CD基因对人胰腺癌细胞株Patu 8988杀伤作用的研究

目的　探讨腺病毒介导胞嘧啶脱氨酶 (CD )基因对人胰腺癌细胞株Patu 8988的杀伤作用。方法　采用细菌内同源重组方法 ,构建含胞嘧啶脱氨酶 (CD)基因重组腺病毒载体 ,经 2 93细胞包装、扩增 ,氯化铯密度梯度离心制备纯化高效的重组腺病毒 ,体外转染人胰腺癌细胞株Patu 8988,并给予前药 5 Fc ,观察其体外杀伤效果。结果　含CD基因的腺病毒载体经酶切鉴定正确 ,包装纯化后 ,检测病毒滴度为 2× 10 11pfu/ml ,将重组腺病毒转染胰腺癌细胞株Patu 8988,加用前药 5 Fc后 ,转染CD基因的Patu 8988细胞及混育的胰腺癌细胞生长明显受抑制。结论　CD腺病毒不仅转染效果强 ,而且可直接或通过旁观者效应杀伤胰腺癌细胞。自杀基因治疗有可能成为治疗胰腺癌的有效方法     

p16基因重组质粒的构建及其对人肺癌细胞的抑制作用

表达大肠杆菌胞嘧啶脱胺酶(CD)基因的重组腺病毒AdCD体外转染小鼠黑色素瘤细胞B16F10,结果显示转染了CD基因的B16F10细胞对5-氟胞嘧啶(5FC)的敏感性显著提高.将经AdCD/5FC系统处理的B16F10细胞上清倍比稀释后.加至野生型B16F10细胞中,发现当上清仅占6.25%时即可对野生型B16F10细胞发挥明显的杀伤作用,提示AdCD/5FC介导的旁观者效应可能是通过5FC经CD酶代谢产生的毒性产物扩散而实现的.本实验还观察了CD基因体内转染后的杀伤效果,荷瘤小鼠经注射AdCD并连续10天给予5FC治疗后,与PBS、对照病毒AdLacZ/5FC治疗小鼠比较,小鼠肿瘤生长明显受到抑制,小鼠存活期明显延长.     

CD/5-FU联合亚叶酸钙对直肠癌细胞杀伤作用的研究

目的 :探讨亚叶酸钙 (CF)联合 5 氟胞嘧啶 (5 FU)对转染胞嘧啶脱氨酶 (CD)基因的直肠癌细胞的杀伤作用。方法 :构建含CD基因的真核表达载体pCDA。应用四唑盐 (MTT)比色试验检测瘤细胞的存活率 ,观察CF联合 5 氟尿嘧啶 (5 FU)对CD阴性细胞及CF联合 5 FU对CD阳性细胞的杀伤作用 ,同时观察CF对CD/ 5 FU旁观者效应的影响。结果 :CF增强 5 FU对 834 8细胞的杀伤作用。单独CD/ 5 FU和CD/ 5 FU联合CF对 834 8细胞的IC5 0分别为 0 .8mmol/L、0 .3mmol/L ,CF明显降低5 FU的IC5 0 (P <0 .0 1)。CF对CD/ 5 FU系统的旁观者效应也有增强作用。结论 :CF明显增强CD/5 FU系统对直肠癌细胞的杀伤效能 ,可作为一种增效剂应用于CD自杀基因治疗直肠癌     

