舌癌细胞系T-TFL的建立和生物学性状检测

背景：基因治疗已成为恶性肿瘤研究领域的热点和发展趋势，但舌癌基因治疗的研究报道极少。目的：构建含相关死亡结构域蛋白(FADD)及肿瘤坏死因子受体1(TNFR1)基因功能结构域的融合基因TFL，稳定转染入人舌鳞状细胞癌细胞系(Tca-8113)中，检测建系细胞T-TFL的生物学性状，探讨一种更有利于舌癌患者治疗期及治疗后期内生活质量的治疗手段。设计：以诊断为依据，前瞻性研究。地点和对象：实验在第四军医大学口腔医学院口腔颌面外科完成，研究对象为人舌鳞状细胞癌细胞系(Tca-8113)，上海第二医科大学口腔医学院建系。干预：反转录PCR获得人FADD及TNFR1基因cDNA，重组PCR法构建含二者功能结构域的融合基因TFL，通过阳离子脂质体法稳定转染TFL基因入Tca-8113细胞中。主要观察指标：Westem blot检测融合蛋白TNFR1／DED表达，通过形态学观察、生长曲线等检测T-TFL细胞的生物学性状。结果：获得了人FADD及TNFR1基因并构建成功融合基因TFL，转染入Tca-8113细胞后，能表达融合蛋白TNFR1／DED活性，且T-TFL细胞与亲本Tca-8113细胞的生物学性状无明显差异。结论：T-TFL细胞能表达融合蛋白TNFR1／DED活性，可以为进一步深入研究舌癌基因治疗提供实验基础。     

稳定转染融合基因TFL舌癌细胞系的建立及辐射敏感性实验

目的：构建含FADD及TNFR1基因功能结构域的融合基因TFL，稳定转染入人舌鳞状细胞癌细胞系(Tca—8113)中，检测建系细胞T—TFL的生物学性状，并初步观察T—TFL细胞对辐射的敏感性。方法：反转录PCR获得人FADD及TNFR1基因cDNA，重组PCR法构建含二者功能结构域的融合基因TFL；阳离子脂质体法稳定转染TFL基因入Tca—8113细胞中，Westem blot检测融合蛋白TNFR1／DED表达，通过生长曲线检测T—TFL细胞的生物学性状；MTT法检测γ射线对T—TFL细胞的作用效应。结果：获得了人FADD及TNFR1基因并构建成功融合基因TFL，转染入Tca—8113细胞后，能表达融合蛋白TNFR1／DED活性，且T—TFL细胞与亲本Tca—8113细胞的生物学性状无明显差异，T—TFL细胞明显增强了对辐射的敏感性。结论：T—TFL细胞能增强对辐射的敏感性，为进一步临床应用提供实验基础。     

siRNA下调VEGF基因沉默对人舌癌细胞株Tca8113的生物学作用

目的利用siRNA干扰技术特异性抑制人舌癌细胞株Tca8113的VEGF基因表达,旨在对口腔舌鳞状细胞癌抗血管生成的基因治疗提供理论依据。方法体外构建两对针对VEGF基因的siRNA重组质粒,利用脂质体转染法导入Tca8113细胞内,MTT法观察转染后的Tca8113细胞的增殖抑制率,流式细胞术检测细胞周期和凋亡率的改变,RT-PCR技术和western Blot法检测VEGF蛋白表达量。结果本研究设计的两个靶位点siRNA能有效抑制Tca8113细胞增殖,流式细胞术结果显示G0/G1期细胞阻滞,S期细胞减少,G2/M期细胞相对增多,细胞凋亡率增高。VEGF基因蛋白表达率降低,与对照组相比,差异有统计学意义P0.01。结论体外构建siRNA可特异有效的下调VEGF基因蛋白表达。瞬时转染siRNA可不同程度的抑制Tca8113细胞增殖和诱导凋亡。为口腔舌鳞状细胞癌抗血管生成基因治疗提供理论依据。     

