靶向AKT1和COX-2的RNAi抑制U251胶质瘤细胞侵袭的体外实验

目的应用RNA干扰(RNA interference,RNAi)技术敲低恶性胶质瘤细胞系U251中AKT1和COX-2表达后,在体外对细胞侵袭转移的抑制作用,初步探讨其可能的作用机制。方法构建重组腺病毒载体rAd5-A-C同时搭载靶向AKT1和COX-2的shRNA干扰序列,将其转染至恶性胶质瘤细胞系U251细胞。Realtime PCR检测RNAi后目的基因mRNA的表达水平,Western Blot检测目的基因及MMP-2、MMP-9、TIMP-2的表达情况。酶联免疫吸附试验检测转染前后分泌到细胞外的MMP-2和MMP-9的浓度变化。划痕实验和Transwell实验评价肿瘤细胞转染前后的细胞侵袭能力的变化。结果rAd5-A-C转染组AKT1和COX-2的mRNA和蛋白表达均明显抑制;MMP-2、MMP-9表达下调,TIMP-2表达则上调。ELISA检测胞外MMP-2、MMP-9浓度明显减低;划痕实验显示细胞转移运动能力明显减弱,Transwell体外侵袭实验结果显示穿过细胞数明显减低(P0.001)。结论重组腺病毒介导的RNAi技术可以序列特异性地抑制U251细胞AKT1和COX-2的表达,在体外对U251细胞侵袭转移产生明显抑制作用,可能成为恶性胶质瘤治疗的新策略。     

FRK通过N-cadherin／E-cadherin胶质瘤细胞侵袭和迁移途径抑制

目的探讨抑癌基因FRK（Fyn-relatedkinase）影响胶质瘤细胞侵袭和迁移的机制。方法将真核表达质粒pcDNA3．0-FRK和对照质粒pcDNA3．0转入人胶质瘤U251细胞中,westernblot技术检测FRK／N．cadherin／E—cadherin蛋白表达,细胞划痕试验检测细胞迁移能力,Transwell侵袭实验检测细胞侵袭能力。结果与对照组比较,转染pcl）NA3．0-FRK质粒24h后U251细胞侵袭能力下降47％、迁移能力下降64％,差异均有统计学意义（P〈0．01）;转染pcDNA3．0-FRK可以明显增加N—cadherin／E—cadherin的表达。结论FRK可以通过增加N．cadherin／E—cadherin的表达,进而抑制胶质瘤细胞侵袭和迁移能力。     

FRK通过FAK信号通路抑制脑胶质瘤细胞迁移与侵袭作用的研究

目的研究酪氨酸相关激酶(fyn-related kinase,FRK)是否通过粘着斑激酶(focal adhesion kinase,FAK)信号通路抑制脑胶质瘤细胞的迁移和侵袭。方法采用Western blot(WB)检测FRK质粒的转染效果,细胞划痕和Transwell侵袭实验检测过表达FRK及下调FAK对胶质瘤U251细胞迁移和侵袭能力的影响;WB检测过表达FRK对FAK、P-FAK蛋白水平的影响以及下调FAK对FRK蛋白水平的影响。结果FRK质粒转染成功。过表达FRK后胶质瘤U251细胞的迁移与侵袭能力下降。FAK siRNA干扰效率达到70%,下调FAK后胶质瘤U251细胞的迁移与侵袭能力下降。过表达FRK后P-FAK的蛋白水平明显下降,而FAK蛋白水平无明显变化,下调FAK对FRK的蛋白水平无明显影响。结论 FRK可能通过抑制FAK的磷酸化来调控胶质瘤的侵袭与迁移。     

Slit2/Robo1 signaling in glioma migration and invasion

Slit2/Robo1 is a conserved ligand-receptor system, which greatly affects the distribution, migration, axon guidance and branching of neuron cells. Slit2 and its transmembrane receptor Robo1 have different distribution patterns in gliomas. The expression of Slit2 is at very low levels in pilocytic astrocytoma, fibrillary astrocytoma and glioblastoma, while Robo1 is highly expressed in different grades of gliomas at both mRNA and protein levels. Acquisition of insidious invasiveness by malignant glioma cells involves multiple genetic alterations in signaling pathways. Although the specific mechanisms of tumor-suppressive effect of Slit2/Robo1 have not been elucidated, it has been proved that Slit2/Robo1 signaling inhibits glioma cell migration and invasion by inactivation of Cdc42-GTP. With the research development on the molecular mechanisms of Slit2/Robo1 signaling in glioma invasion and migration, Slit2/Robo1 signaling may become a potential target for glioma prevention and treatment.     

