大鼠脑干胶质瘤模型的建立

目的 建立大鼠脑干胶质瘤模型,为脑干胶质瘤的研究提供动物实验平台.方法 将1×10~6个大鼠C6胶质瘤细胞通过立体定向头架注射到大鼠脑桥,种植后2周对大鼠行磁共振扫描观察,然后行灌流固定取脑,HE染色.结果 磁共振检查均发现肿瘤生长,肿瘤为长T1和T2信号,经大鼠舌静脉注射Gd-DTPA信号明显增强.HE染色显示肿瘤为胶质母细胞瘤,呈浸润性生长,瘤内新生血管丰富,假栅栏样坏死明显.结论 大鼠C6胶质瘤细胞株可以建立脑干胶质瘤模型,成瘤率高,重复性好.     

Calcium-mediated endothelin signaling in C6 rat glioma cells

Endothelin induced intracellular Ca(2+)signaling was studied in C6 rat glial cells. Endothelins 1 and 3 increased transiently intracellular Ca(2+)concentration, endothelin 3 being less potent inducer. Dibutyryl-cAMP treated cells responded with less sensitivity. While BQ123, a specific endothelin A receptor antagonist, inhibited both endothelins induced response in proliferating cells, it failed to inhibit in dibutyryl-cAMP treated ones. IRL1620, a specific endothelin B receptor agonist, was devoid of any significant effect. Although re-stimulation by both endothelins after endothelin-1 did not cause any Ca(2+)oscillation, both endothelins evoked new Ca(2+)transient after endothelin-3 stimulation. Our findings suggest that endothelin induced Ca(2+)signaling is mediated probably through the receptor A in proliferating C6 cells. The lack of both BQ123 and IRL 1620 effect in dibutyryl-cAMP treated cells could be caused by an alteration of endothelin A receptor alone, by a change of receptor expression pattern, or by more complex postreceptor mechanism.     

脑胶质瘤耐放射细胞亚株的建立方法

目的探索诱导并建立脑胶质瘤耐放射细胞亚株的体外实验方法,为进一步研究胶质瘤放疗抵抗发生的分子生物学机制提供基础。方法以脑胶质瘤U251细胞株为实验对象,通过体外细胞培养,应用60Co射线对脑胶质瘤U251细胞株进行小剂量重复的诱导照射,得到U251耐放射细胞亚株RR-U251。观察RRU251细胞形态的变化;MTT检测其细胞活力,流式细胞仪(FCM)检测其细胞凋亡;集落形成实验检测细胞克隆团形成。结果放射治疗后,RR-U251与U251细胞的相比:细胞增殖活力增强11.5%,迁移能力增强50%,侵袭能力增强87.5%,凋亡率下降69.6%,细胞集落形成率升高88.5%;RR-U251放射敏感性明显下降。结论小剂量重复照射诱导法能较好地建立胶质瘤耐放射细胞亚株RR-U251。     

立体定向法建立大鼠C6脑胶质瘤模型

目的 用不同接种体积立体定向建立大鼠C6脑胶质瘤模型，比较其生长特性。方法 配制浓度为1．0×10^6个／10μL C6单细胞悬液，分别取5、10、20、40、80、160μL立体定向接种于大鼠右侧大脑尾状核区，在四个水平对各组进行比较。结果实验大鼠成瘤率分别为60％（5μ/L）、93％（10μL）、100％（20μL）、93％（40μL）、87％（80μL）、33％（160μL），瘤细胞病理性核分裂像多见，C-erbB1和S-100B等神经胶质瘤常见蛋白强阳性表达。结论 建立大鼠C6脑胶质瘤模型，接种体积在10-80μL时，成瘤率高，颅内肿瘤生长稳定，肿瘤组织形态学及病理学特性与人脑胶质瘤相似，而且实验周期短、可靠性高，是临床胶质瘤基础研究的理想模型。     

X-刀治疗大鼠C6脑胶质瘤诱发的细胞凋亡

目的：观察X-刀治疗胶质瘤的作用，并探讨诱发细胞凋亡效应。方法：采用DNA琼脂糖凝胶电泳、超微结构观察及新兴的DNA片段末端标记方法对各组C6大鼠脑胶质瘤发生的细胞凋亡进行研究。结果：15、20及30Gy各组在治疗后24h内均出现明显的细胞凋亡，DNA末端标记法检测的结果不但与前述方法结果相符，还显示出其准确性高等特性。研究中还发现各治疗组均有坏死同时出现。结论：X-刀治疗后诱发细胞凋亡的同时还致细胞坏死，这种效应随剂量增加渐趋明显，构成SRS治疗胶质瘤发挥作用的两个方面。     

Morphogenesis of measles virus on C6 rat glioma cells

Rat glioma cells (C₆) persistently infected with measles virus show a locally dissociated distribution of budding processes at the cell surface.     

