Preclinical applications of imaging for cancer gene therapy

Gene therapy is a very attractive strategy in experimental cancer therapy. Ideally, the approach aims to deliver therapeutic genes selectively to cancer cells. However, progress in the improvement of gene therapy formulations has been hampered by difficulties in measuring transgene delivery and in quantifying transgene expression in vivo. In clinical trials, endpoints rely almost exclusively on the analysis of biopsies by molecular and histopathological methods, which provide limited information. Therefore, to ensure the rational development of gene therapy, a crucial issue is the utilisation of technologies for the non-invasive monitoring of spatial and temporal gene expression in vivo upon administration of a gene delivery vector. Such imaging technologies would allow the generation of quantitative information about gene expression and the assessment of cancer gene therapy efficacy. In the past decade, progress has been made in the field of in vivo molecular imaging. This review highlights the various methods currently being developed in preclinical models.     

非病毒基因治疗的研究进展

非病毒基因治疗是相对于病毒性基因治疗而言,指采用非病毒的载体进行的基因治疗。非病毒的基因载体比病毒性基因载体具有高安全性、低免疫原性及易于生产的特点。本文就非病毒基因治疗所采用的主要方法、面蜂的主要问题及发展方向作一概括的介绍。随着人类对疾病发病分子机制的深入研究及人类基因组计划的实施,非病毒基因治疗将在人类疾病的治疗中发挥重要作用。     

Progress and problems with the use of viral vectors for gene therapy

Gene therapy has a history of controversy. Encouraging results are starting to emerge from the clinic, but questions are still being asked about the safety of this new molecular medicine. With the development of a leukaemia-like syndrome in two of the small number of patients that have been cured of a disease by gene therapy, it is timely to contemplate how far this technology has come, and how far it still has to go.     

Is cystic fibrosis genetic medicine's canary?

In 1989 the gene that causes cystic fibrosis (CF) was identified in a search accompanied by intense anticipation that the gene, once discovered, would lead rapidly to gene therapy. Many hoped that the disease would effectively disappear. Those affected were going to inhale vectors packed with functioning genes, which would go immediately to work in the lungs. It was a bewitching image, repeatedly invoked in both scientific and popular texts. Gene therapy clinical trials were carried out with a range of strategies and occasionally success seemed close, but by 1996 the idea that gene therapy for CF would quickly provide a cure was being abandoned by the communities engaged with treatment and research. While conventional wisdom holds that the death of Jesse Gelsinger in an unrelated gene therapy trial in 1999 produced new skepticism about gene therapy, the CF story suggests a different trajectory, and some different lessons. This article considers the rise and fall of gene therapy for CF and suggests that CF may provide a particularly compelling case study of a failed genomic technology, perhaps even of a medical "canary." The story of CF might be a kind of warning to us that genetic medicine may create as many problems as it solves, and that moving forward constructively with these techniques and practices requires many kinds of right information, not just about biology, but also about values, priorities, market forces, uncertainty, and consumer choice.     

X-linked severe combined immunodeficiency: from molecular cause to gene therapy within seven years

X-linked severe combined immunodeficiency (XSCID) is the most common form of SCID. The discovery of the genetic defect in this disease, namely mutations in the gene encoding the common cytokine receptor gamma chain, gammac, was reported just over seven years ago. In the subsequent period, a tremendous amount of knowledge about the biology and function of this protein has been generated. Moreover, gammac-knockout mice have been generated and their immune systems successfully reconstituted by gene therapy. Furthermore, initial attempts at using gene therapy to treat patients with XSCID have been successful for more than ten months, making this disease perhaps the most promising to date for treatment with such a strategy.     

RNA干扰技术的基础研究与应用

RNA干扰技术(RNAi)是一项高效率、强特异性的基因沉默技术.自1998年发现RNA干扰现象以来,RNAi吸引很多国内外科学家的研究兴趣.经过10多年的潜心研究,现在对该技术的参与成分、作用机理都有了较深入地了解.同时,随着生物学知识的完善和生物技术与基因工程的发展,研究人员时RNAi在基因功能研究、疾病(如肿瘤)相关的基因治疗、新药的研究与开发等方面的应用进行了广泛的探索,并且已经显示该技术的潜在应用价值,但是RNAi的自身缺陷制约了其在临床治疗等方面的实际应用.综述前人的研究结果,系统阐述了RNAi的发生、作用机理、缺陷以及其应用,为相关科学研究提供参考.     

