Inhibition of genes expression of SARS coronavirus by synthetic small interfering RNAs

RNA interference (RNAi) is triggered by the presence of a double-stranded RNA (dsRNA), and results in the silencing of homologous gene expression through the specific degradation of an mRNA containing the same sequence. dsRNAmediated RNAi can be used in a wide variety of eucaryotes to induce the sequence-specific inhibition of gene expression.Synthetic 21-23 nucleotide (nt) small interfering RNA (siRNA) with 2 nt 3' overhangs was recently found to mediate efficient sequence-specific mRNA degradation in mammalian cells. Here, we studied the effects of synthetic siRNA duplexes targeted to SARS coronavirus structural proteins E, M, and N in a cell culture system. Among total 26 siRNA duplexes, we obtained 3 siRNA duplexes which could sequence-specifically reduce target genes expression over 80％ at the concentration of 60 nM in Vero E6 cells. The downregulation effect was in correlation with the concentrations of the siRNA duplexes in a range of 0～60 nM. Our results also showed that many inactive siRNA duplexes may be brought to life simply by unpairing the 5' end of the antisense strands. Results suggest that siRNA is capable of inhibiting SARS coronavirus genes expression and thus may be a new therapeutic strategy for treatment of SARS.

Combination of small interfering RNAs mediates greater suppression on hepatitis B virus cccDNA in HepG2.2.15 cells

AIM： To observe the inhibition of hepatitis B virus （HBV） replication and expression in HepG2.2.15 cells by combination of small interfering RNAs （siRNAs）. METHODS： Recombinant plasmid psiI-HBV was constructed and transfected into HepG2.2.15 cells. At 48 h, 72 h and 96 h after transfection, culture media were collected and cells were harvested for HBV replication assay. HBsAg and HBeAg in the cell culture medium were detected by enzyme-linked immunoadsorbent assay （ELISA）. Intracellular viral DNA and covalently closed circular DNA （cccDNA） were quantified by real-time polymerase chain reaction （PCR）. HBV viral mRNA was reverse transcribed and quantified by reverse-transcript PCR （RT-PCR）. RESULTS： siRNAs showed marked anti-HBV effects. siRNAs could specifically inhibit the expression of HBsAg and the replication of HBV DNA in a dosedependent manner. Furthermore, combination of siRNAs, compared with individual use of each siRNA, exerted a stronger inhibition on antigen expression and viral replication. More importantlycombination of siRNAs significantly suppressed HBV cccDNA amplification. CONCLUSION： Combination of siRNAs mediates a stronger inhibition on viral replication and antigenexpression in HepG2.2.15 cells, especially on cccDNA amplification.

KNOCKDOWN OF SURVIVIN EXPRESSION BY SMALL INTERFERING RNA SUPPRESSES PROLIFERATION OF TWO HUMAN CANCER CELL LINES

Objective To construct an expression vector of small interfering RNA （siRNA） against survivin and observe its effects on survivin expression and proliferation of human pancreatic cancer cell line PC-2 and breast cancer cell line MCF-7. Methods Constructed an expression vector of siRNA against survivin and transfected it into PC-2 and MCF-7 cells using lipofectamine^TM 2000. The expression of survivin was detected by semi-quanfifive RT-PCR and immunohistochemistry, and its effects on proliferation of PC-2 and MCF-7 cells were detected by MTT assay. Results The introduction of sequence-specific siRNA could efficiently suppress survivin expression at both mRNA and protein levels in the two cancer cell lines. In PC-2 cells, the expression inhibition rates were 81.25% at mRNA level and 74.24% at protein level In MCF-7 cells, the expression inhibition rates were 64.91% at mRNA level and 79. 72% at protein level The proliferation of PC-2 and MCF-7 cells was also suppressed, and24 and 48 hours after the cells were reseeded, the proliferation inhibition rates of PC-2 cells were 28. 00% and 33. 38%, and that of MCF-7 cells were 31.58% and 33.02%, respectively. Conclusions The expression vector of siRNA against survivin can block survivin expression in PC-2 and MCF-7 cells efficiently and specifically. Down regulation of survivin expression can suppress proliferation of PC-2 and MCF-7 cells. Survivin RNAi may have potential value in gene therapy of human cancers.

