Transduction of hepatocellular carcinoma (HCC) using recombinant adeno-associated virus (rAAV): in vitro and in vivo effects of genotoxic agents

Recent advances in various adeno-associated viruses (AAVs) as gene therapy agents in hepatocellular carcinoma

Primary liver cancer, which is scientifically referred to as hepatocellular carcinoma (HCC), is a significant concern in the field of global health. It has been demonstrated that conventional chemotherapy, chemo-hormonal therapy, and conformal radiotherapy are ineffective against HCC. New therapeutic approaches are thus urgently required. Identifying single or multiple mutations in genes associated with invasion, metastasis, apoptosis, and growth regulation has resulted in a more comprehensive comprehension of the molecular genetic underpinnings of malignant transformation, tumor advancement, and host interaction. This enhanced comprehension has notably propelled the development of novel therapeutic agents. Therefore, gene therapy (GT) holds great promise for addressing the urgent need for innovative treatments in HCC. However, the complexity of HCC demands precise and effective therapeutic approaches. The adeno-associated virus (AAV) distinctive life cycle and ability to persistently infect dividing and nondividing cells have rendered it an alluring vector. Another appealing characteristic of the wild-type virus is its evident absence of pathogenicity. As a result, AAV, a vector that lacks an envelope and can be modified to transport DNA to specific cells, has garnered considerable interest in the scientific community, particularly in experimental therapeutic strategies that are still in the clinical stage. AAV vectors emerge as promising tools for HCC therapy due to their non-immunogenic nature, efficient cell entry, and prolonged gene expression. While AAV-mediated GT demonstrates promise across diverse diseases, the current absence of ongoing clinical trials targeting HCC underscores untapped potential in this context. Furthermore, gene transfer through hepatic AAV vectors is frequently facilitated by GT research, which has been propelled by several congenital anomalies affecting the liver. Notwithstanding the enthusiasm associated with this notion, recent discoveries that expose the integration of the AAV vector genome at double-strand breaks give rise to apprehensions regarding their enduring safety and effectiveness. This review explores the potential of AAV vectors as versatile tools for targeted GT in HCC. In summation, we encapsulate the multifaceted exploration of AAV vectors in HCC GT, underlining their transformative potential within the landscape of oncology and human health.

Improvement of Gene Delivery by Minimal Bacteriophage Particles

Direct delivery of therapeutic genes is a promising approach for treating cancers and other diseases. The current human viral vectors, however, suffer from several drawbacks, including poor cell-type specificity and difficult large-scale production. The M13 phage provides an alternative vehicle for gene therapy with engineerable specificity, but the low transduction efficiency seriously limits its translational application. In this work, we discovered important factors of cells and phages that greatly influence the phage transduction. The up-regulation of PrimPol or the down-regulation of DMBT1 in cells significantly enhanced the phage transduction efficiency. Furthermore, we found that the phage transduction efficiency was inversely correlated with the phage size. By carefully reconstructing the phage origin with the gene of interest, we designed "TransPhage" with a minimal length and maximal transduction efficiency. We showed that TransPhage successfully transduced the human cells with an excellent efficiency (up to 95%) comparable to or superior to that of the adeno-associated virus vectors. Moreover, we showed that TransPhage's tropism was specific to the cells that overexpress the target antigen, whereas adeno-associated viruses (AAVs) promiscuously infected many cell types. Using TransPhage as a gene therapy vehicle, we invented an NK-cell-mediated immunotherapy in which a membrane-bound fragment crystallizable region was introduced to cancer cells. We showed in vitro that the cancer cells expressing the membrane-bound fragment crystallizable (Fc) were effectively killed by CD16+ NK cells through an antibody-dependent cell-mediated cytotoxicity (ADCC)-like mechanism. In the xenograft mouse model, the administration of TransPhage carrying the membrane-bound Fc gene greatly suppressed tumor growth.

