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At least 649 records · Page 36Linked to original sources
PubMed2005

RNA interference of PPARgamma using fiber-modified adenovirus vector efficiently suppresses preadipocyte-to-adipocyte differentiation in 3T3-L1 cells.

The peroxisome proliferator-activated receptor (PPAR) gamma is regarded as a "master regulator" of adipocyte differentiation and is abundantly expressed in adipose. To understand the biological role of PPARgamma in adipose, RNA interference (RNAi) of PPARgamma should be a powerful tool. 3T3-L1 cell line serves an excellent model to investigate the mechanism of preadipocyte-to-adipocyte differentiation. However, this cell line is difficult to transfect by plasmid vectors and viral vectors. We optimized the transduction of both 3T3-L1 preadipocytes and adipocytes by means of fiber-modified adenovirus (Ad) vectors. Among the various vectors tested, polylysine modification of the C-terminal of the fiber knob most markedly improved the transduction efficiency in both 3T3-L1 preadipocytes and adipocytes. Then, we examined whether fiber-modified Ad vectors with polylysine peptides expressing the small interfering RNA (siRNA) for PPARgamma inhibit the differentiation of 3T3-L1 preadipocytes into adipocytes. Oil red O staining and measurement of glycerol-3-phosphate dehydrogenase (GPDH) activity indicated that the vectors effectively suppressed the differentiation of 3T3-L1 preadipocytes to adipocytes. These results suggested that the combination of fiber-modified Ad vectors containing polylysine peptides and RNAi is an effective tool for the study of the biological and physiological mechanism of adipogenesis in adiposity and diabetes using 3T3-L1 models. Ad vector-mediated RNAi for PPARgamma should also be useful to clarify the biological role of the PPARgamma pathway in various tissues in addition to adipose and for therapeutic application to a variety of diseases, including adiposity and diabetes.

3T3-L1 Cells↗
PubMed2004

Inhibition of growth and invasive ability of melanoma by inactivation of mutated BRAF with lentivirus-mediated RNA interference.

Oncogenic mutations of molecules involved in the mitogen-activated protein kinase (MAPK) pathways provide signals mediating both tumor growth and invasion in various cancers including melanomas. BRAF somatic mutations, found in 66% of melanomas, have NIH3T3 transforming ability with the elevated kinase activity in vitro. We attempted to mediate RNA interference (RNAi) with HIV lentiviral vectors specific for either wild type or the most frequently mutated form of BRAF (V599E) in 10 melanoma cell lines, and found that RNAi inhibited the growth of most melanoma cell lines in vitro as well as in vivo, which was accompanied by decrease of both BRAF protein and ERK phosphorylation. Interestingly, the mutated BRAF (V599E)-specific siRNA inhibited the growth and MAPK activity of only melanoma cell lines with this mutation. Furthermore, BRAF RNAi inhibited matrigel invasion of melanoma cells accompanied with a decrease of matrix metalloproteinase activity and beta(1) integrin expression. These results clarify that the mutated BRAF (V599E) is essentially involved in malignant phenotype of melanoma cells through the MAPK activation and is an attractive molecular target for melanoma treatment. The lentivirus-mediated RNAi specific for oncogenic mutations may be a powerful technique for gene therapy of cancer.

Cell Division↗
PubMed2006

RNA interference against urokinase in hepatocellular carcinoma xenografts in nude mice.

The serine protease urokinase-type plasminogen activator (u-PA) is overexpressed in hepatocellular carcinoma (HCC) and its expression level is inversely correlated with the patients' survival. The purpose of this study was to examine the effects of vector-based RNA interference (RNAi) of u-PA on the growth of human HCC xenografts in nude mice in order to investigate the role of u-PA in human HCC. Our results showed that the subcutaneous injection of small interfering RNAs (siRNA) u-PA SKHep1C3 stable transfected cells (pS siRNA u-PA) led to a growth delay in xenograft development, compared to those generated from empty vector; the molecular characterization of nodules (carried out by PCR, RT-PCR and immunohistochemical analysis) revealed the presence of plasmid DNA, the u-PA gene expression knockdown, at both mRNA and protein levels, giving evidence of a long-term and target-specific inhibition by vector-based RNAi 11 weeks after cell inoculation. We further studied the effects of u-PA down modulation on extracellular matrix (ECM) proteins evaluating the expression and organization of fibronectin (FN; one of the main ECM proteins). Immunohistochemical and immunofluorescence analysis of FN revealed FN fibrils in pS siRNA u-PA xenografts and in pS siRNA u-PA cells, thus identifying the FN fibril organization as a downstream effect of u-PA knockdown in this system.