Progress of Targeting Transforming Growth Factor-β1 Small Interfering RNA in Liver Fibrosis

Liver fibrosis is a common pathological consequence of a variety of chronic stimuli, including viral, autoimmune, drug-induced, cholestatic and metabolic diseases. Fibrosis is driven by a dynamic process involving increased synthesis of matrix components and a failure of physiological mechanisms of matrix turnover. Activation of hepatic stellate cells(HSCs) remains a central event in fibrosis. HSCs are the main source of extracellular matrix(ECM). Transforming growth factor-beta(TGF-β), which is the fibrogenic master cytokine, can induce the activation of HSCs to produce a large amount of ECM, and is capable of inducing apoptosis of liver cells. RNA interference(RNAi) is a novel gene disruption technology. Studies have shown that small interfering RNA(si RNA) targeting TGF-β1 may inhibit the activation and proliferation of HSCs, suppress ECM synthesis and block liver fibrosis. TGF-β1 si RNA-mediated gene silencing therapy provides a new avenue for liver fibrosis. This review summarizes recent progresses in research on HSCs, TGF-β1 and TGF-β1 si RNA in liver fibrosis.

Small interfering RNA targeting PGC-1α inhibits VEGF expression and tube formation in human retinal vascular endothelial cells

AIMTo determine whether small interfering RNA (siRNA) of PGC-1α could inhibit vascular endothelial growth factor (VEGF) expression and tube formation in human retinal vascular endothelial cells (hRVECs).METHODShRVECs transfected with peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) siRNA were incubated for 24h and then placed into a normoxic (20%, O2) or hypoxic (1%, O2) environment for another 16h. PGC-1α mRNA and protein levels were detected by real-time PCR and Western blot. VEGF mRNA and protein levels were detected by real-time PCR and ELISA. Cell proliferation was evaluated by BrdU incorporation assay. Forty-eight hours after siRNA transfection, hRVECs were planted into Matrigel-coated plates and cultured under normoxic (20%, O2) or hypoxic (1%, O2) conditions for another 48h. The tube formation of hRVECs was observed under an optical microscope and quantified by counting the number of branch points and calculating the total tube length.RESULTSPGC-1α mRNA and protein levels were significantly reduced by PGC-1α siRNA, and VEGF mRNA and protein levels also decreased significantly. The percentage of BrdU-labeled cells in siPGC-1α groups were significantly decreased compared with control siRNA groups under normoxia and hypoxia in cell proliferation assay. In the tube formation assay, PGC-1α siRNA treated cells formed significantly fewer tubes.CONCLUSIONBlocking PGC-1α expression can inhibit VEGF expression in hRVECs and inhibit their ability to form tubes under both normoxic and hypoxic conditions.

Impact of Bovine Skeletal Muscle Satellite Cell Differentiation by Small Interfering RNA Targeting Myogenin Gene

To examine the effect of myogenin gene on the differentiation of bovine skeletal muscle satellite cell, we constructed small interfering RNA plasmid vector to obtain myogenin knockdown bovine skeletal muscle cells, then used cell transfection, real time RCR and Western Blot to detect the influence of myogenin to cell differentiation. Results showed that the knockdown of myogenin significantly decreased its expression and other muscle-specific genes. Compared to the control, it could differentiate into few myotubes when challenged by low serum in the medium. These findings provided an important theoretical basis for further explore of the genetic mechanism in adult skeletal muscle, the remedy of muscle injuries and the cultivation of high-yield transgenic cattle.