nm23-H1基因转染对人舌癌Tca8113细胞株生物学行为的影响

目的研究nm23-H1基因转染对人舌癌Tca8113细胞株生物学行为的影响。方法采用脂质体转染法将真核表达载体pAdEasy-nm23-H1转染Tca8113细胞,分为Tca8113-Ad-nm23-H1组(转染pAdEasy-nm23-H1)、Tca8113-Ad组(转染空载体pAdEasy)和Tca8113组(未转染)。采用RT-PCR检测nm23-H1基因在细胞中的表达,噻唑蓝比色法检测转染前、后细胞体外增殖能力的变化,流式细胞术分析转染前、后细胞周期及凋亡的改变,采用Transwell小室和冲刷实验观察细胞侵袭、黏附、趋化运动能力的变化,克隆形成实验观察转染前、后细胞克隆形成能力。结果与Tca8113-Ad组和Tca8113组比较,Tca8113-Ad-nm23-H1组细胞体外增殖能力、细胞侵袭、黏附、趋化运动能力、克隆形成率及细胞S期比例下降(P<0.05);细胞G2/M期比例及凋亡率明显增高(P<0.05)。结论 nm23-H1基因转染后对人舌癌Tca8113细胞的增殖能力、侵袭转移能力均有明显抑制作用;nm23-H1基因可明显抑制人舌癌Tca8113细胞G2期向M期过渡,同时促进癌细胞凋亡。     

JUP对人口腔鳞状细胞癌生物学特性及预后的影响及机制分析

目的分析心肌桥粒盘状珠蛋白(JUP)的表达水平对人口腔鳞状细胞癌细胞的相关生物学特性和预后的影响,并对其影响机制进行探讨。方法回顾性抽取2016年12月至2018年12月格尔木市人民医院口腔科收治的65例口腔鳞状细胞癌患者癌组织及距离癌组织病灶2 cm左右的癌旁组织标本为研究对象。定量即时聚合酶链锁反应(qRT-PCR)检测口腔鳞状细胞癌患者癌组织及癌旁组织中JUPmRNA的表达情况。构建JUP干扰(对照组:未感染细胞组;shNC组:无关序列片段对照组;shJUP组:JUP沉默慢病毒组)和过表达(对照组:未感染细胞组;NC组:空载体对照组;JUP过表达组:过表达组)载体,包装成慢病毒,感染人口腔鳞状细胞癌Tca8113细胞,建立该基因沉默和过表达的稳转细胞株,并通过qRT-PCR和Western blot分别检测JUP在基因和蛋白水平上的表达情况。CCK-8和细胞划痕实验分别检测两种稳转细胞株的增殖、迁移以及侵袭能力。利用K-M曲线数据库资料分析JUP的表达与口腔鳞状细胞癌病人的预后相关性。结果 JUP基因在口腔鳞状细胞癌中的表达量较癌旁组织显著降低(P <0. 01)。与对照组细胞(sh NC)相比,稳定沉默JUP的人口腔鳞状细胞癌细胞Tca8113,其增殖能力无显著差异(P> 0. 05);与对照组细胞(shNC)相比,稳定沉默JUP的人口腔鳞状细胞癌细胞Tca8113(shJUP),其细胞凋亡能力明显降低(P <0. 05);与对照组(NC)相比,划痕愈合实验显示,外源性导入JUP的Tca8113细胞其迁移、侵袭能力显著下降(P <0. 05);K-M曲线结果显示低表达JUP与人口腔鳞状细胞癌病人的不良预后相关。结论 JUP的低表达与口腔鳞状细胞癌病人的转移密切相关,且与口腔鳞状细胞癌病人的不良预后相关。     

死亡受体信号传导途径研究进展

死亡受体途径是细胞凋亡的3条主要信号传导通路之一.死亡受体属于肿瘤坏死因子受体(TNFR)基因超家族,其胞外部分有一富含半胱氨酸的区域,胞质区有一由同源的氨基酸残基构成的具有蛋白水解功能的“死亡区域“(death domain,DD),目前已知死亡受体有5种,其凋亡诱导信号途径有3条:CD95/CD95L、TRAIL和TNFR信号转导通路.CD95与其三聚体配体的相关死亡结构域(Fas-associated death domain,FADD)结合再募集caspase-8形成死亡诱导信号复合体(death-inducing signaling complex,DISC),启动凋亡.TRAIL在胞膜上与相应受体结合,经过FADD传递信息后与MORT结构域等一起激活caspases发生凋亡.TNFR通路与NF-κ B等有关.本文将详细阐述它们各自的凋亡诱导过程.     