Animals↗
PubMed2006

Adenovirus-mediated RNA interference against foot-and-mouth disease virus infection both in vitro and in vivo.

Foot-and-mouth disease virus (FMDV) infection is responsible for the heavy economic losses in stockbreeding each year. Because of the limited effectiveness of existing vaccines and antiviral drugs, the development of new strategies is needed. RNA interference (RNAi) is an effective means of suppressing virus replication in vitro. Here we demonstrate that treatment with recombinant, replication-defective human adenovirus type 5 (Ad5) expressing short-hairpin RNAs (shRNAs) directed against either structural protein 1D (Ad5-NT21) or polymerase 3D (Ad5-POL) of FMDV totally protects swine IBRS-2 cells from homologous FMDV infection, whereas only Ad5-POL inhibits heterologous FMDV replication. Moreover, delivery of these shRNAs significantly reduces the susceptibility of guinea pigs and swine to FMDV infection. Three of five guinea pigs inoculated with 10(6) PFU of Ad5-POL and challenged 24 h later with 50 50% infectious doses (ID50) of homologous virus were protected from the major clinical manifestation of disease: the appearance of vesicles on the feet. Two of three swine inoculated with an Ad5-NT21-Ad5-POL mixture containing 2 x 10(9) PFU each and challenged 24 h later with 100 ID50 of homologous virus were protected from the major clinical disease, but treatment with a higher dose of adenovirus mixture cannot promote protection of animals. The inhibition was rapid and specific because treatment with a control adenovirus construct (Ad5-LacZ) expressing Escherichia coli galactosidase-specific shRNA showed no marked antiviral activity. Our data highlight the in vivo potential of RNAi technology in the case of FMD.

Adenoviridae↗
PubMed2003

RNA interference shows critical requirement for NF-kappa B p50 in the production of IL-12 by human dendritic cells.

Specific NF-kappaB/Rel proteins regulate murine dendritic cell (DC) survival, differentiation, and activation, but little is known of their role in human cells because of limited loss-of-function analyses. RNA interference (RNAi) is a mechanism to effectively silence gene expression via sequence-specific double-stranded small interfering RNAs (siRNAs). RNAi was used to assess the role of the p50 (NF-kappaB1) protein in the maturation and activation of cultured human monocyte-derived DC (MoDC). Transfection of cultured MoDC with siRNAs reduced p50 mRNA and protein levels in a specific, dose-dependent, and time-dependent manner. Basal or maturation-induced expression of HLA-DR and costimulatory molecules were not affected, whereas transcription of the IL-12 p40 gene and the secretion of IL-12alphabeta were reduced. Such MoDC induced less IFN-gamma production by T cells in MLR. This is the first report of RNAi-induced phenotype in human primary DC with a method that caused no measurable toxicity or type-I IFN response. siRNAs appear useful for the study of signaling pathways in immune cells, revealing a pivotal requirement for p50 in MoDC for IL-12 production and induction of optimal type-1 immune responses.

Cell Differentiation↗
PubMed2006

RNA interference suppression of MUC1 reduces the growth rate and metastatic phenotype of human pancreatic cancer cells.

MUC1 is a highly glycosylated, type I transmembrane protein expressed by normal ductal epithelial cells of the pancreas, breast, lung, and gastrointestinal tract, and overexpressed in many cases of adenocarcinoma. We down-regulated MUC1 expression by RNA interference and investigated the effects on malignant and metastatic potential of a human pancreatic cancer cell line, S2-013. MUC1-suppressed clones, S2-013.MTII.C1 and S2-013.MTII.C2, were established by targeting a sequence 3,151 bp from the initiation codon and characterized in vitro for proliferation, invasion, and adhesion. We evaluated the effects of MUC1 suppression in vivo on tumor growth and metastatic properties following implantation into the cecum or pancreas of athymic mice. MUC1-suppressed clones showed significantly decreased proliferation in vitro and in vivo. Global gene expression was evaluated by oligonucleotide microarray analysis. Surprisingly, genes predicted to increase doubling times (cyclin B1 and cyclin D3) were overexpressed in MUC1-suppressed clones. There were alterations in expression of several genes that may affect the malignant properties of pancreatic cancer. Adhesion of MUC1-suppressed cells in vitro to type IV collagen and fibronectin was slightly increased, and adhesion was slightly decreased to type I collagen and laminin. Results of implantation to cecum and pancreas showed significant reduction of metastasis to lymph nodes, lung, or peritoneal sites compared with S2-013.gfp-neo control cells. These results support the hypothesis that MUC1 contributes significantly to growth and metastasis, and that down-regulation of MUC1 protein expression decreases the metastatic potential of pancreatic adenocarcinoma.

