小鼠BMPRⅠb基因慢病毒载体构建及转染神经干细胞

目的:构建携带小鼠BMPRⅠb基因的慢病毒载体,并转染神经干细胞,为研究BM-PRⅠb在BMPs调控神经干细胞分化中作用奠定基础。方法:利用RT-PCR从小鼠脑组织中获得BMPRⅠb基因,然后定向插入慢病毒表达质粒,进行双酶切及测序鉴定。将鉴定成功的重组慢病毒质粒和另外两种辅助质粒共转染包装细胞,收集、浓缩慢病毒并检测其滴度。利用获得的慢病毒载体转染NSCs,并观察目的基因表达情况。结果:RT-PCR产物经电泳及测序证实克隆成功BM-PRⅠb基因,酶切及测序鉴定成功构建重组慢病毒质粒,共转染293T细胞72h后大部分细胞表达绿色荧光,病毒滴度为5×108 TU/ml。慢病毒感染后的NSCs表达绿色荧光且BMPRⅠb mRNA表达上升。结论:成功构建BMPRⅠb基因慢病毒载体,并成功转染NSCs。

Bcl-2shRNA慢病毒表达载体的构建与鉴定

目的:应用分子克隆技术,针对人bcl-2目的基因设计3个siRNA靶点和一个阴性对照序列,构建4对shRNA重组慢病毒表达载体,并进行测序验证鉴定。方法:以设计的有效靶序列进行引物合成,将单链引物退火成双链oligo序列,连接入经Age I和EcoR I双酶切线性化的慢病毒RNA干扰载体中,经转化DH5α感受态细胞并筛选出阳性转化子,采用PCR扩增和DNA测序分别鉴定阳性克隆。结果:PCR扩增产物经凝胶电泳后阳性克隆得到335bp条带,阴性克隆得到298 bp条带,DNA测序结果证实其含有设计合成序列。结论:成功构建4对bcl-2shRNA重组慢病毒表达载体,为研究靶向bcl-2 siRNA对肿瘤细胞增殖抑制与诱导凋亡作用及基因治疗研究奠定了实验基础。

Lentivirus-mediated shRNA interference targeting STAT3 inhibits human pancreatic cancer cell invasion

AIM： To investigate RNA interference targeting signal transducer and activator of transcription-3 （STAT3） on invasion of human pancreatic cancer cells.METHODS： We constructed three plasmids of RNA interference targeting the STAT3 gene. After LV （lentivirus）-STAT3siRNA （STAT3 small interfering RNA） the vector was transfected into the human pancreatic cell line, SW1990 and cell proliferation was measured by the MTT assay. Flow cytometry was used to assess cell cycle. Vascular endothelial growth favor （VEGF） and matrix metalloproteinase-2 （MMP-2） mRNA and protein expression were examined by quantitative PCR and western blotting, respectively. The invasion ability of SW1990 cells was determined by cell invasion assay.RESULTS： We successfully constructed the LVSTAT3siRNA lentivirus vector and proved that it can suppress expression of STAT3 gene in SW1990 cells. RNA interference of STAT3 by the LV-STAT3siRNA construct significantly inhibited the growth of SW1990 cells, in addition to significantly decreasing both VEGF and MMP-2 mRNA and protein expression. Moreover, suppression of STAT3 by LV-STAT3siRNA decreased the invasion ability of SW1990 cells.CONCLUSION： The STAT3 signaling pathway may provide a novel therapeutic target for the treatment of pancreatic cancer since it inhibits the invasion ability of pancreatic cancer cells.

