Recent progress of the aptamer-based antiviral drugs / 药学学报

Aptamers are capable of binding a wide range of biomolecular targets with high affinity and specificity. It has been widely developed for diagnostic and therapeutic purposes. Because of unique three dimensional structures and cell-membrane penetration, aptamers inhibit virus infection not only through binding specific target, such as the viral envelope, genomic site, enzyme, or other viral components, but also can be connected to each other or with siRNA jointly achieve antiviral activity. Taking human immunodeficiency virus and hepatitis C virus as examples, this paper reviewed the effects and mechanisms of aptamers on disturbing viral infection and replication steps. It may provide an insight to the development of aptamer-based new antiviral drugs.

Selection and anti-cancer effects of siRNAs targeting Hmga2 gene / 药学学报

High mobility group A2 protein (HMGA2), an architectural factor, is highly expressed in various cancer types including lung cancers. It is a candidate target for cancer therapy. RNAi is an effective gene silencing method with low cost and less time-consuming. It is possible to exploit this technology in therapy. Here, 5 siRNAs targeting Hmga2 gene (HMGA2 siRNA1-5) were designed and synthesized. MTT assay, colony formation assay, transwell assay and flow cytometry were used to evaluate the effects of these siRNAs on lung cancer cell lines (NCI-H446 and A549). Results from cell proliferation, clone formation, migration and apoptosis showed that HMGA2 siRNA1, 3, 5 could affect these aspects for both lung cancer cell lines. Among the five siRNAs, HMGA2 siRNA5 showed the greatest inhibition effects. The inhibition effects of HMGA2 siRNA5 are sequence specific and are not due to the induction of interferon response. Taken together, siRNAs targeting Hmga2 gene are potential candidates for lung cancer gene therapy.

Recombinant adeno-associated virus vector related impurities / 生物工程学报

Recombinant adeno-associated virus (rAAV)-based vectors that can stably express therapeutic genes in vivo without detectable side-effect have shown great promise for human gene therapy. A major challenge for translation of promising research to clinical development is how to establish clinically compatible purification methods in separating rAAV from potentially pathogenic impurities, especially rAAV vector-related impurities, a class of impurities corresponding to AAV particles that closely resemble bona fide vectors and are difficult to remove. In this review we summarize the assembly process of rAAV vector-related impurities and their characteristics differed with rAAV vectors, and evaluate several current technologies to prevent their formation or separate them from rAAV stocks.

Capsid assembly and DNA encapsidation of adeno-associated virus / 生物工程学报

Recombinant adeno-associated viral vectors (rAAV) have been widely used as gene therapy vectors in clinical trials. Here, we reviewed the genomic structures and replication mechanisms of wt-AAV. Then, the assembly of capsid and the encapsidation of genomic DNA, two major events during AAV pakaging, was discussed in detail. Although the overall pattern of virus assembly and encapsidation is known, the molecular mechanisms and the structure-function relationship involved in these processes are not well understood. Further elucidatation of these processes may improve the production technology of rAAV and develop gene drug based on rAAV.

Role of cytoglobin in protecting hepatic stellate cells against oxidation induced damage / 生物工程学报

The aim of this study was to reveal the protection role and the related mechanism of cytoglobin on the oxidation induced hepatic stellate cell damage. We applied siRNA to interfere the endogenous cytoglobin gene, used recombinant cytoglobin protein to treat the completely activated human hepatic stellate cell line LX-2 and the incompletely activated primary rat hepatic stellate cells, or over-expressed cytoglobin protein in LX-2 cells. We used two different oxidative-stress related models, the hydrogen peroxide model and the iron-overload model in our experiments and investigated the proliferation status and the intracellular superoxide level of the cells. The results showed that endogenous cytoglobin exerted significant protective effects on hydrogen peroxide or iron-overload induced LX-2 cell damage, confirming that upregulation of cytoglobin was the protective response of activated hepatic stellate cells to oxidative stress. Recombinant cytoglobin protein could protect LX-2 cells from oxidation induced damage, and prevent primary rat hepatic stellate cells from excessive proliferation and injury. The cytoplasmic reactive oxygen species (ROS) scavenging capacity of the recombinant cytoglobin protein was not as good as its capacity in scavenging ROS outside the cells, likely owing to the lack of active transporting mechanisms. Intracellular over-expression of cytoglobin protein could exert significant protective effect on LX-2 cells treated with hydrogen peroxide or iron-overload. Our results would accelerate the exploitation of new anti-fibrotic targets.