基因治疗的应用及研究进展

基因治疗是一种新的治疗手段,可用于癌症、遗传性疾病、感染性疾病、心血管疾病和自身免疫性疾病等的治疗。癌症基因治疗是基因治疗的主要应用领域。过去几年里,全球基因治疗临床试验取得了很大的进步,也遇到了很多困难。未来基因治疗的主要目标是发展安全和高效的基因导入系统,它们能将外源遗传物质靶向性地导入特异的细胞。简要综述了基因治疗研究和应用的进展、困难及其发展前景。     

Development of a microRNA delivery system based on bacteriophage MS2 virus-like particles

Recently, microRNA (miRNA)-mediated RNA interference has been developed as a useful tool in gene function analysis and gene therapy. A major obstacle in miRNA-mediated RNAi is cellular delivery, which requires an efficient and flexible delivery system. The self-assembly of the MS2 bacteriophage capsids has been used to develop virus-like particles (VLPs) for RNA and drug delivery. However, MS2 VLP-mediated miRNA delivery has not yet been reported. We therefore used an Escherichia coli expression system to produce the pre-miR 146a contained MS2 VLPs, and then conjugated these particles with HIV-1 Tat(47-57) peptide. The conjugated MS2 VLPs effectively transferred the packaged pre-miR146a RNA into various cells and tissues, with 0.92-14.76-fold higher expression of miR-146a in vitro and about two-fold higher expression in vivo, and subsequently suppressed its targeting gene. These findings suggest that MS2 VLPs can be used as a novel vehicle in miRNA delivery systems, and may have applications in gene therapy.     

Butyrate as a model for "gene-regulating chemoprevention and chemotherapy."

Recent progress in molecular genetics has facilitated understanding of the mechanisms of carcinogenesis. However, there is not yet any effective therapy or prevention for cancer based on the molecular mechanisms of carcinogenesis. So-called "gene therapy" for cancer is expected to become a new method of treatment, but there are still several serious problems with gene therapy. As a matter of fact, it seems impossible to adopt gene therapy for prevention. We therefore tried to develop a different method of cancer prevention or therapy based on the molecular mechanisms of carcinogenesis. For instance, the tumor-suppressor gene p53 is mutated in about 50% of human malignancies. It is known that p53 stimulates the promoter activities of p21/WAF1, gadd45 and bax genes, resulting in cell cycle arrest, DNA repair and apoptosis, respectively. Therefore, chemical compounds that can stimulate these genes should compensate for the function of p53. As a model of this, we found that histone deacetylase inhibitors such as butyrate or trichostatin A dramatically stimulate the p21/WAF1 gene promoter through the Spl sites, resulting in cell cycle arrest. Interestingly, another group has recently reported that phenylbutyrate, which is also known as a histone deacetylase inhibitor, is very effective for leukemia patients. We therefore consider methods of up-regulating p21/WAF, gadd45 or bax genes should be useful for cancer therapy and termed this method "Gene-regulating chemotherapy". Theoretically, the chemicals up-regulating such genes should be also useful for chemoprevention, and we also termed it as "Gene-regulating chemoprevention". In conclusion, we propose that "Gene-regulating chemotherapy or chemoprevention" may be a promising new method for cancer therapy or prevention and histone deacetylase inhibitor is a good candidate for this method.     

Non-viral gene therapy for Duchenne muscular dystrophy: progress and challenges

Duchenne muscular dystrophy (DMD) is one of the most common lethal, hereditary diseases of childhood. Since the identification of the genetic basis of this disorder, there has been the hope that a cure would be developed in the form of gene therapy. This has yet to be realized, but many different gene therapy approaches have seen dramatic advances in recent years. Although viral-mediated gene therapy has been at the forefront of the field, several non-viral gene therapy approaches have been applied to animal and cellular models of DMD. These include plasmid-mediated gene delivery, antisense-mediated exon skipping, and oligonucleotide-mediated gene editing. In the past several years, non-viral gene therapy has moved from the laboratory to the clinic. Advances in vector design, formulation, and delivery are likely to lead to even more rapid advances in the coming decade. Given the relative simplicity, safety, and cost-effectiveness of these methodologies, non-viral gene therapy continues to have great promise for future gene therapy approaches to the treatment of DMD.     

