吴茱萸次碱对棕榈酸诱导的脂质损伤肝细胞的影响

目的:研究吴茱萸次碱(Rut)对棕榈酸(PA)诱导的脂质损伤肝细胞(LO2)的细胞活力、活性氧(ROS)以及缝隙连接蛋白32(Cx32)和缝隙连接蛋白26(Cx26)表达水平的影响。方法:加入不同浓度的Rut溶液预处理LO2细胞20 min后,每个孔加入PA(0.2 mmol/L)溶液,共同孵育24 h,分别应用细胞增殖及毒性检测试剂盒(CCK-8)检测细胞活力,二氯二氢荧光素-乙酰乙酸酯(DCFH-DA)荧光探针检测细胞内活性氧的表达、划痕负载实验检测缝隙连接细胞间通讯(GJIC)的功能变化及免疫印迹实验(Western blotting)检测缝隙连接蛋白Cx32和Cx26的表达水平。结果:CCK-8实验结果显示,Rut(0.1μmol/L,0.5μmol/L,1μmol/L)能抑制PA诱导的LO2细胞活力的下降;DCFH-DA荧光探针实验显示PA诱导细胞后ROS的表达增强,Rut预处理细胞后能够减少ROS的表达;划痕负载实验结果显示,PA诱导细胞后能够抑制细胞的GJIC功能,预先给予Rut处理能够改善GJIC的功能障碍;Western blotting显示PA诱导细胞后缝隙连接蛋白Cx32和Cx26的表达水平显著降低,给予Rut预处理后能够恢复Cx32和Cx26的表达。结论:PA能够诱导LO2细胞的脂质损伤,导致细胞活性降低、细胞内活性氧增加以及GJIC的功能障碍;Rut预处理LO2细胞后可减轻PA诱导的细胞损伤,并且恢复细胞的缝隙连接蛋白Cx32和Cx26的表达和GJIC的功能。     

槲皮素对热应激后神经胶质瘤细胞凋亡及热激蛋白表达的影响

目的探讨槲皮素对神经胶质瘤细胞(C6细胞)凋亡的影响及作用机制。方法 C6细胞加入槲皮素0~200μmol·L-1培养1 h后,于42℃水浴加热1 h,再正常培养12 h。MTT法检测C6细胞存活率,Hoechst/PI双染法,annexinⅤ-FITC/PI双染检测细胞凋亡率,Western印迹法检测热激蛋白70(HSP70)表达。结果与正常对照组相比,加热组细胞存活率和细胞凋亡率均无明显改变,但加热组HSP70表达水平从正常对照组的0.22±0.01升高到0.36±0.02(P<0.01)。槲皮素能明显抑制C6细胞增殖,槲皮素50,100,150和200μmol·L-1细胞存活率分别为103%,86%,77%和75%,呈浓度依赖性(r=0.94,P<0.05)。槲皮素50,100和200μmol·L-1显著诱导C6细胞凋亡(P<0.05)。与加热组相比,随着槲皮素浓度的增加,C6细胞早期和晚期凋亡率均明显增加,最高细胞凋亡率为59%,槲皮素200μmol·L-1处理后明显降低了加热导致的HSP70表达增加,降低了53%(P<0.01)。结论槲皮素可以抑制HSP70表达并诱导神经胶质瘤细胞凋亡。     

双环醇拮抗DDT引起的细胞间隙连接通讯功能抑制研究

目的研究治肝炎药物双环醇对促癌剂滴滴涕(DDT)引起细胞间隙连接通讯(GJIC)功能抑制的拮抗作用及作用机制。方法划痕标记染料示踪技术直接观察DDT引起的大鼠肝上皮WB-F344细胞GJIC功能抑制并分析双环醇的作用。利用Western blot方法检测间隙连接蛋白43(Cx43)、磷酸化Cx43、E-cadherin及β-Catenin的表达和活性。细胞免疫荧光技术考察WB-F344细胞Cx43蛋白亚细胞定位、间隙连接的形成及E-cadherin和β-Catenin在细胞内的表达。结果 DDT能剂量依赖性的抑制WB-F344细胞GJIC功能,20μM浓度时小分子荧光染料Luciferyellow CH仅能从伤沿细胞向后传递1-2列细胞。双环醇能部分恢复DDT引起的GJIC功能抑制,且具有一定剂量依赖关系,其作用机制与抑制DDT引起的磷酸化Cx43蛋白表达量升高,进而恢复DDT损伤的间隙连接形成有关。DDT和双环醇对与Cx43蛋白功能密切相关的E-cadherin及β-Catenin的表达、活性及细胞内定位均无明显影响。结论双环醇能通过影响Cx43蛋白的磷酸化水平,部分恢复环境促癌剂DDT引起的WB-F344细胞间隙连接的形成,改善GJIC功能。对GJIC的功能抑制是多种促癌剂诱发肿瘤发生的重要原因,前期研究显示双环醇具预防二甲基亚硝胺/苯巴比妥诱发肝癌发生的作用,本文研究结果进一步提示,双环醇在预防杀虫剂DDT(一种主要的环境致癌物)诱发的肿瘤方面亦具有一定潜能。     

