Construction and expression of retroviruses encoding dual drug resistance genes in human umbilical cord blood CD34+ cells

A series of retro viral vectors encoding humanmdr1 gene alone as wetl as in combination with either humanmgmt gene or human mutantSer ³¹-dhfr gene are engineered. The resultant retroviruses are used to transduce human umbilical cord blood CD34⁺ cetls. It has been shown that expression of dual drug resistance genes in transduced cetls confers a broad range of resistance to both kinds of corresponding drugs. These data suggest a rationale for the use of such double chemoresistance gene constructs in anin vivo model in which transduced hematopoietic cetls will acquire multiple protection against the cytotoxic side effects of combination chemotherapy and may have future application in chemoprotection of normal tissues, thus killing tumor cetls more effectivety.     

带HSV－tk基因的重组腺病毒杀伤离体肺癌细胞的研究

带有单纯疱疹病毒脱氧胸苷激酶基因（ＨＳＶ－ｔｋ）的腺病毒结合ｇａｎｃｉｃｌｏｖｉｒ（ＧＣＶ）对分裂细胞有很强的杀伤作用．在感染复数（Ｍ．Ｏ．Ｉ,ＭｕｌｔｉＰｌｉｃｉｔｙｏｆＩｎｆｅｃｔｉｏｎ）达到１０００时对人体肺腺癌细胞Ａ５４９的杀伤几乎达到１００％．四种人体肺癌细胞株（Ａ５４９,ＬＡＸ,ＳＰＣ,ＳＫＹ）对带ＨＳＶ－ｔｋ的腺病毒（ＡＤＶ／ＲＳＶ－ｔｋ）的杀伤作用表现出不同的敏感性．另Ａｃｙｃｌｏｖｉｒ（ＡＣＶ）和ＧＣＶ对感染了重组腺病毒ＡＤＶ／ＲＳＶ－ｔｋ的细胞都有一定杀伤作用,但杀伤效果有很大差别;就Ａ５４９而言,ＧＣＶ的杀伤作用比ＡＣＶ高７～８倍．此外ＡＤＶ／ＲＳＶ－ｔｋ结合ＧＣＶ杀伤肿瘤细胞时有“旁观者效应”,即感染了ＡＤＶ／ＲＳＶ－ｔｋ的细胞与未感染细胞混合后,后者也明显地遭到杀伤．     

Study on interleukin-18 gene transfer into human breast cancer cells to prevent tumorigenicity

To study the effect of interleukin-18 gene transfection on the tumorigenesis of breast cancer cell line Bacp37, human breast cancer cell line Bcap37 were transfected with Lipofectamine and selected by G418. The biological expression of rhIL-18 was tested by RT-PCR and ELISA method; nude mice were injected with Bcap37 cell with or without the hIL-18 gene. The hIL-18 cDNA was successfully integrated into Bcap37 cell; 126.3+/-4.5 pg hIL-18 secreted by one million transduced cells in 24 hours. Nude mice injected with IL-18 gene engineered Bcap37 cell had no tumor growth. These findings indicated that human breast cancer cells were successfully modified by the gene of IL-18 cytokine; the IL-18 gene engineered Bcap37 cells secreted hIL-18 and lost their tumorigenicity. The Bcap37 cells transduced with IL-18 gene may be used as breast cancer vaccine.     

Lineage-specific expression of a human beta-globin gene in murine bone marrow transplant recipients reconstituted with retrovirus-transduced stem cells

Recombinant retroviral genomes encoding a chromosomal human beta-globin gene have been used to transduce murine haematopoietic stem cells in vitro. After permanent engraftment of lethally irradiated recipients with the transduced cells, the human beta-globin gene is expressed at significant levels only within the erythroid lineage. These results indicate that it is possible to obtain stable expression of exogenous chromosomal DNA sequences introduced into mature haematopoietic cells in vivo via stem cell infection, and that human disorders of haemoglobin production may be more feasible candidates for somatic cell gene therapy than previously suspected.     

