ABSTRACT
Background Adeno-associated virus-based vector is one of most efficient vehicles.It presents with a long-term and efficient transfer and expression of therapeutic genes with minimal toxicity.But its delayed-and low-efficient transgene expression limits the application of AAV vector.To explore an improving method of AAV infecting RPE cells is the hot spot. Objeetive Present study was to investigate whether adeno-associated virus (AAV)combined with low dose non-replieable adenovirus(Ad-null)can enhance its infection efficieney on RPE ceils in vitro. Methods Human RPE cells were isolated from the donate eyeballs under the approval of the Ethic Committee of this hospital.The cells were cultured in DMEM containing 10%fetal bovine serum.AAV particles with enhanced green fluorescence protein(EGFP)were added into the medium alone or in combination with different amount of adenovirus for 30 days.The cells were detected under the fluorescence microscope,and the protein expression levels of report gene EGFP in RPE cells were analyzed with Western blotting assay. Results Melanin granules could be found in cultured RPE cells.EGFP was expressed in RPE cells at 2 days after AAV-EGFP infection and peaked at 12 days and remained for about 3-week duration,showing the green influorescence under the influorescence mwroscope.After the cells were infected by AAV2-EGFP with 0.01 to 1000 MOI Ad-null respectively,the number of cells with green influorescence was obviously increased with the enhanced infiuorescence intensity.The enhance of the infection efficiency began in the 0.1 MOI Ad-null group and peaked in 10 MOI Ad-null group.Dead cells were exhibited in the 100 or more MOI Ad-nulor group.Western blotting assay demonstrated that the protein expression level of EGFP in RPE cells enhanced significantly in 1 and 10 MOI Ad-null groups compared with only AAV infection group. Conclusion These finding suggested that the infection efficiency of AAV can be improved significantly when it is used with low dose Ad-null in vitro.This offers a basis for further study of gene therapy.
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<p><b>BACKGROUND AND OBJECTIVE</b>Adenovirus vectors were widely used in gene therapy for tumors. We used adenovirus vector to transfer small interfering RNA (siRNA) against vascular epithelium growth factor A (VEGF-A) molecules to mouse lung adenoma LA795 cells and used low dose of chemotherapeutic drugs to further elevate the infection efficiency of adenovirus vector in and therapeutic effect of RNAi on tumor cells.</p><p><b>METHODS</b>LA795 cells were infected by Ad/EGFP and treated with different dosages of gemcitabin, epirubicin, cisplatin, or 5-fluorouracil (5-FU). Cells were observed under fluorescence microscope continuously using green fluorescent protein (GFP) as the reporter gene. The percentage of GFP-positive cells and fluorescent intensity were tested by flow cytometry to determine optimum concentrations of drugs. Ad/siVEGF-A containing VEGF-A siRNA was constructed. Real-time PCR and ELISA were applied to measure the expression level of VEGF-A after LA795 cells were infected by Ad/siVEGF-A and treated with 5-FU. The combination of Ad/siVEGF-A and 5-FU was also applied in treating subcutaneous tumor in mice.</p><p><b>RESULTS</b>Low dose of 5-FU elevated the Ad/EGFP infection in LA795 cells significantly, and also enhanced the effect of Ad/siVEGF-A in down-regulating VEGF-A mRNA and protein levels in tumor cells. When used in tumor in vivo, the combination strategy repressed tumor growth effectively.</p><p><b>CONCLUSION</b>Low dose of 5-FU can enhance the capability of adenovirus infecting tumor cells and promote the efficiency of gene therapy by adenovirus.</p>
Subject(s)
Animals , Mice , Adenocarcinoma , Metabolism , Pathology , Adenoviridae , Genetics , Antimetabolites, Antineoplastic , Pharmacology , Cell Line, Tumor , Cell Proliferation , Fluorouracil , Pharmacology , Genetic Therapy , Genetic Vectors , Lung Neoplasms , Metabolism , Pathology , RNA Interference , RNA, Messenger , Metabolism , RNA, Small Interfering , Genetics , Transfection , Vascular Endothelial Growth Factor A , Genetics , PhysiologyABSTRACT
