大鼠胶质瘤模型的C6胶质瘤细胞的增殖动力学研究

目的　在建立C6 Wistar胶质瘤大鼠模型的基础上 ,研究大鼠胶质瘤模型的C6胶质瘤细胞的增殖动力学。方法　应用流式细胞仪检测、PCNA免疫组化染色和核仁组织区银染三种方法 ,研究C6胶质瘤细胞的增殖动力学指标 ,并进行相关性分析。结果　 1、肿瘤细胞接种 2周后 ,肿瘤模型建立 ,HE染色见肿瘤细胞增殖活跃 ,各项增殖指标显示该肿瘤增殖活性较强。 2、AgNor面积、AgNOR计数与S期百分比和PCNA指数具有良好的相关性 ,AgNOR面积 (P <0 0 1)比AgNOR计数 (P <0 0 5 )相关性更强     

125I近距离照射对C6胶质瘤细胞的影响

目的 了解不同剂量^125I硅胶球囊内近距离照射对C6胶质瘤细胞的生物学效应。方法 将^125I—NaI溶液放人硅胶球囊内，对体外培养的C6胶质瘤细胞给予不同剂量的近距离照射，检测细胞死亡率、增殖抑制及细胞周期再分布情况。结果 与对照组相比，受照射组细胞死亡率、增殖抑制率明显增加，S期比例降低、G1期阻滞，细胞周期发生紊乱。结论 ^125I近距离照射可以通过导致细胞死亡、细胞增殖抑制以及细胞周期改变在胶质瘤的治疗中发挥作用。     

立体定向建立大鼠C6脑胶质瘤模型

目的　建立大鼠C6脑胶质瘤模型 ,采用影像学方法观察肿瘤的生长规律和时间窗 ,为肿瘤的疗效检测提供可行的方法。方法　 16只SD大鼠随机分成两组 ,每组 8只 ,用立体定向技术将C6细胞接种在大鼠的右侧尾状核 ,接种细胞量分别为 1 0× 10 6 个 (第 1组 )和 1 5× 10 6 个 (第 2组 )。观察大鼠生存期 ,测量肿瘤的最大径 ,计算肿瘤体积 ,计算观察时间窗。结果　两组大鼠皆成功接种肿瘤 ,成功率为10 0 %。第 1组大鼠平均生存期为 ( 2 3 5 0± 3 93 )d ,明显大于第 2组 ( 17 75± 2 3 8)d(P <0 0 1)。肿瘤最大直径与瘤龄呈直线关系 ,体积与瘤龄呈指数关系。观察时间窗第 1组为 ( 12 0 0± 3 5 1)d ,大于第 2组 ( 8 88± 1 73 )d(P <0 0 5 )。结论　立体定向脑内定量注射C6细胞制作大鼠脑胶质瘤模型成功率高 ,肿瘤最大径和体积增长有规律性。观察时间窗能够满足一般的研究要求     

C6/IL-24对鼠脑胶质瘤预防作用的研究

目的观察C6/IL-24对大鼠脑胶质瘤的免疫预防作用。方法实验组皮下注射1×105C6/IL-24细胞,对照组皮下注射同等体积的0.9%氯化钠溶液。28 d后,2组均于对侧颅内接种C6细胞。观察大鼠的生存期及颅内肿瘤的增殖性、致瘤性及生长变化。结果实验组肿瘤生长速度明显减慢、增殖率下降、致瘤性降低（P＆lt;0.05）;实验组大鼠各时段肿瘤体积明显小于对照组（P＆lt;0.05）,存活时间明显长于对照组（P＆lt;0.05）。结论通过逆转录病毒将IL-24导入C6细胞而形成的,C6/IL-24细胞对鼠脑胶质瘤具有较好的免疫预防效果。     

C2-神经酰胺诱导大鼠脑胶质瘤细胞C6的早期凋亡作用

目的 :研究外源性C2 神经酰胺对大鼠脑胶质瘤细胞C6活力的抑制作用以及早期凋亡诱导作用。方法 :采用MTT法测定C2 神经酰胺对C6细胞活力的影响 ;倒置荧光显微系统观察细胞形态变化 ;An nexinⅤ PI双染色流式细胞术对细胞早期凋亡进行定量分析。结果 :C2 神经酰胺可显著抑制C6细胞的活力 ,IC50 为 2 .2× 10 -5mol·L-1;荧光染色可见核浓染等细胞凋亡特征形态改变 ;流式细胞术分析表明C2 神经酰胺可诱导C6细胞发生早期凋亡作用 ,且凋亡百分率呈时间及浓度依赖性 ,C2 神经酰胺 2× 10 -5mol·L-1处理 2 4h后平均早期凋亡率高达4 9 .3%。结论 :C2 神经酰胺主要通过诱导早期细胞凋亡对大鼠脑胶质瘤C6细胞发挥细胞毒作用 ,提高神经酰胺水平有望成为肿瘤化疗的新途径。     