Adenocarcinoma↗
PubMed2005

Towards mutation-independent silencing of genes involved in retinal degeneration by RNA interference.

More than one hundred different mutations in the gene encoding rhodopsin are associated with a group of retinal degenerations including retinitis pigmentosa, congenital stationary night blindness and retinitis punctata albescens. Given this large heterogeneity of mutations, it would be ideal to develop mutation-independent therapies for these diseases. We describe use of RNA interference (RNAi) and specifically short hairpin RNAs (shRNAs) expressed from DNA templates to silence both normal and mutant (P23H) human rhodopsin alleles by 94.34+/-2.17 and 94.9+/-1.9%, respectively, in human embryonic retinoblasts. Degeneracy of the genetic code was used to engineer a codon-exchanged mRNA (cmRNA) that demonstrated complete resistance to silencing by the shRNA. Simulation of autosomal dominant retinitis pigmentosa in cell culture through triple transfection of DNAs expressing a cmRNA, a P23H mRNA and an shRNA revealed shRNA-mediated silencing, specifically of P23H rhodopsin by 90.64+/-5.19% and no loss of rhodopsin translation from the cmRNA in those cells. In addition, we present data on two alternative shRNA sequences targeting human rhodopsin. Our results have implications for the treatment of a very large variety of retinal degenerations in a mutation-independent manner.

Base Sequence↗
PubMed2006

Complete reversal of ABCG2-depending atypical multidrug resistance by RNA interference in human carcinoma cells.

In the chemotherapeutic treatment of patients with disseminated neoplasms, multidrug resistance (MDR) is a major obstacle. ABCG2 (BCRP/MXR), a member of the superfamily of adenosine triphosphate-binding cassette (ABC) transporters, was demonstrated to be associated with "atypical" forms of multidrug-resistant phenotypes of cancer cells. To overcome the ABCG2-depending MDR, two specific anti-ABCG2 small interfering RNAs (siRNAs) were designed for transient triggering of the gene-silencing RNA interference (RNAi) pathway in the human gastric carcinoma cell line EPG85-257RNOV, exhibiting an atypical MDR phenotype. Because both siRNAs showed biological activity, for stable inhibition of ABCG2 corresponding short hairpin RNA (shRNA) expression vectors were constructed. By treatment of EPG85-257RNOV cells with these constructs, expression of the targeted ABCG2-encoding mRNA and transport protein was inhibited completely. Furthermore, anti-ABCG2 shRNA-treated cells increased cellular drug accumulation to the same level measured in drug-sensitive parental cells. These effects were accompanied by complete reversal of the drug-resistant phenotype. Thus, the data indicate that siRNA- and shRNA-mediated RNAi-based gene therapy may be applicable in preventing and reversing ABCG2-depending atypical MDR.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2004

'Knock down' of DNA polymerase beta by RNA interference: recapitulation of null phenotype.

DNA polymerase beta (pol beta) is the major DNA polymerase involved in the base excision repair (BER) pathway in mammalian cells and, as a consequence, BER is severely compromised in cells lacking pol beta. Pol beta null (-/-) mouse embryos are not viable and pol beta null cells are hypersensitive to alkylating agents. Using RNA interference (RNAi) technology in mouse cells, we have reduced the pol beta protein and mRNA to undetectable levels. Pol beta knockdown cell lines display a pattern of hypersensitivity to DNA damaging agents similar to that observed in pol beta null cells. Generation of pol beta knock down cells makes it possible to combine the pol beta null phenotype with deficiencies in other DNA repair proteins, thereby helping to elucidate the role of pol beta and its interactions with other proteins in mammalian cells.

Animals↗
PubMed2004

Intracellular approach for blocking JC virus gene expression by using RNA interference during viral infection.