冷冻治疗大鼠C6脑胶质瘤的实验研究

目的研究冷冻治疗对大鼠C6脑胶质瘤的增殖抑制作用及其机制。方法建立大鼠C6脑胶质瘤模型，60只载瘤大鼠随机均分为对照组和治疗组。治疗组实施冷冻治疗后免疫组化检测P27Kipl蛋白的表达，磁共振检测肿瘤体积变化，并观察动物生存期。对照组未实施冷冻治疗。结果与对照组比较，冷冻治疗可上调P27Kip1蛋白的表达，对照组为（4.81±0.72）％，治疗组为（28.84±3.56）％，P〈0.05；缩小肿瘤体积，对照组为（292.97±19.13）mm^3，治疗组为（76.37±10.22）mm^3，P〈0.05；延长动物生存期，对照组为（37.00±1.55）d。治疗组为（57.00±3.16）d，P〈0.05。P27Kip1蛋白阳性表达率和荷瘤鼠生存期呈正相关（r=0.836，P〈0.05）；同体积呈负相关（r=-0.696，P〈0.05）。结论冷冻治疗可抑制大鼠C6脑胶质瘤的增殖，延长动物生存期，其机制同上调P27Kip1蛋白的表达有关。     

C6大鼠胶质瘤模型及其在脑胶质瘤治疗研究中应用的缺陷

C6细胞是大鼠经化学致癌剂N-亚硝基甲脲体内诱发产生的脑胶质瘤细胞。具有较典型的人脑胶质瘤组织学特点。大鼠脑内立体定向接种C6细胞建立的动物模型。因成瘤高，动物手术死亡率低。所以广泛应用于脑胶质瘤治疗的研究中。国外研究发现，来源于非纯种大鼠的C6细胞具有有强的免疫原性；其主要组织相容性基因复合体中存在与大鼠是异源性的基因；C6细胞接种于大鼠体内引发强烈的免疫排斥反应可使肿瘤不能持续生长甚至自行消退，因此混淆了治疗所产生的效应。尤其当用于免疫和基因免疫治疗的研究时，存在较大缺陷。     

Secretion of S-100 from rat C6 glioma cells

Conditioned media from rat C6 glioma cells contain significant levels of S-100 immunoreactivity as determined by radioimmunoassay. The levels of extracellular S-100 detected could not be accounted for by the release of intracellular S-100 into the media from lysed cells. The extracellular form of S-100 exhibits fractionation properties and immunological characteristics that are different from those of the intracellular form of S-100 in C6 cells. While the intracellular S-100 levels increase as a function of days in culture, the extracellular S-100 levels are high until the cells reach confluency and are lower in postconfluent cultures. Altogether, our data suggest that C6 glioma cells secrete S-100, and that the quantitative levels of the intracellular and secreted forms of S-100 are differentially regulated.     

Regulation of cAMP levels by protein kinase C in C6 rat glioma cells

Cultures of rat C6 rat glioma cells exhibit a diminished response to isoproterenol and forskolin after being treated with phorbol 12,13-dibutyrate (PDbU). An IC50 for PDbU of 38 +/- 5 nM and 62 +/- 8 nM was observed in the isoproterenol and forskolin response, respectively. Similarly, C6 cultures exhibited a diminished response to isoproterenol and forskolin after an overnight incubation with phospholipase C. We previously demonstrated that this treatment will increase diacylglycerol levels in these cells (Bressler: J Neurochem 48:181-186, 1987). An IC50 for phospholipase C of 6.0 +/- 0.1 x 10(-1) and 7.0 +/- 0.1 x 10(-1) units/ml was observed for the isoproterenol and forskolin response, respectively. A kinetic analysis suggests that the site of PDbU-mediated inhibition to beta-adrenergic and forskolin stimulation was different. Degradation of cAMP was a contributory factor since elevated cAMP levels decreased faster in PDbU treated cells than in nontreated cells. In addition, PDbU treated cells exhibited a significantly higher level of phosphodiesterase activity. We conclude that activation of protein kinase C and subsequent stimulation of phosphodiesterase activity contributes to the inhibition of the beta-adrenergic and forskolin mediated increase in cAMP levels in intact C6 rat glioma cells. The consequences of lower cAMP levels in sustaining differentiated function in the C6 rat glioma cell line will be discussed.     