Gene therapy in cancer

Gene therapy, recently frequently investigated, is an alternative treatment method that introduces therapeutic genes into a cancer cell or tissue to cause cell death or slow down the growth of the cancer. This treatment has various strategies such as therapeutic gene activation or silencing of unwanted or defective genes; therefore a wide variety of genes and viral or nonviral vectors are being used in studies. Gene therapy strategies in cancer can be classified as inhibition of oncogene activation, activation of tumor suppressor gene, immunotherapy, suicide gene therapy and antiangiogenic gene therapy. In this review, we explain gene therapy, gene therapy strategies in cancer, approved gene medicines for cancer treatment and future of gene therapy in cancer. Today gene therapy has not yet reached the level of replacing conventional therapies. However, with a better understanding of the mechanism of cancer to determine the right treatment and target, in the future gene therapy, used as monotherapy or in combination with another existing treatment options, is likely to be used as a new medical procedure that will make cancer a controllable disease.     

人前胰岛素原基因裸质粒DNA肌肉注射可显著降低链脲佐菌素诱发糖尿病小鼠的血糖水平

通过基因治疗的方法补充胰岛素已用于实验性治疗胰岛素依赖型糖尿病(IDDM)。本研究构建了含有重组人前胰岛素原基因的棵质粒DNA载体(pCMV—IN),将其肌肉注射入链脲佐菌素(STZ)诱发的糖尿病C57小鼠体内,并辅以电穿孔方法,以获得在体胰岛素转基因治疗。该质粒载体表达的胰岛素mRNA,可通过RT—PCR方法在转基因局部的骨骼肌组织中检测到。在接受pCMV—IN注射的糖尿病小鼠中,血浆胰岛素水平显著升高,达到了未注射STZ的正常对照小鼠的水平,且胰岛素的表达可持续至少35d。pCMV—IN质粒注射转基因治疗显著降低了糖尿病小鼠在第7至35d的血糖水平,其下降幅度约6mmol／L;转基因治疗也显著降低了严重糖尿病小鼠的死亡率,其第6周时的死亡率由100％降为37％。结果表明,直接肌肉注射含人前胰岛素原基因裸质粒可获得胰岛素的有效表达,显著降低糖尿病小鼠的血糖水平并降低严重糖尿病小鼠的死亡率。裸质粒注射胰岛素转基因治疗有望成为IDDM的一种有效治疗手段。     

Possible Novel Therapy for Malignant Gliomas with Secretable Trimeric TRAIL

Malignant gliomas are the most common primary brain tumors. Despite intensive clinical investigation and many novel therapeutic approaches, average survival for the patients with malignant gliomas is only about 1 year. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has shown potent and cancer-selective killing activity and drawn considerable attention as a promising therapy for cancers, but concerns over delivery and toxicity have limited progress. We have developed a secretable trimeric TRAIL (stTRAIL) and here evaluated the therapeutic potential of this stTRAIL-based gene therapy in brain tumors. An adenovirus (Ad-stTRAIL) delivering stTRAIL was injected into intra-cranial human glioma tumors established in nude mice and tumor growth monitored using the magnetic resonance imaging (MRI). Ad-stTRAIL gene therapy showed potent tumor suppressor activity with no toxic side effects at therapeutically effective doses. When compared with 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU), a conventional therapy for malignant gliomas, Ad-stTRAIL suppressed tumor growth more potently. The combination of Ad-stTRAIL and BCNU significantly increased survival compared to the control mice or mice receiving Ad-stTRAIL alone. Our data indicate that Ad-stTRAIL, either alone or combined with BCNU, has promise as a novel therapy for malignant gliomas.     

