靶向腺病毒

本文介绍了靶向腺病毒与传统腺病毒载体相比之优势以及两种不同的靶向腺病毒构建策略,靶向腺病毒需要满足两个条件,一是去除天然嗜性,二是靶向新受体。有两种途径可以到这一目的,“双组分体系”中,腺病毒与双特异分子结合,该双特异分子可同时去除天然嗜性和靶向新受体。“单组分体系”中,病毒颗粒经基因修饰后,不再与天然受体结合,并加入了新配基。双组分体系可灵活地通过某特受体而达到靶向效果,单组分体系则更适于作用为基因治疗药物。     

人35型及11型腺病毒的研究进展

人35型（Ad35）和11型（Ad11）腺病毒同属于B2亚群，病毒受体均为CD46分子，Ad35和Ad11的中和抗体在不同地区不同人种的阳性率都比较低，且对肿瘤细胞、造血干细胞、树突状细胞等一些传统的5型和2型腺病毒嗜性较低的细胞有较高的感染效率，而且转移基因的表达水平较高，提示Ad11和Ad35是一类具有良好开发潜力的肿瘤基因治疗载体。目前，开发利用Ad35或Ad11主要有三种形式：嵌合型腺病毒载体、复制缺陷的35型或11型腺病毒载体和嵌合型的35型或11型“gutless”腺病毒载体。这些载体的体外疗效较好，但体内疗效不理想，原因主要是病毒颗粒在从注射部位到达靶组织会被多重屏障所拦截。因此，深入研究Ad35和Ad11感染细胞的过程和机制，将有助于将它们应用于包括肿瘤在内多种重大疾病的基因治疗。     

复制缺陷型腺病毒Ad-p14ARF治疗肝细胞癌的实验研究及作用机制的探讨

目的 研究复制缺陷型重组腺病毒Ad—p14ARF用于肿瘤基因治疗的可行性及其作用机制。方法 利用Ad—Easy系统构建并扩增了Ad—p14ARF复制缺陷型腺病毒;应用台盼蓝细胞计数法和倒置相差显微镜观察Ad-p14ARF对肝癌细胞的生长抑制作用;AnnexinV／PI双染法结合流式细胞仪检测不同滴度的Ad-p14ARF作用后肝癌细胞的凋亡情况;Western blot法检测相关蛋白的表达情况,构建皮下肝癌移植瘤裸鼠模型,研究Ad—p14ARF在体内的抑瘤活性。结果 Ad—p14ARF可以明显抑制野牛型p53和突变型p53表型的肝癌细胞增殖、生长。AnnexinV／PI双染色法显示,Ad—p14ARF能促进肝癌细胞株HepG2和BEL7402的细胞凋亡,凋亡细胞比例与腺病毒滴度呈现一定的剂量相关性。凋亡相关蛋白检测提示,Ad—p14ARF能上调p53下游基因Bax、p21的表达。体内抑瘤试验显示,Ad—ECRG2可以明显抑制肝癌细胞BEL7402裸鼠移植瘤的生长。结论 p14ARF基因的导入可以通过p53依赖和非依赖途径抑制肿瘤细胞增殖,促进肿瘤细胞凋亡,有望在恶性肿瘤的基因治疗中发挥重要作用。     

快速构建腺病毒载体的新方法

目前腺病毒载体已成为重要的基因治疗载体,随着分子生物学技术的迅速发展,构建重组腺病毒的方法有了很大改进。本文主要介绍3种快速构建腺病毒载体的新方法：一是细菌内同源重组法构建重组腺病毒;二是细胞外连接法构建重组腺病毒,三是在黏粒中构建重组腺病毒。3种构建腺病毒载体的新方法相比于传统方法,具有简便,快速,实验周期短的优点。     