羟基喜树碱对C6胶质瘤细胞的抑制作用

目的:研究羟基喜树碱(HCPT)对大鼠脑胶质瘤细胞的抑制作用。方法:采用MTT法检测不同浓度(1～0.03125mg·mL-1)HCPT对大鼠脑胶质瘤细胞的体外细胞毒作用,同时以脑胶质瘤常规治疗药物作对照,并比较开环与闭环HCPT抑瘤活性。结果:HCPT在高浓度时对细胞抑制率高达(69.43±4.5)%,与对照药比较差异无显著性,且其作用呈浓度依赖性。开环与闭环HCPT比较,前者抑瘤效果较低,二者IC50分别为3.626、0.135mg·mL-1。结论:HCPT对C6胶质瘤细胞的增殖具有明显抑制作用,且其闭环形式抑瘤活性更强。     

抑制HSP 70表达对体外培养的脑胶质瘤细胞生长的影响

目的 探讨抑制热休克蛋白７０（ＨＳＰ７０）表达对脑胶质瘤细胞增殖及凋亡的影响。方法 利用细胞培养、电子显微镜及流式细胞仪的方法，观察阻滞ＨＳＰ７０表达后对肿瘤细胞生长的影响。结果 体外培养脑胶质瘤细胞株、经不同浓度槲皮素作用不同时间后，碘化丙碇染色荧光显微镜观察发现细胞核固缩，致密和破裂现象；流式细胞检测发现亚二倍体峰，提示出现细胞凋亡。分析细胞周期，发现凋亡细胞主要出现在Ｇ０、Ｇ１期，随药物的浓     

II、III组亲代谢型谷氨酸受体激动剂对脂多糖抑制C6胶质瘤细胞摄取谷氨酸的影响

目的：探讨II、III组亲代谢型谷氨酸受体（metabotropic glutamate receptors，mGluRs）激动剂对脂多糖（LPS）抑制C6胶质瘤细胞摄取谷氨酸（glutamate，GIu）的影响。方法：应用同位素标记法测定C6胶质瘤细胞对[^3H]-D，L-Glu的摄取。应用Hoechst染色法、噻唑蓝比色法（MTT）分别检测C6胶质瘤细胞的亡、细胞活力。结果：LPS（4、6μg／mL）显著抑制C6胶质瘤细胞摄取[^3H]-D，L-Glu，抑制率分别达17．6％和22．2％。Ⅱ组mGluRs激动剂DCG-IV100μmol／L和III组mGluRs激动剂L-AP4 100pznol／L逆转LlX3对C6胶质瘤细胞摄取[^3H]．D，L-GIu的抑制作用，这种逆转作用分别被Ⅱ、ⅡI组mGluRs拮抗剂APICA和MSOP取消。结论：DCG-IV和L-AP引起的C6胶质瘤细胞Glu摄取抑制，提示II、III组mGluRs激动剂通过促进Glu摄取，降低细胞外Glu浓度，从而发挥神经保护作用。     

Cx43对脑胶质瘤C6细胞增殖的影响及机制

目的将p CMV-Cx43c DNA重组质粒转染入大鼠脑胶质瘤C6细胞,上调C6细胞Cx43表达,进而探讨C6细胞Cx43过表达对其增殖能力的影响及机制。方法通过脂质体将p CMV-Cx43c DNA重组质粒转入C6细胞,使C6细胞过表达Cx43,并用G418筛选出稳定过表达Cx43的C6细胞;测定细胞倍增时间和软琼脂集落形成实验,检测各组细胞的增殖程度;分别用ERK1/2特异性阻断剂PD98059(30μmol·L~(-1))、p38MAPK特异性阻断剂SB20219(10μmol·L~(-1))处理各组细胞,Western blot检测各组细胞Cx43、p-Cx43、pERK1/2和p-p38MAPK的表达;MTT比色法检测各组细胞活性。结果成功将p CMV-Cx43c DNA重组质粒转入C6细胞,并筛选出稳定转染Cx43基因的C6细胞;测定细胞倍增时间和软琼脂集落形成实验表明C6-Cx43组比C6组、C6-p CMV组细胞增殖速度减慢,细胞集落数明显减少(P<0.01);ERK1/2、p38MAPK特异性阻断剂处理细胞后,Western blot检测发现C6-Cx43+PD98059组、C6-Cx43+SB202190组较C6-Cx43组Cx43表达升高(P<0.01)、pCx43(P<0.05)表达下调。结论阻断ERK1/2、p38MAPK通路,导致Cx43蛋白表达升高,从而抑制C6细胞的增殖。     