CD基因表达诱导结肠癌细胞的凋亡作用

目的:研究胞嘧啶脱氨酶(cytosinedeaminase,CD)基因表达是否具有诱导结肠癌细胞凋亡的作用。方法:用不同浓度的5氟胞嘧啶(5flurocytosine,5FC)加至CD基因阳性人结肠癌细胞株SW1116培养,MTT法检测5FC药物对结肠癌细胞生长抑制作用。AnnexinV/PI法分析细胞凋亡率,用透射电镜观察细胞结构改变。结果:与未导入基因的SW1116细胞相比,CD基因阳性细胞对5FC的敏感性明显增加,50%细胞生长抑制率(IC50)浓度由SW1116细胞的16000μmol/L降低到SWCD2的66μmol/L。CD基因导入细胞能够增加5FC诱导的细胞凋亡率。SW1116细胞凋亡率:未加药为2.52%,加药24h为4.61%,48h为2.25%,72h为8.41%;而SWCD2的凋亡率:未加药为4.81%,加药后24h为4.73%,48h为20.78%,72h为32.92%,细胞凋亡率的增加与给药时间成正比。电镜下可见明显的凋亡细胞形态特征。结论:CD基因表达对人结肠癌细胞生长的抑制作用涉及肿瘤细胞凋亡机制。     

CD与bcl-Xs基因联合转染卵巢癌细胞株对5-氟胞嘧啶作用的影响

目的　了解自杀基因胞嘧啶脱氨酶基因 (cytosinedeaminase ,CD)及其前药 5 氟胞嘧啶 (5 fluorucytosine,5 FC)和bcl Xs基因转移联合作用对卵巢癌细胞株生长的影响。方法　以复制缺陷型腺病毒为载体将CD基因和bcl Xs基因体外转染大鼠卵巢癌细胞株NUTU 19细胞 ,加入含 5 FC的培养基。MTT法检测培养细胞吸光度值 ,计算细胞存活率。结果　单一bcl Xs基因转移及单一CD /5 FC系统作用对NUTU 19细胞的生长抑制作用均随病毒滴度的增加而增大 ;将两者联合作用于NU TU 19细胞 ,其生长抑制率比两者单独使用时的生长抑制率之和更高 ,表现为协同效应 (P <0 .0 0 0 1)。结论　CD /5 FC系统与bcl Xs基因转移联合使用对NUTU 19细胞的生长抑制具有协同作用。     

人生长抑素受体-2和大肠杆菌胞嘧啶脱氨酶共表达细胞系的建立及其对5-氟胞嘧啶杀伤的敏感性

目的建立共表达人生长抑素受体2(SSTR2)和大肠杆菌胞嘧啶脱氨酶(CD)的细胞系,为"自杀基因"/前体药物系统联合SSTR2介导的放射性免疫杀伤和显像治疗肿瘤提供细胞模型.方法应用反转录PCR方法从人胚肾293细胞中克隆人sstr2基因,通过基因重叠延伸拼接(SOE)结合PCR方法将CD、内部核糖体进入位点(IRES2)和sstr2连接,并构建表达载体.体外转染人乳腺癌SKBr3细胞并筛选,通过间接免疫荧光检测SSTR2的表达,并研究前体药物5-氟胞嘧啶(5-FC)对上述细胞的杀伤作用.结果成功克隆了人sstr2基因,并构建了CD和sstr2基因的双顺反子表达载体,进一步建立了稳定转染上述表达载体的SKBr3细胞系,间接免疫荧光证实了SSTR2的表达,同时建系细胞能够被前体药物5-FC高效杀伤.结论本研究建立的人乳腺癌细胞系可以共表达sstr2和CD基因,为在体内研究放射性核素标记的SSTR2配体显像和免疫杀伤,并协同CD/5-FC治疗肿瘤奠定基础.     