Recent advances of metal-based nanoparticles in nucleic acid delivery for therapeutic applications

Recent efforts in designing nanomaterials to deliver potential therapeutics to the targeted site are overwhelming and palpable. Engineering nanomaterials to deliver biological molecules to exert desirable physiological changes, with minimized side effects and optimal dose, has revolutionized the next-generation therapy for several diseases. The rapid progress of nucleic acids as biopharmaceutics is going to alter the traditional pharmaceutics practices in modern medicine. However, enzymatic instability, large size, dense negative charge (hydrophilic for cell uptake), and unintentional adverse biological responses-such as prolongation of the blood coagulation and immune system activation-hamper the potential use of nucleic acids for therapeutic purposes. Moreover, the safe delivery of nucleic acids into the clinical setting is an uphill task, and several efforts are being put forward to deliver them to targeted cells. Advances in Metal-based NanoParticles (MNPs) are drawing attention due to the unique properties offered by them for drug delivery, such as large surface-area-to-volume ratio for surface modification, increased therapeutic index of drugs through site-specific delivery, increased stability, enhanced half-life of the drug in circulation, and efficient biodistribution to the desired targeted site. Here, the potential of nanoparticles delivery systems for the delivery of nucleic acids, specially MNPs, and their ability and advantages over other nano delivery systems are reviewed.

MicroRNA-Based Therapeutic Perspectives in Myotonic Dystrophy

Myotonic dystrophy involves two types of chronically debilitating rare neuromuscular diseases: type 1 (DM1) and type 2 (DM2). Both share similarities in molecular cause, clinical signs, and symptoms with DM2 patients usually displaying milder phenotypes. It is well documented that key clinical symptoms in DM are associated with a strong mis-regulation of RNA metabolism observed in patient’s cells. This mis-regulation is triggered by two leading DM-linked events: the sequestration of Muscleblind-like proteins (MBNL) and the mis-regulation of the CUGBP RNA-Binding Protein Elav-Like Family Member 1 (CELF1) that cause significant alterations to their important functions in RNA processing. It has been suggested that DM1 may be treatable through endogenous modulation of the expression of MBNL and CELF1 proteins. In this study, we analyzed the recent identification of the involvement of microRNA (miRNA) molecules in DM and focus on the modulation of these miRNAs to therapeutically restore normal MBNL or CELF1 function. We also discuss additional prospective miRNA targets, the use of miRNAs as disease biomarkers, and additional promising miRNA-based and miRNA-targeting drug development strategies. This review provides a unifying overview of the dispersed data on miRNA available in the context of DM.

Seek and destroy: targeted adeno-associated viruses for gene delivery to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer with high incidence globally. Increasing mortality and morbidity rates combined with limited treatment options available for advanced HCC press for novel and effective treatment modalities. Gene therapy represents one of the most promising therapeutic options. With the recent approval of herpes simplex virus for advanced melanoma, the field of gene therapy has received a major boost. Adeno-associated virus (AAV) is among the most widely used and effective viral vectors today with safety and efficacy demonstrated in a number of human clinical trials. This review identifies the obstacles for effective AAV based gene delivery to HCC which primarily include host immune responses and off-target effects. These drawbacks could be more pronounced for HCC because of the underlying liver dysfunction in most of the patients. We discuss approaches that could be adopted to tackle these shortcomings and manufacture HCC-targeted vectors. The combination of transductional targeting by modifying the vector capsid and transcriptional targeting using HCC-specific promoters has the potential to produce vectors which can specifically seek HCC and deliver therapeutic gene without significant side effects. Finally, the identification of novel HCC-specific ligands and promoters should facilitate and expedite this process.

Selective in vivo targeting of human liver tumors by optimized AAV3 vectors in a murine xenograft model

Current challenges for recombinant adeno-associated virus (rAAV) vector-based cancer treatment include the low efficiency and the lack of specificity in vivo. rAAV serotype 3 (rAAV3) vectors have previously been shown to be ineffective in normal mouse tissues following systemic administration. In the present study, we report that rAAV3 vectors can efficiently target and transduce various human liver cancer cells in vivo. Elimination of specific surface-exposed serine and threonine residues on rAAV3 capsids results in further augmentation in the transduction efficiency of these vectors, without any change in the viral tropism and cellular receptor interactions. In addition, we have identified a potential chemotherapy drug, shikonin, as a multifunctional compound to inhibit liver tumor growth as well as to significantly enhance the efficacy of rAAV vector-based gene therapy in vivo. Furthermore, we also document that suppression of tumorigenesis in a human liver cancer xenograft model can be achieved through systemic administration of the optimized rAAV3 vectors carrying a therapeutic gene, and shikonin at a dose that does not lead to liver damage. Our research provides a novel means to achieve not only targeted delivery but also the potential for gene therapy of human liver cancer.