Objective To construct a new conditionally replicative adenovirus (CRAds) targeting carcinoembryonic antigen (CEA) positive colorectal cancer cells. Methods The DNA fragment of the CEA gene promoter was amplified through PCR and cloned into the vector carrying fusion reporter gene EGFP-Luc to construct expression plasmid pCEA-EGFPLuc. The constructed plasmid pCEA-EGFPLuc was transfected into CEA positive and negative cells by liposome. The activity of CEA gene promoter was evaluated by detecting the expression of EGFP and luciferase activity. The conditionally replicative adenovirus Ad.CEA-E1A/CMV-TK carrying suicide gene HSVtk was constructed, in which the E1A gene was controlled under CEA promoter. CEA positive(Lovo and SW620)and negative tumor cells(HeLa) were infected with Ad.CEA-E1A/ CMV-TK. The selective cytotoxicity of Ad.CEA-E1A/CMV-TK and the synergistic effect of the virus with GCV in CEA positive tumor cells were evaluated by the expression of E1A, cytopathic effect and cell survival rate. Results CEA promoter possesses a good specificity as well as high activity. The expression of E1A only presented in CEA positive tumor cells. After infection with Ad. CEA-E1A/CMV-TK, the cell survival rates of Lovo and SW620 were (36.72±2.49)% and (39.82±4.76)%, respectively, significantly lower than that of Hela[(87.44±2.76)%1 (P<0.01). When combined with GCV, Ad.CEA-E1A/CMV-TK had better oncolytic effect on Lovo and SW620 cells, with cell survival rates of (17.26±3.65) % and (23.93±5.40) %, respectively, significantly lower than those without GCV[(36.72±2.49) % and (39.82±4.76) %, respectively] (P<0.01). Conclusion Ad. CEA-E1A/CMV-TK under the control of CEA promoter has selective cytotoxic effect on CEA positive colorectal cancer cells, and the effect can be enhanced when combined with GCV.
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<p><b>BACKGROUND</b>Retina is important in converting light into neural signals, but little is known about the regulatory genes essential for the retinal morphological formation, development and functional differentiation. This study aimed to investigate the mRNA expression patterns and cellular or subcellular distribution of 33 differentially expressed genes in the retina belonging to the early and middle-late embryogenesis stages as well as the early adult stage during human development.</p><p><b>METHODS</b>In situ hybridization and real-time fluorescent quantitative reverse transcription polymerase chain reaction (FQ-RT-PCR) were used to assay 33 differentially expressed genes which were screened out using microarray analysis and were not present in the retinal cDNA or the Expressed Sequence Tags (EST) database of the National Eye Institute (NEI) Genebank.</p><p><b>RESULTS</b>Nine of the 33 genes belonged to EST or the unknown cDNA fragments, and the remaining belonged to the novel genes in the retina. During the human retinal development 17 genes were down-regulated, 6 were up-regulated and the remaining 10 were relatively unchanged. Most of the genes expressed in all layers of the retina at the gestation stage, and in the fully developed retina some genes examined did show higher expression level in certain specific cells and structures such as retinal ganglion cells or the outer segment of photoreceptor cells.</p><p><b>CONCLUSION</b>The gene expression profile during retinal development possesses temporal and spatial distribution features, which can provide experimental evidence for further research of the functions of those genes.</p>
Subject(s)
Humans , Expressed Sequence Tags , Fetus , Metabolism , Gene Expression Profiling , In Situ Hybridization , RNA, Messenger , Retina , Embryology , Metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
To improve the targeting of adenovirus vector for gene therapy, a fusion gene sCAR-EGF, in which epidermal growth factor gene was fused to the 3' end of extracellular Coxsackie virus-adenovirus receptor gene, was constructed and cloned into shuttle plasmid pDC315 to obtain a recombinant plasmid pDC315-sCAR-EGF. With the AdMax system, AD-293 cells were co-transfected with pDC315-sCAR-EGF and adenovirus genomic plasmid pBHGloxdeltaE13cre. Through high efficiency site specific recombination, a replication-defective adenovirus Ad5-CMV-sCAR-EGF was constructed. The recombinant adenovirus was analyzed by PCR and Western blotting, the results indicated that Ad5-CMV-sCAR-EGF contained the fusion gene sCAR-EGF, and the adenovirus infected cells was induced to produce and secrete the fusion protein into the supernatant. We have demonstrated that the fusion protein sCAR-EGF is helpful for elevating the infection efficiency of Ad5-CMV-luc with the reporter gene in vitro, which providing a new approach to the gene therapy for tumors overexpressing EGFR.