Intersectin1-s is involved in migration and invasion of human glioma cells

Malignant gliomas have a tendency to invade diffusely into surrounding healthy brain tissues, thereby precluding their successful surgical removal. Intersectin1 (ITSN1) as a molecular linker in the central nervous system is well known as an important regulator of endocytosis and exocytosis. ITSN1 has two isoforms: ITSN1-l and ITSN1-s. In this study, we show that siRNA-mediated down regulation of ITSN1-s inhibited migration and invasion of glioma cells. In addition, we demonstrate the possible mechanisms by which ITSN1-s functions in migration and invasion. Several key proteins, including cofilin, LIMK, PAK, FAK, integrin β1, and MMP-9, which are critical for cells migration and invasion, were probably involved in ITSN1-s signaling pathways. These results suggest that ITSN1-s contributes to glioma cells migration and invasion by regulating the formation of cytoskeleton, influencing adhesion and increasing expression of MMP-9. Our results indicate that ITSN1-s is a critical factor in gliomas invasion and identify that ITSN1-s is a new potentially antiinvasion target for therapeutic intervention in gliomas.     

Knockdown of CDK2AP1 by RNA interference inhibits cell growth and tumorigenesis of human glioma

Abstract

Previous reports support the role of cyclin-dependent kinase 2-associated protein 1 (CDK2AP1) as a tumor suppressor that functions as a key player in cell cycle regulation. Although the misadjustment of CDK2AP1 has been revealed in several types of human malignancies, the functional role of CDK2AP1 in human glioma remains unknown. The present study was undertaken to investigate the effects of CDK2AP1 knockdown by RNA interference (RNAi) on glioma cell growth and tumorigenesis. We employed lentivirus-mediated RNAi to down-regulate CDK2AP1 expression in U251 and U373 cells. Knockdown of CDK2AP1 resulted in a significant reduction in U251 and U373 cell proliferation, as determined by MTT and colony formation assays. Cell cycle analysis showed CDK2AP1 silencing caused U251 cells arrest in G0/G1 phase, especially in the sub-G1 phase representing apoptotic cells. In vivo tumorigenesis was assessed using xenograft formation and CDK2AP1 depletion remarkably inhibited glioma growth and tumorigenesis. Taken together, these results suggest that CDK2AP1 siRNA may have an anti-tumorigenic effect on human glioma.     

Silencing of OTUB1 inhibits migration of human glioma cells in vitro

OTU domain‐containing ubiquitin aldehyde‐binding protein 1 (OTUB1) protein, a deubiquitinating enzyme (DUB) which belongs to the ovarian tumor (OTU) family, was reported to be associated with the development of various malignancies. However, the potential function of OTUB1 in human gliomas was still unclear. In this study, we sought to investigate the function of OTUB1 in the pathological process of gliomas and analyze its related clinical significance. Western blot and immunohistochemistry analyses demonstrated that OTUB1 was overexpressed in glioma tissues, and statistical analysis suggested the expression level of OTUB1 was significantly correlated with the WHO grades of human gliomas (P < 0.05). Moreover, Kaplan–Meier curve also indicated that high expression of OTUB1 was correlated with a poor prognosis. In vitro, silencing OTUB1 retarded the migration ability of glioma cells. Knockdown of OTUB1 increases epithelial‐mesenchymal transition‐related protein E‐cadherin expression, but decreases simultaneously the expression of vimentin and snail. Furthermore, down‐regulated expression of OTUB1 also resulted in decreased expression of some extracellular matrix degradation‐related proteins, such as matrix metallopeptidase (MMP)2 and MMP9. All results suggested that OTUB1 was a valuable marker in the pathogenesis of human gliomas and could be used as a novel biomarker for glioma therapy in the future.     

Leptin induces migration and invasion of glioma cells through MMP-13 production

Leptin, the product of the obese gene, plays an important role in the regulation of body weight by coordinating metabolism, feeding behavior, energy balance, and neuroendocrine responses. However, regulation of leptin gene expression in the central nervous system is different from that in the adipocytes. In addition, leptin has been found in many tumor cell lines and has been shown to have mitogenic and angiogenic activity in a number of cell types. Glioma is the most common primary adult brain tumor with poor prognosis because of the spreading of tumor cell to the other regions of brain easily. Here we found that malignant C6 glioma cells expressed more leptin and leptin receptors than nonmalignant astrocytes. Furthermore, it was found that exogenous application of leptin enhanced the migration and invasion of C6 glioma cells. In addition, we found that the expression of matrix metalloproteinase-13 (MMP-13) but not of MMP-2 and MMP-9 was increased in response to leptin stimulation. The leptin-induced increase of cell migration and invasion was antagonized by MMP-13 neutralizing antibody or silencing MMP-13. The up-regulation of MMP-13 induced by leptin was mainly through p38 MAP kinase and NF-kappaB pathway. In addition, migration-prone sublines demonstrate that cells with increasing migration ability had more expression of MMP-13 and leptin. Taken together, these results indicate that leptin enhanced migration and invasion of C6 glioma cells through the increase of MMP-13 production.     