HSP70在人小细胞肺癌细胞热疗中的作用

目的探讨HSP70在人小细胞肺癌细胞热疗中的作用。方法采用43℃加热联合120μg/L紫杉醇(热化联合组)、120μg/L紫杉醇(单纯化疗组),43℃加热(单纯热疗组)处理H446细胞和BEAS-2B细胞,以未处理的细胞作对照,噻唑蓝比色法检测细胞增殖率,蛋白免疫印记法检测HSP70的表达,SPSS13.0进行统计分析。结果热化联合组H446细胞增殖率低于其余三组,单纯化疗组和单纯热疗组的BEAS-2B细胞低于热化联合组;两种细胞热化联合组HSP70表达均低于单纯热疗组。结论热化疗联合作用于H446细胞,可以明显抑制其生长,可能是通过抑制HSP70实现的。     

缓激肽开放血瘤屏障过程中诱发快速耐受性的机制探讨

目的探讨缓激肽(bradykinin,BK)开放血瘤屏障过程中,HSF1和HSP70对BK诱发快速耐受性的影响。方法首先通过立体定向法接种C6细胞制备恶性胶质瘤大鼠模型。模型制备成功后,经颈内动脉缓慢小剂量给予缓激肽(或生理盐水)10μg.kg-1.min-1,动态观察肿瘤组织内热休克因子1(heatshockfactor1,HSF1)蛋白单体和三聚体的活性及热休克蛋白70(heatshockprotein70,HSP70)的表达(Westernblot法)。免疫组织化学技术检测血瘤屏障上紧密连接蛋白occludin的变化。利用伊文思蓝连续监测缓激肽处理后的C6恶性胶质瘤大鼠血瘤屏障的通透性,同时电镜观察血瘤屏障的病理学改变。结果缓激肽作用于C6大鼠后,紧密连接增宽,血瘤屏障通透性增加,伊文思蓝渗出量分别较对照组增加了5.19μg.g-1(0min),5.06μg.g-1(5min),11.35μg.g-1(10min,P<0.05),21.54μg.g-1(15min,P<0.01),12.81μg.g-1(30min,P<0.05),7.28μg.g-1(60min)。肿瘤组织内HSF1蛋白三聚体活性和HSP70蛋白的表达逐渐增加,且分别于处理后的5min和30min时达高峰(P<0.01,与对照组相比),最大值为对照组的2～3倍。免疫组化检测结果发现,处理后的C6动物,其血瘤屏障的紧密连接蛋白occludin表达减少,15min后逐渐增加。结论缓激肽作用于血瘤屏障后,激活了HSF1并促进了hsp70蛋白的表达。增加的hsp70可能通过发挥分子伴侣作用来修复紧密连接蛋白,进而诱发快速耐受性。     

HSP70在垂体腺瘤中的表达及其与肿瘤侵袭性关系的研究

目的分析HSP70在垂体腺瘤中的表达,探讨HSP70与垂体腺瘤侵袭性之间的关系,研究以HSP70的表达水平作为判断垂体腺瘤侵袭性和预后指标的可能性.方法取经手术切除且病理诊断为垂体腺瘤、具有完整内分泌资料的患者50例,根据Hardy-Wilson及Knosp分级、分期标准,结合病理活检判断其肿瘤侵袭性,用免疫组化方法分别检测每例肿瘤HSP70的表达水平.结果50例病人中HSP70蛋白表达的阳性率为86.0%(43/50),PRL腺瘤和无功能腺瘤之间的HSP70蛋白表达阳性率在统计学上无显著性差异(P＞0.05), HSP70蛋白表达水平与垂体腺瘤侵袭性之间的关系在统计学上存在正相关关系(P＜0.05).结论HSP70的表达水平与垂体腺瘤侵袭性有关,其表达水平有可能作为判断垂体腺瘤侵袭性和预后的指标.     