Effects of Small Interfering RNATargeting Sphingosine Kinase-1 Gene on the Animal Model of Alzheimer's Disease

Summary： Alzheimer＇s disease （AD） is an age-related, progressive neurodegenerative disorder that occurs gradually and results in memory, behavior, and personality changes. Abnormal sphingolipid metabolism was reported in AD previously. This study aimed to investigate whether sphK1 could exacerbate the accumulation of amyloid protein （Aβ） and sharpen the learning and memory ability of the animal model of AD using siRNA interference. An adenovirus vector expressing small interfering RNA （siRNA） against the sphK1 gene （sphKl-siRNA） was designed, and the effects of sphKl-siRNA on the APP/PS1 mouse four weeks after treatment with sphKl-siRNA hippocampal injection were examined. SphK1 protein expression was confirmed by using Western blotting and ceramide content coupled with SIP secretion was evaluated by enzyme-linked immunosorbent assay （ELISA）. Aβ load was detected by immunohistochemical staining and ELISA. Morris water maze was adopted to test the learning and memory ability of the APP/PS 1 mice. A significant difference in the expression of sphK1 protein and mRNA was observed between the siRNA group and the control group. Aβ load in transfected mice was accelerated in vivo, with significant aggravation of the learn- ing and memory ability. The sphKl gene modulation in the All load and the learning and memory ability in the animal model of AD may be important for the treatment of AD.

The influence of small interfering RNA on the expression of Survivin in human glioma cells

Objective This study aims to investigate the feasibility of knockdown of Survivin gene with small interfering RNA and to observe the apoptosis in gliomas which is influenced by siRNA. Methods Survivin specific siRNA oligonucleotides were designed and synthesized artificially. This siRNA

Small RNA- and DNA-based gene therapy for the treatment of liver cirrhosis, where we are?

Chronic liver diseases with different aetiologies rely on the chronic activation of liver injuries which result in a fibrogenesis progression to the end stage of cirrhosis and liver failure.Based on the underlying cellular and molecular mechanisms of a liver fibrosis,there has been proposed several kinds of approaches for the treatment of liver fibrosis.Recently,liver gene therapy has been developed as an alternative way to liver transplantation,which is the only effective therapy for chronic liver diseases.The activation of hepatic stellate cells,a subsequent release of inflammatory cytokines and an accumulation of extracellular matrix during the liver fibrogenesis are the major obstacles to the treatment of liver fibrosis.Several targeted strategies have been developed,such as antisense oligodeoxynucleotides,RNA interference and decoy oligodeoxynucleotides to overcome this barriers.With this report an overview will be provided of targeted strategies for the treatment of liver cirrhosis,and particularly,of the targeted gene therapy using short RNA and DNA segments.

Uncovering Small RNAs in Penicillium digitatum by Transcriptome Sequencing

Small RNAs in Penicillium digitatum were identified and analyzed via transcriptome sequencing on the BGISEQ-500 platform. A total of 15 predicted miRNAs and 10718 novel siRNAs were found. Their length distribution, sequence, predicted construction, base bias, expression levels and potential targets were determined as well. Through pathway and KEGG enrichment analysis, the miRNA target genes were mostly involved in carbohydrate metabolism, transport and catabolism, translation and amino acid metabolism. The target genes involved in aflatoxin biosynthesis and proteasome had a higher rich factor value. The results will provide a theoretical foundation for understanding the developmental and pathogenic mechanisms of P. digitatum at the transcriptional level.

Remodeling the tumor immune microenvironment via siRNA therapy for precision cancer treatment

How to effectively transform the pro-oncogenic tumor microenvironments(TME)surrounding a tumor into an anti-tumoral never fails to attract people to study.Small interfering RNA(siRNA)is considered one of the most noteworthy research directions that can regulate gene expression following a process known as RNA interference(RNAi).The research about siRNA delivery targeting tumor cells and TME has been on the rise in recent years.Using siRNA drugs to silence critical proteins in TME was one of the most efficient solutions.However,the manufacture of a siRNA delivery system faces three major obstacles,i.e.,appropriate cargo protection,accurately targeted delivery,and site-specific cargo release.In the following review,we summarized the pharmacological actions of siRNA drugs in remolding TME.In addition,the delivery strategies of siRNA drugs and combination therapy with siRNA drugs to remodel TME are thoroughly discussed.In the meanwhile,the most recent advancements in the development of all clinically investigated and commercialized siRNA delivery technologies are also presented.Ultimately,we propose that nanoparticle drug delivery siRNA may be the future research focus of oncogene therapy.This summary offers a thorough analysis and roadmap for general readers working in the field.

