IL-18基因转染人膀胱癌T-24细胞及其表达的研究

目的 :建立表达IL-18基因的人膀胱癌细胞系IL-18/T-24,探讨外源性IL-18基因对T-24细胞生长及其生物学性状的影响。 方法 :将插入IL-18基因的质粒,应用逆转录病毒载体LXSN感染ψ2(ecotropic)和PA317(amphotropic)两种包装细胞,通过药物G418筛选获得表达IL-18蛋白的PA317阳性细胞克隆,用IL-18/PA317培养上清转染T-24细胞,获得表达IL-18的IL-18/T-24细胞。分别用RT-PCR、ELISA和免疫组化染色分析IL-18/T-24细胞表达IL-18的mRNA和蛋白的水平,筛选出高表达IL-18的IL-18/T-24细胞克隆用于下层研究中;用流式细胞仪检测转染前后细胞的周期变化及细胞凋亡情况;用ELISA法检测IL-18/T-24细胞培养上清诱导脾细胞分泌IFN-γ的能力;采用二苯基溴化四氮唑蓝(MTT)比色法,测定转染前后细胞增殖及黏附能力的变化。 结果 :外源性IL-18基因转染的人膀胱癌细胞系IL-18/T-24,在mRNA水平和蛋白水平均可获得稳定表达;并且,IL-18/T-24细胞的培养上清可明显促进小鼠脾细胞分泌IFN-γ(P<0.01)。IL-18/T-24细胞与LXSN/T-24和T-24比较,细胞周期及细胞凋亡率无显著性差异(P>0.05),IL-18/T-24细胞的增殖率与LXSN/T-24和T-24细胞相比虽有所降低,但无显著性差异(P>0.05)。 结论 :建立的稳定表达IL-18的IL-18/T-24细胞,既保持了肿瘤细胞原有的免疫原性,又具有分泌IL-18的功能,引起较强的免疫应答反应。IL-18/T-24细胞与LXSN/T-24和T-24细胞相比较,其生物学性状无明显差异,可进一步用于肿瘤相关免疫基因治疗的研究。     

靶向表达的逆转录病毒载体LN.ALBTRS.TK的构建

目的构建出在肝细胞中具靶向表达潜能的逆转录TK基因载体。方法用p2335A-1中的一段2.0kb的人白蛋白组织特异性转录调节序列(ALBTRS)取代pSTK中的SV40启动子,所构建的载体命名为LN.ALBTRS.TK。结果载体LN.ALBTRS.TK的结构中,含有ALBTRS启动子,具有在表达白蛋白的肝细胞中特异表达的潜能,载体经酶切鉴定表明结构符合要求。结论成功地构建出具靶向表达潜能的逆转录载体LN.ALBTRS.TK。     

A defective HIV-1 vector for gene transfer to human lymphocytes

Conclusions All practical development of HIV-1 vectors for in vivo testing will require high titers of recombinant virus free of helper virus. To date, an HIV-based vector system with an efficiency of gene transfer comparable to that achieved by the Mo-MuLV-based system has not yet been developed. Such development will require a better definition of the optimal placement of viral cis-acting sequences within the HIV-1 vector. The establishment of stable packaging cell lines should increase the efficiency of production of recombinant HIV-1 viruses for future use. T-lymphocytes are, in fact, an important potential target for therapeutic gene transfer. The possible advantages of such vectors over currently available retroviral vectors suggest that the continued study of HIV-1 vectors for gene transfer to human T-lymphocytes is warranted.Abbreviations HIV Human immunodeficiency virus - LTR Long terminal repeat     

c-myc和K-ras对小鼠卵巢上皮细胞体外转化和体内致瘤的研究

目的探讨癌基因c-myc和K-ras在卵巢癌发生发展中的作用。方法用逆转录病毒转基因系统,将正常的c-myc基因和突变的K-ras基因先后导入小鼠卵巢上皮（MOSE）细胞,建立表达c-myc和K-ras基因的细胞株,分别称为MOSE-Myc细胞、MOSE-Ras细胞和MOSE-RM细胞。通过细胞增殖实验、克隆形成实验、体外侵袭实验以及体内成瘤实验,研究转基因后MOSE细胞生物学特性的改变及恶性转化。结果c-myc和K-ras基因容易被重组逆转录病毒导入MOSE细胞,转导后靶细胞内分别有相应的c-myc或K-ras mRNA转录,以及相应的c-myc（62ooo）和K-ras（21000）蛋白的表达。MOSE-Ras组和MOSE-RM（MOSE-Ras／Myc）组细胞增殖能力显著强于MOSE和MOSE-Myc组（P〈0．01）,MOSE-RM组细胞增殖能力显著强于MOSE-Myc组（P〈0．05）。MOSE-Ras和MOSE-RM组在软琼脂培养中均能形成克隆集落,而MOSE组和MOSE-Myc组不能形成克隆集落。MOSE-Ras组和MOSE-RM组能够穿透Matrigel,具有侵袭能力。MOSE-Ras组和MOSE-RM组细胞在裸鼠体内形成肿瘤,且肿瘤组织细胞仍然可见有K-ras和c-myc蛋白的表达;而MOSE组和MOSE-Myc组无肿瘤形成。结论重组逆转录病毒载体作为转基因的工具,转导效率高,可稳定表达,可以感染正常的细胞;突变的K-ras可使MOSE发生恶性转化,在体内形成肿瘤;c-myc作为一个核转录调节因子,不能使MOSE发生恶性转化,但可协同其他因子,加强其他因子的功能。     