抗脑胶质瘤中药的研究进展

脑胶质瘤是中枢神经系统最常见的、预后较差的原发性恶性肿瘤,目前t临床上治疗方法是以放射疗法和手术治疗为主,化学药物治疗为辅。患者对于传统的放化疗方法有较大的不良反应,而中药对抗肿瘤具有相对安全性和作用持久性而被广泛研究和关注。本文对近年来国内外抗脑胶质瘤天然产物的研究进展作简要综述。     

Effects of quercetin and quercetin-3-O-glycosides on oxidative damage in rat C6 glioma cells

Flavonoids are reported to be powerful antioxidants in cell free systems. They naturally occur as glycosides rather than as aglycon. In this study the ability of the flavonoid quercetin and its glycosides, quercetin-3-O-rutinoside (rutin), quercetin-3-O-glucoside and quercetin-3-O-(6″-O-acetyl)-glucoside, to protect in vitro rat C6 glioma cells from oxidative damage induced by cumene hydroperoxide was investigated. Cumene hydroperoxide induced cell death and lipid peroxidation. The cytotoxicity of cumene hydroperoxide could be prevented by the radical scavenger dimethyl thiourea and the ferric iron chelator deferoxamine, indicating that its cytotoxic activity is related to the generation of reactive oxygen radicals in the ferrous iron dependent Fenton reaction. Quercetin, in a concentration range of 10-100 μM, but neither rutin nor the other two glycosides, were able to protect C6 cells from cytotoxicity and lipid peroxidation. Furthermore, cytoprotective concentrations of quercetin proved to be cytotoxic itself. These results call in question potential beneficial effects of dietary intake or therapeutic use of naturally occurring flavonoids.     

Effects of chlorpyrifos on transglutaminase activity in differentiating rat C6 glioma cells

The organophosphorothioate compound chlorpyrifos (CPF) is a widely used pesticide, which is known to inhibit the differentiation of mouse N2a neuroblastoma and rat C6 glioma cells. This study in focused on the possible effects of CPF in the activity and expression of tissue transglutaminase (TGase 2) in differentiating C6 cells. Cells exposed for 24 h to 10 μM CPF, which had no effect on cell viability, exhibited a significant increase in cytosolic TGase 2 activity. Western blotting analysis indicated that there was no change in the cytosolic TGase 2 protein levels, suggesting that the enzyme was activated under these conditions. When commercially available TGase 2 was incubated with CPF in vitro, an increase in activity was also observed, suggesting that CPF might interact directly with TGase 2.     

Effects of lead on viability and intracellular metal content of C6 rat glioma cells

Cultured C6 rat glioma cells were exposed to lead (Pb) acetate (0, 1, 10, or 100 microM) for 3-4 d. Cells were analyzed for changes in viability and intracellular lead, iron, and copper concentrations after Pb treatment was discontinued. The results were compared with previous findings on astroglia and oligodendroglia in culture in order to evaluate C6 cultures as a model for Pb toxicity in glia. Viability was measured by three methods on the day Pb was removed from the cells (designated d 0), and 2 and 9 d after Pb treatment was discontinued (designated d 2 and 9). The methods used were trypan blue dye exclusion, total cell counts, and incorporation of [3H]-L-leucine into proteins. Small, dose-dependent reductions were observed on d 2 in the percentages of cells excluding dye. Decreased cell numbers were seen at all three Pb doses only on d 0. With respect to these two viability measurements, C6 cells responded like astroglia in culture to Pb, but not like oligodendroglia, which are more Pb-sensitive. We expected decreased amino acid incorporation to accompany the decreased viability of the cultures. Instead, increased amino acid incorporation, which indicates increased protein synthesis, was seen on d 0 and 2 at all three Pb doses, though total cellular protein did not increase. A similar response has been reported previously in oligodendroglial cultures. C6 cells treated for 3 with 1 or 100 microM Pb acetate were analyzed for intracellular metal content by atomic absorption aspectroscopy on d 4 and 11 after exposure to Pb was discontinued. The cells were found to take up large amounts of Pb intracellularly and store it for at least 11 d. Cells treated with FeCl2 instead of Pb took up Fe, but required a higher extracellular Fe concentration to achieve an intracellular Fe level comparable to that of Pb in Pb-treated cells. Pb uptake did not affect intracellular Fe or Cu concentrations. With respect to Pb and Fe uptake, C6 cells closely resembled immature astroglia in culture. Unlike C6 cells, however, astroglia showed elevations of intracellular Fe and Cu after Pb treatment. Thus, Pb effects on C6 cells resembled those on cultured oligodendroglia and astroglia in some respects but not in others. C6 cells appear to be an adequate model for selected events in glial toxicosis, such as Pb-stimulated protein synthesis in oligodendroglia and Pb uptake in astroglia, but not Pb-induced alterations of intracellular Cu and Fe in astroglia. Their use as a model for glial progenitor cells in Pb toxicity studies remains to be determined.     