Retrovirus-mediated transfer and expression of drug resistance genes in human haematopoietic progenitor cells

Patients with certain genetic disorders can be cured by bone marrow transplantation. However, as prospective donors do not exist for most patients with potentially curable genetic abnormalities, an alternative treatment for such patients involves the transfer of cloned genes into the patient's haematopoietic stem cells followed by re-infusion of the treated cells. Retroviral vectors provide an efficient means for transferring genes into mammalian cells and have been used to transfer genes into mouse haematopoietic cells. We have now produced amphotropic retroviral vectors containing either the bacterial gene for neomycin resistance or a mutant dihydrofolate reductase gene that confers resistance to methotrexate and have used these vectors to infect and confer drug resistance to human haematopoietic progenitor cells in vitro. Transfer could be demonstrated in the absence of helper virus by using an amphotropic retrovirus packaging cell line, PA12 (ref. 9). These studies are an important step towards the eventual application of retrovirus-mediated gene transfer to human gene therapy and for molecular approaches to the study of human haematopoiesis.     

Prestin is the motor protein of cochlear outer hair cells

The outer and inner hair cells of the mammalian cochlea perform different functions. In response to changes in membrane potential, the cylindrical outer hair cell rapidly alters its length and stiffness. These mechanical changes, driven by putative molecular motors, are assumed to produce amplification of vibrations in the cochlea that are transduced by inner hair cells. Here we have identified an abundant complementary DNA from a gene, designated Prestin, which is specifically expressed in outer hair cells. Regions of the encoded protein show moderate sequence similarity to pendrin and related sulphate/anion transport proteins. Voltage-induced shape changes can be elicited in cultured human kidney cells that express prestin. The mechanical response of outer hair cells to voltage change is accompanied by a 'gating current', which is manifested as nonlinear capacitance. We also demonstrate this nonlinear capacitance in transfected kidney cells. We conclude that prestin is the motor protein of the cochlear outer hair cell.     

Widespread potential for growth-factor-driven resistance to anticancer kinase inhibitors

Mutationally activated kinases define a clinically validated class of targets for cancer drug therapy. However, the efficacy of kinase inhibitors in patients whose tumours harbour such alleles is invariably limited by innate or acquired drug resistance. The identification of resistance mechanisms has revealed a recurrent theme—the engagement of survival signals redundant to those transduced by the targeted kinase. Cancer cells typically express multiple receptor tyrosine kinases (RTKs) that mediate signals that converge on common critical downstream cell-survival effectors—most notably, phosphatidylinositol-3-OH kinase (PI(3)K) and mitogen-activated protein kinase (MAPK). Consequently, an increase in RTK-ligand levels, through autocrine tumour-cell production, paracrine contribution from tumour stroma or systemic production, could confer resistance to inhibitors of an oncogenic kinase with a similar signalling output. Here, using a panel of kinase-'addicted' human cancer cell lines, we found that most cells can be rescued from drug sensitivity by simply exposing them to one or more RTK ligands. Among the findings with clinical implications was the observation that hepatocyte growth factor (HGF) confers resistance to the BRAF inhibitor PLX4032 (vemurafenib) in BRAF-mutant melanoma cells. These observations highlight the extensive redundancy of RTK-transduced signalling in cancer cells and the potentially broad role of widely expressed RTK ligands in innate and acquired resistance to drugs targeting oncogenic kinases.     

血友病B基因治疗临床试验的安全性研究

报道了血友病Ｂ基因治疗临床Ｉ期试验的安全性研究，包括反转录病毒基因的ＤＮＡ聚合酶反应（ＰＣＲ）、反转录ＰＣＲ（ＲＴ／ＰＣＲ）、Ｓｏｕｔｈｅｍ杂交以及ｎｅｏ基因和ｌａｃＺ基因的补求分析（ｒｅｓｏｕｅａｓｓａｙ）．从ＤＮＡ水平，ＲＮＡ水平和病毒活性体水平对野生型病毒进行了检测，没有检测到反转录病毒，并对兔和人转基因细胞进行形态学观察，染色体核型分析，软琼脂实验，裸鼠接种实验，兔和裸鼠的病理检测及电镜分     

