Small interference RNA (siRNA) is a class of short double-stranded RNA molecules that cause mRNA degradation through an RNA interference mechanism and is a promising therapeutic modality. RBD1016 is a siRNA drug in clinical development for the treatment of chronic Hepatitis B Virus (HBV) infection, which contains a conjugated with N-acetylglucosamine moiety that can facilitate its hepatic delivery. We aimed to construct a semi-mechanistic model of RBD1016 in pre-clinical animals, to elucidate the pharmacokinetic/pharmacodynamic (PK/PD) profiles in mice and PK profiles in monkeys, which can lay the foundation for potential future translation of RBD1016 PK and PD from the pre-clinical stage to the clinic stage. The proposed semi-mechanistic PK/PD model fitted PK and PD data in HBV transgenic mice well and described plasma and liver concentrations in the monkeys well. The simulation results showed that our model has a reasonable predictive ability for Hepatitis B surface antigen (HBsAg) levels after multiple dosing in mice. Further PK and PD data for RBD1016, including clinical data, will assist in refining the model presented here. Our current effort focused on model building for RBD1016, we anticipate that the model could apply to other GalNAc-siRNA drugs.

Insect-specific virus (ISV) is one of the most promising agents for the biological control of insects, which is abundantly distributed in hematophagous insects. However, few ISVs have been reported in Riptortus pedestris (Fabricius), one of the major pests threatening soybeans and causing great losses in yield and quality. In this work, field Riptortus pedestris was collected from six soybean-producing regions in China, and their virome was analyzed with the metatranscriptomic approach. Altogether, seven new insect RNA viruses were identified, three of which had complete RNA-dependent RNA polymerase (RdRp) and nearly full-length genome sequences, which were named Riptortus pedestris alphadrosrha-like virus 1 (RpALv1), Riptortus pedestris alphadrosrha-like virus 2 (RpALv2) and Riptortus pedestris almendra-like virus (RiALv). The three identified novel ISVs belonged to the family Rhabdoviridae, and phylogenetic tree analysis indicated that they were clustered into new distinct clades. Interestingly, the analysis of virus-derived small-interfering RNAs (vsiRNAs) indicated that only RiALv-derived siRNAs exhibited 22 nt length preference, whereas no clear 21 or 22 nt peaks were observed for RpALv1 and RpALv2, suggesting the complexity of siRNA-based antiviral immunity in R. pedestris. In conclusion, this study contributes to a better understanding of the microenvironment in R. pedestris and provides viral information for the development of potential soybean insect-specific biocontrol agents.

Rheumatoid arthritis (RA) is a common clinical inflammatory disease of the autoimmune system manifested by persistent synovitis, cartilage damage and even deformities. Despite significant progress in the clinical treatment of RA, long-term administration of anti-rheumatic drugs can cause a series of problems, including infections, gastrointestinal reactions, and abnormal liver and kidney functions. The emergence of RNA interference (RNAi) drugs has brought new hope for the treatment of RA. Designing a reasonable vector for RNAi drugs will greatly expand the application prospects of RNAi. Nanoparticles as a promising drug carrier provide reliable support for RNAi drugs. The review summarizes the pathogenesis of RA as a possible target for small interference RNA (siRNA) design. At the same time, the review also analyzes the nanoparticles used in siRNA carriers in recent years, laying the foundation and prospect for the next step in the development of intelligent nanocarriers.

Negeviruses are a proposed group of insect-specific viruses that can be separated into two distinct phylogenetic clades, Nelorpivirus and Sandewavirus. Negeviruses are well-known for their wide geographic distribution and broad host range among hematophagous insects. In this study, the full genomes of two novel negeviruses from each of these clades were identified by RNA extraction and sequencing from a single dungfly (Scathophaga furcata) collected from the Arctic Yellow River Station, where these genomes are the first negeviruses from cold zone regions to be discovered. Nelorpivirus dungfly1 (NVD1) and Sandewavirus dungfly1 (SVD1) have the typical negevirus genome organization and there was a very high coverage of viral transcripts. Small interfering RNAs derived from both viruses were readily detected in S. furcata, clearly showing that negeviruses are targeted by the host antiviral RNA interference (RNAi) pathway. These results and subsequent in silico analysis (studies) of public database and published virome data showed that the hosts of nege-like viruses include insects belonging to many orders as well as various non-insects in addition to the hematophagous insects previously reported. Phylogenetic analysis reveals at least three further groups of negeviruses, as well as several poorly resolved solitary branches, filling in the gaps within the two sub-groups of negeviruses and plant-associated viruses in the Kitaviridae. The results of this study will contribute to a better understanding of the geographic distribution, host range, evolution and host antiviral immune responses of negeviruses.