腺病毒介导的肝癌自杀基因疗法的实验研究

本文观察了胞嘧啶脱氨酶(CD)基因/5-氟胞嘧啶(5FC)自杀基因疗法对肝癌模型的治疗作用。以CMV启动子调控CD基因的重组腺病毒载体AdexCMV.CD在体外能有效转染人肝癌细胞株SMMC-7721和HepG2,转染后的细胞体外生长能力无明显变化,对5FC的敏感性明显增高。当以AFP上游调控序列驱动CD基因的重组腺病毒载体AdexAFP.CD分别转染SMMC-7721和HepG2时,CD基因能在HepG2中表达,使HepG2对5FC的敏感性增高,但不能使SMMC-7721的生长受到5FC的抑制。[~3H]TdR掺入法观察体外旁观者效应时发现,当细胞总数中转染细胞数超过20％时,其生长明显被5FC抑制。将AdexCMV.CD直接注射入裸鼠接种SMMC-7721细胞形成的皮下肿瘤中,并全身应用5FC后,与对照组相比,肿瘤大小在开始治疗后第8天约缩小3倍,第18天约缩小4倍,以上结果表明,腺病毒介导的CD/5FC自杀基因系统能在体内、外有效地抑制肝癌的生长。以AFP上游调控序列驱动CD基因的腺病毒载体介导的基因转染能在AFP阳性的肝癌细胞中特异表达。     

CD/5-FC系统对小鼠胃癌细胞杀伤作用的研究

目的：探讨CD5／5－FC自杀基因系统对小鼠胃癌细胞的体外杀伤作用及其机制。方法：以逆转录病毒载体介导CD基因转导小鼠胃癌细胞株MFC,采用MTT法测定CD／5－FC系统的体外杀伤作用及其“旁观者”效应;利用Hoechst 33258荧光染色法、琼脂糖凝胶电泳法检测凋亡细胞,同时采用半定量RT－PCR技术检测凋亡相关基因的表达。结果：转导CD基因可使MFC对5－FC高度敏感,并且显示出强大的“旁观者”效应。经5－FC作用后,荧光染色可见到典型的凋亡细胞核形态学改变,琼脂糖凝胶电泳出现典型的DNA梯度,同时发现凋亡相关基因bcl-2基因表达下调,而bax与caspase-3基因表达上调。结论：CD／5－FC自杀基因系统对小鼠胃癌细胞MFC具有强大的杀伤作用,体外杀伤作用是通过诱导MFC的凋亡来完成。     

腺病毒介导CD/5FC“自杀基因”疗法对人肝癌裸鼠和小鼠结肠腺癌的治疗作用研究

“自杀基因”疗法应用于肿瘤治疗时,通常是在肿瘤局部直接转染“自杀基因”,以期达到在肿瘤局部发挥抗肿瘤作用而避免全身毒性.在本实验中,我们观察了腺病毒介导的“自杀基因”疗法(CD/5FC系统)对人肝细胞癌SMMC-7721及小鼠结肠腺癌CT26的生长抑制作用,证实了腺病毒介导的CD/5FC系统在体外能杀伤人肝癌细胞SMMC-7721,并且能明显地抑制裸鼠SMMC-7721肿瘤模型的生长,对小鼠的结肠腺癌CT26也有一定的治疗作用.同时观察了以AFP启动子驱动的CD基因合并5FC的使用对AFP阳性肝癌细胞的特异性杀伤作用,证实了以肝癌特异启动子驱动的CD基因能在高表达AFP的肝癌细胞HepG2中特异表达,合并5FC的使用能在体外特异地杀伤HepG2细胞.这一组织特异性的“自杀基因”系统能特异地抑制高水平分泌AFP的人肝细胞癌裸鼠模型7721AFP( )的生长,上述研究结果表明,腺病毒介导的CD/5FC系统是一个有效的治疗方案,组织特异性的表达调控更能体现该疗法的实用价值.     

