PCNA反义脱氧寡核苷酸体外抑制BT325细胞增殖的实验研究

目的 观察增殖细胞核抗原(PCNA)基因反义脱氧寡核苷酸对人多形性胶质母细胞瘤细胞增殖的影响。方法 采用人工合成的PCNA反义和正义脱氧寡核苷酸经阳离子脂质体包裹后转染人多形性胶质母细胞瘤细胞BT325。用MTT比色法检测转染后瘤细胞的生长抑制率;~3H-TdR法检测细胞DNA合成速率;流式细胞仪检测细胞周期分布;RT-PCR检测PCNA mRNA表达;免疫组化方法检测PCNA蛋白表达水平。结果 PCNA反义寡核苷酸可明显抑制BT325细胞的生长;明显减慢其DNA合成速率,阻滞细胞由GO/G1期→S期,PCNA mRNA及其蛋白质表达也同时受到抑制。抑制效应在转染后12h即出现,24h达到高峰,48h后逐渐减弱。抑制作用随反义寡核苷酸浓度的升高而增强,0.8μM PCNA反义寡核苷酸的细胞生长抑制率达84.6％。同样浓度的正义寡核苷酸和脂质体则无明显的细胞生长抑制作用。结论 PCNA反义寡核苷酸在体外能明显抑制人脑多形性胶质母细胞瘤细胞BT325生长、DNA合成、mRNA和PCNA蛋白表达。PCNA基因可望成为胶质瘤基因治疗的新靶点。     

锌指蛋白A20 RNAi载体的构建及筛选

目的我们前期的实验结果显示A20 mRNA和蛋白在人脑胶质瘤组织及细胞系（U251、U87、BT325）中高表达，本研究拟构建A20RNAi载体，并检测其对U251细胞A20表达的抑制作用。方法构建三种针对人A20基因的真核干涉表达载体，以脂质体法将其分别转染人脑胶质瘤细胞系U251，以RT-PCR、蛋白印迹法检测各干涉载体对U251细胞中A20mRNA和蛋白表达的抑制作用。结果成功构建三种针对A20基因的RNAi载体，经RT-PCR、蛋白印迹检测筛选出对A20基因干涉效果最佳的载体，命名为pSilencer3．1-A20R1。结论成功构建A20基因干涉载体，为进一步探讨A20与脑胶质瘤恶性增殖、血管形成以及抗凋亡的关系奠定实验基础。     

应用差异显示技术克隆胶质瘤细胞诱导分化相关基因

目的 克隆胶质瘤细胞诱导分化相关新基因。方法 应用RNA随机引物差异显示，SSCP纯化，PCR产物快速克隆，反Northern杂交及生物信息学分析等方法，观察人脑胶质瘤细胞株SHG－44－9分化过程中的基因表达变化。结果 克隆了诱导分化前后表达差异显著的15个基因，其中诱导后下调基因4个，上调基因11个。同源性分析表明，5个是已知基因，10个是未知基因。诱导后上调的DIG－1基因与c-myc内含子结合蛋白1（MIBP1）基因高度同源，此基因具有转录因子活性，表达的蛋白可抑制c-myc基因的表达。结论 克隆了15个人脑胶质瘤细胞诱导分化相关基因，其中控制c-myc基因表达的MIBP1基因诱导分化后上调提示，它可能是调控胶质瘤细胞分化基因，值得进一步研究。     

