Regulation of hypoxia-inducible factor-1alpha,vascular endothelial growth factor,and angiogenesis by an insulin-like growth factor-I receptor autocrine loop in human pancreatic cancer

Activation of the insulin-like growth factor-I receptor (IGF-IR) was recently shown to modulate angiogenesis by up-regulating the expression of vascular endothelial growth factor (VEGF). We hypothesized that inhibiting IGF-IR function would inhibit angiogenesis and growth of pancreatic cancer in vivo and sought to identify major signaling pathways regulated by IGF-IR in pancreatic cancer cells. Human pancreatic cancer cells (L3.6pl) were stably transfected with a dominant-negative form of IGF-IR (IGF-IR DN) or an empty vector (pcDNA). In vitro, IGF-IR DN cells exhibited a decrease in both constitutive and inducible phosphorylation of IGF-IR and Erk1/2. Constitutive expression of nuclear hypoxia-inducible factor-1alpha and secreted VEGF (P < 0.01) protein levels also were significantly lower in IGF-IR DN cells than in pcDNA cells. In vivo, IGF-IR inhibition led to decreases in pancreatic tumor volume and weight, vessel density, and tumor cell proliferation (P < 0.01 for all) and increases in tumor cell apoptosis (P < 0.02). Our results suggest that autocrine activation of the IGF-IR system significantly affects VEGF expression and angiogenesis in human pancreatic cancer. Thus, IGF-IR may be a valid target in the treatment of pancreatic cancer.     

VEGF165反义RNA对人食管鳞癌细胞影响的实验研究

目的 :观察血管内皮生长因子16 5 (VEGF16 5 )反义RNA对人食管鳞癌细胞EC10 9的影响 ,探讨其治疗食管癌的可行性。方法 :采用亚克隆技术 ,构建并鉴定VEGF16 5 反义RNA的真核表达载体。以重组质粒转染人食管鳞癌细胞EC10 9后 ,将其接种于裸鼠皮下 ,分别利用原位杂交、激光共聚焦、图象分析及微血管计数等方法 ,观察转染前后EC10 9细胞的生物学性状和致瘤性。结果 :成功地构建了VEGF16 5 反义RNA的真核表达载体 ,并在EC10 9细胞中获得表达。转染细胞中VEGF16 5 的表达下降 75% ,其生物学性状不受外源基因表达的影响 ,但其在裸鼠皮下的致瘤性和和瘤组织中血管的生成明显下降。VEGF16 5 反义RNA转染组、空载体转染组和对照组中肿瘤的体积 ,分别为 (82 0± 112 .5)mm3 、(793 0± 10 3 5)mm3 和 (7850± 950 )mm3(P <0 .0 1) ;微血管的密度分别为 (8.5± 1.2 ) /mm2 、(44.3± 9.4) /mm2 和 (46.4± 12 .6) /mm2 (P <0 .0 1)。结论 :VEGF16 5反义RNA能够明显减少食管鳞癌细胞内VEGF16 5 的表达 ,具有抑制肿瘤生长和血管生成的作用 ,可望用于实体肿瘤的辅助治疗。     

骨髓间充质干细胞中突变型人低氧诱导因子1α真核表达载体的表达

背景：转基因小鼠体内实验证实,重组的低氧诱导因子1α可以促进皮肤形态功能正常的血管新生。 目的：构建能够在常氧条件下同时表达突变型低氧诱导因子1α目的蛋白和绿色荧光蛋白报告分子的新型腺病毒真核表达载体,并转染SD大鼠骨髓间充质干细胞,检测该基因在细胞中的表达情况。 方法：利用Lipofectamine 2000介导将构建成功的重组腺病毒真核表达载体pAd-HIF1αmu- IRES-hrGFP-1转染HEK293A细胞,包装病毒,以最佳感染指数=50将重组腺病毒转染大鼠骨髓间充质干细胞,并设3个对照组,即阳性对照组：转染Ad-CMV-HIF1α-IRES-hrGFP-1;阴性对照组：转染Ad-CMV-IRES-hrGFP-1组;空白组：未转染病毒。 结果与结论：①腺病毒载体成功转染HEK293A细胞,包装成功,细胞内有大量绿色荧光表达。②转染突变型低氧诱导因子1α腺病毒表达载体的细胞在常氧条件下蛋白表达量明显高于转其他3组,3个对照组间差异无显著性意义(P > 0.05)。提示突变型腺病毒真核表达载体Ad-HIF1α-IRES-hrGFP-1在HEK293A内成功包装;突变后低氧诱导因子1α基因能够在常氧条件下大量且高效表达。     