注射维生素C治疗脑胶质瘤的实验研究

目的探讨维生素C治疗脑胶质瘤的作用机制,为胶质瘤的临床治疗提供实验室依据。方法制作大鼠C6脑胶质瘤模型。荷瘤7d后将Wistar大鼠随机分为5组,每组10只,即对照组;维生素C低剂量组（2．0g／kg）;维生素C中剂量组（4．0g／kg）;维生素C高剂量组（8．0g／kg）;5-Fu组（20mg／kg）。于用药结束后次日处死各组小鼠,计算肿瘤体积和抑瘤率;流式细胞术检测各组肿瘤组织细胞凋亡率;免疫组化法检测各组肿瘤组织Ki-67蛋白表达情况。结果维生素C可抑制大鼠肿瘤生长,且呈剂量依赖性,实验组肿瘤体积与对照组相比有显著差异（P〈0.05）,维生素C高剂量组与5--Fu组肿瘤体积比较无统计学差异（P〉0.05）。维生素C可诱导大鼠肿瘤细胞凋亡,维生素C各组与对照组相比均有极显著性差异（P〈0.01）,维生素C高剂量组凋亡率高于5-Fu组（P〈0.05）。免疫组化法检测肿瘤组织细胞Ki-67蛋白表达中,维生素C各组与对照组相比均有极显著性差异（P〈0.01）,维生素C高剂量组与5-Fu组细胞凋亡率比较无统计学差异（P〉0.05）。结论维生素C在-定剂量范围内可抑制C6大鼠脑胶质瘤的生长,诱导肿瘤细胞发生凋亡是其机制之一;药理剂量的维生素C能降低C6大鼠脑胶质瘤细胞增殖活性,具有-定的抗肿瘤作用。     

反义寡核苷酸逆转大鼠胶质瘤细胞多药耐药性的实验研究

目的探讨针对多药耐药基因(MDR-1)上特异位点的反义寡核苷酸对体外培养的大鼠胶质瘤细胞多药耐药性的逆转作用。方法根据MDR-1基因的碱基序列设计合成硫代修饰的寡核苷酸,通过阳离子脂质体介导转染胶质瘤耐药细胞,应用流式细胞仪、RT-PCR等方法,对转染后的耐药细胞进行P-170、MDR-1mRNA水平的检测;用MTT法对转染后的细胞进行化疗药物敏感性试验,评价寡核苷酸对多药耐药性的逆转效果。结果流式细胞结果显示转染后胶质瘤耐药细胞P-170表达明显低于转染前(P<0.05);RT-PCR可见转染后细胞的MDR-1mRNA水平减低;药物敏感性试验显示反义寡核苷酸转染后胶质瘤耐药细胞对化疗药物的敏感性增强(P<0.05),含有脂质体的转染体系组对化疗药物的敏感性显著高于不含脂质体的转染体系组(P<0.01)。结论特异序列的反义寡核苷酸能够明显抑制大鼠胶质瘤细胞的P-170表达和减低MDR-1mRNA水平,进而对胶质瘤细胞的多药耐药性产生明显的逆转作用;应用阳离子脂质体作为转染载体可显著提高转染效率。     

立体定向大鼠C6脑胶质瘤动物模型的建立

目的通过立体定向在SD大鼠右尾状核区接种C6细胞,建立类似于人脑胶质瘤的动物模型.方法SD大鼠在立体定向条件下,左右尾状核区接种1×106个C6胶质瘤细胞,接种后观察实验大鼠的生成状态,分别于接种后1,2,3周时进行MRI检查.在实验三周时解剖标本,做组织病理学和GFAP免疫组化检查.结果该方法建立的胶质瘤动物模型在组织病理学上接近人脑胶质瘤,而且具有颅内生长稳定,成瘤率高,没有颅外种植生长,实验周期短,重复性好.结论该大鼠脑胶质瘤动物模型能够满足胶质瘤实验治疗研究的需要,而且在细胞接种后1～2周,为实验治疗较好的时机.     