Expression and purification of human soluble TRAIL in Pichia pastoris and its anti-tumor activity in vitro / 中国生化药物杂志

Purpose To investigate human soluble TRAIL(sTRAIL)protein expression and purification and its potential anti-tumor activity on hepatocellular carcinoma(HepG2).Methods Soluble TRAIL gene ligated with expression vector pPIC9 was transfected into GS115(his4)and the recombination strain expressing sTRAIL was screened by MD plate.The effects of different media,methanol inducement period,methanol concentration,and pH were investigated and optimized using shaking flask.The anti-tumor activity of sTRAIL with HepG2 cells Was analyzed after purification.Results The highest expression of sTRAIL was obtained at pH 6.0,1% methanol in BMMY medium,with the concentration of(58.7±2.4)mg/L at 48 h.Recombinant sTRAIL protein could induce HepG2 cells apoptosis and inhibit HepG2 cells proliferation effectively.Conclusion The optimized condition of human sTRAIL expression and purification Was developed and the obtained recombinant sTRAIL protein may be a promising therapeutic agent for hepatocellular carcinoma.

High level expression of recombinant human kallistatin in Pichia pastoris and its bioactivity / 生物工程学报

In order to research the bioactivity of kallistatin (Kal), we obtained the recombinant Kal using Pichia pastoris expression system. Kal cDNA was amplified from pAAV-Kal and inserted into pPIC9 vector to generate a recombinant vector of pPIC9-Kal. Then, pPIC9-Kal was linearized and transformed into Pichia pastoris strain GS115 (His4) by electroporation. The positive transformants were selected by MD plate and confirmed by PCR. High level of Kal was obtained in BMMY medium (pH 7.0) after 96 hours induction of 29 degrees C and 2% methanol, with the highest yield of 14 mg/L in shake flask culture. Kal protein was purified from the supernatant with Phenyl Superose and Heparin Sepharose FF chromatograph. The recombinant Kal had a molecular weight of 58 kDa with 98% purity, showing by SDS-PAGE. Moreover, it had a high peroxidase activity (163+/-4) U/(mgmin), which could protect LX-2 cell against oxidation of H2O2. Recombinant Kal also effectively inhibited HUVEC proliferation. In this report, we successfully established the expression system using Pichia pastoris and obtained the bioactive recombinant human Kal. It lays a foundation for its further anti-cancer therapy.

Progress in application of targeting viral vector regulated by microRNA in gene therapy: a review / 生物工程学报

A safe and effective targeting viral vector is the key factor for successful clinical gene therapy. microRNA, a class of small, single-stranded endogenous RNAs, act as post-transcriptional regulators of gene expression. The discovery of these kind regulatory elements provides a new approach to regulate gene expression more accurately. In this review, we elucidated the principle of microRNA in regulation of targeting viral vector. The applications of microRNA in the fields of elimination contamination from replication competent virus, reduction of transgene-specific immunity, promotion of cancer-targeted gene therapy and development of live attenuated vaccines were also discussed.

Cellular immunotoxicity of rAAV gene medicine and possible solutions / 药学学报

Gene medicine based on recombinant adeno-associated virus (rAAV) vector has rapidly become the prior-choose reagent for gene therapy, since it had been shown that the rAAV was able to stably express many genes in vivo without detectable side-effect. However, recent findings of CTL immune responses to AAV capsid in a clinical trial highlighted a new issue regarding safety that previously was not identified in animal studies. Obviously it is so important to understand the interaction of rAAV with the immune system in details for the safety and success of rAAV gene medicine. In this review we evaluate several current hypotheses aiming to explain the cellular immunotoxicity, also analysis the current findings including the presentation kinetics of the capsid antigen and the activation of CTL. Focusing on the key steps of the immune response several solutions are proposed, including immunosuppression, optimization of vector and improvement of purity, in order to insure clinical safety and efficacy of rAAV.