Livin基因对口腔鳞癌细胞TCA8113增殖及凋亡调控作用的研究

目的研究Livin基因在口腔鳞癌细胞TCA8113凋亡和增殖中的作用。方法通过建立高表达的Livin基因、RNA的干扰载体和脂质体转染的TCA8113细胞,采用Western blot和荧光定量PCR进行转染mRNA及蛋白表达变化的验证。细胞经Annexin V/PI染色,流式细胞仪检测其凋亡;四甲基偶氮唑蓝(MTT)分析转染后细胞增殖。结果细胞转染pcDNA3.1-Livin后高表达,而pSuper-shLivin转染后Livin基因被有效沉默。MTT增殖检测结果表明,高表达的Livin基因能促进TCA8113细胞增殖,而沉默的Livin基因能抑制细胞的增殖。细胞凋亡检测结果表明,高表达的Livin基因能抑制细胞凋亡,而沉默的Livin基因促进细胞凋亡。转染细胞时与顺铂同时使用后发现沉默的Livin基因能增强顺铂诱导细胞凋亡的能力。结论本研究证实,Livin基因的高表达和沉默能有效调控口腔鳞癌细胞TCA8113系的凋亡和增殖。顺铂与沉默的LIVIN基因联合使用后,诱导细胞凋亡的能力显著增强。     

靶向BIRC5,Bcl-2siRNA慢病毒表达载体最佳干扰序列的筛选

目的 针对设计合成构建的BIRC5和Bcl-2小分子干扰RNA(siRNA)的慢病毒质粒表达载体进行有效靶序列筛选,探讨其对靶基因的封闭和抑制作用.方法 将BIRC5和Bcl-2 siRNA慢病毒质粒表达载体通过脂质体介导,分别转染体外培养的Tca-8113细胞.采用半定量RT-PCR检测转染细胞BIRC5和Bcl-2 mRNA表达及Western blot检测蛋白表达水平.结果 BIRC5和Bcl-2 mRNA抑制率分别为35%～76%和30%～72%,所设计的siRNA序列不同程度降低和下调其mRNA及相应的蛋白表达,实验组与对照组比较差异有统计学显著性意义(P<0.05),阴性对照组无此作用(P>0.05).结论 设计合成的siRNA干扰序列能抑制其靶基因mRNA和蛋白的表达,不同的干扰靶点其抑制效果不同,本实验成功筛选出两对最佳干扰序列作为对肿瘤细胞基因治疗的实验研究.     

MicroRNA-21调控口腔鳞癌细胞顺铂耐药及其作用机制

目的:探讨micro RNA-21(mi RNA-21)在人口腔鳞癌顺铂耐药细胞中的表达及其作用机制。方法 :采用实时荧光定量PCR(RT-PCR)法检测mi RNA-21在口腔鳞癌细胞株Tca8113及顺铂耐药细胞株Tca8113/DDP的表达;采用体外转染法将mi RNA-21模拟物(mimics)或抑制物(inhibitor)分别转染Tca8113和Tca8113/DDP细胞,采用RT-PCR检测转染前后细胞中mi RNA-21的表达情况;采用CCK8实验检测转染前后细胞对顺铂敏感性的变化;并用Western blot检测转染前后细胞中PTEN的表达变化。采用双荧光素酶报告基因验证mi RNA-21是否作用于PTEN基因的3’-UTR区预测靶位。结果:mi RNA-21在Tca8113/DDP细胞中的表达水平是Tca8113细胞的(8.26±1.37)倍(P<0.01)。Tca8113细胞转染mi RNA-21 mimics后,细胞中mi RNA-21表达水平是转染前的(10.51±2.18)倍(P<0.01),顺铂对Tca8113细胞增殖的抑制率较转染前明显下降(P<0.05),细胞内PTEN表达水平较转染前明显下降(P<0.05)。Tca8113/DDP细胞在转染mi RNA-21 inhibitor后,细胞中mi RNA-21表达水平是转染前的(0.32±0.14)倍(P<0.01),顺铂对Tca8113/DDP细胞增殖的抑制率与转染前比较明显增加(P<0.05),细胞内PTEN表达水平较转染前明显增高(P<0.05)。经双荧光素酶报告基因验证PTEN是mi RNA-21的靶基因。结论:mi RNA-21在口腔鳞癌顺铂耐药细胞Tca8113/DDP中异常高表达,下调其表达可部分逆转细胞耐药性,mi RNA-21可能通过作用于PTEN参与口腔鳞癌细胞顺铂耐药的发生和发展。     