CD／5—FU联合亚叶酸钙对直肠癌细胞杀伤作用的研究

目的：探讨亚叶酸钙（CF）联合5－氟胞嘧啶（5－FU）对转染胞嘧啶脱氨酶（CD）基因的直肠癌细胞的杀伤作用。方法：构建含CD基因的真核表达载体pCDA。应用四唑盐（MTT）比色试验检测瘤细胞的存活率,观察CF联合5－氟尿嘧啶（5－FU）对CD阴性细胞及CF联合5－FU对CD阳性细胞的杀伤作用,同时观察CF对CD／5－FU旁观者效应的影响。结果:CF强5－FU对8384细胞的杀伤作用,单独CD／5－FU和CD／5－FU联合CF对8348细胞的IC50分钟为0．8mmol/L,0.3mmol/L,CF明显降低5－FU的IC50（P＜0．01）,CF对CD／5－FU系统的旁观者效应也有增强作用。结论：CF明显增强CD／5－FU系统对直肠癌细胞的杀伤效能,可作为一种增效剂应用于CD自杀基因治疗直肠癌。     

Cytosine deaminase/5-fluorocytosine gene therapy can induce efficient anti-tumor effects and protective immunity in immunocompetent mice but not in athymic nude mice

Murine hepatocellular carcinoma cells were retrovirally transduced with the bacterial cytosine deaminase (CD) gene. CD-transduced cells exhibited more than 120-fold higher sensitivity to 5-fluorocytosine (5-FC) compared with parental cells. When syngeneic immunocompetent mice were inoculated s.c. with parental hepatocellular carcinoma cells containing as little as 5% CD-transduced cells, significant inhibition of tumor formation was induced by 5-FC treatment. Furthermore, established solid tumors in immunocompetent mice containing only 5% CD-transduced cells were infiltrated markedly with CD4- and CD8+ T lymphocytes and macrophages by 5-FC treatment, such that significant reduction or even complete regression of tumors was observed. These tumor-free mice resisted subsequent rechallenge with wild-type tumor. Conversely, when athymic nude mice were inoculated with a cell mixture containing CD-transduced cells and parental cells at a ratio of 40:60, all developed tumors despite 5-FC treatment. Our results indicate that gene therapy using the CD/5-FC system can induce efficient anti-tumor effects and protective immunity in immunocompetent mice but not in athymic immunodeficient mice, suggesting that the host's immunocompetence may be a critical factor for achieving successful gene therapy against cancer.     

前药 5-FC 联合胃泌素拮抗剂 CI-988 对转 CD 基因大肠癌 SW480细胞的杀伤作用

目的：探讨联合应用前药5-氟胞嘧啶（5-iluorocytosine，5-FC）和胃泌素拮抗剂CI-988对转组织特异性胞嘧啶脱氨基酶（cytosinedeaminase，CD）基因的大肠癌SW480细胞生长的影响。方法：将转CD基因大肠癌SW480细胞接种至4块24孔细胞培养板中，依次分为实验组1、2、3及对照组，分别以含有前药5-FC、胃泌素拮抗剂CI-988、5-FC联合CI-988及正常培养液进行培养。每天胰酶消化法计数各组4孔，共6d，绘制细胞生长曲线并计算生长抑制率。按上述分组方法另接种培养4组细胞，于培养72h行M1Tr法检测490nm处吸光度A值，计算细胞杀伤率。结果：应用5-FC联合CI-988处理的转CD基因大肠癌SW480细胞在6d后生长抑制率达97％；于培养72h时，实验组1、3细胞杀伤率较对照组有显著性差异（P〈0．01）；实验组2与对照组无显著性差异（P〉0．05）；实验组3较实验组1、2有显著性差异（P〈0．01）。结论：CD／5-FC系统和胃泌素拮抗剂CI-988对转基因大肠癌SW480细胞具有杀伤或抑制作用，联合应用胃泌素拮抗剂可以提高CD／5-FC自杀基因系统对大肠癌细胞的杀伤效应。     

