis suggests that irradiated glioma progeny have a stronger ability to repair DNA damage. This would suggest that when progeny are continuously irradiated, resistance to irradiation-induced DNA increases, and radiosensitivity decreases. OBJECTIVE： To investigate radiosensitivity and growth features after irradiation to progeny of the human glioma cell line SHG-44. DESIGN, TIME AND SETTING： A randomized, controlled experiment, which was performed at the Department of Radiology Laboratory, the First Hospital Affiliated to Soochow University, between September 2004 and January 2006. MATERIALS： The glioma cell line SHG-44 was provided by the Institute of Neuroscience, First Affiliated Hospital of Suzhou University. Propidium iodide reagent was provided by Coulter Corporation. A linear accelerator, KD-2 type, was provided by Siemens, Germany. The flow cytometer EPICS-XL was provided by Coulter Corporation. METHODS： Brain glioma SHG-44 cells were divided into four groups： SHG-44, SHG-44-2, SHG-44-6, and SHG-44-10 . The SHG-44-2, SHG-44-6, and SHG-44-10 cells were vertically irradiated with varying doses of 2, 6 and 10 Gy by a linear accelerator （6 MVX）. The cells were passaged for 15 generations and cultured in RPMI-1640 culture media. MAIN OUTCOME MEASURES： Community re-double time, mean lethal dose （D0）, extrapolation number （N）, fraction surviving fraction irradiated by 2 Gy dose （SF2）, quasi-threshold dose （Dq）, and cell cycle. RESULTS： The Population doubling time （PDT） of SHG-44-2, SHG-44-6, and SHG-44-10 cell groups was not significant （P = 0.052）. Compare     

人BTBD10新基因克隆及组织表达和在脑胶质瘤中的表达谱及聚类

目的探讨人脑胶质瘤相关BTBD10新基因克隆、正常成人组织分布及在不同级别星形细胞瘤中的表达。方法构建胎脑cDNA文库和大规模测序获得全长BTBD10新基因;用Clontech人多组织文库(MTC)为模板研究BTBD10在8种正常组织中的分布;用含13 939种人类基因(8 347种已知基因,5 592种未知基因)的BioStarH140S型表达谱芯片检测BTBD10在星形细胞瘤中的表达,Hierarchical聚类分析与BTBD10表达谱相近的基因群;Northern杂交验证BTBD10在不同级别胶质瘤中的表达。结果人胎脑文库中克隆的BTBD10新基因含1 428bp长的开放阅读框,编码475个氨基酸的蛋白;芯片结果提示BTBD10基因在18例胶质瘤组织中表达一致降低,与促性腺诱导素转录阻抑蛋白GIOT1、血管性肠肽VIP等7条基因的表达谱相似;BTBD10在正常脑组织中表达量最高,而心、肺、肝、肾、胰腺中表达较低;Northern显示BTBD10与胶质瘤发生密切相关,与芯片结果一致。结论表达谱芯片可快速高效筛选脑胶质瘤相关基因,BTBD10基因与胶质瘤发生密切相关,在脑胶质瘤的转录调控中起重要作用。     

胶质瘤U87细胞中AKT2基因表达对化疗药物替尼泊苷敏感性的影响

目的探讨脑胶质瘤U87细胞中AKT2基因表达对替尼泊苷（VM-26）敏感性的影响。方法体外将慢病毒介导的AKT2-shRNA表达载体转染胶质瘤U87细胞,作为实验组;转染GFP—shRNA的U87细胞作为阴性对照组,未转染的U87细胞作为空白对照组。应用RT—PCR、Westernblot检测3组U87细胞中AKT2mRNA和蛋白的表达变化。应用MTT法检测3组U87细胞对VM-26敏感性的变化。结果与阴性对照组和空白对照组比较,实验组转染后的U87细胞AKT2mRNA和蛋白的表达水平明显下降（P〈0．01）。实验组VM-26对U87细胞的半数抑制量（IC50）为（6．46±0．42）μg／ml,阴性对照组为（1．16±0．25）μg／ml,空白对照组为（1．15±0．22）μg／ml,实验组与两对照组间差异有统计学意义（P〈0．05）。结论AKT2-shRNA抑制AKT2基因表达,能增加人脑胶质瘤U87细胞株对化疗药物VM-26的敏感性。     