基因治疗心肌缺血的载体应用新进展

近年来,随着基因治疗技术的不断进步,为心肌缺血的治疗开辟了一条全新的途径,并取得了一些令人鼓舞的进展。基因治疗主要包括治疗基因、基因转移载体以及基因导入途径三个方面。基因转移载体又在治疗基因和基因表达之间起着桥梁作用,因此,发展安全、高效的基因转移系统是基因治疗的关键之一。目前用于基因治疗心肌缺血基因转移的载体主要有病毒载体和非病毒载体。下面将就不同载体在心肌缺血的基因治疗中的应用进展进行简要的总结。     

基因治疗心肌缺血的载体应用新进展

近年来,随着基因治疗技术的不断进步,为心肌缺血的治疗开辟了一条全新的途径,并取得了一些令人鼓舞的进展。基因治疗主要包括治疗基因、基因转移载体以及基因导入途径三个方面。基因转移载体又在治疗基因和基因表达之间起着桥梁作用,因此,发展安全、高效的基因转移系统是基因治疗的关键之一。目前用于基因治疗心肌缺血基因转移的载体主要有病毒载体和非病毒载体。下面将就不同载体在心肌缺血的基因治疗中的应用进展进行简要的总结。     

血管内皮细胞生长因子基因治疗闭塞性血管病研究进展

概述了近年来利用血管内皮细胞生长因子（ＶＥＧＦ）基因治疗闭塞性血管病的成果,初步探讨了ＶＥＧＦ基因的临床疗效及其应用的安全性。     

Identity and the ethics of gene therapy

Some conditions detrimental to human well-being, such as sickle-cell anaemia, cystic fibrosis, muscular dystrophy, Lesch-Nyhan disease and various immunodeficiencies, are genetically determined. One potential means of preventing the development of such conditions is the manipulation of genetic material in the conceptus of an organism which would otherwise develop such conditions. Genetic manipulations could take the form either of excising and substituting genetic material, excising but not substituting genetic material, adding but not excising genetic material or reorganizing existing genetic material. To succeed, manipulation would have to change genetic structure so as to change its informational content. It might be thought, however, that all or some such manipulations would involve causing particular individuals to cease to exist and involve bringing into existence new, distinct individuals. Gene therapy could not, therefore, be a procedure which improved the circumstances of the particular individual to whom it is applied. It might be suggested that once the metaphysics of identity and the facts of gene therapy are understood, certain interesting conclusions concerning the ethics of gene therapy emerge. Some such conclusions have been discussed in this journal by Noam J. Zohar and Jeffrey P. Kahn. More, however, needs to be said about them since neither Zohar nor Kahn draws the correct conclusions. While both have pertinent things to say, neither has given a completely clear account of the metaphysics of gene therapy and so neither has completely traced out the implication of the metaphysics for the ethics of gene therapy. This paper attempts to remedy these defects.     

Adenoviral gene therapy, radiation, and prostate cancer

Viral gene therapy has exceptional potential as a specifically tailored cancer treatment. However, enthusiasm for cancer gene therapy has varied over the years, partly owing to safety concerns after the death of a young volunteer in a clinical trial for a genetic disease. Since this singular tragedy, results from numerous clinical trials over the past 10 years have restored the excellent safety profile of adenoviral vectors. These vectors have been extensively studied in phase I and II trials as intraprostatically administered agents for patients with locally recurrent and high-risk local prostate cancer. Promising therapeutic responses have been reported in several studies with both oncolytic and suicide gene therapy strategies. The additional benefit of combining gene therapy with radiation therapy has also been realized; replicating adenoviruses inhibit DNA repair pathways, resulting in a synergistic sensitization to radiation. Other, nonreplicating suicide gene therapy strategies are also significantly enhanced with radiation. Combined radiation/gene therapy is currently being studied in phase I and II clinical trials and will likely be the first adenoviral gene therapy mechanism to become available to urologists in the clinic. Systemic gene therapy for metastatic disease is also a major goal of the field, and clinical trials are currently under way for hormone-resistant metastatic prostate cancer. Second- and third-generation "re-targeted" viral vectors, currently being developed in the laboratory, are likely to further improve these systemic trials.     

肿瘤基因治疗的研究进展

肿瘤是严重影响人类身体健康的重大疾病之一,肿瘤的发生发展是一个复杂的涉及到众多基因的过程,肿瘤的基因治疗也已经成为肿瘤治疗的研究热点之一。目前,肿瘤基因治疗的策略主要包括以下几个方面:基因沉默治疗、抑癌基因治疗、免疫基因治疗、自杀基因疗法、抑制肿瘤血管生成基因治疗、肿瘤多药耐药基因治疗、抗端粒酶疗法和多基因联合疗法等。我们简要地对上述策略及相关研究进展进行综述。