Overexpression of the 18A2/mts1 gene and down–regulation of the TIMP–2 gene in invasive human glioma cell lines in vitro

Invasion of the reconstituted extracellular matrix composite, Matrigel, by eight human glioma–derived cell lines and human fetal brain cells was assessed in vitro using 8 um polycarbonate filters in a modified Boyden migration chamber. With the exception of one low grade glioma derived cell line, all lines studied proved to be invasive while normal fetal brain cells failed to invade. This invasive potential was independent of the histological grade of the tumour from which the cell lines originated. In addition, the expression of the metastasis–associated gene 18A2lmts1 as well as the tissue inhibitor of metalloproteinases–2 (TIMP–2) was analysed in each of the glioma–derived cell lines. The 18A2/mtsl was expressed in all the cells studied with the exception of fetal brain cells and the low grade non–invasive glioma derived IPRK–7 cell line. The 18A2/mtsl related genes coding for the S100 subfamily of calcium binding proteins were found to be differentially and overexpressed in invasive cell lines. TIMP–2 was expressed only in noninvasive cell lines. These results suggest that the 18A2/ mtsl and TIMP–2 genes could play an important role in the invasive behaviour of human glioma cells in vitro. .     

VE-statin/Egfl7-siRNA抑制恶性胶质瘤诱导内皮细胞血管生成能力的体外研究

目的通过细胞培养及RNA干扰技术探讨类表皮生长因子域7(VE-statin/Egfl 7)在恶性胶质瘤血管生成中的作用和机制。方法Transwell培养技术建立U 251-HUVEC共培养系统,体外模拟恶性胶质瘤与内皮细胞的相互作用;并通过构建靶向VE-statin/Egfl7基因的siRNA慢病毒载体抑制U251和HUVEC细胞中该基因的表达。通过内皮细胞增殖、粘附、迁移及成管实验检测该基因在体外恶性胶质瘤微环境中对血管生成的影响。结果沉默VE-statin/Egfl 7基因表达后,HUVEC生长出现暂时性减缓,但很快恢复正常增殖状态,而且内皮细胞的迁移能力不受影响,但是内皮细胞的粘附能力明显受到抑制;成管实验发现,VE-statin/Egfl7基因沉默后内皮细胞不能形成毛细血管样结构。结论 VE-statin/Egfl7可通过调节内皮细胞的粘附性而在恶性胶质瘤血管生成过程的血管管腔形成过程中起着关键性调控作用。     

RNA干扰敲低Wnt2的表达抑制U251细胞生长的体内外研究

目的 在体内外研究转染靶向Wnt2的siRNA对U251细胞的抑制效果.方法 向U251细胞转染靶向Wnt2的siRNA后,免疫印记检测转染后Wnt2及相关蛋白表达,MTT检测细胞增殖,annexin标记细胞凋亡,流式细胞仪检测细胞周期分布,鼠尾胶3D生长实验检测细胞侵袭能力的变化.建立裸鼠胶质瘤皮下动物模型,瘤内注射Wnt2 siRNA观察肿瘤生长情况.结果 转染Wnt2siRNA后,U251细胞的Wnt2、frizzled2、磷酸化GSK-3β、β-catenin等表达降低,细胞增殖受抑,凋亡率升高,细胞阻滞于G0/G1期.体内研究发现转染靶向Wnt2的siRNA后,裸鼠皮下肿瘤的生长速度缓慢,相应的蛋白表达降低.结论 转染靶向Wnt2的siRNA可有效敲低该基因在U251细胞内的表达,从而抑制了胶质瘤细胞生长,具有潜在的治疗前景.     