Effect and mechanism of Mitomycin C combined with recombinant adeno-associated virus type II against glioma

The effect of chemotherapy drug Mitomycin C (MMC) in combination with recombinant adeno-associated virus II (rAAV2) in cancer therapy was investigated, and the mechanism of MMC affecting rAAV2’s bioactivity was also studied. The combination effect was evaluated by the level of GFP and TNF expression in a human glioma cell line, and the mechanism of MMC effects on rAAV mediated gene expression was investigated by AAV transduction related signal molecules. C57 and BALB/c nude mice were injected with rAAV-EGFP or rAAV-TNF alone, or mixed with MMC, to evaluate the effect of MMC on AAV-mediated gene expression and tumor suppression. MMC was shown to improve the infection activity of rAAV2 both in vitro and in vivo. Enhancement was found to be independent of initial rAAV2 receptor binding stage or subsequent second-strand synthesis of target DNA, but was related to cell cycle retardation followed by blocked genome degradation. In vivo injection of MMC combined with rAAV2 into the tumors of the animals resulted in significant suppression of tumor growth. It was thus demonstrated for the first time that MMC could enhance the expression level of the target gene mediated by rAAV2. The combination of rAAV2 and MMC may be a promising strategy in cancer therapy.

Development of optimized AAV3 serotype vectors: mechanism of high-efficiency transduction of human liver cancer cells

Our recent studies have revealed that among the 10 different commonly used adeno-associated virus (AAV) serotypes, AAV3 vectors transduce human liver cancer cells extremely efficiently because these cells express high levels of human hepatocyte growth factor receptor (hHGFR), and AAV3 utilizes hHGFR as a cellular co-receptor for viral entry. In this report, we provide further evidence that both extracellular as well as intracellular kinase domains of hHGFR are involved in AAV3 vector entry and AAV3-mediated transgene expression. We also document that AAV3 vectors are targeted for degradation by the host cell proteasome machinery, and that site-directed mutagenesis of surface-exposed tyrosine (Y) to phenylalanine (F) residues on AAV3 capsids significantly improves the transduction efficiency of Y701F, Y705F and Y731F mutant AAV3 vectors. The transduction efficiency of the Y705+731F double-mutant vector is significantly higher than each of the single mutants in liver cancer cells in vitro. In immunodeficient mouse xenograft models, direct intratumoral injection of AAV3 vectors also led to high-efficiency transduction of human liver tumor cells in vivo. We also document here that the optimized tyrosine-mutant AAV3 vectors lead to increased transduction efficiency following both intratumoral and tail-vein injections in vivo. The optimized tyrosine-mutant AAV3 serotype vectors containing proapoptotic genes should prove useful for the potential gene therapy of human liver cancers.

Confocal microscopy for the analysis of siRNA delivery by polymeric nanoparticles

Clinical applications of genetic therapies, including delivery of short, interfering RNAs (siRNAs) for RNA interference (RNAi), are limited due to the difficulty of delivering nucleic acids to specific cells of interest while at the same time minimizing toxicity and immunogenicity. The use of cationic polymers to deliver nucleic acid therapeutics has the potential to address these complex issues but is currently limited by low-delivery efficiencies. Although cell culture studies have shown that some polymers can be used to deliver siRNAs and achieve silencing, it is still not clear what physical or chemical properties are needed to ensure that the polymers form active polymer-siRNA complexes. In this study, we used multicolor fluorescence confocal microscopy to analyze the cellular uptake of siRNAs delivered by novel propargyl glycolide polymeric nanoparticles (NPs). Delivery by these vehicles was compared with delivery by linear polyethyleneimine (LPEI) and Lipofectamine 2000 (LF2K), which are both known as effective delivery vehicles for siRNAs. Our results showed that when LF2K and LPEI were used, large quantities of siRNA were delivered rapidly, presumably overwhelming the basal levels of mRNA to initiate silencing. In contrast, our novel polymeric NPs showed delivery of siRNAs but at concentrations that were initially too low to achieve silencing. Nonetheless, the exceptionally low cytotoxicity of our NPs, and the simplicity with which they can be modified, makes them good candidates for further study to optimize their delivery profiles and, in turn, achieve efficient silencing.