Small RNA Interference-mediated Gene Silencing of TREK-1 Potassium Channel in Cultured Astrocytes

This study was aimed to examine the effect of TREK-1 silencing on the function of astrocytes. Three 21-nucleotide small interfering RNA (siRNA) duplexes (siT1, siT2, siT3) targeting TREK-1 were constructed. Cy3-labeled dsRNA oligmers were used to determine the transfection efficiency in cultured astrocytes. TREK-1-specific siRNA duplexes (siT1, siT2, siT3) at the optimal concentration were transfected into cultured astrocytes, and the most efficient siRNA was identified by the method of immunocytochemical staining and Western blotting. The proliferation of astrocytes tranfected with TREK-1-targeting siRNA under hypoxia condition was measured by fluorescence-activated cell sorting (FACS). The results showed that TREK-1 was expressed in cultured astrocytes. The dsRNA oligmers targeting TREK-1 could be transfected efficiently in cultured astrocytes and down-regulate the expression of TREK-1 in astrocytes. Moreover, the down-regulation of TREK-1 in astrocytes contributed to the proliferation of astrocytes under hypoxia condition as determined by cell cycle analysis. It was concluded that siRNA is a powerful technique that can be used to knockdown the expression of TREK-1 in astrocytes, which helps further investigate the function of TREK-1 channel in astrocytes under physicological and pathological condition.

Transplantation of human placental chorionic plate-derived mesenchymal stem cells for repair of neurological damage in neonatal hypoxic-ischemic encephalopathy

Neonatal hypoxic-ischemic encephalopathy is often associated with permanent cerebral palsy,neurosensory impairments,and cognitive deficits,and there is no effective treatment for complications related to hypoxic-ischemic encephalopathy.The therapeutic potential of human placental chorionic plate-derived mesenchymal stem cells for various diseases has been explored.However,the potential use of human placental chorionic plate-derived mesenchymal stem cells for the treatment of neonatal hypoxic-ischemic encephalopathy has not yet been investigated.In this study,we injected human placental chorionic plate-derived mesenchymal stem cells into the lateral ventricle of a neonatal hypoxic-ischemic encephalopathy rat model and observed significant improvements in both cognitive and motor function.Protein chip analysis showed that interleukin-3 expression was significantly elevated in neonatal hypoxic-ischemic encephalopathy model rats.Following transplantation of human placental chorionic plate-derived mesenchymal stem cells,interleukin-3 expression was downregulated.To further investigate the role of interleukin-3 in neonatal hypoxic-ischemic encephalopathy,we established an in vitro SH-SY5Y cell model of hypoxic-ischemic injury through oxygen-glucose deprivation and silenced interleukin-3 expression using small interfering RNA.We found that the activity and proliferation of SH-SY5Y cells subjected to oxygen-glucose deprivation were further suppressed by interleukin-3 knockdown.Furthermore,interleukin-3 knockout exacerbated neuronal damage and cognitive and motor function impairment in rat models of hypoxic-ischemic encephalopathy.The findings suggest that transplantation of hpcMSCs ameliorated behavioral impairments in a rat model of hypoxic-ischemic encephalopathy,and this effect was mediated by interleukin-3-dependent neurological function.

Suppression of matrix metalloproteinase-2 via RNA interference inhibits pancreatic carcinoma cell invasiveness and adhesion