Objective:To study the relationship between transcription factor Snail and the sensitivity of cisplatin on human laryngeal resistant cancer cells.Method:siRNA interference of Snail was transfected by small RNA interference technology. The interference efficiency on mRNA level were detected by RT-qPCR assay; the expression of Snail protein level was assessed by immunofluorescence. The inhibition ratio of different cisplatin concentration (0, 1, 2, 4, 8, 16 μg/ml) was detected by CCK-8 assay; the protein level of Snail, E-cadherin, MDR1were detected by Western blot assay.Result:RT-qPCR assay show the expression of Snail on mRNA level was decreased to (67.85±9.50)% after transfection in Hep-2/CDDP cell(P<0.05). Immunofluorescence show fluorescence intensity of si-Hep-2/CDDP group was reduced both in nucleus and cytoplasm; CCK-8 assay show the inhibitory ratio of transfected group was increased compared to negative control and Hep-2/CDDP group in different cisplatin concentration (0, 1, 2, 4, 8, 16 μg/ml) (P<0.05). Western blot assay show the protein expression of Snail and MDR1 were down-regulated in transfected Hep-2/CDDP cells (allP<0.05), while epithelial marker E-cadherin was up-regulated in protein level (P<0.05).Conclusion:Small interference of transcription factor Snail could increase the expression of E-cadherin while decrease the expression of MDR1, and it was confirmed that interference Snail contribute to enhanced cisplatin sensitivity on human laryngeal resistant cancer cells.

Although radiotherapy remains the most powerful as well as the primary treatment modality for nasopharyngeal carcinoma (NPC), approximately 20% of NPC patients still have local recurrence. Carbonic anhydrase IX (CAIX)-related signaling pathways that mediate radioresistance have been found in various kinds of cancer. However, the role of CAIX in NPC radioresistance is still unknown. In this study, we investigated the effect of CAIX silencing on sensitization to ionizing radiation in NPC by using Lipofectamine 2000, which delivers small interfering ribonucleic acid (siRNA) that targets CAIX. Results showed that Lipofectamine 2000 effectively delivered siRNA into the CNE-2 cells, which resulted in the decrease of CAIX expression and cell viability, decrease in cell proliferation and colony formation, and increase in the number of CNE-2 cells stuck in the G2/M phase of the cell cycle upon induction of ionizing radiation. Increased sensitivity of radiotherapy in CNE-2 cells under hypoxic conditions was correlated with the suppression of CAIX. Cells treated with irradiation in addition to CAIX-siRNA1 demonstrated reduced radiobiological parameters (survival fraction at 2 Gy [SF2]) compared with those treated with irradiation only, with a sensitization-enhancing ratio of 1.47. These findings suggest that CAIX can be a promising therapeutic target for the treatment of radioresistant human NPC.