葡萄糖调节蛋白78真核表达载体及稳定转染人视网膜色素上皮细胞株的构建

背景:葡萄糖调节蛋白78 是存在于内质网上最多的分子伴侣蛋白,具有保护细胞对抗细胞调亡的作用.目的:构建携带并正确表达外源性人葡萄糖调节蛋白78 基因的重组真核表达载体,建立葡萄糖调节蛋白78 基因稳定转染的人视网膜色素上皮细胞系.方法:扩增人葡萄糖调节蛋白78 全长编码序列,将该目的基因与真核表达载体PEGFP-N1 进行定向连接,其产物转化细菌感受态细胞,以PCR 方法鉴定阳性克隆,并进行测序和分析比对,获得融合蛋白表达质粒载体pEGFP-grp78.通过阳离子脂质体介导将重组质粒pEGFP-grp78 转染入体外培养的人视网膜色素上皮细胞,经G418 筛选,建立稳定表达细胞系.结果与结论:体外培养的人视网膜色素上皮细胞株作为真核细胞表达系统,经荧光显微镜和RT-PCR 方法检测,G418 筛选的稳定转染细胞系中GFP大量表达,葡萄糖调节蛋白78 mRNA 的表达量是正常视网膜色素上皮细胞的4 倍左右,表示脂质体介导的pEGFP-grp78 质粒成功转染视网膜色素上皮细胞,并高效稳定表达葡萄糖调节蛋白78.     

The molecular mechanisms of XBP-1 gene silencing on IRE1α-TRAF2-ASK1-JNK pathways in oral squamous cell carcinoma under endoplasmic reticulum stress

BackgroundProteasome inhibitor Carbobenzoxy-Leu-Leu-leucinal (MG132) induces the unfolded protein response (UPR) in oral squamous cell carcinoma (OSCC). X-box binding protein 1 (XBP1) is a key UPR component that regulates endoplasmic reticulum stress (ER) homeostasis. This study was aimed to investigate the activation of IRE1α-TRAF2-ASK1-JNK pathway by silencing the XBP1 expression in an OSCC cell line.MethodsThe XBP1 specific short hairpin RNA (shRNA) plasmid vector was constructed and then transfected into the Tca-8113 cells. The effect of XBP-1 gene silencing on IRE1α-TRAF2-ASK1-JNK pathway under MG132 induced endoplasmic reticulum stress in Tca-8113 were investigated by real-time RT-PCR or western blot. Cell apoptosis was detected by flow cytometry.ResultsXBP1 expression was reduced in transfected groups and MG132 groups. shRNA-XBP1 induces IRE1α-TRAF2-ASK1 signaling activation to activate pro-apoptotic ASK1-JNK signaling. Moreover, combined shRNA-XBP1 with MG132 further enhanced downregulated XBP1 expression and upregulated activation of ASK1-JNK signaling.ConclusionsSilencing XBP1 expression under MG132 induced ER stress block the XBP1 survival pathway and synergism with MG132 to promote Tca8113 cell apoptosis. These findings provide a therapeutic option in oral squamous cell carcinoma by inhibition of proteasome and XBP1 splicing.     

Upregulated ROS production induced by the proteasome inhibitor MG-132 on XBP1 gene expression and cell apoptosis in Tca-8113 cells

Exposure of Tca-8113 cells to proteasome inhibitor carbobenzoxy-Leu-Leu-leucinal (MG-132) causing apoptosis is associated with endoplasmic reticulum (ER) stress. X-box-binding protein-1 (XBP1) is an important regulator of a subset of genes active during ER stress, which is related to cell survival and is required for tumor growth. The present study is to evaluate the effect of MG-132 on ROS production, XBP1 gene expression, tumor necrosis factor receptor-associated factor 2 (TRAF2), ASK1 and c-jun protein expression in tongue squamous cell carcinoma cell line Tca-8113 cells. ROS production was measured by reactive oxygen species assay. X-box binding protein-1 (XBP1) mRNA was analyzed by real-time–PCR, TRAF2, ASK1 and c-jun protein were investigated by western blot and immunocytochemistry respectively. The result indicated that ROS production, TRAF2, ASK1 and c-jun were elevated in MG-132 treated cells. Giving ROS scavenger N-acetyl-L-cysteine (NAC) largely prevented the effects of MG-132. Furthermore, treating with MG-132 lead to decreased XBP1 mRNA expression but could not completely block the expression of XBP1. Taken together, these findings provide the evidence that MG-132 induced ER stress lead to Tca-8113 cells apoptosis through ROS generation and TRAF2-ASK1-JNK signal pathway activation.     