银纳米颗粒增强磁流体热疗对脑胶质瘤C6细胞的杀伤作用

目的研究20 nm银纳米颗粒(AgNPs)对脑胶质瘤C6细胞磁流体热疗的作用。方法脑胶质瘤C6细胞分为对照组、AgNPs组、磁流体热疗组和AgNPs结合磁流体热疗组。通过集落形成实验检测20 nm AgNPs对脑胶质瘤C6细胞热疗的效果;流式细胞术检测AgNPs对细胞周期和凋亡率的影响;HE染色检测AgNPs对荷瘤鼠磁流体热疗凋亡的影响。结果与对照组比较,20 nmAgNPs能够引起脑胶质瘤C6细胞G2/M期阻滞,并使细胞在接受磁流体热疗后凋亡率显著提高(P<0.05)。结论银纳米颗粒能提高脑胶质瘤C6细胞的热敏感性。     

白介素-1β在缓激肽开放血脑屏障过程中的作用及其机制

目的探讨白介素-1β(IL-1β)在缓激肽(BK)开放血脑屏障(BBB)过程中的作用及其机制。方法缓激肽处理C6细胞后,动态观察培养液中IL-1β含量(放射免疫法)、C6细胞内热休克因子1(HSF1)蛋白的表达(Western blot法)及IL-1β的mRNA水平(RT-PCR法)。利用伊文思蓝检测C6恶性胶质瘤大鼠经颈内动脉给予IL-1β及缓激肽后血脑屏障的通透性。结果缓激肽作用于C6细胞后,培养液中IL-1β的含量明显增加,于120 min含量最多,其后开始减少。C6细胞内HSF1的表达及IL-1β的mRNA水平也在给予缓激肽后明显增加,并分别于干预后的30 min和60 min达高峰后逐渐减少。缓激肽与IL-1β单独作用于C6动物后均可引起胶质瘤大鼠的血脑屏障通透性增加,且IL-1β对肿瘤模型动物血脑屏障通透性的影响与C6细胞培养液中IL-1β的含量相一致。结论 IL-1β可能介导了缓激肽开放血脑屏障的作用,此作用可能是由于缓激肽诱导C6细胞内HSF1的表达增加,增加的HSF1促进神经胶质瘤细胞释放IL-1β所致。     

大黄素对Cx32组成的细胞缝隙连接通讯功能的影响

目的在转染并稳定表达Cx32的Hela细胞上,观察大黄素对Cx32的GJIC以及Cx32蛋白表达水平的影响。方法采用SRB法检测不同浓度大黄素对Hela细胞的毒性;用细胞接种荧光示踪法("parachute"dye-couplinga ssay)观察不同浓度大黄素对GJIC的影响;用western blot法研究大黄素在影响GJIC功能浓度范围内对Cx32蛋白表达的影响。结果大黄素在0~1μmol/L浓度时对Hela细胞无毒性作用;大黄素(24~600nmol/L)预处理4h,能浓度依赖性地增强GJIC及Cx32蛋白表达量。结论大黄素能够增强Cx32的细胞GJIC;此增强作用可能与其增加Cx32蛋白表达水平有关。     

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。     

Inhibition of ATP-sensitive potassium channels increases HSV-tk/GCV bystander effect in U373 human glioma cells by enhancing gap junctional intercellular communication

It is well known that the efficiency of Herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) therapy is improved by the bystander effect, which mainly relies on gap junctional intercellular communication (GJIC). Malignant gliomas communicate poorly through gap junctions, consequently, agents with the ability to increase GJIC are good candidates to improve the efficiency of this therapy. Since we previously showed that the inhibition of ATP-sensitive potassium (KATP) channels promoted by tolbutamide increased GJIC in rat C6 glioma cells, we have investigated whether tolbutamide could increase the bystander effect in HSV-tk/GCV therapy against human glioma cells. We found that tolbutamide increased GJIC in U373 human glioma cells, an effect that was due to the up-regulation of connexin43, a protein that forms gap junctions channels. More interestingly, our results show that tolbutamide increased the efficiency of HSV-tk/GCV in co-cultures containing U373 cells and U373 cells transfected with HSV-tk. This effect was impaired in the presence of carbenoxolone, an inhibitor of GJIC. Furthermore, tolbutamide did not enhance the bystander effect in connexin43-silenced co-cultures. Together our results reveal that the inhibition of KATP channels promoted by tolbutamide enhances the bystander effect in HSV-tk/GCV therapy by increasing connexin43-mediated gap junctional intercellular communication in U373 human glioma cells.     