5—氟胞嘧啶对表达胞嘧啶脱氨酶的人肾母细胞瘤裸鼠异种移植瘤 …

OBJECTIVE: To study the effect of 5-fluorocytosine (5-FC) as prodrug in the treatment of Wilms' tumor xenografts transduced with cytosine deaminase (CD) gene. METHODS: An in vivo model of a poorly differentiated Wilms' tumor transplanted in nude mice was established. Expression adenoviral-vector of CD gene (Ad/CMV-CD) or lac gene (Ad/CMV-lac) was transduced to the tumor xenografts by intratumoral injections. Expression of the transduced genes were confirmed by RT-PCR. Mice with Wilms' tumor xenograft were treated with 5-FC (500 mg.kg-1.d-1 x 10 d). Tumor growth was monitored. RESULTS: The growth of tumor xenografts transduced with lac gene grew as quick as the untransduced ones. In contrast, the growth of the tumor xenografts transduced with CD gene was significantly inhibited as compared to untransduced and lac gene transduced xenografts. The average rate of inhibition was 65% according to the tumor weight at 8 wk. Cell necrosis was observed in the CD gene transduced tumors. CONCLUSION: Intratumoral cytosine deaminase gene transduction followed by systemic 5-fluorocytosine is effective in the treatment of Wilms' tumor.     

Interaction of endothelial progenitor cells expressing cytosine deaminase in tumor tissues and 5-fluorocytosine administration suppresses growth of 5-fluorouracil-sensitive liver cancer in mice

The drug delivery system to tumors is a critical factor in upregulating the effect of anticancer drugs and reducing adverse events. Recent studies indicated selective migration of bone marrow-derived endothelial progenitor cells (EPC) into tumor tissues. Cytosine deaminase (CD) transforms nontoxic 5-fluorocytosine (5-FC) into the highly toxic 5-fluorouracil (5-FU). We investigated the antitumor effect of a new CD/5-FC system with CD cDNA transfected EPC for hepatocellular carcinoma (HCC) in mice. We used human hepatoma cell lines (HuH-7, HLF, HAK1-B, KYN-2, KIM-1) and a rat EPC cell line (TR-BME-2). Escherichia coli CD cDNA was transfected into TR-BME-2 (CD-TR-BME). The inhibitory effect of 5-FU on the proliferation of hepatoma cell lines and the inhibitory effect of 5-FU secreted by CD-TR-BME and 5-FC on the proliferation of co-cultured hepatoma cells were evaluated by a tetrazolium-based assay. In mouse subcutaneous xenograft models of KYN-2 and HuH-7, CD-TR-BME was transplanted intravenously followed by 5-FC injection intraperitoneally. HuH-7 cells were the most sensitive to 5-FU and KYN-2 cells were the most resistant. CD-TR-BME secreted 5-FU and inhibited HuH-7 proliferation in a 5-FC dose-dependent manner. CD-TR-BME were recruited into the tumor tissues and some were incorporated into tumor vessels. Tumor growth of HuH-7 was significantly suppressed during 5-FC administration. No bodyweight loss, ALT abnormality or bone marrow suppression was observed. These findings suggest that our new CD/5-FC system with CD cDNA transfected EPC could be an effective and safe treatment for suppression of 5-FU-sensitive HCC growth.     

Hypoxia imaging predicts success of hypoxia-induced cytosine deaminase/5-fluorocytosine gene therapy in a murine lung tumor model

Tc-99m-HL91 is a hypoxia imaging biomarker. The aim of this study was to investigate the value of Tc-99m-HL91 imaging for hypoxia-induced cytosine deaminase (CD)/5-fluorocytosine (5-FC) gene therapy in a murine lung tumor model. C57BL/6 mice were implanted with Lewis lung carcinoma cells transduced with the hypoxia-inducible promoter-driven CD gene (LL2/CD) or luciferase gene (LL2/Luc) serving as the control. When tumor volumes reached 100?mm(3), pretreatment images were acquired after injection of Tc-99m-HL91. The mice were divided into low and high hypoxic groups based on the tumor-to-non-tumor ratio of Tc-99m-HL91. They were injected daily with 5-FC (500?mg?kg(-1)) or the vehicle for 1 week. When tumor volumes reached 1000?mm(3), autoradiography and histological examinations were performed. Treatment with 5-FC delayed tumor growth and enhanced the survival of mice bearing high hypoxic LL2/CD tumors. The therapeutic effect of hypoxia-induced CD/5-FC gene therapy was more pronounced in high hypoxic tumors than in low hypoxic tumors. This study provides the first evidence that Tc-99m-HL91 can serve as an imaging biomarker for predicting the treatment responses of hypoxia-regulated CD/5-FC gene therapy in animal tumor models. Our results suggest that hypoxia imaging using Tc-99m-HL91 has the predictive value for the success of hypoxia-directed treatment regimens.     