复制缺陷型重组腺病毒介导mlFN-β基因治疗小鼠黑色素瘤的研究

目的：探讨人类复制缺陷型重组腺病毒载体介导mIFN-β基因治疗小鼠黑色素瘤的可行性和效果。方法：利用人类复制缺陷型重组腺病毒将目的基因mIFN-β经体外、体内两种途径导入小鼠黑色素瘤细胞（B16细胞）中，观察体外转mlFN-β基因的B16细胞的体内致瘤性和瘤苗作用，及通过腺病毒载体介导的mIFN-β对体内局部肿瘤治疗和抗肿瘤转移的作用。结果：1）携带目的基因的重组腺病毒感染B16细胞能获得较高的转移效率和目的基因的有效表达；2）将mIFN-β基因导入B16细胞对B16细胞的体外增殖能力无明显影响，但能显著提高细胞表面MHC-I类抗原的表达；3）将转mIFN-β基因的B16细胞接种小鼠，其体内致瘤性明显降低．且对对侧野生型B16细胞的致瘤性有抑制作用；4）瘤体内注射和经尾静脉注射途径给予AdCMV mIFN-β．对局部肿瘤和转移瘤有治疗作用。结论：利用人类复制缺陷型腺病毒载体介导mIFN-β基因治疗小鼠黑色素瘤是可行的，并具有较好疗效，提示用腺病毒载体携带有效的目的基因来开发瘤苗和治疗肿瘤具有良好的临床应用前景。     

肿瘤细胞CAR表达水平与5型腺病毒转导效率的关系

目的: 通过体外、体内实验探讨肿瘤细胞柯萨奇腺病毒受体(coxsackie adenovirus receptor, CAR)表达水平与腺病毒转导效率的关系,为腺病毒相关的生物制剂在临床个体化应用提供实验依据.方法: 将载有绿色荧光蛋白的Ad5 型腺病毒(Ad-GFP) 以100 MOI、200 MOI分别感染人食管癌细胞系KYSE510、KYSE150、EC9706、人宫颈癌细胞系HeLa、人卵巢癌细胞系SKOV3、人肝癌细胞系HepG2和人肺癌细胞系A549,感染后48 h通过流式细胞术检测Ad-GFP对不同细胞系的转导效率.采用Western blotting方法检测这些细胞中CAR的表达水平.将HeLa、A549、SKOV3、EC9706细胞分别接种于裸鼠腋下,接种细胞数分别为3×106、3×106、3×106、2×106,建立裸鼠移植瘤模型.待肿瘤长径达5～7 mm时,在裸鼠移植瘤内注射Ad-GFP,每次1×109PFU,间隔48 h注射第2次.第2次注射后48 h处死裸鼠,剖取瘤组织,荧光显微镜观察冰冻切片中GFP的表达情况以判定腺病毒在瘤体内的转导效率,同时用免疫组化法检测瘤组织内的CAR表达水平.结果: 200 MOI Ad-GFP感染A549、HeLa、HepG2、KYSE150细胞48 h后分别有92.67%、89.31%、84.98%、74.59%的细胞表达GFP;而SKOV3、KYSE510、EC9706细胞中腺病毒的转导效率明显降低,GFP阳性率分别为30.06%、27.40%、18.93%;各种细胞的CAR蛋白表达水平与腺病毒的转导效率呈正相关.注射Ad-GFP的裸鼠移植瘤组织中可见HeLa、A549瘤组织内有明显的点状绿色荧光,而SKOV3、EC9706瘤组织内表达GFP的细胞数明显少于前两种瘤组织;HeLa、A549裸鼠移植瘤组织内大多数瘤细胞高表达CAR ( ),SKOV3、EC9706移植瘤组织内CAR表达水平较低( 或-),表明瘤体内CAR表达水平与Ad-GFP的转导效率也呈正相关.结论: 体内外实验均显示肿瘤细胞的CAR表达水平与5型腺病毒转导效率密切相关.肿瘤患者治疗前检测组织中CAR表达水平有助于规范腺病毒载体的基因治疗药物的个体化使用.     