三元复合因子Net基因的克隆及其真核表达

目的克隆人Net基因,构建Net基因表达载体并诱导融合蛋白表达。方法从正常人脐静脉内皮细胞(HUVEC)中抽提总RNA,经逆转录-聚合酶链反应(RT-PCR)扩增出人全长Net cDNA,构建pEGFP-N1/Net重组体质粒,并将其转染入高表达原癌基因c-fos的人胰腺癌细胞PANC-1中,分析转染细胞的Net表达水平和对细胞增殖力的影响。结果从人胰腺癌细胞PANC-1中克隆出长约1 224 bp的Net基因目的片段,成功构建了重组质粒pEGFP-N1/Net,诱导表达目的蛋白后,Net抑制原癌基因c-fos的表达,进而抑制人胰腺癌细胞的增殖。结论构建重组质粒pEGFP-N1/Net并表达Net融合蛋白,其抑制了细胞的增殖,为进一步研究Net的各种生物学活性及作用机制奠定了基础。     

lncRNA RP5-916L7.2 correlates with advanced tumor stage,and promotes cells proliferation while inhibits cells apoptosis through targeting miR-328 and miR-939 in tongue squamous cell carcinoma

BackgroundThis study aimed to investigate the correlation of lncRNA RP5-916L7.2 with tumor features of tongue squamous cell carcinoma (TSCC), and its effect on cells proliferation and apoptosis as well as its target miRNAs in TSCC cells.Methods30 TSCC patients underwent surgery were consecutively enrolled, tumor tissue and paired adjacent tissue were obtained for lncRNAs determination. Blank mimic (NC(+)), lncRNA RP5-916L7.2 mimic (RP5-916L7.2(+)), blank inhibitor (NC(−)), lncRNA RP5-916L7.2 inhibitor (RP5-916L7.2(−)), lncRNA RP5-916L7.2 inhibitor/miR-328-5p inhibitor (RP5-916L7.2(−)/miR-328(−)) and lncRNA RP5-916L7.2 inhibitor/miR-939-5p inhibitor (RP5-916L7.2(−)/miR-939(−)) plasmids were transfected into Tca-8113 cells. qPCR assay, CCK-8 assay, AV/PI assay were performed to detect the miRNA/lncRNA expression, cells proliferation and cells apoptosis, respectively.ResultslncRNA RP5-916L7.2 was increased in tumor tissue compared with paired adjacent tissue, and correlated with higher T stage, N stage as well as TNM stage in TSCC patients. In vitro experiments revealed that lncRNA RP5-916L7.2 promoted cells proliferation and repressed cells apoptosis in Tca-8113 cells. Subsequently, we selected top five potential target miRNAs of lncRNA RP5-916L7.2, and found that lncRNA RP5-916L7.2 reversely regulated the levels of miR-328-5p and miR-939-5p in Tca-8113 cells. Thus, we conducted rescue experiments, which showed that lncRNA RP5-916L7.2 enhanced cells proliferation and inhibited cells apoptosis through targeting miR-328-5p and miR-939-5p in Tca-8113 cells.ConclusionslncRNA RP5-916L7.2 was up regulated in tumor tissue and positively correlated with tumor stage, and promoted cells proliferation while inhibited cells apoptosis by targeting miR-328-5p and miR-939-5p in TSCC.     

Apoptotic effect of MG-132 on human tongue squamous cell carcinoma

The aim of this study was to investigate the apoptotic effect of a proteasome inhibitor MG-132 on Tca-8113, a cell line of human tongue squamous cell carcinoma. Tca-8113 cells were treated with 10, 20, and 30 μM of MG-132, or 5 μM thapsigargin. Apoptosis rate was determined with annexin V/propidium iodide double staining. Expression of E3ubiquitin-protein ligase was determined by ELISA, and Grp78 and caspase-12 mRNA, and Grp78 and caspase-12 protein was assessed by RT-PCR and Western blot, respectively. Apoptosis was observed 18 h after MG-132 treatment. The apoptotic rate in the 10, 20, and 30 μM MG-132 group was 13.5, 19.6 and 34.7%, respectively, which was higher than in the thapsigargin (8.5%, P < 0.01) or control group (0.5%, P < 0.01). The expression of E3 ubiquitin-protein ligase in the 10, 20, and 30 μM MG-132 group was 28.75 ± 2.28, 18.16 ± 0.65, 8.85 ± 0.72, respectively, which was lower than in the thapsigargin (38.96 ± 0.33, P < 0.05 or 0.01) or control (40.88 ± 4.52, P < 0.05 or 0.01) group. The levels of Grp78 and capase-12 mRNA, Grp78 and caspase-12 protein in the MG-132 groups were higher than in the control group (P < 0.01). In conclusion, MG-132 induces apoptosis in Tca-8113 cells in a concentration-dependent manner. The MG-132-induced apoptosis may involve downregulation of E3 ubiquitin ligase, and upregulation of Grp78 and caspase-12.     