OBJECTIVE: To explore angiogenesis in osteosarcoma under the condition of hypoxia-inducible factor (HIF)-1α gene silenced by small interference RNA (siRNA).
METHODS: The SaOS-2 osteosarcoma cells, transfected with the recombinant plasmid pSilencer2.1-HIF-1α or pSilencer2.1-SCR, were classified as HIF-1α/siRNA group or SCR/siRNA group, respectively. In which, vascular endothelial growth factor (VEGF) immunohistochemistry were performed. HIF-1α and VEGF protein contents were detected by western blot. Gene expressions of HIF-1α and VEGF were quantified by qPCR. Then the transfected SaOS-2 cells were inoculated in nude mice and transplantation tumor were checked via HE staining, VEGF and CD34 immunohistochemistry, and calculation of microvascular density (MVD).
RESULTS: In vitro, VEGF immunohistochemistry stains, HIF-1α and VEGF protein contents, and the relative expressions of HIF-1α mRNA and VEGF mRNA in HIF-1α/siRNA group were obviously reduced. In vivo, morphological observation illustrated that heteromorphism were not obvious in the cells of HIF-1α/siRNA group and vascular systems were sparse in its transplantation tumor tissue, and immunohistochemistry revealed that both VEGF and CD34 stains were significantly decreased in HIF-1α/siRNA group, and MVD in HIF-1α/siRNA group (7.3±1.1) were obviously less than that in SCR/siRNA group (17.2±3.2) (P<0.05).
CONCLUSIONS: Angiogenesis in osteosarcoma can be inhibited by siRNA-mediated HIF-1α gene silencing, which is expected to provide a novel and attractive target of therapeutic strategies of osteosarcoma.

Gene therapy is a prospective strategy to modulate gene expression level in specific cells to treat human inherited diseases, cancers, and acquired disorders. A subset of noncoding RNAs, microRNAs (miRNAs) and small interference RNAs (siRNAs), compose an important class of widely used effectors for gene therapy, especially in cancer treatment. Functioning through the RNA interference (RNAi) mechanism, miRNA and siRNA show potent ability in silencing oncogenic factors for cancer gene therapy. For a better understanding of this field, we reviewed the mechanism and biological function, the principles of design and synthesis, and the delivery strategies of noncoding RNAs with clinical potentials in cancer gene therapy.

OBJECTIVE: To investigate the impact of silencing of the PTEN gene using siRNA on the invasion, proliferation, cell cycle, and epithelial-mesenchymal transition of the Tca8113 cell line.
METHODS: The established Tca8113 cell model with siRNA interference to silence the PTEN gene was used. The transfection efficiency was examined by RT-qPCR and Western blot analysis. CCK-8 assay was utilized to analyze the proliferation of Tca8113 cells and cell invasion was evaluated using a transwell assay. The cell cycle distribution was analyzed by flow cytometry. The protein expression levels of the epithelial-mesenchymal transition (EMT) markers E-cadherin and Vimentin and the EMT-related proteins β-catenin and TGF-β1 were analyzed by Western blot.
RESULTS: The expression level of PTEN was significantly reduced in the PTEN-siRNA group. The invasiveness and proliferation rate of Tca8113 cells in the PTEN-siRNA group were significantly greater than those of the control and negative control groups. The expression levels of E-cadherin and β-catenin were reduced, whereas the expression levels of vimentin and TGFβ-1 were elevated in the PTEN-siRNA group compared with those of control and negative groups. These results were significantly different.
CONCLUSIONS: The silencing of PTEN by siRNA increased the proliferation and promoted cell invasion of Tca8113 cells. PTEN gene silencing may accelerate the EMT in Tca8113 cells.

OBJECTIVE: Up-regulation of clusterin is associated with the survival and progression of various malignancies, and down-regulation of clusterin promotes apoptosis and inhibits invasion. The aim of this study was to explore the effect of clusterin small interference RNA (siRNA) on the proliferation, apoptosis and invasion of HL-60 acute myeloid leukemia (AML) cells.
METHODS: siRNA transfection was performed using Lipofectamine™2000 reagent. Relative protein expressions were quantified by Western blot. Trypan blue assay was performed to assess tumor cell proliferation after siRNA transfection. The cytotoxic effect of clusterin siRNA on leukemic cells was measured using MTT assay. Apoptosis was detected using fluorescence microscopy assay. Migration and invasion was detected after clusterin was silenced.
RESULTS: Clusterin siRNA clearly lowered clusterin protein levels in a time- dependent manner, leading to marked inhibition of cell survival, proliferation and invasion. Furthermore, clusterin down-regulation significantly enhanced the extent of HL-60 apoptotic cells.
CONCLUSIONS: Our results suggest that the down-regulation of clusterin by siRNA can effectively trigger apoptosis and inhibit the proliferation and invasion of leukemic cells. Therefore, clusterin siRNA may be a potent adjuvant in AML therapy.