siMDR1基因转染人类BT325胶质瘤细胞系的表达

目的探讨siMDR1基因转染人类胶质母细胞瘤细胞BT325后细胞的表达能力。方法设计并合成siRNA质粒,取培养对数期生长良好的胶质母细胞系BT325,传代培养。将阳离子脂质体(Lipofectamine 2000)和质粒MDR1 DNA按比例共转染。瞬时对转染成功的细胞系应用抗性药物-嘌呤霉素进行筛选,筛出稳定的细胞系后,分别在荧光显微镜下分析转染情况。通过免疫细胞化学染色及图像分析对瞬时转染和稳定转染的BT325细胞进行检测,确定MDR1基因产物P-糖蛋白(P-gp)表达水平。阿霉素对瞬时转染及稳定转染的BT325耐药性进行分析。结果成功构建了逆转录病毒si RNA质粒载体,经过瞬时转染BT325细胞生长状态良好,48h表达绿色荧光最强。加入嘌呤霉素筛选后,在第8天出现单细胞克隆。免疫细胞化学染色证实瞬时转染与稳定转染BT325细胞P-gp的表达下降。细胞的转染效率为70%～80%。BT325细胞经过RNA干扰,细胞对MDR1耐药性明显下降,IC_(50)降低,细胞的耐药因子(RF)有所升高。结论siMDR1基因瞬时转染和稳定转染都可以抑制P-gp蛋白的表达,其可以作为基因治疗的重要手段。     

尿激酶型纤维蛋白酶原激活物受体的反义基因片断抑制胶质瘤u25i细胞的体外侵袭

目的：研究尿激酶型纤维蛋白酶原激活物受体（uPAR）的反义基因片断对胶质瘤细胞株u251体外侵袭能力的影响。方法：脂质体介导寡核苷酸转染培养的u251胶质瘤细胞，用RT—PCR、原位杂交和免疫组化方法分别检测相关基因和蛋白的表达，Boyden小室模型研究对肿瘤细胞侵袭能力的影响。结果：uPAR反义寡核苷酸作用u251胶质瘤细胞后相关基因的mRNA及蛋白的表达明显减弱，细胞的体外侵袭能力被明显抑制。结论：uPAR的反义寡核苷酸片断能有效地抑制胶质瘤细胞u251相关基因的表达，并能抑制胶质瘤细胞的体外侵袭能力。     

Flt-1基因对BT325细胞VEGF蛋白表达及细胞增殖的影响

目的 探讨Flt-1基因对BT325胶质瘤细胞VEGF蛋白表达及细胞增殖的影响.方法 从人脐静脉内皮细胞中提取总RNA,逆转录聚合酶链式反应(RT-PCR)扩增Flt-1基因片段,基因重组技术将Flt-1基因片段插入真核表达载体pEGFP-C1中,双酶切及DNA测序鉴定pEGFP-C1-Flt-1重组质粒.pEGFP-C1-Flt-1重组质粒转染BT325胶质瘤细胞,转染后72hELISA法检测培养上清液中VEGF含量,MTT法检测细胞的增殖情况.结果 RT-PCR方法证实从人脐静脉血内皮细胞中成功获得1 384 bp Flt-1基因片段;经双酶切分析和DNA测序鉴定表明重组质粒pEGFP-C1-Flt-1构建成功;ELISA检测发现,BT325细胞被转染后72 h VEGF含量转染组为(56.3±41.2) pg/ml,空载体转染组为(95.5±35.3) pg/ml(P＜0.05);MTT法检测发现,转染组和空载体转染组的生存率分别为(42.6±3.7)％和(92.8±6.6)％(P＜0.05).结论 Flt-1基因可抑制BT325细胞VEGF的蛋白表达,抑制细胞增殖.     

Livin基因短发卡RNA表达质粒的构建及其对胶质瘤Livin基因表达的影响

目的构建凋亡抑制基因livin基因的特异性短发卡RNA（siRNA）真核表达载体,并观察其在人脑胶质瘤细胞中对livin基因表达的抑制。方法设计有小发夹结构的2条livinβ siRNA对应的DNA序列,将其克隆入pSliencer 3.1质粒,构建重组质粒pSliencer-livinβ,对重组质粒进行酶切分析和DNA序列测定。以脂质体法将pSliencer-livinβ转染人胶质瘤细胞。采用RT-PCR和Western-blot检测Livinβ蛋白的表达,筛选最有效的一组pSliencer-livinβ质粒。结果酶切及测序证实质粒pSliencer-livinβ构建成功。转染后胶质瘤细胞livinβmRNA和蛋白表达均受到明显抑制。结论成功构建livinβ基因的特异性短发卡RNA（siRNA）真核表达载体能够显著抑制人胶质瘤细胞livinβ基因的表达。     