The human polyomavirus, JC virus (JCV), encodes two regulatory proteins at the early (T antigen) and the late (agnoprotein) phases of viral infection whose activities are important for the production of the viral capsid proteins and the dysregulation of several host factors and their functions. For this study, we designed and utilized an RNA interference strategy via small interfering RNAs (siRNAs) that targeted the expression of T antigen and agnoprotein in human astrocytic cells. The treatment of cells with specific siRNA oligonucleotides targeting a conserved region of T antigen, nucleotides (nt) 4256 to 4276 (Mad-1 strain), caused a >50% decline in the level of T antigen and in its transcriptional activity upon the viral capsid genes as well as a significant reduction in viral DNA replication in infected cells. Similarly, a single siRNA that aimed at nt 324 to 342 of agnoprotein noticeably reduced early and late viral protein production. A combined treatment of the infected cells with both T-antigen and agnoprotein siRNAs completely abolished viral capsid protein production, indicative of the ability of the siRNAs to effectively halt multiplication of the virus in infected cells. These observations provide a new avenue for possible treatments of patients with the JCV-induced demyelinating disease progressive multifocal leukoencephalopathy.

Antigens, Viral, Tumor↗
PubMed2005

Dissecting Wnt/beta-catenin signaling during gastrulation using RNA interference in mouse embryos.

Differential gene regulation integrated in time and space drives developmental programs during embryogenesis. To understand how the program of gastrulation is regulated by Wnt/beta-catenin signaling, we have used genome-wide expression profiling of conditional beta-catenin mutant embryos. Known Wnt/beta-catenin target genes, known components of other signaling pathways, as well as a number of uncharacterized genes were downregulated in these mutants. To further narrow down the set of differentially expressed genes, we used whole-mount in situ screening to associate gene expression with putative domains of Wnt activity. Several potential novel target genes were identified by this means and two, Grsf1 and Fragilis2, were functionally analyzed by RNA interference (RNAi) in completely embryonic stem (ES) cell-derived embryos. We show that the gene encoding the RNA-binding factor Grsf1 is important for axial elongation, mid/hindbrain development and axial mesoderm specification, and that Fragilis2, encoding a transmembrane protein, regulates epithelialization of the somites and paraxial mesoderm formation. Intriguingly, the knock-down phenotypes recapitulate several aspects of Wnt pathway mutants, suggesting that these genes are components of the downstream Wnt response. This functional genomic approach allows the rapid identification of functionally important components of embryonic development from large datasets of putative targets.

Alkaline Phosphatase↗
PubMed2005

RNA interference targeting of Bcr-Abl increases chronic myeloid leukemia cell killing by 17-allylamino-17-demethoxygeldanamycin.

17-Allylamino-17-demethoxygeldanamycin (17-AAG) induces degradation of Hsp90 client proteins, including Bcr-Abl, however, its clinical use as an anti-tumor agent may be limited by toxicity and modest efficacy. We reasoned that Bcr-Abl targeting by RNA interference (RNAi) might selectively increase the activity of 17-AAG against Bcr-Abl+ leukemia cells. 17-AAG in combination with targeting small interfering RNAs (siRNAs) reduced Bcr-Abl protein levels, triggered increases in markers of apoptosis and decreased cell viability more effectively than did control siRNA and 17-AAG together, or Bcr-Abl targeting siRNA alone. Combination targeting strategies such as this may therefore achieve enhanced therapeutic potency.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2004

Induction of RNA interference in dendritic cells.

Dendritic cells (DC) reside at the center of the immunological universe, possessing the ability both to stimulate and inhibit various types of responses. Tolerogenic/regulatory DC with therapeutic properties can be generated through various means of manipulations in vitro and in vivo. Here we describe several attractive strategies for manipulation of DC using the novel technique of RNA interference (RNAi). Additionally, we overview some of our data regarding yet undescribed characteristics of RNAi in DC such as specific transfection strategies, persistence of gene silencing, and multi-gene silencing. The advantages of using RNAi for DC genetic manipulation gives rise to the promise of generating tailor-made DC that can be used effectively to treat a variety of immunologically mediated diseases.

Animals↗
PubMed2003

Use of RNA interference and complementation to study the function of the Drosophila and human 26S proteasome subunit S13.