125I对体外培养的胶质瘤细胞C-myc、p53基因表达及细胞增殖的影响

目的探讨125I对体外培养的胶质瘤细胞SHG-44C-myc、p53基因表达及细胞增殖的影响。方法利用免疫组化技术检测经125粒子放射处理3d后,SHG-44细胞的C-myc蛋白表达与p53蛋白表达水平。结果经1粒、3粒125粒子放射处理3d后,SHG-44细胞C-myc蛋白表达明显减弱,而p53蛋白表达显著增强。二者呈负相关。结论125I可以通过影响C-myc基因与p53基因的表达抑制人脑恶性胶质瘤细胞株SHG-44增殖,从而抑制胶质瘤的生长。     

脂质体介导CD基因转染SHG-44胶质瘤细胞凋亡的实验研究

目的以含胞嘧啶脱氨酶（CD）基因的pCMVCD重组表达质粒转染SHG-44胶质瘤细胞，体外观察5-氟胞嘧啶（5-FC）对转染CD基因的胶质瘤细胞的凋亡诱导作用。方法体外扩增、酶切鉴定pCMVCD质粒并采用DNA序列测定pCMVCD质粒中的CD基因；脂质体Lipofectamine 2000介导pCMVCD质粒转染SHG-44细胞，G418筛选培养获取抗性细胞克隆（即SHG-44／CD细胞）；免疫细胞化学检测SHG-44／CD细胞的CD基因蛋白水平表达；流式细胞仪、TUNEL实验及透射电子显微镜观察5-FC对表达CD基因的SHG-44／CD细胞凋亡的诱导作用。结果含CD基因的pCMVCD质粒成功转染进入SHG-44细胞，获取了含CD基因的SHG-44／CD细胞，免疫细胞化学染色显示SHG-44／CD细胞成功地表达了CD。在含5-FC的培养液中培养，SHG-44／CD细胞出现典型的凋亡形态，TUNEL显示凋亡细胞比例极高；透射电镜可见凋亡改变；流式细胞术检测凋亡率达18．6％，凋亡率呈剂量依赖性。结论建立了SHG-44恶性人脑胶质瘤细胞的CD／5-FC自杀基因系统。诱导SHG-44／CD胶质瘤细胞产生凋亡可能是脑胶质瘤CD基因疗法的重要机制。     

华蟾素对人脑胶质瘤细胞SHG44增殖及凋亡的影响

目的初步探讨华蟾素对人脑胶质瘤细胞SHG44增殖、细胞周期分布及凋亡的影响机制。方法利用MTT法、流式细胞仪检测华蟾素对人脑胶质瘤细胞SHG44增殖及细胞周期变化的影响。AO／EB染色、透射电镜观察人脑胶质瘤细胞SHG44凋亡细胞形态学的变化。Westernblot检测Bcl-2与Caspase8蛋白的表达。结果华蟾素（1μg／ml、10μg／ml）对细胞株增殖具有显著抑制作用（P〈0．05）,并呈时间和浓度依赖性。沆式细胞仪检测可见凋亡峰,Go／G。期细胞明显增多（P〈0．05）;华蟾素作用后可使Bcl-2蛋白表达降低．Caspase8蛋白表达升高。结论华蟾素可调控人脑胶质瘤细胞SHG44的周期进程,诱导Bcl-2及Caspase8差异性表达,且具有抑制肿瘤细胞增殖及促凋亡的作用。     

缺氧条件下全反式维甲酸对U87胶质瘤细胞血管内皮生长因子表达的影响

目的研究模拟缺氧条件下全反式维甲酸(ATRA)对U87胶质瘤细胞血管内皮生长因子(VEGF)表达的影响及其可能的机制。方法 U87胶质瘤细胞分为空白对照组、缺氧对照组、低浓度干预组、高浓度干预组。CoCl2模拟缺氧,U87胶质瘤细胞经不同浓度ATRA(5、10μmol/L)干预后,实时定量PCR法及Western blot法分别检测细胞中VEGF mRNA、缺氧诱导因子1α(HIF-1α)mRNA及VEGF蛋白的表达。结果与缺氧对照组相比,低、高浓度干预组VEGF mRNA表达分别为缺氧对照组的(2.08±0.23)倍及(3.13±0.14)倍,两组与缺氧对照组的差异均具有统计学意义(均P<0.01);低、高浓度干预组HIF-1αmRNA表达分别为缺氧对照组的(1.62±0.07)倍及(1.83±0.09)倍,两组与缺氧对照组的差异均具有统计学意义(均P<0.01)。而VEGF蛋白相对表达量在缺氧对照组为(2.15±0.12),低浓度干预组为(2.32±0.20),高浓度干预组为(3.09±0.08),各组间差异均具有统计学意义(均P<0.05)。结论在模拟缺氧条件下,ATRA可在转录及翻译水平增加U87细胞中VEGF的表达,而这种表达上调可能部分通过上调HIF-1α表达实现。     