IGF-IR反义寡核苷酸对胶质瘤细胞增殖的影响

目的 根据胰岛素样生长因子-受体（IGF-IR）基因序列设计了IGF-IR mRNA起始密码子下游的硫代磷酸型反义寡核苷酸和正义寡核苷酸，研究其对C6胶质瘤细胞增殖作用。方法 实验分为反义核酸组、正义核酸组和空白对照组，经细胞计数、MTT法研究反义核苷酸对胶质瘤细胞生长和增殖的抑制作用。并应用免疫细胞化学方法检测胶质瘤细胞IGF-IR和增殖细胞核抗原（PCNA）蛋白的表达。结果 反义寡核苷酸能有效地降低IGF-IR基因的表达，抑制体外培养的胶质瘤细胞的增殖，其抑制作用24h显效，96h仍有作用，反义寡核苷酸的抑制效果与其作用浓度有关。而正义寡核苷酸对其无抑制作用。同时可见反义寡核苷酸抑制增殖作用中，能明显下调PCNA蛋白的表达。结论 IGF-IR介导的IGF-I-IGF-IR的自（旁）分泌环对胶质瘤生长极其重要，通过IGF-IR反义寡核苷酸治疗能较有效地抑制胶质瘤细胞的增殖。     

Lentivirus介导RNAi抑制人胶质瘤干细胞STAT3基因生物学效应观察

目的了解慢病毒载体对胶质瘤干细胞的亲嗜性及对靶基因表达的干扰效率，初步探索干扰STAT3基因对胶质瘤干细胞增殖的影响。方法构建STAT3基因shRNA的慢病毒表达载体，经293T细胞包装后，获得可表达STAT3基因shRNA的慢病毒颗粒；活性载体病毒感染人原代胶质瘤干细胞后流式细胞分析细胞感染效率；实时定量多聚酶链反应（PCR）和Westernblot检测细胞STAT3基因mRNA和蛋白表达及活化水平；增殖分析试剂盒测定细胞生长曲线，流式细胞分析细胞周期分布。结果在病毒感染比率值20：1时慢病毒载体对人原代胶质瘤干细胞的感染效率为98．6％；细胞感染可表达STAT3基因shRNA的载体慢病毒后，STAT3基因mRNA显著下降，抑制率为84．3％，STAT3蛋白表达下降81．5％，活化的pSTAT3下降97．9％；胶质瘤干细胞STAT3表达、活化受抑后细胞生长显著变慢，G1期细胞比例显著增高。结论慢病毒载体对人原代胶质瘤干细胞有着很高的感染效率，介导的RNAi可显著抑制靶基因的表达与活化，是对人胶质瘤干细胞基因功能研究的理想工具。人胶质瘤干细胞STAT3基因受抑后细胞生长显著变慢，出现G1期阻滞。     

ATRA诱导胶质瘤C6细胞凋亡过程中Bcl-2和Caspase-3表达的研究

目的研究全反式维甲酸（ATRA）诱导胶质瘤C6细胞凋亡过程中Caspase-3和Bcl-2表达情况,探讨ATRA诱导胶质瘤C6细胞凋亡的机制。方法用四甲基偶氮唑蓝（MTT）比色法绘制ATRA不同浓度不同时间（6、12、24、48、72h）对胶质瘤C6细胞作用后细胞生长曲线,逆转录酶-多聚酶链反应（RT—PCR）检测凋亡相关基因Bcl-2和Caspase-3 mRNA水平的表达变化影响,Western blot分析Caspased和Bcl-2在胶质瘤C6细胞中的表达情况。结果胶质瘤C6细胞经ATRA诱导后,细胞的增殖明显受到抑制,通过RT-PCR结果证实Bcl-2 mRNA在ATRA作用下明显呈低表达而Caspase-3 mRNA的表达随时间延长逐渐增高,Western blot检测结果显示ATRA作用后,下调凋亡抑制蛋白Bcl-2的表达并激活了凋亡蛋白Caspase-3的表达。结论ATRA对胶质瘤C6细胞的增殖具有抑制作用。     