Therapeutic microRNA delivery suppresses tumorigenesis in a murine liver cancer model

Therapeutic strategies based on modulation of microRNA (miRNA) activity hold great promise due to the ability of these small RNAs to potently influence cellular behavior. In this study, we investigated the efficacy of a miRNA replacement therapy for liver cancer. We demonstrate that hepatocellular carcinoma (HCC) cells exhibit reduced expression of miR-26a, a miRNA that is normally expressed at high levels in diverse tissues. Expression of this miRNA in liver cancer cells in vitro induces cell-cycle arrest associated with direct targeting of cyclins D2 and E2. Systemic administration of this miRNA in a mouse model of HCC using adeno-associated virus (AAV) results in inhibition of cancer cell proliferation, induction of tumor-specific apoptosis, and dramatic protection from disease progression without toxicity. These findings suggest that delivery of miRNAs that are highly expressed and therefore tolerated in normal tissues but lost in disease cells may provide a general strategy for miRNA replacement therapies.

Bioelectronome. Integrated Approach to Receptor Chemistry, Radicals, Electrochemistry, Cell Signaling, and Physiological Effects Based on Electron Transfer

Bioelectronome refers to the host of electron transfer (ET) reactions that occur in living systems. This review presents an integrated approach to receptor chemistry based on electron transfer, radicals, electrochemistry, cell signaling, and end result. First, receptor activity is addressed from the unifying standpoint of redox transformations in which various receptors are discussed. After a listing of receptor-binding modes, receptor chemistry is treated with focus on generation of reactive oxygen species (ROS), activation by ROS, and subsequent cell signaling involving ROS. A general electrostatic mechanism is proposed for receptor-ligand action with supporting evidence. Cell-signaling processes appear to entail electron transfer, ROS, redox chains, and relays. The widespread involvement of phosphate from phosphorylation may be rationalized electrostatically by analogy with DNA phosphate. Extensive evidence supports important participation of ET functionalities in the mechanism of drugs and toxins. The integrated approach is applied to the main ET classes, namely, quinones, metal complexes, iminium species, and aromatic nitro compounds.

Augmented transgene expression in transformed cells using a parvoviral hybrid vector

Autonomous parvoviruses possess an intrinsic oncotropism based on viral genetic elements controlling gene expression and genome replication. We constructed a hybrid vector consisting of the H1 parvovirus-derived expression cassette comprising the p4 promoter, the ns1 gene and the p38 promoter flanked by the adeno-associated viruses 2 (AAV2) inverted terminal repeats and packaged into AAV2 capsids. Gene transduction using this vector could be stimulated by coinfection with adenovirus, by irradiation or treatment with genotoxic agents, similar to standard AAV2 vectors. However, the latter were in most cases less efficient in gene transduction than the hybrid vector. With the new vector, tumor cell-selective increase in transgene expression was observed in pairs of transformed and non-transformed cells, leading to selective killing of the transformed cells after expression of a prodrug-converting enzyme. Preferential gene expression in tumor versus normal liver tissue was also observed in vivo in a syngeneic rat model. Comparative transduction of a panel of different tumor cell lines with the H1 and the H1/AAV hybrid vector showed a preference of each vector for distinct cell types, probably reflecting the dependence of the viral tropism on capsid determinants.

