Cx43基因转染胶质瘤细胞抑制细胞增殖与下调若干重要生长因子

目的：研究连接蛋白43(Cx43)基因对胶质瘤细胞增殖的抑制作用及其可能的机制。方法：以脂质体介导，将Cx43cDNA转染于内源性Cx43表达缺失的鼠C6胶质瘤细胞和人TJ905胶质母细胞瘤细胞。采用MTT法及AgNORs(核仁组成区嗜银蛋白)平均数检测细胞增殖、。TUNEL法检测细胞凋亡、划痕标记染料示踪技术检测细胞间隙连接通讯(GJIC)。应用Western蛋白印迹及免疫组化法检测CX43cDNA转染细胞前后若干与胶质瘤发生密切相关的重要生长因子及受体表达，其中包括IGF1、bFGF、PDGF、IGFBP3、EGFR。结果：胶质瘤细胞转染Cx43cDNA后细胞增殖被抑制，细胞凋亡并未增加；GJIC明显恢复。BFGF、PDGF，IGF1、IGFBP3表达显著下调，但EGFR表达无变化。结论：Cx43基因对胶质瘤细胞增殖的抑制作用与GJIC恢复以及bFGF，PDGF，IGF1，IGFBP3表达下调相关，CX43可望成为胶质瘤基因治疗的靶基因。     

连接蛋白基因Cx43抑制胶质瘤细胞增殖及其机理的初步探讨

目的 探讨连接蛋白基因Cx43对胶质瘤细胞增殖的抑制及其可能的机理。方法 将含Cx43cDNA的质粒以脂质体介导转染Cx43表达缺失的人和鼠的恶性胶质瘤细胞,通过Northem杂交、原位杂交及免疫组化染色检测Cx43mRNA及蛋白表达;MTT法测定细胞增殖率;核仁组成区嗜银蛋白染色检测细胞增殖活性;TUNEL法检测细胞凋亡;划痕标记荧光染料示踪技术检测细胞间隙连接通讯(GJIC);Western杂交及免疫组化染色检测bFGF、PDGF、EGFR、IGF-I和IGFBP3的表达。结果 转染Cx43基因的胶质瘤细胞增殖下降,GJIC恢复,同时伴有bFGF、PDGF、IGF-I和IGFBP3表达下降,而EGFR表达和细胞凋亡则无改变。结论 Cx43基因可能通过恢复GJIC功能及抑制某些重要生长因子的自分泌,实现对胶质瘤细胞增殖的抑制。     

连接蛋白43基因治疗鼠C6脑胶质瘤的体内实验研究

目的 研究连接蛋白（Cx）43基因抑制脑胶质瘤生长的作用。方法 将Cx43基因表达缺失的大鼠C6胶质瘤细胞（对照组）和转染Cx43 cDNA的C6细胞（转染组）种植于SD大鼠右侧尾状核,荷载C6脑胶质瘤鼠用Cx 43 cDNA原位治疗（治疗组）,并以空载体治疗作为对照（空载组）,每组10只,观察各组大鼠一般情况、生存期、MRI动态变化及病理改变,通过原位杂交及免疫组化染色检测肿瘤Cx43 mRNA及蛋白表达,以AgNOR平均计数检测增殖活性,以Tunel法检测细胞凋亡。结果 对照组和空载组大鼠均于3周内死亡;转染组6只大鼠和治疗组8只大鼠观察120 d内无自然死亡。除治疗组1只尚有残瘤外,余瘤体消失,转染组和治疗组肿瘤细胞均有Cx43 mRNA及蛋白表达,且增殖治疗组1只尚有残瘤外,余瘤体消失。转染组和治疗组肿瘤细胞均有Cx43 mRNA及蛋白表达,且增殖活性下降,但凋亡不增加。结论 转染Cx43基因后的C6胶质瘤细胞致瘤性显著降低,且对荷载脑胶质瘤鼠具有明显的治疗作用,有可能成为恶性胶质瘤基因治疗的优先靶的之一。     