Beclin 1 基因对恶性胶质瘤细胞 U87 自噬活性和增殖的影响简

目的研究BeclinJ基因对U87胶质瘤细胞自噬和增殖的影响。方法实验分5组：空白对照组．pSUPER—Bec组（表达BeclinsiRNA）与其阴性对照组（pSUPER—non组）,pcDNA3．1-Bec组（表达BeclinJ基因质粒）与其阴性对照组（pcDNA3．1-non组）。分别转染U87细胞,采用免疫印迹检测Beclin1、LC3和p62蛋白在各组的表达;用氚标胸腺嘧啶脱氧核苷（3H-TdR）检测各组细胞增殖率。结果转染后48h,pSUPER—Bec组Beclin1、LC3B—11蛋白表达下降,p62蛋白表达升高。pcDNA3．1-Bec组Beclin1、LC3B-Ⅱ蛋白表达升高,p62蛋白表达下降。与空白对照组或pcDNA3．1-non组相比．pcDNA3．1-Bec组细胞增殖速度降低（P〈0．05）,其他各组细胞增殖速度无明显差异。结论恶性胶质瘤细胞中自噬相关基因Beclinj表达下降,过表达Beclinl蛋白能增强细胞的自噬活性,抑制细胞的增殖活性。     

血管内皮生长因子反义RNA对C6鼠胶质瘤细胞体外作用的研究

目的探讨VEGF反义RNA对C6鼠胶质瘤细胞体外作用。方法用Lipofectamine介导的方法将VEGF反义eDNA转染入C6鼠胶质瘤细胞系,观察其对细胞增殖和凋亡的影响。结果在体外VEGF反义RNA可有效抑制C6鼠胶质瘤细胞内源性VEGFmRNA和VEGF蛋白的产生,但对细胞增殖和凋亡无明显影响。结论采用VEGF反义RNA可能成为抗血管形成肿瘤治疗的新策略之一。     

特异性小干扰RNA沉默Polo样激酶1基因表达对恶性胶质瘤细胞增殖的影响

目的 探讨Polo样激酶1(PLK1)基因对胶质瘤细胞增殖的影响和可能机制. 方法 根据PLK1基因特点,设计并用化学方法合成了5个小干扰核糖核酸分子(siRNA)(P1、P2、P3、P4和P5).以这5个siRNA转染人胶质瘤TJ905细胞后.分别采用荧光实时定量RT-PCR和Western blot检测PLK1 mRNA和蛋白表达水平.分别采用MTT法和Western blot方法检测癌细胞增殖和增殖细胞核抗原(PCNA)蛋白水平,用TRA-.ELISA方法检测胶质瘤细胞端粒酶活性. 结果 所设计的5个siRNA均能明显抑制胶质瘤TJ905细胞PLK1 mRNA水平,以P4效果最好.以P4转染处理胶质瘤细胞后与脂质体对照组比较,PLK1基因mRNA水平和蛋白水平明显下调,差异有统计学意义(P均=0.000).MTT结果显示.与脂质体对照组比较P4 siRNA转染组癌细胞生长明显受到抑制,且呈浓度依赖性(r=0.868,P=0.000).Western blot结果显示,与脂质体对照组比较P4 siRNA转染组PCNA蛋白水平明显下降,差异有统计学意义(F=181.36,P=0.000).TRAP-ELISA结果显示,与脂质体对照组比较P4 siRNA转染组胶质瘤细胞端粒酶活性明显受到抑制,且呈浓度和时间依赖性(P=0.000). 结论 PLK1基因对胶质瘤细胞增殖具有重要的调控作用;以PLK1 siRNA转染处理胶质瘤细胞,可明显抑制胶质瘤细胞的恶性增殖,其机制可能与抑制端粒酶活性有关.     

Bex2对人脑胶质瘤干细胞增殖、生长和凋亡影响的体外实验研究

目的观察Bex2真核表达载体对脑胶质瘤干细胞增殖、生长和凋亡的影响,为胶质瘤治疗提供理论基础。方法采用免疫磁珠系统分离、Nestin免疫组化鉴定人脑胶质瘤干细胞;将RT-PCR法获得的Bex2与质粒pcDNA3.1(+)连接,脂质体法转染胶质瘤干细胞,于转染18h、36h、48h、72h、96h后,采用Western Blot检测Bex2表达,MTT法及Hoechst染色试剂盒检测生长抑制率和凋亡情况。结果分离、培养出人脑胶质瘤干细胞,并成功构建Bex2的真核表达载体。转染后18hBex2即有表达,48h达到高峰,后渐下降;转染36h、48h、72h、96h时,细胞生长抑制率和凋亡率明显高于空载体组和空白对照组(P<0.05);转染72h时,细胞生长抑制率和凋亡率最高(P<0.05)。结论Bex2能够抑制脑胶质瘤干细胞的增殖和生长,诱导胶质瘤干细胞凋亡。     

Survivin-specific small interfering RNAs enhance sensitivity of glioma U-87MG cells to paclitaxel by promoting apoptosis

A survivin siRNA expression vector was transfected into glioma U-87MG cells and these cells were then treated with paclitaxel.The results showed that survivin-specific siRNA combined with paclitaxel treatment synergistically inhibited glioma U-87MG cell proliferation and promoted apoptosis.This treatment also inhibited the expression of the cell cycle regulatory proteins,survivin,cyclinD1,c-Myc and CDK4 and enhanced the sensitivity of U-87MG cells to paclitaxel.     