Dexamethasone reduced invasiveness of human malignant glioblastoma cells through a MAPK phosphatase-1 (MKP-1) dependent mechanism

Dexamethasone has been shown to inhibit tumor invasiveness. In the present study, the effects of dexamethasone on matrix metalloproteinases-2 (MMP-2) secretion, cell invasiveness, and intravasation in human U87MG glioma cells were examined. Dexamethasone decreased MMP-2 secretion and cell invasiveness in human glioma cells. Incubation of cells with dexamethasone increased mitogen activated protein kinase phosphatase-1 (MKP-1) expression. Ectopic expression of MKP-1 decreased cell invasiveness in vitro and intravasation in vivo. Because expression of inducible nitric oxide synthase (iNOS) has been implicated in the progression of malignant gliomas, we next investigated the possible roles of NO(-) in MMP-2 secretion and cell invasiveness in human U87MG glioma cells. Treatment of glioma cells with nitric oxide donor, sodium nitroprusside (SNP), increased MMP-2 secretion and the capacity of cell invasion in U87MG cells. Addition of dexamethasone or ectopic expression of wild-type MKP-1 suppressed the SNP-stimulated MMP-2 activation and glioma cell invasiveness in U87MG cells. Taken together, these results suggest that dexamethasone may suppress MMP-2 secretion and cell invasion through MKP-1 induction in human glioma cells.     

Chloroquine induces the expression of inducible nitric oxide synthase in C6 glioma cells.

Chloroquine, a well-known lysosomotropic agent, has long been used for the treatment of malaria and rheumatologic disorders. However, therapeutic doses of chloroquine are known to cause behavioral side effects. In the present study, we investigated whether chloroquine stimulates inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) synthesis in C6 glioma cells. Chloroquine caused dose-dependent increase in iNOS protein expression and NO production in C6 glioma cells. A tyrosine kinase inhibitor (genistein), a protein kinase C (PKC) inhibitor (Ro 31-8220), and a p38 mitogen-activated protein kinase (MAPK) inhibitor (SB 203580) all respectively suppressed chloroquine-induced iNOS expression and NO release from C6 glioma cells. Chloroquine activates p38 MAPK and stimulates PKC-alpha and -delta translocation from the cytosol to the membrane in C6 glioma cells. Chloroquine-stimulated p38 MAPK activation was blocked by genistein (20 microM), Ro 31-8220 (3 microM), and SB 203580 (10 microM). Incubation of lipopolysaccharide (LPS)-stimulated cells with chloroquine at non-toxic concentrations (10-100 microM) for 48 h increased iNOS expression, and led to a significant loss of adherent cells. Induction of DNA fragmentation in floating cells indicated that the C6 glioma cells were undergoing apoptosis. Taken together, our data suggest that chloroquine may activate tyrosine kinase and/or PKC to induce p38 MAPK activation, which in turn induces iNOS expression and NO production.     

Inhibitory effects of 1-methyl-4-phenylpyridinium on glutamate uptake into cultured C6 glioma cells

INTRODUCTION Glutamate is a predominant excitatory neurotrans-mitter in the mammalian central neuron system[1]. En-hanced glutamatergic activity is implicated in the pa-thology of neurological diseases, such as Parkinson dis-ease (PD)[1]. PDis characterized by a progressive andselective loss of dopaminergic neurons in substantianigra pars compacta (SNpc) which is the site of a glialactivation in PD. Regulation of glutamate level in thesynaptic cleft by glutamate transporters loca…     

Preparation,characterization and in vitro-targeted delivery of novel Apolipoprotein E-based nanoparticles to C6 glioma with controlled size and loading efficiency

Apolipoprotein E (APOE) with its extraordinary features is readily assembled with hydrophobic compounds via its compact hydrophobic units (CHUs). These assemblies can then be converted to stable particles by protein–protein interactions via coiled coil regions (CCRs) which exist in APOE structure. Applying these features of APOE, we prepared novel nanoparticles called NAPOE, using no cross-linker. Vitamin D3 – a hydrophobic antitumor model – was loaded within the nanoparticles (NPs). The NPs were mostly spherical with the mean diameter and zeta potential of 94.39?±?5.71?nm and ?20?±?0.3?mV, respectively. The molar ratio of VD3/APOE in NPs was 37.2?±?0.61. The NPs targeted C6 glioma cells in vitro via over-expressed LDLRs. The efficiency of the NPs uptake to malignant C6 glioma cells was remarkable compared to non-tumor glial cells (p?<?0.05). The releasing rate of hydrophobic cargo from the particles was high (p?<?0.05) and reached to maximum, 12?h after targeting C6 cells. The size and drug loading of NPs were found to be controlled by the definite numbers of CCRs and CHUs in APOE. In conclusion, it is suggested that NAPOE NPs can facilitate the controlled delivery of hydrophobic drugs to the malignant C6 glioma cells according to the degree of invasiveness.     