反义封闭MMP-9基因表达对胶质母细胞瘤细胞系增殖的影响

目的 探讨反义封闭胶质瘤细胞MMP-9基因表达对胶质瘤细胞增殖的影响。方法 利用基因重组的方法构建正义和反义MMP-9重组体;经脂质体介导,分别将pcDNA3.0空载质粒、正义重组体、反义重组体转染TJ905细胞;通过RT-PCR和Western blot检测转染细胞MMP-9的mRNA和蛋白表达水平;利用免疫组织化学法分析了转染细胞中MMP-9和Ki-67的表达。结果经限制性酶切鉴定和DNA测序分析,基因重组成功,且正义与反义重组体插入位点间的序列方向正好相反。与TJ905对照组、空载体组和正义对照组相比较,转染反义重组体后的TJ905细胞中MMP-9 mRNA和蛋白的表达水平明显下降（P<0.001）。转染空载体和正义重组体后,TJ905细胞内MMP-9 mRNA和蛋白的表达水平与未进行转染的TJ905细胞相比差异无统计学差异（P>0.05）。免疫组织化学结果显示反义封闭有效,MMP-9的表达下调,TJ905细胞增殖活性下降。结论 转染反义MMP-9重组体可以有效抑制胶质母细胞瘤细胞的MMP-9基因的表达,同时可以抑制肿瘤细胞的增殖。     

探讨bcl-2下调后对胶质瘤细胞系的增殖、凋亡和侵袭能力的影响

目的 研究下调bcl-2基因表达后对神经胶质瘤细胞增殖、凋亡和侵袭能力的影响。方法 利用小分子RNA干扰（Small interfering RNA,siRNA）技术人工合成bcl-2靶向siRNA,转染神经胶质瘤细胞系SHG44和TJ905细胞,特异性沉默神经胶质瘤细胞SHG44和TJ905细胞bcl-2基因表达。通过蛋白质印迹（Western blot）分析、噻唑蓝（MTT）实验、Transwell实验和流式细胞仪（FCM）检测,观察bcl-2 siRNA对转染细胞bcl-2基因抑制效果、增殖能力的变化、侵袭能力的改变和细胞凋亡的影响。结果 bcl-2 siRNA可特异性下调神经胶质瘤细胞系SHG44和TJ905细胞bcl-2基因表达。bcl-2下调的神经胶质瘤细胞增殖能力在不同时间点都受到抑制,侵袭能力也明显下降,但实验中未见细胞明显凋亡。结论 下调bcl-2基因表达可有效抑制神经胶质瘤细胞生长,降低细胞增殖和侵袭能力。     

转染Cx43cDNA对胶质瘤细胞生长影响的观察

背景与目的：缝隙连接与肿瘤的发生、发展、转移和凋亡密切相关。本研究观察转染Cx43cDNA对C6细胞缝隙连接细胞间通讯功能（gap iunctional intercellular communication，GJIC）功能及生长影响情况。方法：①通过氯化钙法将质粒转入JM109菌株，筛选阳性菌落扩增，用Wizard Pure Fection质粒DNA纯化系统试剂盒进行提取及纯化，最后用Ecor Ⅰ、Hind Ⅲ内切酶进行酶切鉴定；②基因转染：通过Lipofect AMINE2000介导对C6细胞进行质粒DNA转染，用G418筛选浓度筛选出转染成功细胞：③用半定量RT—PCR检测转染后c6细胞Cx43mRNA表达的改变；④划痕荷载染料传输实验（scrape loading dye transfer test，SLDT）检测转染前后GJIC的改变；⑥以MTT法检测转染细胞培养72h后的A值，观察转染Cx43cDNA对C6细胞生长抑制情况；⑥用流式细胞仪技术检测转染细胞培养72h后细胞凋亡率，观察转染Cx43cDNA对C6细胞凋亡的影响。结果：①转染了Cx43cDNA的C6-Cx43细胞Cx43mRNA表达显著增加；②C6-Cx43细胞染料传输能力较空载质粒转染细胞C6-Non明显增强；⑧MTT法检测表明同C6-Non相比，C6-Cx43细胞A值较低，两者差异有显著性（P〈0．01）；④流式细胞仪检测发现C6-Cx43与C6-Non细胞凋亡率无显著性差异（P〉0．05）。结论：①转染Cx43cDNA可上调c6细胞GJIC水平。②转染Cx43cDNA可显著抑制C6细胞生长，但细胞凋亡并未增加。     