Application of doxorubicin-induced rAAV2-p53 gene delivery in combined chemotherapy and gene therapy for hepatocellular carcinoma

p53 gene transfer has been proposed as a potential therapeutic option for treatment of hepatocellular carcinoma (HCC). Compared to other commonly used gene transfer vectors such as adenovirus and retrovirus, recombinant adeno-associated virus serotype 2 (rAAV2) has shown promising results in human clinical trials. Significant enhancement in the gene transfer efficiency is needed, however, for HCC applications. In the present study, we applied chemotherapy drug Doxorubicin (DOX) to induce rAAV2 transduction of hepatomas. Using reporter assays, we showed that the DOX-treated hepatomas became more susceptible to rAAV2 infection in comparison to untreated controls: the permissiveness increased >350-fold and >120-fold for HepG2 (p53 wild-type) and Hep3B (p53 null) hepatomas, respectively. Using the induced permissiveness, we applied rAAV2-p53 transduction to restore p53 expression in the p53-null Hep3B hepatomas. Compared to rAAV2-p53 transduction alone, rAAV2-p53 transduction with DOX resulted in a >16-fold induction of p53 expression. The transduced Hep3B expressed as much as 380% more immunoreactive p53 in comparison to the wild-type p53 expression in the HepG2 hepatomas. Significantly, when Hep3B cells were treated with 0.5 muM of DOX and rAAV2-p53 (MOI = 10) for twelve hours, the cell viability dropped to 66% four days after the administration. This decrease in cell viability was similar to that of treatment with 1 microM of DOX alone in the absence of rAAV2. The 50% reduction in DOX administration--from 1 microM to 0.5 microM--revealed the antitumor property of the rAAV2-p53 transduction as well as the joint cytotoxicity of DOX and rAAV2-p53 against the p53-null hepatomas. We conclude that DOX mediates the enhancement effect on rAAV2 transduction of human hepatomas. Combined DOX and rAAV2-p53 administration may facilitate more efficient treatment for the HCC caused by p53 mutations.

Adeno-associated viral delivery of a metabolically regulated insulin transgene to hepatocytes

Transduction with a liver specific, metabolically responsive insulin transgene produces near-normal blood sugars in STZ-diabetic rats. To overcome the limited duration of hepatic transgene expression induced by E1A-deleted adenoviral vectors, we evaluated recombinant adeno-associated virus (rAAV2) for cell type specificity and glucose responsiveness in vitro. Co-infection of AAV2 containing the glucose responsive, liver-specific (GlRE)(3)BP-1 promoter with an empty adenovirus enhanced transduction efficiency, and shortened the duration of transgene expression in HepG2 hepatoma cells, but not primary hepatocytes. However, in the context of rAAV2, (GlRE)(3)BP-1 promoter activity remained confined to cells of hepatocyte lineage, and retained glucose responsiveness. While isolated infection with an insulin expressing rAAV2 failed to attenuate blood sugars in diabetic mice, adenoviral co-administration with the same rAAV2 induced transient, near-normal random blood sugars in a diabetic animal. We conclude that rAAV2 can induce metabolically responsive insulin secretion from hepatocytes in vitro and in vivo. However, alternative AAV serotypes will likely be required to efficiently deliver therapeutic genes to the liver for the treatment of diabetes mellitus.

Topoisomerase Inhibition Accelerates Gene Expression after Adeno-associated Virus-mediated Gene Transfer to the Mammalian Heart

Utility of adeno-associated virus 2 (AAV2) vectors for cardiac gene therapy is limited by the prolonged lag phase before maximal gene expression. Topoisomerase inhibition can induce AAV2-mediated gene expression in vivo, but with variable success in different tissues. In this study, we demonstrate that topoisomerase inhibition can accelerate AAV2-mediated gene expression in the mouse heart. We used an AAV2 vector expressing firefly luciferase and monitored expression kinetics using non-invasive bioluminescence imaging. In the group receiving vector alone, cardiac luciferase activity was evident from week 2 onward and increased progressively to reach a steady plateau by 9 weeks postinjection. In the group receiving vector and camptothecine (CPT), luciferase expression was evident from days 2 to 4 onward and increased rapidly to reach a steady plateau by 3-4 weeks postinjection, nearly three times faster than in the absence of CPT (P<0.05). Southern blot analysis of AAV2 genomes in cardiac tissue showed rapid conversion of the AAV2 genome from its single-stranded to double-stranded form in CPT-treated mice. Non-invasive determinations of luciferase expression correlated well with in vitro luciferase assays. Direct injection of the AAV2 vector and long-term luciferase gene expression had no detectable effects on normal cardiac function as assessed by magnetic resonance imaging.