Intracellular pH regulation in primary rat astrocytes and C6 glioma cells

We used the pH-sensitive fluorescent dye BCECF to study intracellular pH (pH_i) regulation in primary cultures of rat astrocytes and C6 glioma cells. Both cell types contain three pH-regulating transporters: (1) alkalinizing Na⁺/H⁺ exchange; (2) alkalinizing Na⁺ + HCO₃ ?/Cl_? exchange; and (3) acidifying Cl^?/HCO₃ ^? exchange. Na⁺/H⁺ exchange was most evident in the absence of CO₂; recovery from acidification was Na⁺ dependent and amiloride sensitive. Exposure to CO₂ caused a cell alkalinization that was inhibited by DIDS, dependent on external Na⁺, and inhibited 75% in the absence of Cl^? (thus mediated by Na⁺ + HCO₃ ^?/Cl^? exchange). When pH_i was increased above the normal steady-state pH_i, a DIDS-inhibitable and Na⁺ -independent acidifying recovery was evident, indicating the presence of Cl^? /HCO₃ ^? exchange. Astrocytes, but not C6 cells, contain a fourth pH-regulating transporter, Na⁺ ?HCO₃ ^? cotransport; in the presence of CO₂, depolarization caused an alkalinization of 0.12 ⁺_? 0.01 (n = 8) and increased the rate of CO₂-induced alkalinization from 0.23 ± 0.02 to 0.42 ± 0.03 pH unit/min. Since C6 cells lack the Na⁺ -HCO₃ ⁺ cotransporter, they are an inferior model of pH_i regulation in glia. Our results differ from previous observations in glia in that: (1) Na⁺ /H⁺ exchange was entirely inhibited by amiloride; (2) Na⁺ + HCO₃ ^?/Cl^? exchange was present and largely responsible for CO₂?induced alkalinization; (3) Cl^? /HCO₃ ^? exchange was only active at pH_i values above steady state; and (4) depolarization-induced alkalinization of astrocytes was seen only in the presence of CO₂.     

FLIP蛋白抑制顺铂诱导大鼠C6胶质瘤细胞凋亡

目的探讨自杀相关因子（Fas）相关死亡结构域样白介素1（IL-1）β转化酶抑制蛋白（FLIP）对于顺铂（CDDP）诱导大鼠脑胶质瘤细胞（C6细胞株）凋亡的抑制作用,为进一步研究胶质瘤的耐药性奠定分子生物学基础。方法利用由Ad—Max腺病毒包装系统成功构建的携载大鼠FLIP基因的腺病毒表达载体Ad—FLIP感染大鼠C6胶质瘤细胞,24h后经逆转录酶一多聚酶链反应（RT—PCR）及Westernblot检测感染组及对照组细胞中FLIP基因的mRNA及蛋白表达水平;分别给予Ad—FLIP感染组及对照组细胞不同浓度的CDDP（0,1,2,4,8mg／ml）,药物处理48h后,经流式细胞仪（FCM）分析细胞凋亡状况;四唑蓝显色法（MTF）测定并比较两组细胞活力。结果Ad—FLIP感染组细胞与对照组细胞相比,FLIPmRNA和蛋白表达水平明显增高;流式细胞仪检测结果显示Ad—FLIP感染组细胞凋亡率明显低于对照组。MTT法结果提示经CDDP处理后,Ad—FLIP感染组与对照组细胞活力均有下降,但FLIP蛋白具有明显的抑制作用。结论FLIP蛋白在大鼠c6胶质瘤细胞中具有抵抗化疗药物的作用。     