miR-146b-5p对胶质瘤TJ905细胞生长的抑制作用及其机制探讨

  目的  在TJ905胶质母细胞瘤细胞系中观察miR-146b-5p对MMP16的调控作用及其对细胞侵袭、迁移、增殖和凋亡的影响。  方法  分别用无义序列表达质粒(对照组)和miR-146b-5p表达质粒(P-miR-146b-5p组)转染TJ905细胞, 用qRT-PCR和Western blot检测两组细胞miR-146b-5p的表达水平及MMP16 mRNA和蛋白的表达水平, 用体外迁移侵袭实验及流式细胞术检测转染细胞迁移、侵袭、细胞周期分布和凋亡水平, 并分析这些变化的相互关系。  结果  与对照组相比, p-miR-146b-5p组MMP16 mRNA和蛋白表达量明显降低, 二者间呈正相关且均与miR-146b-5p表达量呈负相关。p-miR-146b-5p组侵袭和迁移细胞数均明显低于对照组, 并均与同组MMP16蛋白表达量呈正相关; 而凋亡水平明显高于对照组, 并与同组miR-146b-5p表达量呈正相关, 但两组细胞周期时相分布无显著性差异。  结论  miR-146b-5p是胶质瘤的抑瘤miRNA; 补充外源性miR-146b-5p可促进胶质瘤细胞凋亡, 并通过抑制靶基因MMP16表达阻止其侵袭迁移; 提示miR-146b-5p在恶性胶质瘤基因治疗方面具有重要的潜在应用价值。      

全反式维甲酸与单纯疱疹病毒胸苷激酶基因对胶质瘤的协同杀伤作用

背景与目的：细胞间缝隙连接通讯（gap junctional intercellular communication,GJIC)是介导单纯疱疹病毒胸苷激酶（herpes simplx virus thymidine kinase,HSV-tk)基因治疗中旁观者效应的重要机制。全反式维甲酸(all-trans-retinotic acid,ATRA)或能通过上调胶质细胞GJIC和抑制肿瘤细胞生长的双重作用,促进HSV-tk基因治疗的疗效。本研究的目的在于证实HSV-tk和ATRA联合应用对胶质瘤细胞的协同杀伤作用。方法：分别以1μmol/L、10μmol/L、100μmol/L3种浓度的ARTA作用于培养的大鼠C6胶质瘤细胞,并研究ATRA对C6胶质瘤细胞分化、增殖、GJIC及connexin43(Cx43)基因转录等方面的影响。将C6细胞与稳定表达HSV-tk基因的C6tk细胞按不同比例混合,分别在含GCV和不同浓度ATRA或仅含GCV的培养基中培养,并于药物作用7天后用MTT法检测旁观者效应。结果：经3种浓度的ARTA作用后,C6胶质瘤细胞均显示出细胞分化的形态学特征。C6细胞的增殖也明显受到ATRA的抑制,绝大多数的活细胞都静止于G1期,100μmol/L ATRA对C6细胞增殖的抑制尤其明显,并诱导细胞凋亡。经3种浓度的ATRA分别作用后,C6细胞的GJIC也明显提高,而Cx43基因的转录未受明显影响。旁观者效应实验的结果显示,3种浓度的ATRA均可明显增强旁观者效应。结论：联合应用ATRA与HSV-TK基因治疗可以产生显著的杀伤胶质瘤细胞的作用。     

脑胶质瘤中bcl-2 基因表达水平及临床意义

 目的 探讨bcl-2基因在胶质瘤细胞中的表达水平与肿瘤恶性程度和临床预后的关系. 方法 用免疫组化染色和原位杂交检测61例人胶质瘤组织和20例正常人脑组织中bcl-2蛋白和bcl-2 mRNA的表达. 结果 免疫组化染色55例（87.0%）表达bcl-2蛋白,原位杂交显示58例（92.8%）表达bcl-2 mRNA,两者的表达水平呈正相关,bcl-2在转录水平的表达明显高于蛋白质水平,且bcl-2表达水平与胶质瘤病理分级呈显著正相关系,而20例正常人脑组织中仅4例表达bcl-2蛋白,6例表达bcl-2 mRNA（均P〈0.01）. 结论 恶性胶质瘤细胞中普遍存在bcl-2基因的高表达,表达水平与胶质瘤的恶性程度、临床预后存在密切关系,bcl-2基因可能成为恶性胶质瘤基因治疗的靶点.     