Construction of a lentiviral vector for RNA interference of human VIM gene and its silencing effect in pancreatic cancer cells

Objective： To construct a lentiviral expression vector for RNA interference （RNAi） of human VIM gene; and assess its gene silencing effect in pancreatic cancer cell line Panc-1. Methods： Three pairs of human VIM gene short hairpin RNA（shRNA） sequences were designed using a software available on-line and one pair came from document. After synthesis and annealing, four double-stranded oligonucleotides （dsOligo） were cloned into the pGCL-GFP/U6 plasmid, which were subsequently confirmed by polymerase chain reaction （PCR） and DNA sequencing analysis. Real-time PCR and Westemblotting were used to screen the effective pGCL-GFP-shRNA plasmid in 293T cells, then the most effective one was packed into the recombinant lentivirus Lv-VIM-shRNA with lentiviral packing materials pHelper 1.0 and pHelper 2.0 in 293T cells. The titer of lentivirus was determined by hole-by-dilution titer assay. The silencing effect of Lv-VIM-shRNA in Panc-1 calls were validated by real-time PCR and Western-blotting. Results： An effective Lv-VIM-shRNA was successfully constructed. The titer of lentivirus was determined on 2× 10^9TU/mL. The expressions of VIM mRNA and vimentin were down-regluated in the Panc-1 cells infected with Lv-VIM-shRNA. Conclusion： An effective Lv-VIM-shRNA could inhibit the expression of VIM gene in Panc-1 cells in vitro, which provides a tool for investigating the role of VIM gene in the signaling pathway involved in tumorigenesis and progression of pancreatic cancer and searching new therapeutic targets.

Efficient production of transgenic chickens using self-inactive HIV-based lentiviral vectors

We demonstrated the simple and effective production of transgenic chickens, in which the enhanced green fluorescence protein （EGFP） was expressed by using third-generation self-inactive HIV-based lentiviral vectors. In our experiments, lentiviruses were injected into 204 fertilized eggs, from which 30 （15%） chickens were hatched. The exogenous gene was detected in the genomes of 16 out of 30 （53%） chickens. The green fluorescence signal was observed directly in various body parts, and was particularly significant in the testes. The transgenes were also found in the offspring of these chickens. The results indicate that HIV-based lentiviral vectors can be used to generate transgenic birds economically and effectively [ Current Zoology 55 （5）： 383 - 387,2009].

Effect of cytokine gene polymorphism on histological activity index, viral load and response to treatment in patients with chronic hepatitis C genotype 3

AIM： To investigate the association between cytokine gene polymorphism and disease status in chronic hepatitis C genotype 3 by liver biopsy, ALl, HCV RNA levels and response to treatment. METHODS： Patients with chronic hepatitis C genotype 3 were analyzed for single nucleotide polymorphisms of interleukin （IL）-10, IL-1 beta, interferon-gamma （IFN-y）, tumor necrosis factor-alpha （TNF-y） and transforming growth factor-beta （TGF-β） by polymerase chain reaction using sequence-specific oligonucleotide primers. Liver biopsies were assessed by modified histological activity index （HAI） scoring system using a scale of 0-18 for grading the necro-inflammatory activity and 0-6 for staging the fibrosis. HCV RNA levels were determined by bDNA assay. The patients were treated with interferon alpha and ribavirin for 6 mo. Sustained virological response was assessed 6 mo after the completion of the treatment. RESULTS： Out of the 40 patients analyzed, 26 were males. Mean age was 40.5±12.5 years （range 18- 65 years）. The frequencies of different dimorphic polymorphisms based on single nucleotide substitution were as follows： IL-10-1082 G/A 85%, A/A 12.5%, G/ G 2.5%; IL-10-819 A/C 87.5%, C/C 10%, A/A 2.5%; IL-10-592 C/A 72.5%, C/C 27.5%; IL-1 C 90%, U 10%; IFN-874 T/A 50%, T/T 27.5%, A/A 22.5%; TNF-308 A/G 95%, G/G 5%; TGF-10 T/C 52.5%, C/C 35%, T/T 12.5%. The mean grades of necroinflammatory activity of different genotypes of IL-10 at promoter site -1082 were A/A = 3.6, A/G = 5.0, and G/G = 10.0 and the difference was significant （P = 0.029）. The difference in the stage of disease at a scale of 0-6 was A/A 0.8, A/G 2.3, and G/G 4.0 （P = 0.079）. The difference in the HAI seemed to be related to the presence of allele -1082G.For IL-10 -819 genotypes, mean scores of fibrosis were A/A = 6.0, A/C = 2.2, and C/C = 1.0 （P = 0.020） though the inflammatory activity was not much different. No significant differences in HAI were noted among polymorphisms of other cytokines. Moreover, ALT and HCV RNA levels were not significantly different among different cytokine polymorphisms. There was a significant correlation of HAI and HCV RNA levels with the duration of disease. TGFI3 -10 genotype CC patients had a better end of treatment response than those with other genotypes （P = 0：020）. Sustained virological response to the treatment was not influenced by the cytokine polymorphism. No effect of other factors like viral load, degree of fibrosis, gender, steatosis, was observed on sustained virological response in this population infected with genotype 3. CONCLUSION： There is no significant correlation between cytokine polymorphisms and HAI except for the polymorphisms of anti-inflammatory cytokine IL-10, which may influence hepatic inflammatory activity and fibrosis in patients with chronic hepatitis C genotype 3. Sustained virological response in this genotype does not seem to be influenced by cytokine gene polymorphisms.