COX-2/VEGF-dependent facilitation of tumor-associated angiogenesis and tumor growth in vivo

Nonsteroidal anti-inflammatory drugs are known to suppress the occurrence and progression of malignancies such as colorectal cancers. However, the precise mechanism of these actions remains unknown. We have evaluated the role of an inducible cyclo-oxygenase (COX-2) in tumor-associated angiogenesis and tumor growth, and identified the downstream molecules involved using a ddy mouse model of sponge angiogenesis, which mimics tumor angiogenesis and is COX-2 and vascular endothelial growth factor (VEGF) dependent. In this model, VEGF expression was down-regulated by selective COX-2 inhibition with NS-398. To find out the involvement of COX-2/VEGF pathway in tumor-associated angiogenesis, we estimated angiogenesis occurring around implanted Millipore chambers containing sarcoma-180 (S-180) cells or Lewis lung carcinoma cells. Daily oral administration of NS-398 or of aspirin, a nonselective COX inhibitor, suppressed angiogenesis seen around the Millipore chambers. S-180 cells implanted in ddy mice formed substantial tumors with extensive angiogenesis markedly suppressed by aspirin and COX-2 inhibitors NS-398 and JTE522, but not by mofezolac, an inhibitor of constitutive COX-1. Tumor-associated angiogenesis was also significantly suppressed by a neutralizing antibody against VEGF. S-180 tumor growth in the subcutaneous tissues was also suppressed by aspirin, COX-2 selective inhibitors, and the VEGF antibody, but not by the COX-1 inhibitor. These results demonstrate that the inhibition of the COX-2/VEGF-dependent pathway was effective in tumor-associated angiogenesis, tumor growth, and tumor metastasis.     

逆转录病毒的高效包装及转基因鸡技术平台的建立

转基因鸡及输卵管生物反应器正日益成为生物领域研究的热点之一,当前研究转基因鸡最成功的方法即为逆转录病毒介导法,但目前国内尚无系统报道逆转录病毒法制备转基因鸡的平台技术。为加快国内这一领域的研究步伐,本文较详尽的介绍了从逆转录病毒包装、竞争法包装泛嗜性VSV-G病毒、病毒包装条件的优化、病毒的浓缩、辅助病毒检测、鸡胚盘下腔注射等方法技术,并分别在体外鸡胚胎原代成肌细胞(CFM)和体内鸡胚中检测目的标记基因GFP的病毒感染整合效率,为今后转基因鸡的研究提供了一个实用的技术平台。     

In vitro and in vivo study of the expression vector encoding vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) is an angiogenic cytokine with potential therapeutic applications in human diseases. It is a mitogen primarily for endothelial cells. The transfer of the cDNA encoding VEGF to ischemic tissues, which cannot be revascularized otherwise, represents a novel and promising approach to the treatment of vascular disorders. In this work the VEGF165 cDNA was cloned into the expression vector pSecTag2B. The activity of the construct was studied in cell culture as well as in vivo. Western blotting study showed that the cells transfected with the vector secreted significantly higher amounts of VEGF to the culture medium than the non-transfected cells. In vivo study revealed an increased number of new vessels in animals injected with vector encoding VEGF as compared with empty plasmid. Also, tumor cells transfected with the VEGF plasmid exhibited extensive vascularization.     

反义VEGF165基因转染对人神经母细胞瘤生物学行为的影响

目的探讨反义VEGF165基因转染在抑制肿瘤血管生成和肿瘤生长中的作用。方法构建正义和反义VEGF165真核表达载体,用脂质体转染人神经母细胞瘤细胞SH-SY5Y,G418筛选稳定表达细胞克隆。应用RT-PCR证实外源性反义VEGF mRNA的表达,免疫细胞化学和EUSA检测VEGF蛋白的表达水平,MTT法检测肿瘤细胞体外生长情况,并接种于裸鼠皮下,观察体内肿瘤增殖能力。结果RT-PCR证实转染反义VEGF的细胞中有外源性反义VEGF mRNA的表达,免疫细胞化学和EUSA显示VEGF蛋白表达明显降低,MTT实验显示转染前后细胞体外生长速度基本一致。而转染反义VEGF的肿瘤细胞裸鼠体内生长速度明显减慢。结论反义VEGF基因转染能够有效抑制SH-SY5Y细胞内源性VEGF蛋白的表达,抑制裸鼠体内肿瘤的生长。     