Lysophosphatidylserine increases membrane potentials in rat C6 glioma cells

Previously, we reported on the distinct effects of bioactive lysophospholipids, including lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), and sphingosylphosphorylcholine (SPC), on membrane potentials in rat C6 glioma cells. In the present report we have tested lysophosphatidylserine (LPS), another bioactive lysophospholipid, on membrane potentials in the same cell line. Membrane potentials were estimated by measuring the fluorescence changes of DiBAC-loaded glioma cells. LPS largely increased membrane potentials in a concentration-dependent manner. The LPS-induced membrane potential increases were not affected by treatment with pertussis toxin, implying no involvement of Gi/o proteins. In contrast to other lysophospholipids, the LPS-induced membrane potential increase was not diminished by a Na(+)-free media but was enhanced by suramin. Furthermore, this change was blunted by EIPA, an inhibitor of Na(+)/H(+) exchanger, but not by SITS, a specific inhibitor of bicarbonate transporter. Our observations suggest that LPS acts on membrane potentials in a unique manner in the C6 glioma cells, although the precise action mechanism requires additional investigation.     

Diazinon oxon interferes with differentiation of rat C6 glioma cells

The purpose of this study was to evaluate the toxicity of diazinon oxon (DZO), a major in vivo metabolite of the organophosphate insecticide diazinon (DZ), on differentiating rat C6 glioma cells. At concentrations shown to be non-cytotoxic by both the MTT and the Kenacid blue dye binding assays (1, 5 and 10 μM), DZO caused after 24 h a reduction in the number of extensions developed from C6 cells induced to differentiate by serum withdrawal and addition of sodium butyrate. Densitometric scanning of Western blots of extracts of C6 cells demonstrated that, at all concentrations used, DZO decreased after 24 h the expression of glial fibrillary acidic protein (GFAP) compared to controls. In addition, exposure to 10 μM DZO for 24 h reduced the levels of tubulin and microtubule associated protein 1B (MAP1B). On the other hand, levels of MAP2c were not affected by DZO treatment. In contrast to our previous data on DZ, the above findings suggest that its oxon metabolite, DZO, may, at biologically relevant, subcytotoxic concentrations, interfere with glial cell differentiation.     

牛蒡子苷元对大鼠脑胶质瘤的作用及初步作用机制探讨

目的观察牛蒡子苷元对大鼠C6胶质瘤的作用及作用机制的研究。同时探讨牛蒡子苷元与替莫唑胺合用对脑胶质瘤是否有协同作用。方法采用脑内注射C6胶质瘤细胞建立大鼠C6胶质瘤模型;牛蒡子苷元连续皮下给药15 d,替莫唑胺从d 5开始给药,连续灌胃给药5 d;测量肿瘤的长短径,计算肿瘤体积;采用免疫组化方法检测脑瘤组织中GFAP、PCNA和CD40的表达。结果与模型组相比,牛蒡子苷元均能明显降低大鼠C6胶质瘤的肿瘤体积(P<0.05),给予牛蒡子苷元可使脑胶质瘤大鼠的PCNA和CD40表达明显降低(P<0.05),GFAP表达明显升高(P<0.05);牛蒡子苷元与替莫唑胺合用能明显减少脑胶质瘤大鼠的肿瘤体积(P<0.01),其肿瘤抑制率均高于单独牛蒡子苷元和替莫唑胺;与模型组相比,联合用药组的PCNA和CD40表达均明显降低(P<0.05),GFAP明显升高(P<0.05),均好于单独用药。结论牛蒡子苷元能明显抑制大鼠C6胶质瘤生长,并且与替莫唑胺合用具有协同作用,作用机制与影响脑胶质瘤相关蛋白(PCNA和GFAP)表达和调节机体免疫(抑制CD40表达)相关,为牛蒡子苷元上报新药提供临床前药理试验支持。     