Modified infusion procedures affect recombinant adeno-associated virus vector type 2 transduction in the liver

Recombinant adeno-associated virus (rAAV) vectors have therapeutic potential for the treatment of several types of liver diseases including hepato-deficiency disorders. Most of the preclinical and clinical applications involve the use of adeno-associated vector serotype 2 (AAV-2). However, when this vector is delivered at high doses into the portal vein or hepatic artery, a relatively small number of hepatocytes are stably transduced. We elected to determine if the route of vector administration and altering the vascular delivery route within the liver influenced the relative level of transduction. First, we delivered an AAV vector expressing the human factor IX gene from a liver-specific promoter into the hepatic artery, portal vein, or general circulation of rats. Transgene expression was equal with hepatic artery and portal vein infusion, which was higher than vector administered via peripheral venous infusion. Next, we determined how localized perfusion or changing the vector dwell time affected AAV transduction in vivo. To do this, we infused an AAV vector lacking a functional expression and quantified transduction by quantifying the number of double-stranded vector DNA genomes. By increasing vector dwell time in the liver to 5 min, vector transduction was enhanced approximately 4- to 5- fold. To establish if gene transduction could be restricted to a specific anatomic location in the liver, we delivered vector into specific liver lobes by clamping the venous inflow to the middle and left liver lobes (noninfused lobes) and infusing vector into the right two liver lobes through the hepatic artery followed by vector circulation between the two right lobes and general circulation for 5 min. With this selective infusion, 40 to 120 times higher vector genome was observed in the perfused lobes than the nonperfused lobes. All the procedures described in this study were performed without detectable liver injury or toxicity. In all, the present study clearly demonstrated that hepatic arterial infusion of rAAV is effective for liver-directed gene therapy and that other parameters related to blood flow can be adjusted to further optimize gene transfer.

Proteasome modulating agents induce rAAV2-mediated transgene expression in human intestinal epithelial cells

Intestinal gene transfer offers promise as a therapeutic option for treatment of both intestinal and non-intestinal diseases. Recombinant adeno-associated virus serotype 2, rAAV2, based vectors have been utilized to transduce lung epithelial cells in culture and in human subjects. rAAV2 transduction of intestinal epithelial cells, however, is limited both in culture and in vivo. Proteasome-inhibiting agents have recently been shown to enhance rAAV2-mediated transgene expression in airway epithelial cells. We hypothesized that similar inhibition of proteasome-related cellular processes can function to induce rAAV2 transduction of intestinal epithelial cells. Our results demonstrate that combined treatment with proteasome-modulating agents MG101 (N-acetyl-L-leucyl-L-leucyl-L-norleucine) and Doxorubicin synergistically induces rAAV2-mediated luciferase transgene expression by >400-fold in undifferentiated Caco-2 cells. In differentiated Caco-2 monolayers, treatment with MG101 and Doxorubicin induces transduction preferentially from the basolateral cell surface. In addition to Caco-2 cells, treatment with MG101 and Doxorubicin also results in enhanced rAAV2 transduction of HT-29, T84, and HCT-116 human intestinal epithelial cell lines. We conclude that MG101 and Doxorubicin mediate generic effects on intestinal epithelial cells that result in enhanced rAAV2 transduction. Use of proteasome-modulating agents to enhance viral transduction may facilitate the development of more efficient intestinal gene transfer protocols.

Effects of augmentation of liver regeneration recombinant plasmid on rat hepatic fibrosis

AIM

To investigate the effects of eukaryotic expression of plasmid on augmentation of liver regeneration (ALR) in rat hepatic fibrosis and to explore their mechanisms.

METHODS

Ten rats were randomly selected from 50 Wistar rats as normal control group. The rest were administered intraperitoneally with porcine serum twice weekly. After 8 wk, they were randomly divided into: model control group, colchicine group (Col), first ALR group (ALR1), second ALR group (ALR2). Then colchicine ALR recombinant plasmid were used to treat them respectively. At the end of the 4th wk, rats were killed. Serum indicators were detected and histopathological changes were graded. Expression of type I, III, collagen and TIMP-1 were detected by immunohistochemistry and expression of TIMP-1 mRNA was detected by semi-quantified RT-PCR.