Expression of vascular endothelial growth factor induces an invasive phenotype in human squamous cell carcinomas

Inhibition of the vascular endothelial growth factor (VEGF) receptor Flk-1 has been shown to prevent invasion of experimental squamous cell carcinomas (SCC). To directly investigate the role of VEGF in tumor invasion, we stably transfected human SCC-13 cells, which are characterized by a noninvasive phenotype in vivo, with expression vectors containing murine VEGF(164) in sense (SCC/VEGF+) or antisense (SCC/VEGF-) orientation or with vector alone (SCC/vec). SCC/vec cells formed slowly growing, well-differentiated tumors with well-defined borders between tumor and stroma, after intradermal or subcutaneous injection. In contrast, SCC/VEGF+ tumors were characterized by rapid tumor growth, with small cell groups and single cells invading into the surrounding tissue, and by admixture of blood vessels and tumor cells in areas of tumor invasion. We detected an increase in tumor vessel density and size in VEGF-overexpressing tumors, resulting in a more than fourfold increase in total vascular areas. In contrast, SCC/VEGF- clones formed noninvasive, sharply circumscribed tumors with reduced vascular density. These findings demonstrate that selective VEGF overexpression was sufficient to induce tumor invasiveness, and they provide further evidence for an active role of the tumor stroma in cancer progression.     

RNAi沉默Cripto基因对结肠癌细胞血管内皮生长因子的抑制

目的：研究Cripto基因对结肠癌细胞血管内皮生长因子的影响。方法:设计合成针对Cripto基因的小干扰RNA(small interfering RNA，siRNA)，转染结肠癌LS-174T细胞。细胞分4组：空载对照组（对照组）和不同浓度（3.125、6.25和12.5 nmol/L）的siRNA组。分别于转染24、48、72 h后收集细胞，以实时定量PCR检测结肠癌细胞Cripto mRNA，分别采用Northern blotting和免疫荧光标记法检测癌细胞VEGF mRNA和蛋白表达。分别收集转染72 h的12.5 nmol/L组和对照组细胞，接种于裸鼠背部。30 d后处死裸鼠，收集裸鼠肿瘤组织，对组织VEGF进行免疫组化染色，计算染色平均强度。结果:实时定量PCR检测显示，转染组Cripto mRNA被有效地抑制，且呈浓度和时间依赖性。转染组细胞VEGF 蛋白和mRNA明显低于对照组。裸鼠肿瘤免疫组化分析显示，转染组VEGF平均染色强度明显低于对照组。结论:Cripto基因参与了结肠癌组织血管生成的调控。采用siRNA下调Cripto基因表达，可抑制结肠癌组织血管生成。     

DNA修复蛋白MGMT基因的克隆及转导脐血CD23^＋细胞后耐药特征的研究

目的：增强脐血ＣＤ３４＾＋造血细胞对化疗药物的耐药表型,探讨逆转录病毒介导的基因转移效率和耐药基因特性,以及在脐血造血干细胞保护性基因治疗中的作用和意义。方法：应用逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）从人肝细胞中获得编码六氧甲基鸟嘌呤－ＤＮＡ－甲基转移酶（Ｏ＾６－ｍｅｔｈｙｌｇｕａｎｉｎｅ－ＤＮＡ－ｍｅｔｈｙｌｔｒａｎｓｆｅｒａｓｅ,ＭＧＭＴ）ｃＤＮＡ;利用基因重组技术,将其克隆于ｐＧＥＭ－Ｔ质粒载体并构建了逆转录病毒载体Ｇ１Ｎａ－ＭＧＭＴ;应用脂质体ＬｉｐｏｆｅｃｔＡＭＩＮＥ基因转移法将后者导入ＧＰ＋Ｅ８６和ＰＡ３１７病毒包装细胞,以卡氮芥１,３－Ｂｉｓ（２－Ｃｈｌｏｒｏｅｔｈｙｌ）－１－Ｎｉｔｒｏｓｏｕｒｅａ（ＢＣＮＵ）加压筛选后的阳性克隆上清经乒乓效应后继而感染脐血ＣＤ３４＾＋细胞。应用ＰＣＲ,Ｓｏｕｔｈ     