C6/IL-24对鼠脑胶质瘤血管生成的影响

目的探讨IL-24基因对荷瘤大鼠脑胶质瘤组织血管生成的影响。方法将24只SD大鼠随机分为C6/IL-24细胞组和C6细胞组,每组12只,分别于颅内尾状核部位接种转染IL-24基因的C6细胞(C6/IL-24)和鼠胶质瘤C6细胞。接种后21d取大鼠脑肿瘤组织,采用RT-PCR法检测大鼠脑肿瘤组织中VEGFmRNA的表达,免疫组化法检测VEGF和CD34的表达,并根据免疫组化结果计算两组肿瘤组织中的微血管密度(MVD)。结果RT-PCR结果显示:C6/IL-24细胞组VEGFmRNA表达水平明显低于C6细胞组(P0.01)。免疫组化法结果显示:C6/IL-24细胞组大鼠VEGF表达水平及CD34阳性MVD计数明显低于C6细胞组(P0.01)。结论IL-24基因转染后可抑制大鼠脑肿瘤组织中VEGF基因的表达,降低MVD,抑制肿瘤组织中新生血管的生长。     

Induction of GDNF mRNA expression by melatonin in rat C6 glioma cells

In order to determine the physiological effect of melatonin on glial cell line-derived neurotrophic factor (GDNF), which is reportedly up-regulated by high doses of this hormone, concentration-dependent studies were carried out in cultured cells. RT-PCR studies indicated that, in addition to GDNF, rat C6 glioma cells express both of the G protein-coupled melatonin receptor subtypes, MT1 and MT2. When C6 cells were treated with physiological (0.05-1 nM) or higher (10 and 100 nM) concentrations of melatonin for 24 h, a significant induction of relative GDNF mRNA levels (n = 4) was detected by semi-quantitative RT-PCR. These findings suggest that induction of GDNF is involved in physiological neuroprotection by melatonin. Given the potency of GDNF in maintaining nigrostriatal dopaminergic integrity, understanding the mechanisms of its induction by melatonin could provide novel therapies for Parkinson's disease.     

Lithium chloride inhibits thrombin-induced intracellular calcium mobilization in C6 rat glioma cells

In this study, the authors have demonstrated the effect of lithium, a typical mood stabilizer, on thrombin-evoked Ca2+ mobilization in C6 cells to elucidate the action mechanisms of the drug. Thrombin-induced Ca2 mobilization was reduced 24 hr after 1 or 10 mM lithium chloride (LiCl) pretreatment. The Ca2+ rise was reduced in a time-dependent manner, and the significant inhibition was observed 9 hr pretreatment with 10 mM LiCl. On the other hand, pretreatment of the cells with 10 mM LiCl for 24 hr did not alter the amount of Galphaq/11 significantly. Pretreatment with 10 mM LiCl for 24 hr failed to reduce the 5-HT-induced Ca2+ mobilization or to affect the desensitization of the 5-HT signal. Finally, thrombin-elicited Ca2+ rise was markedly inhibited in the presence of 0.05 U/ml plasmin, however, the Ca2+ rise was not further attenuated in the presence of plasmin in C6 cells pretreated with LiCl for 24 hr. These results indicate that pretreatment with LiCl attenuated thrombin-evoked intracellular Ca2+ mobilization in plasmin sensitive manner in C6 rat glioma cells. Thus, it is important to investigate the effect of lithium on thrombin-induced cellular responses to clarify the action mechanism of lithium in relation to some abnormality in thrombin-evoked Ca2+ rise observed in bipolar disorders.     

Individual C6 glioma cells migrate in adult rat brain after neural homografting

Cultured C6 glioma cells were prelabeled with the plant lectin Phaseolus vulgaris leuco-agglutinin (PHAL) and grafted as a cell suspension (10(6) cells in 5.0 microliters) into freshly made cortical implantation pockets in adult host rats. Animals were killed 1-21 days post-implantation (DPI). The brains were removed, dehydrated, embedded in paraffin and sectioned at 8 microns. Paraffin sections were processed for light level immunofluorescent double labeling for PHAL, a marker for graft derived cells, and glial fibrillary acidic protein (GFAP), a specific marker for C6 glioma cells and astrocytes. Cells positive for both PHAL and GFAP were graft-derived C6 cells. By 7 DPI a large mass developed which extended above the surface of the brain and invaded (displacement of host tissue by a cell mass) the host parenchyma. This mass increased in size over the next 14 days. The invading tumor mass contained double labeled cells at all time periods examined. In addition to the invasion process, grafted C6 cells spread through the host parenchyma by migration (movement of single cells). Individual graft-derived C6 (GFAP/PHAL positive) cells migrated into host cortex surrounding the implantation pocket, corpus callosum ventral to the implantation pocket, ipsilateral internal capsule and bilaterally in the habenula.