AIM:To investigate the inhibitory effects of RNA interference (RNAi) on expression of matrix metalloproteinase-2 (MMP-2) gene and invasiveness and adhesion of human pancreatic cancer cell line,BxPC-3.METHODS:RNAi was performed using the vector (pGPU6)-based small interference RNA (siRNA) plasmid gene silence system to specifically knock down MMP-2 expression in pancreatic cancer cell line,BxPC-3. Four groups of different specific target sequence in coding region of MMP-2 and one non-specific sequence were chosen to construct four experimental siRNA plasmids of pGPU6-1,pGPU6-2,pGPU6-3 and pGPU6-4,and one negative control siRNA plasmid of pGPU6 (-). MMP-2 expression was measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Cell proliferation and apoptosis were examined by methyl thiazolyl tetrazolium (MTT) and flow cytometry,respectively. The abilities of adhesion and invasion were detected by cell adhesion assay and cell invasion assay using Transwell chambers.RESULTS:The expression of MMP-2 was inhibited and the inhibitory effects of different sequence varied. pGPU6-1 group had the most efficient inhibitory effect,followed by pGPU6-2 and pGPU6-3 groups.Invasiveness and adhesion were more significantly reduced in pGPU6-1,pGPU6-2 and pGPU6-3 groups as compared with pGPU6 (-) and blank control groups. However,no difference concerning cell proliferation and apoptosis was observed after transfection between experiment groups and control groups.CONCLUSION:RNAi against MMP-2 successfully inhibited the mRNA and protein expression of MMP-2 in the pancreatic cancer cell line,BxPC-3,leading to a potent suppression of tumor cell adhesion and invasion without affecting cell proliferation and apoptosis. These findings suggest that the RNAi approach towards MMP-2 may be an effective therapeutic strategy for the clinical management of pancreatic tumor.

Non-coding RNAs and gastric cancer

Non-coding RNAs(ncRNAs)play key roles in development,proliferation,differentiation and apoptosis.Altered ncRNA expression is associated with gastric cancer occurrence,invasion,and metastasis.Moreover,aberrant expression of microRNAs(miRNAs)is significantly related to gastric cancer tumor stage,size,differentiation and metastasis.MiRNAs interrupt cellular signaling pathways,inhibit the activity of tumor suppressor genes,and affect the cell cycle in gastric cancer cells.Some miRNAs,including miR-21,miR-106a and miR-421,could be potential markers for the diagnosis of gastric cancer.Long non-coding RNAs (lncRNAs),a new research hotspot among cancerassociated ncRNAs,play important roles in epigenetic,transcriptional and post-transcriptional regulation.Several gastric cancer-associated lncRNAs,such as CCAT1,GACAT1,H19,and SUMO1P3,have been explored.In addition,Piwi-interacting RNAs,another type of small ncRNA that is recognized by gastroenterologists,are involved in gastric carcinogenesis,and piR-651/823represents an efficient diagnostic biomarker of gastric cancer that can be detected in the blood and gastric juice.Small interfering RNAs also function in posttranscriptional regulation in gastric cancer and might be useful in gastric cancer treatment.

siRNA, miRNA and HIV: promises and challenges

Small interfering RNA (siRNA) and microRNA (miRNA) are small RNAs of 18-25 nucleotides (nt) in length that play important roles in regulating gene expression. They are incorporated into an RNA-induced silencing complex (RISC) and serve as guides for silencing their corresponding target mRNAs based on complementary base-pairing. The promise of gene silencing has led many researchers to consider siRNA as an anti-viral tool. However, in long-term settings, many viruses appear to escape from this therapeutical strategy. An example of this may be seen in the case of human immunodeficiency virus type-1 (HIV-1) which is able to evade RNA silencing by either mutating the siRNA- targeted sequence or by encoding for a partial suppressor of RNAi (RNA interference). On the other hand, because miRNA targeting does not require absolute complementarity of base-pairing, mutational escape by viruses from miRNA- specified silencing may be more difficult to achieve. In this review, we discuss stratagems used by various viruses to avoid the cells’ antiviral si/mi-RNA defenses and notions of how viruses might control and regulate host cell genes by encoding viral miRNAs (vmiRNAs).