EGFL7基因沉默对裸鼠乳腺癌血管生成的影响

目的探讨类表皮生长因子域7（EGFL7）基因沉默对乳腺癌裸鼠模型瘤内血管生成的影响。方法构建EGFL7短发夹状RNA表达质粒并转染SGC-7901细胞（pshEGFL7组）,以空质粒转染为对照组。观察两组皮下种植瘤生长曲线及体积。免疫组织化学法检测抗-CD34、血管内皮生长因子（VEGF）、血小板反应蛋白（TSP1）表达;RT—PCR检测MMP-2和TIMP2表达。结果pshEGFL7组种植瘤体积为（1．86±0．65）cm^3,微血管密度（MVD）为20．84±6．38,分级为1～2级,对照组体积为（4．86±1．15）cm^3,MVD为39．48±9．01,分级为3～4级,两组种植瘤体积、MVD和分级的差异有统计学意义,P值均〈0．05。EGFL7组TSP1蛋白阳性表达,而VEGF蛋白为弱阳性或阴性表达,MMP-2mRNA表达下调,TIMP2mRNA表达上调,与对照组比较差异有统计学意义,P值均〈0．01。结论EGFL7基因沉默可降低乳腺痛种植瘤血管牛成．与调节MMP-2／TIMP2表汰和影响VEGF/TSP1平衡有关。     

Regulation of angiogenesis in vivo by ligation of integrin alpha5beta1 with the central cell-binding domain of fibronectin

Angiogenesis depends on the cooperation of growth factors and cell adhesion events. Although alphav integrins have been shown to play critical roles in angiogenesis, recent studies in alphav-null mice suggest that other adhesion receptors and their ligands also regulate this process. Evidence is now provided that the integrin alpha5beta1 and its ligand fibronectin are coordinately up-regulated on blood vessels in human tumor biopsies and play critical roles in angiogenesis, resulting in tumor growth in vivo. Angiogenesis induced by multiple growth factors in chick embryos was blocked by monoclonal antibodies to the cell-binding domain of fibronectin. Furthermore, application of fibronectin or a proteolytic fragment of fibronectin containing the central cell-binding domain to the chick chorioallantoic membrane enhanced angiogenesis in an integrin alpha5beta1-dependent manner. Importantly, antibody, peptide, and novel nonpeptide antagonists of integrin alpha5beta1 blocked angiogenesis induced by several growth factors but had little effect on angiogenesis induced by vascular endothelial growth factor (VEGF) in both chick embryo and murine models. In fact, these alpha5beta1 antagonists inhibited tumor angiogenesis, thereby causing regression of human tumors in animal models. Thus, fibronectin and integrin alpha5beta1, like integrin alphavbeta3, contribute to an angiogenesis pathway that is distinct from VEGF-mediated angiogenesis, yet important for the growth of tumors.     

血管内皮生长因子基因的表达及血管生成作用

构建新的血管内皮生长因子（ＶＥＧＦ）高效真核表达载体ｐｃＤ２／ＶＥＧＦ,体外转染ＶＳＭＣ〈发现其在ＶＳＭＣ中的表达效率较ｐｃＤＮＡ３／ＶＥＧＦ明显增高,体外和体内实验证实ＶＥＧＦ基因具有显著促进血管生成的作用。     