骨髓间充质干细胞表达外源性IL-12对胶质瘤C6细胞增殖的影响

目的:探讨以骨髓间充质干细胞（mesenchymal stem cells,MSCs） 为基因治疗载体表达外源性IL12对胶质瘤C6细胞增殖的影响。方法：分离培养大鼠MSCs, 腺病毒介导IL12基因转染大鼠MSCs(AdIL12MSCs),RTPCR 及Western Blotting检测AdIL12MSCs中IL12基因mRNA及蛋白表达。MTT法检测AdIL12MSCs分泌的外源性IL12对C6胶质瘤细胞增殖活性 的影响,光镜下观察外源性IL12对C6细胞形态的影响。结果：腺病毒介导IL12基因成功转染MSCs形成AdIL12MSC,其IL12基因在mRNA及蛋白水平均有明显表达。AdIL12MSC分泌的外源性IL12显著抑制胶质瘤C6细胞的增殖（P<0.05）。结论：转染IL12的MSCs(AdIL12MSC)能够在mRNA及蛋白水平表达外源性IL12基因,显著抑制胶质瘤C6细胞的增殖。     

The effect of transfected Cx43 gene on the GJIC and proliferation of glioma cells

Cell to cell communication via gap junction plays an important role in the maintanence of normal cell growth. Its disruption may lead to aberrant cell growth and eventually development of tumors[1]. Gap junctions (GJ) are specialized intercellular channels between plasma membrane of two adjacent cells. Each GJ channel is composed of two connexons contributed by each of two communicating cells and each connexon is a hexameric assembly of protein subunits known as connexins (Cx). Cx genes fun…     

miR-221/222 is the regulator of Cx43 expression in human glioblastoma cells

The miR-221/222 cluster is significantly upregulated in malignant glioma cells and regulates the expression of multiple genes associated with glioma cell proliferation, invasion and apoptosis, which was shown in our previous studies. Cx43 has been identified as a tumor suppressor and major component for the establishment of gap junction intercellular communication (GJIC) in glial cells, which is frequently reduced or deleted in high-grade gliomas. According to bioinformatic analysis, connexin 43 (Cx43) may be one of the target genes of miR-221/222. The aim of the present study was to validate Cx43 as a target gene of miR-221/222 and to determine whether overexpression of miR-221/222 is one of the molecular mechanisms for the reduced expression of Cx43 in malignant gliomas. We transfected miR-221/222 antisense oligonucleotides (AS-miR-221/222) into U251 human glioblastoma cells using a lipofectamine method. Northern blot analysis was conducted to detect the expression of the miR-221/222 cluster. Luciferase reporter assays were exploited to confirm Cx43 as a target gene of miR-221/222. Cx43 expression was assessed by western blotting and immunofluorescence staining. Scrape loading and dye transfer (SLDT) assays were used for examination of GJIC. Proliferation and invasion of U251 cells were evaluated by MTT and transwell assays, respectively. Cell cycle kinetics and apoptosis were determined with flow cytometry. We found that expression of the miR-221/222 cluster was significantly reduced while Cx43 expression was upregulated in U251 cells transfected with AS-miR-221/222, and the GJIC deficiency in parental U251 cells was re-established. Moreover, the luciferase activity determined by the luciferase reporter assay was enhanced in AS-miR-221/222-treated cells, and cell proliferation and invasion were suppressed while apoptosis was induced. We conclude that miR-221/222 function as oncogenic microRNAs in human gliomas, at least in part, by targeting Cx43.     

IN VIVO GROWTH OF CEREBRAL C6 GLIOMA CELLS TRANSFECTED AND TREATED WITH CX43 GENE

Objective: To study the role of connexin gene (Cx43) on the development of glioma and the feasibility of using Cx43cDNA as a target of gene therapy of gliomas.Methods: Parental rat C6 cells and C6 cells transfected with Cx43cDNA were implanted into right caudate nucleus of SD rats as control and transfected group.Rats bearing cerebral C6 gliomas were treated with Cx43cDNA and empty vector as treated group and empty vector group. The general manifestation, survival time, MRI dynamic scanning and histopathological changes of all rats were observed. In situ hybridization and immunohisto- chemistry were used for examination of Cx43mRNA and its protein in gliomas. Average number of AgNOR staining was used for detection of cell proliferation activity, and TUNEL method for determination of cell apoptosis. Results: All rats in control and empty vector group died of cerebral gliomas within 3 weeks after implantation of C6 cells. Six out of nine rats in the transfected group and eight out of ten rats in treated group kept alive beyond 120 days with totally disappearing of the tumor foci, except one treated rat having a little residue of tumor. In gliomas of transfected and treated groups Cx43 gene expression was upregulated, proliferation activity was lowered,However, the apoptotic cells did not increase.Conclusion: The present study indicates that Cx43 gene is of crucial importance in the development of malignant glioma. It can be an effective target for gene therapy of gliomas.     