YAP-c-Myc信号通路抑制涉及冬凌草甲素抗神经胶质瘤作用

目的探讨冬凌草甲素对神经胶质瘤U87细胞增殖、迁移和凋亡影响及其作用机制是否涉及抑制YAP-c-Myc信号通路。方法采用MTT法检测冬凌草甲素对U87细胞活力的影响;划痕试验检测细胞迁移能力;流式细胞术检测细胞凋亡率;实时荧光定量PCR检测caspase-3、Bcl-2、Bax、YAP、c-Myc mRNA的表达;Western blot检测caspase-3、Bcl-2、Bax、YAP、p-YAP(Ser127)、c-Myc蛋白的表达。结果冬凌草甲素呈剂量依赖性抑制神经胶质瘤U87细胞增殖(P<0.05)及迁移(P<0.01);流式细胞术分析细胞凋亡率明显增加(P<0.01);caspase-3 mRNA和蛋白表达均增高(P<0.05),Bcl-2/Bax mRNA和蛋白表达均明显降低(P<0.05),YAP、c-Myc的mRNA和蛋白表达均明显降低(P<0.05),p-YAP的蛋白表达增高(P<0.05)。结论冬凌草甲素可促进神经胶质瘤U87细胞增殖、迁移并促进胶质瘤细胞凋亡,其机制可能与抑制YAP信号通路相关。     

Silver nanoparticles up-regulate Connexin43 expression and increase gap junctional intercellular communication in human lung adenocarcinoma cell line A549

Abstract

Silver nanoparticles (Ag NPs) are increasingly being used in wound dressings, medical settings, and various household products due to their unique properties and antimicrobial activity. Despite the widespread use of Ag NP products, the molecular mechanisms underlying the biological effects of Ag NPs remain unclear. Gap junctional intercellular communication (GJIC), formed by the connexin protein family, plays a critical role in the maintenance of tissue and organ homeostasis. This study was undertaken to investigate the effects of well characterized, PVP-coated Ag NPs (69 ± 3 nm) and silver nitrate on GJIC and connexin43 (Cx43) expression in human lung adenocarcinoma cell line A549. Our results showed that Ag NPs increased GJIC in A549 cells as assayed by dye transfer method. Western blot analysis showed that incubation of cells with Ag NPs significantly increased the expression of Cx43 protein. In addition, Ag NPs up-regulated expression of Cx43 mRNA in a dose-dependent manner. Silver nitrate failed to increase GJIC and the expression of Cx43 protein. It, however, increased Cx43 mRNA expression in A549 cells. Taken together, our results provide the first evidence that Ag NPs induced the increase of GJIC activity in A549 cells through up-regulation of Cx43 protein, suggesting that Cx43 and GJIC may be one of the targets for Ag NPs biological effects.     

Apoptosis induced by box jellyfish (Chiropsalmus quadrigatus) toxin in glioma and vascular endothelial cell lines.

This study was made to investigate whether Chiropsalmus Quadrigatus toxins (CqTX), which isolated from box jellyfish C. Quadrigatus venom, could induce apoptosis in human U251 and rat C6 malignant glioma cells and transformed vascular endothelial ECV 304 cell lines. Cell viability was estimated by MTT assay. Apoptosis was evaluated using TdT (terminal deoxynucleotidyl transferase)-mediated dUTP nick-end labeling (TUNEL) method and DNA gel electrophoresis. Furthermore, the expression of p53 protein was examined immunohistochemically in the U251 cells. After the CqTX treatment, the growth of all cell lines was inhibited, the fragmented DNA was observed and some cells became TUNEL positive. The expression of p53 protein was increased in the tested U251 cells. The results suggested that CqTX induced apoptosis in these cell lines. The promotion of the p53 expression might be one mechanism of apoptosis induced by CqTX in the glioma cells.