人血管内皮生长因子165基因转染兔骨髓间充质干细胞的蛋白表达

背景：骨髓间充质干细胞是最好的组织工程种子细胞来源,含有血管内皮生长因子165(vascular endothelial growth factor 165,VEGF165)不仅对血管再生和启动成骨修复有重要意义,其持续稳定的释放还能够提高新生骨的矿化程度,增强修复组织的力学性能。 目的：观察hVEGF165基因转染的兔骨髓间充质干细胞分泌血管内皮生长因子的蛋白功能。 方法：体外分离、培养兔骨髓间充质干细胞,纯化并鉴定兔骨髓间充质干细胞;免疫荧光法检测细胞表面标志;传代培养后的骨髓间充质干细胞以pcDNA3.1-VEGF165质粒和脂质体1∶3比例的混合液转染,并分为3组：转染组应用pcDNA3.1-VEGF165转染细胞,空载体转染组应用pcDNA3.1-空载体转染,未转染组不处理。通过ELISA和Western-blot检测转染后细胞中外源性血管内皮生长因子的表达。 结果与结论：转染组与其他两组比较,VEGF165蛋白含量显著增高,差异有显著性意义(P < 0.05),但空载体转染组与未转染组之间差异无显著性意义(P > 0.05),转染组不同时间点之间VEGF165蛋白含量差异均有显著性意义(P< 0.05),hVEGF165基因转染的骨髓间充质干细胞能成功分泌VEGF165蛋白。提示采用基因转染技术可将hVEGF165基因转染到骨髓间充质干细胞中并可有效表达具有生物活性的VEGF165。     

转染PF4 cDNA的GRC-1细胞培养液对于ECV-304细胞生长及VEGF表达的影响

目的：构建真核表达载体pcDNA3-PF4-SS，检测稳定转染后的GRC-1细胞的培养上清对于血管内皮细胞ECV304的生长以及转染细胞中血管内皮生长因子(VEGF)表达的影响。方法：构建真核表达载体pcDNA3-PF4-SS，并经Bgl Ⅱ／Bam HI双酶切鉴定.通过脂质体介导，以该载体稳定转染GRC-1细胞，转染细胞中VEGF因子的表达情况用免疫组化染色法检测，转染细胞的培养上清对于ECV304细胞生长的影响用MTT法检测。结果：经Bgl Ⅱ／BamH I双酶切证实，hPF4 cD—NA已成功地克隆到真核表达载体pcDNA3-CD34-SS中。RT—PCR法检测证实，hPF4 cDNA已成功地转染GRC-1细胞。免疫组化染色检测显示，转染PF4基因的GRC—1细胞的胞浆及胞膜均有VEGF表达，但较转染前明显减弱。细胞计数及MTT法显示，转染后GRC-1细胞的培养上清对ECV304细胞的生长具有抑制作用，吸光度值(A)明显降低。结论：构建了真核表达载体pcDNA3-PF4-SS，并稳定转染GRC-1细胞。转染细胞的培养上清对ECV304细胞的生长及VEGF的表达，均具有明显的抑制作用，为探讨抗肿瘤生长机制和肿瘤疫苗的研制奠定了一定的基础。     

病毒载体致突变性的实验研究

目的 :观察逆转录病毒pLXSN与腺病毒LacZ作为转基因载体所构建的转基因细胞的致突变作用 ,为转基因肿瘤细胞作为瘤苗进行临床提供安全性检测参数。方法 :将病毒与细胞共培养 ,用细胞DNA通过遗传毒理学实验技术进行体内和体外的致变性实验研究。结果 :转基因细胞DNA及培养上清液未显出致突变作用。结论 :经过修饰的病毒作为转基因载体未见其致突变作用     

血管内皮生长因子和E26转录因子在乳腺癌中的表达及意义

目的 试图揭示血管内皮生长因子（VEGF）和E26转录因子（E26 transformation-specificl,ETS-1)在乳腺癌组织中的表达规律,探讨其在血管生成和肿瘤浸润转移中的作用机制。方法 应用原位杂交和免疫组织化学链霉素抗生物系－过氧化物酶复合物法（SP）法,检测48例乳腺癌组织中VEGF和ETS－1的mRNA和蛋白的表达。结果 乳腺癌细胞高表达VEGF mRNA和蛋白,阳性率分别为75％（36／48）,70．8％（34／48）,而血管内皮细胞几乎不表达;ETS－1既表达在乳腺癌细胞,也表达在血管内皮细胞。癌细胞中mRNA和蛋白表达阳性率分别为85．4％（41／48）,79．2％（38／48）;VEGF和ETS－1高表达组的血管密度明显高于低表达组（均P＜0．01）;VEGF和ETS－1的表达与组织学分级和淋巴结转移密切相关,并且高表达组的微血管密度明显高于低表达组（P＜0．01）。结论 VEGF和ETS－1可促进乳腺癌血管形成,同时也促进肿瘤的浸润和转移;检测VEGF和ETS－1的表达可做为乳腺癌恶性度,浸润转移等生物学行为的参考指标。