人SLPI启动子调控下eGFP基因表达载体的构建与表达

目的构建SLPI基因启动子驱动下EGFP表达载体并验证该启动子在非小细胞肺癌细胞株中的特异调控活性。方法通过PCR方法从人外周血基因组中扩增SLPI启动子，经序列分析后，利用peDNA3．1（＋）和pEGFP构建SLPI启动子调控下EGFP表达载体，以脂质体介导转染入人宫颈上皮癌Hela、肺腺癌A549、SPC-A1和肝细胞癌HepG2细胞中，经G418稳定筛选后，在荧光显微镜下观察该启动子在非小细胞肺癌细胞株中的特异调控EGFP表达的活性。结果克隆出的SLPI启动子序列与Genebank上SLPI基因上游5’末端转录调控区的序列完全一致，稳定转染的细胞株Hela、A549、SPC—A1和HepG2中，CMV启动子控制下的EGFP基因均有表达，发出绿色荧光；而SLPI启动子词控下的EGFP基因在Hela、A549和SPC-A1中有表达，发出绿色荧光，在HepG2中则未见荧光发出。结论钓取的人SLPI启动子在非小细胞肺癌细胞中具有特异调控其下游基因表达的活性，为探索该启动子调控下的抗肺癌基因治疗提供实验基础。     

野生型与突变型PS1真核表达载体的构建及其在SH-SY5Y细胞中的表达

目的为了对我们发现的中国人家族性阿尔茨海默病早老素-1(presenilin1,PS1)基因新的点突变进行蛋白功能研究,分别构建野生型和突变型PS1(G289T)与绿色荧光蛋白(EGFP)共表达载体,并检测其在SHSY5Y细胞内的表达。方法利用含人全长PS1cDNA的pcDNA3·1(zeo ),采用定点突变技术,构建PS1(G289T)-pcDNA3·1(zeo )载体。采用基因重组技术构建野生型和突变型PS1与绿色荧光蛋白共表达载体。应用脂质体将携带野生型和突变型PS1的质粒转染至SH-SY5Y细胞,检测报告基因表达,RT-PCR检测PS1mRNA表达。结果经限制性内切酶酶切图谱分析及DNA测序证实融合蛋白表达载体构建成功;RT-PCR产物经测序显示突变型PS1mRNA在SH-SY5Y中有表达。结论成功构建了人野生型和突变型PS1与EGFP共表达载体并成功转染至SH-SY5Y细胞,为进一步的研究工作奠定了基础。     

Kinetics of cell death in T lymphocytes genetically modified with two novel suicide fusion genes

Donor lymphocyte infusions (DLI) following allogeneic stem cell transplantation are known to mediate graft-versus-leukemia effect (GVL). A major side effect of these immunotherapies is the development of graft-versus-host diseases (GVHD). One promising approach to prevent GVHD is to genetically modify donor T cells with a suicide mechanism that can be induced in the case of GVHD. Here we report on a retroviral vector containing the death effector domain (DED) of the human Fas-associated protein with death domain (FADD). The DED was fused to two copies of an FKBP506-binding protein and a truncated version of the human low-affinity receptor for nerve growth factor (LNGFR). Activation of the death signal pathway can be triggered upon the addition of chemical inducers of dimerization. This construct was functionally compared to an optimized HSV-TK vector in which a hypersensitive mutant of the herpes simplex virus thymidine kinase gene (TK39) was fused to a cytoplasmic truncated version of the cell surface antigen CD34. A direct comparison between both vectors in primary T lymphocytes showed that the number of T cells transduced with vectors containing the DED was significantly reduced within 24 h of drug administration whereas ganciclovir treatment of TK39-transduced T cells showed a delay in cell death of approximately 3-4 days. Our results indicate that constructs containing the DED may prove to be the most efficient mechanism to quickly eliminate alloreactive T cells.