Mutant K-ras-specific siRNA inhibits proliferation, migration and induces apoptosis of lung cancer A549 cells / 中国肿瘤生物治疗杂志

Objective:To construct K-ras-targeted siRNAs (K-ras siRNA) and to investigate the inhibitory effects of K-ras siRNAs on the growth and migration of lung cancer A549 cells (containing mutant K-ras gene) and NCI-H446 cells (containing wild-type K-ras gene). Methods: Four K-ras siRNAs (K-ras siRNA1～K-ras siRNA3 targeting wild-type K-ras and K-ras siRNA4 targeting mutant K-ras) were designed and artificially synthesized; they were used to transfect A549 cells and NCI-H446 cells. The expressions of Ras mRNA and protein were examined by RT-PCR and Western blot-ting. The inhibitory effects of K-ras siRNAs on the proliferations of A549 and NCI-H446 cells were determined by MTT assay. The effects of K-ras siRNAs on the cell migration and apoptosis were observed by Transwell assay and Hoechst 33258 staining, respectively. Results: Mutant K-ras-targeted siRNA (K-ras siRNA4) specifically inhibited the K-ras ex-pression but had no influence on H-ras and N-ras expression in A549 cells. K-ras siRNA4 inhibited the proliferation of A549 cells but did not inhibit that of NCI-H446 cells, which contained wild type K-ras gene. K-ras siRNA4 also induced apoptosis and inhibited migration of A549 cells. Conclusion: Mutant K-ras-targeted siRNA4 can inhibit the proliferation, migration and induce apoptosis of A549 cells. It may be a potential and personalized drug for the treatment against lung cancer containing mutant K-ras gene.

Trends in development of self-complementary adeno-associated virus vector / 生物工程学报

Numerous studies and clinical trials have demonstrated the efficacy of recombinant adeno-associated virus gene delivery vectors. However, prior to expression, it is necessary to convert the single-stranded DNA genome into double-stranded DNA, which hinders the efficiency of these vectors. We can entirely circumvent this step through the use of self-complementary recombinant adeno-associated virus vector (scrAAV). ScrAAV packages an inverted repeat genome that can fold into double-stranded DNA without the requirement for DNA synthesis or base-pairing between multiple vector genomes. By using scrAAV, we could increase expression efficiency and reduce immune response caused by vectors themselves. Therefore, it is a promising vector for gene therapy. So far, it has been used in the treatment of hepatic diseases, central nervous system diseases, and eye diseases. It has also been used in the modifications of stem cells and as vectors for siRNA/miRNA and ribozymes. In this review, we focused on the preparation, expression and location of scrAAV both in vitro and in vivo. We mainly introduced the recent progress of scrAAV based therapy of Hemophilia B, in order to elucidate the potential and prospects of scrAAV in gene therapy.

Dose-response and control of adeno-associated viral vectors based preclinical and clinical gene therapy / 中国临床药理学与治疗学

Human gene therapy needs to express exogenous DNA at the targeting cells,producing a practical and efficient therapeutic dosage at an approp-riate time(quantitative pharmacology)with a safe man-ner.Recombinant adeno-associated virus(rAAV)Vec-tom possess a number of properties and recent progress in rAAV production made it rapidly become the reagent of choice for therapeutic gene tmasfer.Over 60 clinical trials of gene therapy based on rAAV have been carried out.The dose response reaction between rAAV vectors and gene expression activity or clinical outcome is one of major aspects of these trials.Most studies showed that vector genomes(vg)and gene expression had a concentration-dependent relationship during a certain scope.However,gene expr~sion Can be afffected by viral serotypes,tissue tropisms,cell targeting,drug regulation,injection route,age and sex,etc.Thus,these aspects should be carefully comidered by scienti-sts,pharmacologisis and physicians during animal ex-periments or clinical trails.KEY WORDS gene therapy;viral vector;dose-re-sponse;quantitative pharmacology;clinical thempy