Effect of siRNAs on HSV-1 Plaque Formation and Relative Expression Levels of RR mRNA

RNA interference (RNAi) is a process by which introduced small interfering RNA (siRNA) can cause the specific degradation of mRNA with identical sequences. The human herpes simplex virus type 1 (HSV-1) RR is composed of two distinct homodimeric subunits encoded by UL39 and UL40,respectively. In this study,we applied siRNAs targeting the UL39 and UL40 genes of HSV-1. We showed that synthetic siRNA silenced effectively and specifically UL39 and UL40 mRNA expression and inhibited HSV-1 replication. Our work offers new possibilities for RNAi as a genetic tool for inhibition of HSV-1 replication.

Oxygen-glucose deprivation of neurons transfected with toll-like receptor 3-siRNA Determination of an optimal transfection sequence

Toll-like receptor 3 protein expression has been shown to be upregulated during cerebral ische- mia/reperfusion injury in rats. In this study, rat primary cortical neurons were subjected to oxy- gen-glucose deprivation to simulate cerebral ischemia/reperfusion injury. Chemically synthesized small interfedng RNA （siRNA）-1280, -1724 and -418 specific to toll-like receptor 3 were transfected into oxygen-glucose deprived cortical neurons to suppress the upregulation of toll-like receptor 3 protein expression. Western blotting demonstrated that after transfection with siRNA, toll-like re- ceptor 3 protein expression reduced, especially in the toll-like receptor 3-1724 group. These results suggested that siRNA-1724 is an optimal sequence for inhibiting toll-like receptor 3 expression in cortical neurons following oxygen-glucose deprivation.

Effects of RNA Interference Combined with Ultrasonic Irradiation and SonoV ue Microbubbles on Expression of STAT3 Gene in Keratinocytes of Psoriatic Lesions

The most effective sequence of small interfering RNA（si RNA） silencing STAT3 of psoriatic keratinocytes（KCs） was screened out,and the effects of the most effective si RNA combined with ultrasonic irradiation and Sono Vue microbubbles on the expression of STAT3 of KCs and the dose-and time-response were investigated.Three chemically-synthetic si RNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs,and the effects on STAT3 expression were detected,then the most effective si RNA was selected for the subsequent experiments.The negative controls of siR NA（si RNA-NC） labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and Sono Vue microbubbles were transfected into KCs,then the optimal parameters of ultrasonic irradiation were determined.The most effective si RNA carried by Lipofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and Sono Vue microbubbles was transfected into KCs,and the dose-and time-response of RNA interference was determined.The effect of RNA interference by the most effective si RNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and Sono Vue microbubbles（LUS group） was compared with that only carried by Lipofectamine 3000（L group）.The results showed that si RNA-3 achieved the highest silencing efficacy.0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation.The si RNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and Sono Vue microbubbles could effectively knock down the STAT3 expression at m RNA and protein levels in dose-and time-dependent manners determined at 100 nmol/L with maximum downregulation on m RNA at 48 h,and on protein at 72 h after transfection.The LUS group achieved the highest silencing efficacy.It was concluded that si RNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoV ue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs,and the optimized transfection condition and the sequence of si RNA-3 could serve for further research on gene therapy of psoriasis.

Amelioration of β^(654)-thalassemia in mouse model with the knockdown of aberrantly spliced β-globin mRNA

Large amounts of aberrantly spliced mRNA from the β^654 allele was present in erythroid cells, which might impair the erythropoiesis. A therapeutic strategy for β-thalassemia was explored by knocking down the aberrantly spliced mRNA of β-globin. Lentiviral vector with siRNA fragment targets on the specific portion of β^654-globin aberrantly spliced pre-mRNA was constructed. In HeLa β^654 cells, the siRNA vector could reduce approximately 60% of aberrantly spliced mRNA, which was assessed by RT-PCR and qRT-PCR. Furthermore, a disease model of β^654 thalassemia mice with lentiviral-mediated siRNA was produced by subzonal injection （named Hβi-Hbb^th-4/Hbb^＋ transgenic mice）. Our results showed that the hemotological parameters were improved in Hβi-Hbb^th-4/Hbb^＋ transgenic mice. This study provides a potential way for β^654-thalassemia therapy by knocking down the aberrantly spliced β-globin mRNA, whilst supporting that the aberrantly spliced β-globin mRNA may aggravate the disease.