转录因子FOXR2对脑胶质瘤细胞增殖的影响

目的探讨下调或过表达FOXR2对脑胶质瘤细胞增殖能力的影响。方法以正常脑组织标本为模板,PCR法克隆FOXR2基因,并构建FOXR2过表达质粒;Western blot法检测FOXR2在胶质瘤细胞系中的表达水平。用慢病毒系统构建稳定下调及过表达FOXR2的脑胶质瘤细胞株;CCK8实验检测下调或过表达FOXR2对胶质瘤细胞增殖速率的影响。结果成功克隆FOXR2基因;WB检测结果显示稳定下调FOXR2的U251细胞株及过表达FOXR2的U87细胞株构建成功。CCK8实验结果表明,与对照组相比,96 h后下调FOXR2的胶质瘤细胞增殖速率减少45.13%;相反,过表达FOXR2后,胶质瘤细胞的增殖速率可增加43.98%。结论转录因子FOXR2可促进胶质瘤细胞的增殖。     

Proteomics‐based analysis of invasion‐related proteins in malignant gliomas

One of the insidious biological features of gliomas is their potential to extensively invade normal brain tissue, yet molecular mechanisms that dictate this locally invasive behavior remain poorly understood. To investigate the molecular basis of invasion by malignant gliomas, proteomic analysis was performed using a pair of canine glioma subclones – J3T‐1 and J3T‐2 – that show different invasion phenotypes in rat brains but have similar genetic backgrounds. Two‐dimensional protein electrophoresis of whole‐cell lysates of J3T‐1 (angiogenesis‐dependent invasion phenotype) and J3T‐2 (angiogenesis‐independent invasion phenotype) was performed. Twenty‐two distinct spots were recognized when significant alteration was defined as more than 1.5‐fold change in spot intensity between J3T‐1 and J3T‐2. Four proteins that demonstrated increased expression in J3T‐1, and 14 proteins that demonstrated increased expression in J3T‐2 were identified using liquid chromatography‐mass spectrometry analysis. One of the proteins identified was annexin A2, which was expressed at higher levels in J3T‐1 than in J3T‐2. The higher expression of annexin A2 in J3T‐1 was corroborated by quantitative RT‐PCR of the cultured cells and immunohistochemical staining of the rat brain tumors. Moreover, immunohistochemical analysis of human glioblastoma specimens showed that annexin A2 was expressed at high levels in the tumor cells that formed clusters around dilated vessels. These results reveal differences in the proteomic profiles between these two cell lines that might correlate with their different invasion profiles. Thus, annexin A2 may be related to angiogenesis‐dependent invasion.     

shRNA表达载体特异性抑制人脑胶质瘤细胞BT325绿色荧光蛋白基因的表达

目的探讨绿色荧光蛋白(GFP)特异性发夹结构RNA (shRNA)对人类胶质瘤BT325细胞系GFP基因表达的抑制作用。方法设计并合成针对GFP基因的shRNA序列,与报告基因质粒pEGFP-N1共转染,选择最佳转染比例,荧光显微镜下观察GFP表达的效率和对GFP的抑制效应。结果质粒pSIREN-RetroQ-RNAi经双酶切得到6 kb和100 bp条带,结合测序验证,与实验设计的shRNA长度相符。质粒DNA与XP-1转染比例为1∶2.5时GFP表达最强。BT325细胞干扰48 h时GFP表达显著减少。结论BT325细胞系中存在RNA干扰现象,且干扰效果特异、稳定;本实验为研究基因功能提供了新的策略。     

Epigallocatechin-3-gallate induces apoptosis,inhibits proliferation and decreases invasion of glioma cell

Epigallocatechin-3-gallate (EGCG), a major polyphenol in green tea, has been considered a potential therapeutic and chemopreventive agent for cancer. Glioma is a malignant tumor with high mortality but effective therapy has not yet been developed. In this study, we found that EGCG induced apoptosis in U251 glioma cells via the laminin receptor (molecular weight 67kDa) in a time- and dose-dependent manner, decreased their invasiveness and inhibited their proliferation. The mitogen-activated protein kinase pathway was shown to be involved in glioma cell apoptosis and proliferation. Furthermore, the mRNA levels of matrix metalloproteinase (MMP)-2 and MMP-9 were reduced after EGCG treatment. These results suggest that EGCG has important therapeutic effects with low toxicity and side-effects, and could be used in cancer chemoprevention.