含胞嘧啶脱氨酶基因重组腺病毒的构建及其对肺癌抑制作用的研究

目的：构建含胞嘧啶脱氨酶基因（CD基因）重组腺病毒（AdE1CMVCD），并鉴定；用自杀基因治疗系统（AdE1CMVCD/5-FC）对肺癌进行抑瘤作用的实验研究。方法：体外实验：用不同稀释度的AdE1CMVCD)转染人肺癌细胞H460后分别加入不同浓度的5-氟胞嘧啶（5-FC），用MTT法检测OD570nm值，按公式计算细胞生长抑制率；体内实验：建立T739鼠肺腺癌荷瘤模型，瘤体内导入AdE1CMVCD，腹腔注射5-Fc，观察实验组及各对照组瘤体及生存期差异。结果：该系统转染的人肺癌H460细胞生长抑制率随前药5-FC浓度及感染重组病毒剂量的增加而增加，最大抑制率达61.29％，同时观察到了明显的旁杀伤作用；在体内实验中观察到AdE1CMVCD/5-FC对小鼠肺癌有明显的生长抑制作用，明显延长荷瘤小鼠生存期。结论：本文建立的AdE1CMVCD/5-FC系统体内外对肺癌均有明显的抑制作用，为临床肺癌基因治疗的应用奠定了基础。     

Mechanisms of thymidine kinase/ganciclovir and cytosine deaminase/ 5-fluorocytosine suicide gene therapy-induced cell death in glioma cells

Suicide gene transfer using thymidine kinase (TK) and ganciclovir (GCV) treatment or the cytosine deaminase (CD)/5-fluorocytosine (5-FC) system represents the most widely used approach for gene therapy of cancer. However, molecular pathways and resistance mechanisms remain controversial for GCV-mediated cytotoxicity, and are virtually unknown for the CD/5-FC system. Here, we elucidated some of the cellular pathways in glioma cell lines that were transduced to express the TK or CD gene. In wild-type p53-expressing U87 cells, exposure to GCV and 5-FC resulted in a weak p53 response, although apoptosis was efficiently induced. Cell death triggered by GCV and 5-FC was independent of death receptors, but accompanied by mitochondrial alterations. Whereas expression of Bax remained unaffected, in particular, GCV and also 5-FC caused a decline in the level of Bcl-2. Similar findings were obtained in 9L and T98G glioma cells that express mutant p53, and also underwent mitochondrial apoptosis in both the TK/GCV and CD/5-FC system. Upon treatment of 9L cells with 5-FC, Bcl-xL expression slowly declined, whereas exposure to GCV resulted in the rapid proapoptotic phosphorylation of Bcl-xL. These data suggest that TK/GCV- and CD/5-FC-induced apoptosis does neither require p53 nor death receptors, but converges at a mitochondrial pathway triggered by different mechanisms of modulation of Bcl-2 proteins.     