Boundary sequences stabilize transgene expression from subtle position effects in retroviral vectors

Transgene expression shut-down, attenuation and/or variability from integrated retroviral vectors pose a major obstacle to gene therapy trials involving hematopoietic cells. We have undertaken a systematic assessment of the behavior of different configurations containing IFN-β SAR and/or 5′HS4 β-globin insulator sequences within a gammaretroviral vector optimized for high-level expression, focusing on the long-term achievement of stable, homogeneous transgene expression in the successfully transduced cells. Introduction of these cis regulatory elements did not perturb virus production and stability. Conversely, the SAR/5′HS4 insulator combination appeared to increase the homogeneity of EGFP expression in mass cultures. Furthermore, a clonal analysis of the dispersion of EGFP expression revealed that the IFN-SAR/5′HS4 insulator dyad was particularly effective in reducing the variability of transgene expression when both sequences were placed in opposite orientations within the retroviral backbone. These results may prove useful for the design of more stable retroviral expression cassettes able to counteract chromosomal position effects.     

BRD7逆转录病毒稳定系的构建及其功能评价

目的探索BRD7（bromodomain．containingprotein7）是否具有抑癌基因的功能。方法根据NCBI提供的BRD7基因序列设计特异性引物扩增其编码区序列,经酶切、连接转化后进一步挑取单克隆菌落进行菌液PCR筛选及测序鉴定得到阳性重组质粒。共转293T细胞后收集浓缩病毒上清并感染U20S细胞,24h后用嘌呤霉素（puromycin）筛选稳定表达BI①7、的细胞株。结果菌落PCR扩增及DNA测序分析证明重组pMSCV-BRD7．GFP质粒克隆成功。GFP绿色荧光结果显示,绝大部分细胞成功整合了pMSCV-GFP或pMSCV-BRD7．GFP外源质粒;Westernblotting检测发现感染重组质粒pMSCV-BRD7．GFP的细胞株中BRD7蛋白的表达水平显著高于对照组。功能结果显示,过表达BRD7显著抑制U20S细胞的增殖,促进下游靶基因p21与MDM2的表达。结论本研究成功构建了针对BRD7基因的逆转录病毒稳定系,且初步证明了BRD7发挥抑癌基因的功能,为下一步深入研究其被调控的机制与功能奠定了基础。     

A potent immunosuppressive retroviral peptide: cytokine patterns and signaling pathways

A synthetic bioactive peptide composed of 17 amino acids (CKS-17) homologous to a highly conserved region of human and animal retroviral transmembrane envelope proteins induces not only significant immunoregulatory functions but also exhibits Th1-inhibiting properties, as described by its ability to suppress cell-mediated immunity and inhibit the production of interleukin (IL) 12, IL-2, gamma interferon, and tumor necrosis factor alpha, while enhancing IL-10. An important molecular mechanism responsible for the observed cytokine profiles by CKS-17 is provided by our findings demonstrating that this small peptide activates several intracellular signaling molecules, i.e., elevates intracellular cyclic adenosine monophosphate (cAMP) levels, and induces phosphorylation of extracellular signal-regulated kinase (ERK) 1 and 2, mitogen-activated protein kinase/ERK kinase (MEK), protein kinase D, Raf1, and phospholipase C gamma1 (PLCgamma1). The activation of ERK1/2 is via the PLCgamma1-protein kinase C-Raf1-MEK signaling cascade. The activation of both ERK1/2 and cAMP appears to be via a mechanism sensitive to AG879, a receptor tyrosine kinase inhibitor, but not to AG825, AG1296, or AG1478. Furthermore, phosphoinositide-3 kinase appears to mediate the CKS-17-induced activation of ERK1/2, but not of cAMP. A specific amino acid sequence as well as the dimerization of this peptide is required to confer these biological activities. The results obtained are compelling and reproducible. This highly conserved molecule may enable us to understand a basic mechanism(s) of intracellular signaling pathways, regulation of Th1/Th2 cytokines, immunosuppression, and immunologic tolerance.