RESULTS

The histologic examination showed that the degree of the rat hepatic fibrosis in two ALR groups was lower than those in model control group. Compared with model group, ALR significantly reduced the serum levels of ALT, AST, HA, LN, PCIII and IV (P<0.05). Immunohistochemical staining showed that expression of type I, III, collagen and TIMP-1 in two ALR groups was ameliorated dramatically compared with model group (I collagen: 6.94+/-1.42, 5.80+/-1.66 and 10.83+/-3.58 in ALR1, ALR2 and model groups, respectively; III collagen: 7.18+/-1.95, 4.50+/-1.67 and 10.25+/-2.61, respectively; TIMP-1: 0.39+/-0.05, 0.20+/-0.06 and 0.53+/-0.12, respectively, P<0.05 or P<0.01). The expression level of TIMP-1 mRNA in the liver tissues was markedly decreased in two ALR groups compared with model group (TIMP-1 mRNA/beta-actin: 0.89+/-0.08, 0.65+/-0.11 and 1.36+/-0.11 in ALR1, ALR2 and model groups respectively, P<0.01).

CONCLUSION

ALR recombinant plasmid has beneficial effects on rat hepatic fibrosis by enhancing regeneration of injured liver cells and inhibiting TIMP-1 expressions.

Adeno-associated virus serotypes 1 to 5 mediated tumor cell directed gene transfer and improvement of transduction efficiency

BACKGROUND

Gene therapy is an attractive new approach for the treatment of cancer. Therefore, the development of efficient vector systems is of crucial importance in this field. Different adeno-associated virus (AAV) serotypes have been characterized so far, which show considerable differences in tissue tropism. Consequently, we aimed to characterize the most efficient serotype for this application.

METHODS

To exclude all influences other than those provided by the capsid, all serotypes contained the same transgene cassette flanked by the AAV2 inverted terminal repeats. We systematically compared these vectors for efficiency in human cancer cell directed gene transfer. In order to identify limiting steps, the influence of second-strand synthesis and proteasomal degradation of AAV in a poorly transducible cell line were examined.

RESULTS

AAV2 was the most efficient serotype in all solid tumor cells and primary melanoma cells with transduction rates up to 98 +/- 0.3%. Transduction above 70% could be reached with serotypes 1 (in cervical and prostate carcinoma) and 3 (in cervical, breast, prostate and colon carcinoma) using 1000 genomic particles per cell. In the colon carcinoma cell line HT-29 proteasomal degradation limited AAV1-AAV4-mediated gene transfer. Moreover, inefficient second-strand synthesis prevents AAV2-mediated transgene expression in this cell line.

CONCLUSIONS

Recent advances in AAV-vector technology suggest that AAV-based vectors can be used for cancer gene therapy. Our comparative analysis revealed that, although AAV2 is the most promising candidate for such an application, serotypes 1 and 3 are valid alternatives. Furthermore, the use of self-complementary AAV vectors and proteasome inhibitors significantly improves cancer cell transduction.

Adeno-associated virus mediated endostatin gene therapy in combination with topoisomerase inhibitor effectively controls liver tumor in mouse model

AIM: rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer. However, a sustained and high protein delivery is required to achieve the desired therapeutic effects. We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model.

METHODS: rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines. To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin, Western blotting and ELISA were performed. The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor, etoposide, were evaluated in a mouse liver tumor model.

RESULTS: Topoisomerase inhibitors, including camptothecin and etoposide, were found to increase the endostatin expression level in vitro. The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active. In animal experiments, the combined therapy of topoisomerase inhibitor, etoposide with the rAAV-endostatin vector had the best tumor-suppressive effect and tumor foci were barely observed in livers of the treated mice. Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice. Finally, the mice treated with rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models.

CONCLUSION: rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.

Gene therapy of hepatocarcinoma: a long way from the concept to the therapeutical impact

Hepatocellular carcinoma (HCC), the most prevalent histological form of primary liver cancer is one of the most frequent cancer worldwide. This pathology still requires the development of new therapeutical approaches. Gene therapy strategies focusing on the genetic manipulation of accessory cells involved in the immune reaction against cancer cells, or on the direct transduction of tumor cells with transgenes able to "suicide" cancer cells have been largely developed for more than ten years.