Antitumor activity of mutant bacterial cytosine deaminase gene for colon cancer

AIM： To evaluate bacterial cytosine deaminase （bCD） mutant D314A and 5-fluorocytosine （5-FC） for treatment of colon cancer in a mouse model. METHODS： Recombinant lentivirus vectors that contained wild-type bCD gene （bCDwt）, and bCD mutant D314A gene （bCD-D314A） with green fluorescence protein gene were constructed and used to infect hu- man colon carcinoma LoVo cells, to generate stable transfected cells, LoVo/null, LoVo/bCDwt or LoVo/bCD- D314A. These were injected subcutaneously into Balb/c nude mice to establish xenograft models. Two weeks post-LoVo cell inoculation, PBS or 5-FC （500 mg/kg） was administered by intraperitoneal （i.p.） injection once daily for 14 d. On the day after LoVo cell injection, mice were monitored daily for tumor volume and survival. RESULTS： Sequence analyses confirmed the construction of recombinant lentiviral plasmids that contained bCDwt or bCD-D314A. The lentiviral vector had high elficacy for gene delivery, and RT-PCR showed that bCDwt or bCD-D314A gene was transferred to LoVo cells. Among these treatment groups, gene delivery or 5-FC administration alone had no effect on tumor growth. However, bCDwt/5-FC or bCD-D314A/5-FC treatment inhibited tumor growth and prolonged survival of mice significantly （P 〈 0.05）. Importantly, the tumor volume in the bCD-D314A/5-FC-treated group was lower than that in the bCDwt/5-FC group （P 〈 0.05）, and bCD- D314A plus 5-FC significantly prolonged survival of mice in comparison with bCDwt plus 5-FC （P 〈 0.05）. CONCLUSION： The bCD mutant D314A enhanced significantly antitumor activity in human colon cancer xenograft models, which provides a promising approach for human colon carcinoma therapy.

Research on construction and identification of lentiviral vector of expressing miRNA targeting IGF1R gene regulated by survivin promoter and its inhibition to liver cancer cell growth

Objective： The aim of the study was to investigate the interference and anti-tumor effects of lentiviral vector of miRNA targeting IGF1R gene regulated by survivin promoter. Methods： The fragment of the survivin promoter was acquired by PCR amplification and inserted into pPRIME to recombinant plasmid sur-pPRIME. The complementary DNA containing both sense and antisense Oligo DNA of the targeting sequence was designed, synthesized and cloned into the sur-pPRIME vector, named sur-pPRIME-IGF1R-miR30-shRNA. Viruses were propagated on 293T cells. Viruses were purified by CsCI gradient according to standard techniques, and functional PFU titers were determined by plaque assay on 293 cells. The effect of sur-pPRIME-IGF1R-miR30-shRNA on IGF1R expression of Hep3B cells was detected by RT-PCR and Western blot. The antitumor potential of sur-pPRIME-IGF1R-miR30-shRNA to Hep3B cells was evaluated by CCK-8 assay. Results： sur-pPRIME-IGF1R-miR30-shRNA was constructed successfully. Functional PFU titers of sur-pPRIME-IGF1R-miR30-shRNA were 4.58×10^9 PFU/rnL. Sur-pPRIME-IGF1R-miR30-shRNA was more effective to inhibit IGF1R expression in mRNA or protein levels and the proliferation of Hep3B cells. Conclusion： sur-pPRIME-IGF1R-miR30-shRNA expressing IGF1R-siRNA can inhibit IGF1R expression and may be used for further investigation of gene therapy of liver cancer.