End-plate growth exceeds nerve terminal growth in juvenile mice

An electron microscopic investigation of neuromuscular synapses of the tensor fasciae latae muscle in juvenile mice was carried out to determine the relationship between the presynaptic (nerve terminal) and postsynaptic (end-plate plaque) elements during the major phase of postnatal growth. In the first month of life growth of the synapse was accompanied by a decrease in the size of pre- and postsynaptic elements in cross section. A decrease in the fraction of the width of end-plate plaque opposed by nerve terminal was also observed to age 2 months, and in older animal some end-plate plaques were completely unopposed by nerve terminal. This implies that end plates grow at a faster rate than nerve terminals and suggests that the availability of uninnervated, differentiated end plate permits or promotes nerve terminal growth.     

Characteristics of the nerve growth factor receptors and a nerve growth factor receptor--nerve growth factor covalent complex

Nerve growth factor is a polypeptide hormone that is required for the normal growth and development of the embryonic sensory and sympathetic nervous systems. On these cells, there are two different receptors for the nerve growth factor. Recently, these receptors have been isolated from three cell types and shown to have essentially the same binding characteristics. Molecular weights for receptors from two of these cell types, embryonic sensory and rat pheochromocytoma cells, have been determined. In addition, the formation of a covalent nerve growth factor, nerve growth factor receptor complex, has been investigated on embryonic sensory and sympathetic neurons. The formation of this covalent complex containing 125I-beta nerve growth factor is prevented by the addition of excess unlabeled nerve growth factor or by the addition of sodium fluoride and dinitrophenol. This complex forms at 4 degrees, 22 degrees, and 37 degrees, indicating that it is occurring on the cell surface. A disulfide bond is involved in the formation of this covalent complex.     

Central opiate modulation of growth hormone and insulin-like growth factor-I

The effects of central administration of morphine-sulfate (MOR:80 μg) and morphine-6-glucuronide (M6G:1 μg) on the growth hormone (GH)/insulin-like growth factor (IGF) system were assessed. MOR and M6G were injected intracerebroventricularly (ICV) in chronically catheterized 24 h fasted rats; time-matched control animals received H₂O (5 μl). MOR increased plasma GH concentrations 3-fold 2 h after ICV injection, and transiently increased the plasma concentration and liver content of IGF-I (60% and 90%, respectively) 30 min after ICV injection. M6G did not produce any significant alterations in plasma GH and IGF-I levels at the time-points measured. Both MOR and M6G increased the concentration of IGF binding protein-1 (IGFBP-1) in plasma and liver 2 h after injection. However, MOR showed 2- to 2.5-fold greater effect than M6G in stimulating plasma and liver IGFBP-1. MOR and M6G produced similar increases in plasma epinephrine (5-fold), norepinephrine (3-fold) and corticosterone (1.5-fold). Neither opiate significantly altered circulating insulin levels. These findings suggest that opiate modulation of GH and IGF may be hormone-independent and centrally modulated. We speculate that differential affinities of MOR and M6G to the different opiate receptor subtypes might be responsible for their distinct effects on GH/IGF-I system.     