The S13 subunit (also called Pad1, Rpn11, and MPR1) is a component of the 19S complex, a regulatory complex essential for the ubiquitin-dependent proteolytic activity of the 26S proteasome. To address the functional role of S13, we combined double-stranded RNA interference (RNAi) against the Drosophila proteasome subunit DmS13 with expression of wild-type and mutant forms of the homologous human gene, HS13. These studies show that DmS13 is essential for 26S function. Loss of the S13 subunit in metazoan cells leads to increased levels of ubiquitin conjugates, cell cycle defects, DNA overreplication, and apoptosis. In vivo assays using short-lived proteasome substrates confirmed that the 26S ubiquitin-dependent degradation pathway is compromised in S13-depleted cells. In complementation experiments using Drosophila cell lines expressing HS13, wild-type HS13 was found to fully rescue the knockdown phenotype after DmS13 RNAi treatment, while an HS13 containing mutations (H113A-H115A) in the proposed isopeptidase active site was unable to rescue. A mutation within the conserved MPN/JAMM domain (C120A) abolished the ability of HS13 to rescue the Drosophila cells from apoptosis or DNA overreplication. However, the C120A mutant was found to partially restore normal levels of ubiquitin conjugates. The S13 subunit may possess multiple functions, including a deubiquitinylating activity and distinct activities essential for cell cycle progression that require the conserved C120 residue.

Adenosine Triphosphate↗
PubMed2006

Survivin gene RNA interference inhibits proliferation, induces apoptosis, and enhances radiosensitivity in HeLa cells.

OBJECTIVE: Survivin is a new member of the inhibitors of apoptosis (IAPs) family. It is upregulated in various malignancies including human cervical carcinomas. Reduction of this molecule has resulted in chemosensitization, but it is uncertain whether it can lead to radiosensitization. We observed the effect of survivin gene RNA interference (RNAi) on the proliferation, apoptosis, and radiosensitivity of the human cervical carcinoma cells HeLa. STUDY DESIGN: Human cervical carcinoma cells (HeLa) were transfected with the specific siRNA expression vector (pSilencer2.1-s2) designed to target survivin mRNA. A corresponding site-mutated vector was constructed as a negative control (pSilencer2.1-NC). The expression of survivin mRNA and its protein among the stable transfected cells and the untransfected ones was detected by semi-quantitative RT-PCR and Western blotting respectively. The cell growth was examined by methyl thiazolyl tetrazolium (MTT) assay. The cell cycle distribution and cell apoptosis were measured by flow cytometry. The changes in cell radiosensitivity were observed by clonogenic survival assay. RESULTS: Three stable transfected cell lines: HeLa-s2 (with pSilencer2.1-s2), HeLa-NC (with pSilencer2.1-NC), and HeLa-U6 neo (with empty vector pSilencer2.1-U6 neo) were established. The expression levels of survivin gene mRNA and protein in HeLa-s2 were significantly lower than in HeLa-NC, HeLa-U6 neo, and those untransfected HeLa cells. The expression inhibitory rates were 62.8% and 60.1%. The cell proliferation of HeLa-s2 was inhibited, and the highest inhibitory rate was 57.8+/-2.1%. The changes in cell cycle distribution in HeLa-s2 compared with the other three cell lines were obvious, many cells were blocked in the G(0)/G(1) phase 72.7+/-3.1% (P<0.05), reduced sharply in the G(2)/M phase (5.1+/-2.9)% (P<0.05), and also the apoptotic rate was 29.2+/-1.4%, obviously increasing (P<0.05). At the same dose of radiation, the cloning efficiency of HeLa-s2 declined notably (P<0.05); the cell survival curve showed a significant decrease in D(0) and D(q), which were 3.15 and 1.21, respectively (P<0.05), and the radiation enhancement ratios were 2.01 (a ratio of D(0)) and 1.77 (a ratio of D(q)). CONCLUSIONS: Survivin gene RNAi not only could inhibit the proliferation of human cervical carcinoma cells (HeLa), but also could significantly enhance the radiosensitivity of those cells through the reduction of its mRNA and protein. Therefore, an RNAi-targeted survivin gene strategy would be a potential approach to radiosensitization therapy in human cervical carcinomas.

Apoptosis↗
PubMed2001

RNA interference is mediated by 21- and 22-nucleotide RNAs.

Double-stranded RNA (dsRNA) induces sequence-specific posttranscriptional gene silencing in many organisms by a process known as RNA interference (RNAi). Using a Drosophila in vitro system, we demonstrate that 21- and 22-nt RNA fragments are the sequence-specific mediators of RNAi. The short interfering RNAs (siRNAs) are generated by an RNase III-like processing reaction from long dsRNA. Chemically synthesized siRNA duplexes with overhanging 3' ends mediate efficient target RNA cleavage in the lysate, and the cleavage site is located near the center of the region spanned by the guiding siRNA. Furthermore, we provide evidence that the direction of dsRNA processing determines whether sense or antisense target RNA can be cleaved by the siRNA-protein complex.

Animals↗