A novel mechanism of synergistic cytotoxicity with 5-fluorocytosine and ganciclovir in double suicide gene therapy

The combination of cytosine deaminase (CD) and herpes simplex virus thymidine kinase (HSV-TK) suicide gene protocols has resulted in enhanced antitumor activity in cultured tumor cells and animal models. In this study, we show that concurrent addition of prodrugs 5-fluorocytosine (5-FC) and ganciclovir (GCV) was less efficacious than sequential treatment in human DU145 prostate carcinoma cells infected with an adenovirus containing a CD/HSV-TK fusion gene. If cells were incubated for 24 hours with 5-FC followed by a 24-hour GCV treatment, GCV triphosphate levels were 2-fold higher, incorporation of GCV monophosphate into DNA was 2.5-fold higher, and growth inhibition was increased 4-fold compared with simultaneous treatment. As expected, cellular dTTP levels were reduced during the 5-FC preincubation. However, dGTP pools also declined parallel to the dTTP decrease. Similar results were obtained when 5-fluorouracil or 5-fluoro-2'-deoxyuridine was used instead of CD/5-FC. These data allowed us to propose a novel hypothesis for the synergistic interaction between CD/5-FC and HSV-TK/GCV treatments. We suggest that the CD/5-FC-mediated reduction of dTTP results in a concurrent decrease of dGTP due to allosteric regulation of ribonucleotide reductase. Because dGTP is the endogenous competitor of GCV triphosphate, depleted dGTP at the time of GCV addition results in increased GCV in DNA and cell kill. In fact, addition of deoxyguanosine during the 5-FC incubation reverses the dGTP depletion, reduces the amount of GCV monophosphate incorporated into DNA, and prevents the CD/5-FC-mediated enhancement of HSV-TK/GCV cytotoxicity. Understanding this mechanistic interaction may help recognize better strategies for creating more efficacious clinical protocols.     

HIF依赖性表达的自杀基因抑制肾细胞癌生长的实验研究

目的探讨依赖乏氧诱导因子(hypoxiainduciblefactor.HIF)依赖性表达的自杀基因治疗系统对肾细胞癌的治疗效果。方法借助DNA重组技术构建HIF依赖性表达的重组腺病毒载体Ad-5HRE/hCMVmp-BCD。用Westernblot检测细菌胞苷脱氨酶(bacterialcytosinedeaminase,BCD)的表达,细胞生长抑制试验检测人肾细胞癌786-0细胞对5-氟胞嘧啶(5-fluorocytosine,5-FC)的敏感性,裸鼠移植瘤试验观察Ad-5HRE/hCMVmp-BCD/5-FC对786-0细胞移植瘤的抑制效应。结果786-0细胞感染Ad-5HRE/hCM-Vmp-BCD后,可诱导BCD蛋白的表达,并显著提高细胞对5-FC的敏感性。裸鼠移植瘤试验结果显示,Ad-5HRE/hCMVmp-BCD/5-FC可抑制肾细胞癌移植瘤的生长。结论HIF依赖性表达的Ad-5HRE/hCM-Vmp-BCD/5-FC自杀基因系统可显著抑制肾细胞癌生长,具有良好的临床应用前景。     

胞嘧啶脱氨酶基因联合放射对食管癌细胞株的杀伤作用

目的：观察大肠杆菌胞嘧啶脱氨酶／5-氟胞嘧啶（CD／5-FC）自杀基因系统对食管癌细胞株（EC109细胞）的杀伤效应以及与放射联合应用时对食管癌肿瘤细胞协同杀伤效应。方法：采用PCR方法,从大肠杆菌基因组DNA中扩增出CD基因;构建重组真核载体pcDNA3．1-CD;用脂质体转染法转染食管癌ECl09细胞,观察CD／5-FC体系对EC109细胞的杀伤效应和杀伤时的旁观者效应以及对放射的增敏效应。结果：RTP—CR分析结果表明CD基因已转入ECl09细胞并开始转录。体外实验证实,5-FC对转CD基因后的食管癌细胞株有明显的细胞毒作用,CD／5-FC体系对肿瘤细胞对放射增敏效果明显,加5-FC及放射治疗组细胞存活曲线低于单纯加前药5-FC对照组或单纯放射对照组。结论：CD／5-FC体系对肿瘤细胞的自杀效应具有旁观者效应和放射增敏效果。