Several alleles of the multidrug-resistance gene are closely linked to chloroquine resistance in Plasmodium falciparum

The lethal form of human malaria caused by Plasmodium falciparum is virtually uncontrollable in many areas because of the development of drug resistance, in particular chloroquine resistance (CQR). CQR is biologically similar to the multiple drug resistance phenotype (MDR) of mammalian tumour cells, as both involve expulsion of drug from the cell and both can be reversed by calcium channel antagonists. A homologue (pfmdr1) of the mammalian multidrug resistance gene has been implicated in CQR because it is amplified in some CQR isolates of P. falciparum as is an mdr gene in MDR tumour cells. We show here that the complete sequences of pfmdr1 genes from 2 CQ sensitive (CQS) P. falciparum isolates are identical. In 5 CQR isolates, 1-4 key nucleotide differences resulted in amino acid substitutions. On the basis of these substitutions, we have correctly predicted the CQS/CQR status of a further 34 out of 36 isolates. This is a paradox as CQR arises much less frequently than would be predicted if single point mutations were sufficient. We conclude that a mutated pfmdr1 gene is one of at least two mutated genes required for CQR.     

非小细胞肺癌中转化生长因子βⅠ型受体基因的缺陷表达

转化生长因子β(TGF-β)信号转导通路的紊乱可使细胞逃避TGF-β介导的生长抑制效应,从而导致多种肿瘤的发生.本研究探讨了转化生长因子βⅠ型受体(TGFβRⅠ)在非小细胞肺癌(NSCLC)发生中的作用.采用免疫组化进行TGFβRⅠ基因的表达分析:采用单链构象多态性(SSCP)分析TGFβRⅠ基因结构的变异.结果发现37.2%NSCLC中TGFβRⅠ的表达下降,表明TGFβRⅠ在NSCLC发生中起着重要的作用.同时在TGFβRⅠ基因的第7号内含子中发现了一个单核苷酸多态性(SNP),该SNP与TGFβRⅠ的表达下降无显著关系(P>0.05).     

Polycistronic strategy for cyanobacterial expression vector construction: Co-transcription of a human gene and a selective marker gene

A polycistronic expression vector, pKGA-NTF1, was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002 chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3 gene (NTF1) to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1 gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.     

Molecular identification of a human DNA repair gene following DNA-mediated gene transfer

Although it has long been evident that the response of eukaryotes to DNA damaging agents is determined by the effectiveness of a variety of DNA repair systems, there is little detailed knowledge of the nature of these systems or the genes which control them. In humans, a number of hereditary conditions, including xeroderma pigmentosum, ataxia telangiectasia and Fanconi's anaemia, exhibit increased sensitivity to a variety of DNA damaging agents and a predisposition to cancer, suggesting a defect in some aspect of DNA repair. This report describes the identification of a human DNA repair gene following DNA-mediated gene transfer into Chinese hamster ovary (CHO) mutant cells, that like xeroderma pigmentosum cells, are sensitive to a variety of DNA damaging agents and are defective in the initial incision step of DNA repair. The resulting transformants exhibit normal resistance to DNA damaging agents and independent transformants demonstrate a common set of human DNA sequences associated with a human DNA repair gene. These observations provide the basis for the isolation and characterization of the human genes responsible for DNA repair.     