间隙连接基因Cx43表达对肺癌细胞体内成瘤生长的抑制

目的探讨间隙连接基因表达和细胞通讯功能对肿瘤生长的抑制作用。方法以高转移性人肺癌ＰＧ细胞为材料,该细胞的间隙连接基因Ｃｘ４３表达抑制,细胞通讯功能缺陷。用Ｃｘ４３ｃＤＮＡ转染ＰＧ细胞,分离转染子克隆,与只转染空载体ｃＤＮＡ的对照组ＰＧ进行比较。用Ｎｏｒｔｈｅｒｎ分子杂交和染料传输方法检查间隙连接表达情况,并观察细胞在体外和裸鼠体内生长。结果空载体对照组与未转染组ＰＧ相似,Ｃｘ４３ｍＲＮＡ无表达,通讯功能缺陷,细胞生长快,在软琼脂内集落形成率高（１１．６％）,植入裸鼠体内２８天,平均瘤重３．４７ｇ。转染组细胞Ｃｘ４３ｍＲＮＡ表达升高,通讯功能增强,细胞生长慢,在软琼脂内集落形成率和在裸鼠体内生长速度明显低于对照组,抑制率分别为９０％和７５％。结论间隙连接基因Ｃｘ４３表达对肺癌细胞有抑瘤作用。     

Suppression of tumorigenicity of human lung carcinoma cells after transfection with connexin43

The human lung carcinoma cell line PG is defective in gap junctional intercellular communication (GJIC). Connexin43 (Cx43) mRNA, which is expressed in normal human lung cells, is undetectable in these tumor cells. To explore if up-regulation of Cx43 gene expression will suppress malignancy of PG cells, Cx43 cDNA was co-transfected with pSV2neo cDNA into PG cells. Control cells were transfected with the blank vector plus neo cDNA. Several stable Cx43 transfectant clones, which acquired high levels of Cx43 expression and the capacity of GJIC, were compared with control clones and the parental cell line, both of which lacked Cx43 expression and GJIC. The control clones resembled the parental cells in exhibiting high cell growth rate, weak attachment to the substratum and a high frequency of colony formation in soft agar. In contrast to the control cells, Cx43 transfected clones showed reduced growth rate, enhanced attachment to the substratum and inhibition of colony formation in soft agar. In vivo results from nude mice experiments showed high tumorigenicity with control clones and inhibition of tumorigenicity in Cx43 transfected clones. The consistency between in vitro and in vivo results strongly suggests a tumor suppressing effect of the Cx43 gene in human lung carcinoma cells.      

反义及显性负调节 AKT2 RNA对脑胶质瘤细胞增殖抑制作用的体外研究

背景与目的:表皮生长因子受体(epidermal growth factor receptor,EGFR)下游的丝苏氨酸激酶2(serine/threoninE-kinase-2,AKT2)信号转导通路对肿瘤细胞的生存和凋亡具有十分重要的作用.本文研究了反义AKT2(antisensE-AKT2,AS-AKT2)和显性负调节AKT2(dominant negative AKT2,DN-AKT2)构建体对人脑胶质瘤细胞系TJ905的增殖和凋亡的调控作用.方法:脂质体介导AKT2构建体转染人脑胶质瘤细胞系TJ905,原位杂交和蛋白印迹法检查AKT2的表达水平,Ki-67标记指数和 MTT法检测细胞增殖能力,TUNEL法计算凋亡指数评价肿瘤细胞凋亡的变化.结果:对每种 AKT2构建体转染后随机选择3个扩增后进一步分析.原位杂交和蛋白印迹结果表明,转染AS-AKT2后AKT2表达显著抑制,转染DN-AKT2后AKT2表达无明显变化.MTT研究发现:AS-AKT2组和DN-AKT2组的6天细胞生存率分别为(49.30～ 51.46)％和(50.52～55.23)％,细胞存活率显著低于对照组和空载体组( P<0.001);AS-AKT2组和DN-AKT2组的标记指数(Ki-67 labeling index,Ki- 67 LI)分别为(57.50～59.33)％和(59.17～61.00)％,明显低于对照组(76.50％)和空载体组(74.83％)(P<0.001);TUNEL法凋亡分析表明:对照组和空载体组几乎没有凋亡细胞,AS-AKT2组(8.33％～8.83％)和DN-AKT2组( 7.50％～7.83％)的凋亡指数显著增加(P<0.001).结论:AKT2通路可以对胶质瘤细胞的增殖和凋亡发挥重要的调控作用.     