Construction and functional activity of a recombinant vector expressing rat glutamic acid decarboxylase 65

Objective Glutamic acid decarboxylase 2（GAD65） is a gamma-aminobutyric acid（GABA） synthetase.This study aimed to construct a recombinant lentivirus-rGAD65（rLV-rGAD65） vector containing the cDNA of rat GAD65（rGAD65） and assess its functional activity in vitro and in vivo.Methods cDNA of rGAD65 was amplified by RT-PCR and subcloned into the LV vector,forming the rLV-GFP-rGAD65 plasmid.The recombinant lentivirus particles（rLVrGAD65） were packaged by the LV Helper-Free System and the titer was measured.Primary rat lung fibroblasts were transfected with rLV-rGAD65.The expression of rGAD65 in fibroblasts was detected by immunocytochemistry and western blot and the level of GABA in the medium was assessed by high-performance liquid chromatograph（HPLC）.In vivo,rLV-rGAD65 was injected into the subthalamic nucleus（STN） of Sprague-Dawley rats using stereotaxic methods,and rGAD65 protein levels in the STN were assessed by immunohistochemistry and Western blot,while the GABA concentration in the substantia nigra pars reticulata（SNr） was assayed by HPLC.Results The sequence of rGAD65 cDNA was in accord with that in GenBank.The amino-acid sequence of rGAD65 had no mutations and the titer of rLVrGAD65 reached 6.8 × 108/mL.The efficiency of infection of fibroblasts was 80%,and the concentration of GABA in the medium was（48.14 ± 9.35） nmol/L.In vivo,rGAD65 expression was detected in the STN,and the concentration of GABA in the SNr increased from（5.95 ± 1.09） to（12.44 ± 3.79） nmol/g tissue.Conclusion The recombinant LVGFP-rGAD65 vector was successfully constructed.rLV-rGAD65-infected primary fibroblasts in vitro and the expressed rGAD65 catalyzed the formation of GABA from glutamic acid.In vivo,the concentration of GABA in the SNr was increased after rLV-rGAD65 injection into the STN.

Non-integrating lentiviral vectors based on the minimal S/MAR sequence retain transgene expression in dividing cells

Safe and efficient gene transfer systems are the basis of gene therapy applications. Non-integrating lentiviral(NIL) vectors are among the most promising candidates for gene transfer tools, because they exhibit high transfer efficiency in both dividing and non-dividing cells and do not present a risk of insertional mutagenesis. However, non-integrating lentiviral vectors cannot introduce stable exogenous gene expression to dividing cells, thereby limiting their application. Here, we report the design of a non-integrating lentiviral vector that contains the minimal scaffold/matrix attachment region(S/MAR) sequence(SNIL), and this SNIL vector is able to retain episomal transgene expression in dividing cells. Using SNIL vectors, we detected the expression of the eGFP gene for 61 days in SNIL-transduced stable CHO cells, either with selection or not. In the NIL group without the S/MAR sequence, however, the transduced cells died under selection for the transient expression of NIL vectors. Furthermore,Southern blot assays demonstrated that the SNIL vectors were retained extrachromosomally in the CHO cells. In conclusion,the minimal S/MAR sequence retained the non-integrating lentiviral vectors in dividing cells, which indicates that SNIL vectors have the potential for use as a gene transfer tool.