Lipoproteins produced by ApoE-/- astrocytes infected with adenovirus expressing human ApoE

We have developed an astrocyte cell culture system that is attractive for the study of apoE structure and its impact on astrocyte lipoproteins and neuronal function. Primary astrocytes from apoE-/- mice were infected with adenovirus expressing apoE3 or apoE4 and the nascent lipoproteins secreted were characterized. The nascent apoE-containing astrocyte particles were predominantly the size of plasma high density lipoprotein (HDL). ApoE4, in contrast to apoE3, appeared to be distributed in two distinct lipoprotein peaks and the apoE4-containing lipoproteins contained significantly more radiolabeled triglyceride. On electron micrographs the astrocyte particles were both discoidal and spherical in shape with a prevalence of stacked discs in apoE3 particles, but single discs and larger spheres in apoE4 particles. The apoE4 discs were significantly wider than apoE3 discs. These properties of the astrocyte lipoproteins are similar to those obtained from apoE isoform transgenic mice. Astrocyte lipoproteins containing apoE3, but not apoE4, stimulated neurite outgrowth in Neuro-2a cells. These studies suggest that the isoform-specific effects of apoE lipoproteins may involve differences in particle size and composition. Finally we demonstrate the usefulness of this system by expressing a truncated apoE3 (delta202-299) mutant and show preliminary data indicating that a liver X receptor agonist promotes HDL output by the astrocytes without an increase in apoE in the media. This cell culture system is more flexible and allows for more rapid expression of apoE mutants.

Suicide gene therapy using AAV-HSVtk/ganciclovir in combination with irradiation results in regression of human head and neck cancer xenografts in nude mice

The application of adeno-associated virus (AAV) vectors to cancers is limited by their low transduction efficiency. Previously, we reported that gamma-ray enhanced the second-strand synthesis, leading to the improvement of the transgene expression, and cytocidal effect of the herpes simplex virus type-1 thymidine kinase (HSVtk) and ganciclovir (GCV) system. In this study, we extended this in vitro findings to in vivo. First, the laryngeal cancer cell line (HEp-2) and HeLa were treated with AAVtk/GCV, the number of surviving cells was reduced as the concentration of GCV increased. Furthermore, the 4 Gy irradiation enhanced the killing effects of AAVtk/GCV by four-fold on HeLa cells and 15-fold on HEp-2 cells. Following the in vitro experiments, we evaluated the transgene expression and the antitumor activity of the AAV vectors in combination with gamma-ray in nude mice inoculated with HEp-2 subcutaneously. The LacZ expression was observed in the xenografted tumors and significantly increased by gamma-ray. The AAVtk/GCV system suppressed the tumors growth, and gamma-ray augmented the antitumor activity by five-fold. These findings suggest that the combination of AAVtk/GCV system with radiotherapy is significantly effective in the treatment of cancers and may lead to reduction of the potential toxicity of both AAVtk/GCV and gamma-ray.

Transduction of ovarian cancer cells: a recombinant adeno-associated viral vector compared to an adenoviral vector

Recombinant adeno-associated virus (rAAV) vectors have emerged as vehicles for gene therapy. In addition, anti-neoplastic properties have been attributed to wild-type AAV. To take advantage of both features and to overcome technical problems associated with rAAV preparation, we developed a production method in which rAAV particles are amplified in an infectious cycle in the presence of wtAAV. This results in a 10(3)-10(4)-fold amplification of rAAV input particles. rAAV-GFP particles generated by this method were used to transduce ovarian cancer cell lines to evaluate their potential in ovarian cancer gene therapy, in comparison to a rAd-GFP vector. The transduction efficiency of NIH-OVCAR3, MDAH 2774 and SKOV3 cells with rAAV-GFP particles was low (< 1%) and did not improve by increasing the number of particles/cell. Repeated administration and continued exposure of NIH-OVCAR3 and MDAH 2774 improved transduction to over 3%. In contrast, these cell lines were more efficiently transduced by rAAV-GFP in the presence of adenovirus (approximately 15%) and by rAd-GFP (> 50%). These results indicate that in contrast to rAd vectors, rAAV particles are not suitable for therapeutic gene transfer in ovarian cancer cells unless efficient help can be provided to mediate ss to ds DNA conversion.