双启动子调控的条件复制腺病毒制备及其体外抑瘤作用

目的：构建并制备survivin及hTERT双启动子调控的条件复制腺病毒,探讨其特异性溶瘤作用。方法：PCR方法分别扩增肿瘤特异性survivin及hTERT启动子,分别克隆入腺病毒载体pXCl的两个复制必需基因E1A和E1B序列上游启动子区,构建出双肿瘤特异性启动子调控的条件复制腺病毒载体pXCl-SP—TP;脂质体法与pBHGE3骨架质粒共转染293E细胞进行重组腺病毒包装,稀释法测定腺病毒滴度;应用MTT、活细胞计数等方法观察其对肝癌细胞HepG2的特异性溶瘤作用并以正常人的血管内皮细胞ECV304作为对照。结果：测序及双酶切鉴定结果证实,成功构建了双肿瘤特异性启动子调控复制腺病毒载体;在293E细胞中获得了重组腺病毒Ad—sP—TP,滴度测定显示病毒滴度达到3．9×10^10TCID50／ml;MTT结果显示,Ad—sP—TP可有效抑制肝癌细胞增殖而对正常细胞无增殖抑制作用;活细胞计数及细胞形态观察结果显示,重组腺病毒在肝癌细胞中选择性复制并发挥溶细胞作用。结论：双启动子调控的腺病毒具有显著的溶瘤作用但对正常人血管内皮细胞不发挥溶细胞作用,实验结果为肝癌靶向治疗提供了更为良好的条件复制型病毒载体及新的治疗策略。     

双启动子调控的条件复制腺病毒制备及其体外抑瘤作用

目的:构建并制备survivin及hTERT双启动子调控的条件复制腺病毒,探讨其特异性溶瘤作用.方法:PCR方法分别扩增肿瘤特异性survivin及hTERT启动子,分别克隆入腺病毒载体pXC1的两个复制必需基因E1A和E1B序列上游启动子区,构建出双肿瘤特异性启动子调控的条件复制腺病毒载体pXC1-SP-TP;脂质体法与pBHGE3骨架质粒共转染293E细胞进行重组腺病毒包装,稀释法测定腺病毒滴度;应用MTT、活细胞计数等方法观察其对肝癌细胞HepG2的特异性溶瘤作用并以正常人的血管内皮细胞ECV304作为对照.结果:测序及双酶切鉴定结果证实,成功构建了双肿瘤特异性启动子调控复制腺病毒载体;在293E细胞中获得了重组腺病毒Ad-SP-TP,滴度测定显示病毒滴度达到3.9×1010TCID50/ml;MTT结果显示,Ad-SP-TP可有效抑制肝癌细胞增殖而对正常细胞无增殖抑制作用;活细胞计数及细胞形态观察结果显示,重组腺病毒在肝癌细胞中选择性复制并发挥溶细胞作用.结论:双启动子调控的腺病毒具有显著的溶瘤作用但对正常人血管内皮细胞不发挥溶细胞作用,实验结果为肝癌靶向治疗提供了更为良好的条件复制型病毒载体及新的治疗策略.     

重组腺病毒抗小鼠移植瘤生长

目的:研究携带细胞因子基因hIL-2、hTNF-a的重组腺病毒对小鼠移植瘤生长抑制作用。方法:将分别携带有hIL-2基因、hTNF-a基因的重组腺病毒感染人肺腺癌Anip973细胞系,应用ELISA试剂盒检测转染后的细胞IL-2、TNF-α的分泌量;通过肿瘤局部注射重组腺病毒的方法观察其在小鼠体内的抗肿瘤作用。结果:转基因的肿瘤细胞生长能力、克隆形成率等无明显变化。24h细胞培养上清IL-2的分泌量为50pg/2×105细胞,TNF-α的分泌量为20pg/2×105细胞。体内实验表明注射重组腺病毒后小鼠肿瘤生长缓慢,体积明显小于对照组(P<0.05),存活期显著延长。结论:瘤内注射重组腺病毒具有明显抗肿瘤作用。     