Dihydroartemisinin potentiates the cytotoxic effect of temozolomide in rat C6 glioma cells

Gliomas are the most common primary brain tumor in adults, but the efficacy of chemotherapy is limited. Artemisinin and its analogs, such as dihydroartemisinin (DHA), can kill cancer cells via generating free radicals. In the present study, we determined whether DHA at low concentrations potentiates the cytotoxic effect of temozolomide in rat glioma C6 cells. We found that the IC50 values of DHA and temozolomide for cell viability were 23.4 and 560 micromol/l, respectively. The cytotoxic effect of temozolomide was enhanced by 177% at a nontoxic DHA concentration (1 micromol/l), and by 321% at a low-toxic DHA concentration (5 micromol/l). DHA substantially increased temozolomide-induced apoptosis and necrosis. The generation of intracellular reactive oxygen species (ROS) was increased by temozolomide combined with DHA at noneffective concentrations of both agents. Edaravone (20 micromol/l), a ROS scavenger, reversed the effects of temozolomide/DHA on both ROS generation and cell viability reduction. These results indicate that DHA at low concentrations potentiates the cytotoxic effects of temozolomide in C6 cells partly via generating ROS, suggesting a beneficial combination for the chemotherapy of gliomas.     

缓激肽对C6胶质瘤细胞IL-1β表达的影响

目的探讨缓激肽对大鼠C6胶质瘤细胞内白细胞介素-1β(IL-1β)表达水平的影响,为进一步研究缓激肽开放血肿瘤屏障的机制提供实验依据。方法采用逆转录-聚合酶链反应(RT-PCR)半定量技术和放射免疫法分别检测缓激肽作用C6胶质瘤细胞后,胶质瘤细胞IL-1β mRNA及细胞培养液中IL-1β的含量。结果RT-PCR结果显示缓激肽作用15min后,IL-1β mRNA的表达水平较对照组升高(P<0.05),然后逐渐下降;放射免疫法结果亦证明了C6胶质瘤细胞在缓激肽作用15min后,其细胞培养液中IL-1β的含量最高。结论缓激肽可刺激大鼠C6胶质瘤细胞中IL-1β的分泌增强,IL-1β的表达上调可能在缓激肽增加血肿瘤屏障通透性的过程中发挥一定作用。     

白介素2和肿瘤坏死因子α对大鼠C6胶质瘤细胞产生一氧化氮的影响

用Griess法检测细胞培养上清中NO^÷₂含量作为反映细胞产生一氧化氮(NO)量的指标，观察细菌脂多糖(LPS)，干扰素γ(IFN-γ)，肿瘤坏死因子α(TNF-α)及白介素2(IL-2)对大鼠C6胶质瘤细胞产生NO的影响. 结果C6细胞于体外培养8 h时可自发产生NO，24 h达峰值(17.5±1.9 vs溶剂对照组6.5±1.9 μmol·L^-1)，48 h仍有产生. 在所用剂量范围，上述因素单独作用24 h均不影响C6产生NO，而5-500 kU·L^-1 IL-2与0.5 mg·L^-1 LPS或50 kU·L^-1 IFN-γ合用可增强C6产生NO(10.6-13.4 vs 7.2 μmol·L^-1)，LPS，IFN-γ及TNF-α三者合用亦有一定促进C6产生NO作用. 提示炎性刺激与炎性细胞因子共同作用可促进中枢神经胶质细胞产生NO.     

骨髓间充质干细胞对胶质瘤C6细胞增殖的影响

目的探讨大鼠骨髓间充质干细胞(MSCs)对胶质瘤C6细胞体外增殖的影响。方法从大鼠骨髓中分离MSCs,体外培养和鉴定。取MSCs培养上清液,按照1/5,2/5,3/5的比例加入到C6培养基中,用MTT实验和BrdU标记指数(BrdU LI)评估C6细胞增殖。将MSCs与C6按照1∶1,1∶2,2∶1比例共培养。结果大鼠MSCs贴壁生长,有较强的增殖能力。经硫代甘油和巯基乙醇诱导分化后,分化为神经元或胶质细胞样细胞。C6培养基中加入MSCs培养上清液后,活性受到明显抑制,BrdU LI明显减低(P<0.05)。C6与MSCs共培养后,生长明显受到抑制,BrdU LI明显降低,尤其在MSCs周围,表现更加明显。结论大鼠MSCs在体外有明显的抑制胶质瘤C6增殖作用。