脑胶质瘤中BAI1基因转录表达的研究

目的探讨BAI1 mRNA表达水平与不同级别胶质瘤间的关系。方法选取病理分级为WHOⅡ、Ⅲ、Ⅳ级脑胶质瘤标本依次为12例、12例、14例，正常脑组织标本6例；提取总RNA，用半定量RT—PCR法检测BAI1基因的转录表达情况。结果BAI1 mRNA在所有正常脑组织和26例（68．4％）胶质瘤中表达。正常脑组织的BAI1基因转录表达水平高于胶质瘤组．P〈0．05：各级胶质瘤间BAI1基因转录表达水平差异没有统计学意义。结论BAI1基因在胶质瘤中的转录表达水平显著性下降，在部分胶质瘤中表达缺失。BAI1可能与胶质瘤的发展有关。BAI1基因在胶质瘤中的转录表达水平与胶质瘤的级别无关。     

一条人脑胶质瘤相关新基因的克隆与表达

目的运用基因芯片技术获取正常成人脑组织与人脑胶质瘤中差异表达的基因，并对其中一条与脑胶质瘤相关的新基因进行了克隆和表达的研究。方法抽提正常成人脑组织与人脑胶质瘤组织中的mRNA来制备探针，经杂交、洗涤后，通过计算机观察二者表达谱的差异情况，对681F05克隆子进行了Northern blot，生物信息学分析和蛋白质的表达。结果通过四次基因芯片筛选，获得15条与胶质瘤相关的新基因，经northern blot证实681F05基因在人正常脑组织中低表达，而在人脑胶质瘤中高表达。BLASTn和BLASTx分析显示，它们编码蛋白与线虫Cyp-10蛋白同源性分别为52％和72％。cDNA序列分析发现这两个克隆是同一个基因[命名为cyclophilin—like gene（PPIL3）]的两个不同的剪切体（PPIL3a和PPIL3b）。并在大肠杆菌中得到了PPIL3a和PPIL3b与GST较好表达的融合蛋白。结论基因芯片筛选正常脑组织与人脑胶质瘤差异表达的基因具有样品用量少，高质量，高速度，高敏感等特性。681F05基因可能是与人脑胶质瘤形成有关的一条全长新基因。     

RNA干涉CD44基因抑制脑胶质瘤细胞U251的增殖与侵袭性研究

目的通过合成靶向分化抗原簇44(CD44)基因的siRNA片段,下调CD44在脑胶质瘤细胞U251中的表达,揭示其在胶质瘤增殖、迁移和侵袭中所起的作用。方法根据CD44基因序列设计并合成的siRNA片段转染U251细胞,利用荧光实时定量(qRT-PCR)检测细胞中CD44基因mRNA水平的变化;蛋白印迹实验(Western blot)检测CD44基因蛋白水平的变化;四甲基偶氮唑蓝染色(methyhhiazolyl tetrazolium,MTT)法检测U251细胞增殖;单细胞划痕愈合实验、Transwell小室侵袭实验检测U251细胞的迁移与侵袭能力变化。结果体外合成的CD44-siRNA能有效抑制U251细胞中CD44基因在mRNA水平与蛋白水平的表达(P0.05),并抑制细胞的增殖(P0.05)和迁移侵袭能力(P0.05)。结论 CD44-siRNA能够有效抑制U251脑胶质瘤细胞的增殖及其迁移侵袭力,为以CD44为靶点的肿瘤基因治疗奠定了基础。     

鸟氨酸脱羧酶及其基因表达在脑胶质瘤研究中的进展

鸟氨酸脱羧酶(ODC)足多胺合成的关键酶，ODC活性的改变可作为反映脑胶质瘤恶性程度的可靠的生物学标志；ODC基凶的诱导与恶性肿瘤的发生及其浸润性密切相关，因而具备癌基因的特性。ODC抑制剂DFMO及针对ODC的抗酶蛋白(AZ)可能对脑胶质瘤有着潜在的治疗作用。