自杀基因靶向核素治疗肿瘤研究进展

肿瘤的基因治疗是近年来的研究热点。而基因治疗与放射性核素结合产生的基因靶向性放射性核素治疗，是在自杀基因疗法等基础上建立起来的一种新的肿瘤基因治疗方法。它形成了自杀基因和放射性核素对肿瘤的双重杀伤作用，为肿瘤的基因治疗开拓了新的研究方向。     

Combination therapy with conditionally replicating adenovirus and replication defective adenovirus

Low gene transfer rate is the most substantial hurdle in the practical application of gene therapy. One strategy to improve transfer efficiency is the use of a conditionally replicating adenovirus (CRAD) that can selectively replicate in tumor cells. We hypothesized that conventional E1-deleted adenoviruses (ad) can become replication-competent when cotransduced with a CRAD to selectively supply E1 in trans in tumors. The resulting selective production of large numbers of the E1-deleted ad within the tumor mass will increase the transduction efficiency. We used a CRAD (Delta24RGD) that produces a mutant E1 without the ability to bind retinoblastoma but retaining viral replication competence in cancer cells with a defective pRb/p16. Ad-lacZ, adenovirus-luciferase (ad-luc), and adenovirus insulin-like growth factor-1R/dominant-negative (ad-IGF-1R/dn; 482, 950) are E1-deleted replication-defective adenoviruses. The combination of CRAD and ad-lacZ increased the transduction efficiency of lacZ to 100% from 15% observed with ad-lacZ alone. Transfer of media of CRAD and ad-lacZ cotransduced cells induced the transfer of lacZ (media transferable bystander effect). Combination of CRAD and ad-IGF-1R/dn increased the production of truncated IGF-1R or soluble IGF-1R > 10 times compared with transduction with ad-IGF-1R/dn alone. Combined intratumoral injection of CRAD and ad-luc increased the luciferase expression about 70 times compared with ad-luc alone without substantial systemic spread. Combined intratumoral injection of CRAD and ad-IGF-1R/482 induced stronger growth suppression of established lung cancer xenografts than single injections. The combination of CRAD and E1-deleted ad induced tumor-specific replication of CRAD and E1-deleted ad and increased the transduction rate and therapeutic efficacy of these viruses in model tumors.     

肿瘤选择增殖型腺病毒载体研究进展

近年来，人们利用肿瘤细胞与正常细胞之间某些生物学性状的差异，构建了肿瘤选择增殖型腺病毒（CRAd）。其仅在肿瘤细胞中增殖，对正常细胞损伤小，以其为载体具有特别的优势。现就肿瘤CRAd的研究进展作一综述。     

肿瘤选择增殖型腺病毒载体研究进展

近年来,人们利用肿瘤细胞与正常细胞之间某些生物学性状的差异,构建了肿瘤选择增殖型腺病毒(CRAd)。其仅在肿瘤细胞中增殖,对正常细胞损伤小,以其为载体具有特别的优势。现就肿瘤CRAd的研究进展作一综述。     

Survivin-responsive conditionally replicating adenovirus exhibits cancer-specific and efficient viral replication