敏感和抗性的白血病HL60细胞对staurosporine诱导凋亡的不同反应(英)

用对蛋白激酶具有强烈抑制、作用广泛的抑制剂staurosporine（Sta）,研究敏感和抗三尖杉酯碱的人白血病HL60细胞中凋亡和多药抗药性的关系．Sta均能诱导2种细胞发生典型的凋亡,但抗性细胞发生凋亡需更长的时间,凋亡的细胞数减少．Sta增加柔红霉素在抗性细胞内的积聚,说明其能逆转多药抗药性．在抗性细胞凋亡过程中,mdrl基因表达没有变化,c-myc基因表达稍有增加．结果显示：Sta能诱导敏感和抗三尖杉酯碱的HL60细胞发生凋亡,mdrl基因表达与凋亡过程无关．     

arrow encodes an LDL-receptor-related protein essential for Wingless signalling

The Wnt family of secreted molecules functions in cell-fate determination and morphogenesis during development in both vertebrates and invertebrates (reviewed in ref. 1). Drosophila Wingless is a founding member of this family, and many components of its signal transduction cascade have been identified, including the Frizzled class of receptor. But the mechanism by which the Wingless signal is received and transduced across the membrane is not completely understood. Here we describe a gene that is necessary for all Wingless signalling events in Drosophila. We show that arrow gene function is essential in cells receiving Wingless input and that it acts upstream of Dishevelled. arrow encodes a single-pass transmembrane protein, indicating that it may be part of a receptor complex with Frizzled class proteins. Arrow is a low-density lipoprotein (LDL)-receptor-related protein (LRP), strikingly homologous to murine and human LRP5 and LRP6. Thus, our data suggests a new and conserved function for this LRP subfamily in Wingless/Wnt signal reception.     

MDR1-targeted siRNA delivery with cationic dendritic conjugated polymers

A cationic dendritic polyfluorene (PFP) is examined as a siRNA delivery vector. This material was designed to facilitate the nucleic acid binding, encapsulation and efficient cellular uptake. PFP can effectively protect siRNA against nuclease degradation, which is necessary for gene carriers. PFP can be used for multidrug resistance gene-targeted siRNA delivery in doxorubicin (Dox)-resistant human breast cancer cells (MCF7) cells. As a siRNA transfection agent, PFP can efficiently achieve the reversal of drug resistance and enhance the drug sensitivity. These new features and capabilities represent a major step toward conjugated polymers that can function for therapeutic application.     

Role of VEGF in the growth and metastasis of a murine bladder carcinoma

Bladder transitional cell carcinoma is the most common form of carcinoma in the urinary system. Although overexpression of VEGF has been identified in tissue, serum,and urine of patients with bladder cancer, the role of VEGF in transitional cell carcinoma of the bladder has not been clearly elucidated. Here, we dissected the effect of VEGF during bladder tumor growth and progression by modifying a BBN (N-butyl-N-(4-hydroxybutyl) nitrosamine) induced mouse bladder transitional cell carcinoma cell line BTT-T739 by stable transfection of antisense VEGF121 cDNA. The transfection resulted in-more than 80% reduction in VEGF production. The growth of the transduced tumor cells in vitro was not affected, however, these cells formed small or no tumors in vivo. Even in the tumors formed, there were minimal vascularization, extensive necrosis and longer latency compared to those formed by parental cells. The permeability of tumor vasrulatuce and metastatic tumor growth were also significantly suppressed in antisense VEGF cDNA transfected cells. In addition, the transfer of anti-angiogenic gene in a rumbination of sFlk-I and ExTek with electroporation can suppress the tumor growth efficiently. Taken together,these results demonstrated that VEGF plays an important role in bladder tumor angiogenesis and angiogenesis plays an important role in bladder tumor growth and metastasis.     

Decreased osmotic stability of dystrophin-less muscle cells from the mdx mouse

Human X-linked Duchenne and Becker muscular dystrophies are due to defects in dystrophin, the product of an exceptionally large gene. Although dystrophin has been characterized as a spectrin-like submembranous cytoskeletal protein, there is no experimental evidence for its function in the structural maintenance of muscle. Current hypotheses attribute necrosis of dystrophin-less fibres in situ to mechanical weakening of the outer membrane, to an excessive influx of Ca2+ ions, or to a combination of these two mechanism, possibly mediated by stretch-sensitive ion channels. Using hypo-osmotic shock to determine stress resistance and a mouse model (mdx) for the human disease, we show that functional dystrophin contributes to the stability of both cultured myotubes and isolated mature muscle fibres.