缝隙连接通讯抑制剂对Cx43cDNA转染后化疗旁观者效应的影响

背景与目的:有研究通过转染Cx43cDNA观察到C6细胞化疗过程中存在旁观者效应,并推测缝隙连接细胞间通讯可能为化疗旁观者效应机制之一,本研究旨在探讨脑胶质瘤化疗旁观者效应与缝隙连接细胞间通讯功能的关系。方法:(1)质粒扩增,提取纯化及酶切鉴定:氯化钙法将质粒转入JM109菌株扩增,提取纯化后酶切鉴定;(2)基因转染:LipofectAMINE2000介导C6细胞质粒DNA转染,G418筛选,半定量RT-PCR及划痕荷载染料传输实验(SLDT)鉴定。(3)将转染后细胞分为实验组和对照组:将VM-26处理细胞与VM-26未处理细胞按不同比例在无VM-26环境混合培养,培养液中加入缝隙连接细胞间通讯功能抑制剂18α-次甘草酸(AGA)为实验组,不加AGA为对照组,以MTT法及流式细胞仪技术观察AGA对Cx43cDNA转染后化疗旁观者效应的影响。结果:(1)获得转染了相应质粒的细胞株C6-Cx43及C6-Non;(2)C6-Cx43细胞Cx43mRNA表达显著增加,染料传输能力较C6-Non明显增强;(3)C6胶质细胞缝隙连接细胞间通讯功能低下;(4)当转染Cx43cDNA,明显上调C6细胞缝隙连接细胞间通讯功能后...     

Restoration of gap-junctional intercellular communication in a communication-deficient rat liver cell mutant by transfection with connexin 43 cDNA

To study the biochemical basis of gap-junctional intercellular communication (GJIC) and its role in tumorigenesis, a mammalian cell expression vector carrying both a rat connexin 43 (Cx43) cDNA and an amplifiable dihydrofolate reductase (DHFR) gene was transfected into the GJIC-deficient rat liver mutant cell line aB1. Two stable transfectants were selected for further amplification of the transfected Cx43 gene by increasing stepwise the concentration of methotrexate (MTX) in the culture medium. The results indicate that GJIC was restored in these two Cx43 cDNA transfectants after they became highly resistant to MTX but not in the control-vector transfectants, in which the DHFR gene was similarly amplified. The amount of Cx43 DNA revealed by Southern blot analysis and the expression of Cx43 gene revealed by northern and western blot analyses were concomitantly increased in the Cx43 cDNA transfectants resistant to high concentrations of MTX. Western blot analysis, using an antipeptide antibody that specifically recognizes Cx43 protein, further revealed that an approximately 46-kDa phosphorylated Cx43 protein that was prominent in the parental GJIC-competent cells was absent in the aB1 cells. This Cx43 protein, however, reappeared in the two Cx43 cDNA transfectants after amplification. After treatment of the membrane proteins with alkaline phosphatase in vitro, the approximately 46- and 44-kDa proteins disappeared, whereas the approximately 42-kDa proteins remained with increasing intensity, indicating that the higher molecular-weight proteins were the phosphorylated Cx43. These results indicate that a defect in posttranslational phosphorylation of Cx43 protein associated with low expression of the Cx43 gene might be responsible for the GJIC deficiency in aB1 cells and that increased expression of Cx43 by gene amplification might restore this phosphorylated Cx43 protein and so reestablish GJIC. © 1993 Wiley-Liss, Inc.