Although a conditionally replicating adenovirus (CRA) exhibiting cancer-selective replication and induction of cell death is an innovative potential anticancer agent, current imperfections in cancer specificity and efficient viral replication limit the usefulness of this technique. Here, we constructed survivin-responsive CRAs (Surv.CRAs), in which expression of the wild-type or mutant adenoviral early region 1A (E1A) gene is regulated by the promoter of survivin, a new member of the inhibitor of apoptosis gene family. We explored the cancer specificity and effectiveness of viral replication of Surv.CRAs, evaluating their potential as a treatment for cancer. The survivin promoter was strongly activated in all cancers examined at levels similar to or even higher than those seen for representative strong promoters; in contrast, low activity was observed in normal cells. Surv.CRAs efficiently replicated and potently induced cell death in most types of cancer. In contrast, minimal viral replication in normal cells did not induce any detectable cytotoxicity. A single injection of Surv.CRAs into a preestablished tumor expressing survivin, even at relatively low levels, induced significant tumor death and inhibition of tumor growth. Furthermore, Surv.CRAs were superior to telomerase-dependent CRAs, one of the most effective CRAs that have been examined to date, both in terms of cancer specificity and efficiency. Thus, Surv.CRAs are an attractive potential anticancer agent that could effectively and specifically treat a variety of cancers.     

A fiber-modified mesothelin promoter-based conditionally replicating adenovirus for treatment of ovarian cancer

PURPOSE: Recently, virotherapy has been proposed as a new therapeutic approach for ovarian cancer. Conditionally replicative adenoviruses (CRAd) may contain tumor-specific promoters that restrict virus replication to cancer cells. Mesothelin, a cell surface glycoprotein, is overexpressed in ovarian cancer but not in normal ovarian tissues. The purpose of this study was to explore the therapeutic utility of a mesothelin promoter-based CRAd in a murine model of ovarian cancer, using noninvasive in vivo imaging. EXPERIMENTAL DESIGN: We constructed a mesothelin promoter-based CRAd with a chimeric Ad5/3 fiber (AdMSLNCRAd5/3) that contains an Ad5 tail, Ad5 shaft, and an Ad3 knob. Previously, a chimeric Ad5/3 fiber has shown improved infectivity in many ovarian cancer cells. Viral replication and oncolysis were assessed in a panel of ovarian cancer cell lines. To test the oncolytic efficacy of AdMSLNCRAd5/3 in a murine model, bioluminescence imaging of tumor luciferase activity and survival analysis were done. RESULTS: AdMSLNCRAd5/3 achieved up to a 10,000-fold higher cell killing effect and up to 120-fold higher levels of viral replication in all human ovarian cancer cells, compared with wild-type Ad5. AdMSLNCRAd5/3 significantly inhibited tumor growth as confirmed by in vivo imaging (P < 0.05). Survival with AdMSLNCRAd5/3 was significantly enhanced when compared with no virus or with a wild-type Ad5-treated group (P < 0.05). CONCLUSIONS: The robust replication, oncolysis, and in vivo therapeutic efficacy of AdMSLNCRAd5/3 showed that this CRAd is a promising candidate for treating ovarian cancer. Importantly, we have applied in vivo imaging that has allowed repeated and longitudinal measurements of tumor growth after CRAd treatment.     

Replication of an integrin targeted conditionally replicating adenovirus on primary ovarian cancer spheroids

Replication competent viruses hold promise for treatment of advanced cancers resistant to available therapeutic modalities. Although preliminary clinical results have substantiated their efficacy, preclinical development of these novel approaches is limited by assay substrates. The evaluation of candidate agents could be confounded by differences between primary tumor cells and tumor cell lines, as discordance in the levels of surface receptors relevant for viral entry has been reported. Since primary tumor cells are difficult to analyze ex vivo for longitudinal observation of virus replication, we developed three-dimensional aggregates or spheroids of unpassaged and purified ovarian cancer cells as a means for prolonging primary tumor cell viability and as a three-dimensional in vitro model for replicative viral infection. Ovarian cancer cells purified from ascites samples were sustained for 30 days while retaining the infection profile with tropism modified and unmodified adenoviruses (Ads). Cell line and primary cell spheroids were used to quantitate the replication and oncolytic potency of replicative Ads in preclinical testing for human ovarian cancer trials. Therefore, spheroids provide a method to sustain purified unpassaged primary ovarian cancer cells for extended periods and to allow evaluation of replicative viruses in a three-dimensional model.