胰岛素样生长因子1和成纤维细胞生长因子7与毛乳头细胞的生长*

背景：毛乳头细胞凝集性生长与其诱导毛发生长有关。毛乳头细胞分泌的多种生长因子如胰岛素样生长因子1、成纤维细胞生长因子7可能对毛乳头细胞生长具有重要的影响。 目的：观察正常人毛乳头细胞的增长与生长方式与胰岛素样生长因子1、成纤维细胞生长因子7的相关性。 方法：采用二步酶消化法分离培养毛乳头细胞,免疫组化法和流式细胞仪分别检测两种生长因子在凝集性与非凝集性生长的毛乳头细胞中的表达,MTT法检测2.5~100 μg/L质量浓度胰岛素样生长因子1对人毛乳头细胞增殖的影响。 结果与结论：胰岛素样生长因子1与成纤维细胞生长因子7均表达于细胞胞浆,但表达量随时间减弱,其中第3代明显比第9代毛乳头细胞中成纤维细胞生长因子7的表达强烈(P < 0.05)。与对照组相比,不同质量浓度胰岛素样生长因子1均有明显促进毛乳头细胞增殖的作用(P < 0.05),其中以2.5 μg/L最为显著。提示毛乳头细胞的凝集性生长状态的改变可能与胰岛素样生长因子1、成纤维细胞生长因子7表达下降有关,胰岛素样生长因子1可明显刺激毛乳头细胞增殖。     

Substrate-bound nerve growth factor promotes neurite growth in peripheral nerve

Nerve growth factor (NGF), in addition to its well-known effects as a soluble neurite growth-promoting factor, also appears to promote the elongation of neurites when it is adsorbed to tissue culture substrates. Peripheral nerve Schwann cells appear to possess a receptor for NGF on their surfaces which is induced substantially after axotomy. We have found that the adsorption of NGF onto cryostat sections of the distal stump of previously severed sciatic nerve enhances neurite growth over this tissue. This finding, coupled with the two previous observations, suggests that Schwann cell surface NGF receptors serve to bind to NGF-like growth factors so as to provide favorable surfaces for regenerating peripheral nerve axons.     

Insulin-like growth factor 1 is essential for normal dendritic growth

This study evaluated somatic and dendritic growth of neurons in the frontoparietal cortex of Igf1-/- brains. Pyramidal neuron density was increased by approximately 25% (P =.005) and soma size reduced by approximately 10% (P <.001). Golgi staining revealed that cortical layer II-III neurons exhibited a significant reduction in dendritic length and complexity in Igf1 null mice. Dendritic spine density and presumably synaptic contacts were reduced by 16% (P =.002). Similar findings were obtained for cortical layer V and piriform cortex pyramids. Supporting a reduction in synapses, synaptotagmin levels were reduced by 30% (P <.02) in the Igf1 null brain. Investigation of factors critically involved in dendritic growth and synaptogenesis showed an approximately 50% reduction in cortical CDC42 protein expression (P <.001) and an approximately 10% reduction in brain cholesterol levels (P <.01) in Igf1 null mice. Evidence is presented that Igf1 deletion causes disruptions in lipid and microtubule metabolism, leading to impaired neuronal somatic and dendritic growth. Published 2003 Wiley-Liss, Inc.     

Methylphenidate-related growth impairment

Growth deficit associated with stimulants in children who have attention deficit hyperactivity disorder (ADHD) has long been the subject of scientific discussion. More recent studies describe the effects on the final height of children with ADHD who are treated with methylphenidate (MPH) as only slight. There are only a handful of reports of severe growth deficits attributed to MPH that are associated with gastrointestinal side effects. We describe a 10-year-old boy with ADHD and chronic asthma who underwent corticosteroid therapy and developed an almost complete growth arrest during MPH treatment. Growth hormone (GH) stimulation tests and measurement of GH-dependent growth factors point to the influence of MPH on GH secretion with subsequent impaired growth. One may conclude that some children are at risk of serious growth decrement when treated with MPH. The growth of children should thus be monitored carefully, even if there are no alarming gastrointestinal side effects from MPH. We found that the determination of growth velocity was a sensitive marker for the evaluation of growth impairment in our patient.     

Neural growth hormone

It is now well established that growth hormone (GH) gene expression is not restricted to the pituitary gland and occurs in many extrapituitary tissues, including the central and peripheral nervous systems. Indeed, GH gene expression occurs in the brain prior to its ontogenic appearance in the pituitary gland, and GH may have evolved phylogenetically as a neuropeptide, rather than as an endocrine. Recent studies on the regulation and roles of neural GH in health and disease are the focus of this brief review.