结肠癌组织NRP-1和VEGF表达及其与预后相关性

目的结肠癌的发生发展过程与肿瘤血管生成密切相关,神经纤毛蛋白-1(neuropilin-1,NRP-1)和血管内皮生长因子(vascular endothelial growth factor,VEGF)在肿瘤血管生成中发挥重要作用。本研究旨在探讨结肠癌组织NRP-1和VEGF表达及其预后的关系。方法收集2010-08-01-2012-05-31南华大学附属南华医院普外胃肠病区手术切除、具有完整资料、术后经病理确诊的结肠癌及癌旁(>5cm)组织标本73例,采用免疫组织化学法检测NRP-1及VEGF在结肠癌及癌旁正常组织的表达;另外选取2016年南华大学附属南华医院切除结肠癌新鲜组织及癌旁组织(距癌组织>5cm)16对,采用蛋白质印迹法检测NRP-1及VEGF表达。结果免疫组化结果显示,与结肠癌癌旁组织比较,结肠癌组织中NRP-1及VEGF呈高表达,χ^2=55.857,P<0.001;χ^2=44.042,P<0.001。蛋白质印迹法检测结果显示,新鲜结肠癌组织中NRP-1及VEGF蛋白呈高表达,而癌旁组织中表达降低,差异有统计学意义,t=-63.238,P<0.001;t=-78.712,P<0.001。结肠癌组织中NRP-1和VEGF高表达均与肿瘤大小、TNM分期、淋巴结有无转移有关联,差异有统计学意义,P<0.05;癌胚抗原(carcinoembryonic antigen,CEA)的数值与NRP-1表达有关联(χ^2=15.966,P=0.002),而与VEGF表达无统计学意义的关联,χ^2=0.061,P=0.862;Cox多因素回归分析显示,CEA(RR=4.851,95%CI:1.013~23.427)、肿瘤大小(RR=0.157,95%CI:0.017~1.228)、TNM分期(RR=5.419,95%CI:2.179~32.479)、淋巴结转移(RR=0.137,95%CI:0.023~0.728)是NRP-1阳性表达的独立影响因素;生存分析显示,NRP-1阳性表达组患者生存周期短于阴性患者,χ^2=5.081,P=0.029。结论NRP-1参与结肠癌的血管生成,并导致预后不良,提示NRP-1在结肠癌发生发展中起重要作用,为评估结肠癌预后及研究靶向药物提供新的思路。     

胃癌组织MACC1表达及其临床意义分析

目的:研究结肠癌转移相关基因1(MACC1)在胃癌组织中的表达及其临床意义。方法:采用RT-qPCR检测胃癌组织株和67例胃癌组织及癌旁正常组织中MACC1mRNA的表达,免疫组化技术检测67例胃癌组织及癌旁正常组织中MACC1蛋白的表达,并分析其与临床病理资料的关系。结果:BGC823、SGC7901和MGC803 3种胃癌细胞株中MACC1mRNA的相对表达量分别为3.458 4±0.047 9、4.768 5±0.100 6和4.257 5±0.029 5,差异有统计学意义,F=295.131,P<0.05。癌组织MACC1mRNA表达量(5.560 0±2.853 1)较癌旁正常组织(2.190 1±1.675 9)显著增高,t=6.907,P=0.000。肿瘤组织中MACC1蛋白的阳性率为64.18%(43/67),显著高于癌旁正常组织5.97%(4/67),χ2=49.844,P<0.05,且MACC1蛋白的异常高表达与分化程度(χ2=14.492,P=0.000)、腹膜转移(χ2=4.251,P=0.039)、淋巴转移(χ2=11.978,P=0.001)、临床分期(χ2=11.024,P=0.001)密切相关,而与年龄(χ2=0.129,P=0.720)、性别(χ2=0.407,P=0.523)、肿瘤大小(χ2=0.017,P=0.897)、部位(χ2=3.021,P=0.082)及远处转移(χ2=0.000,P=1.000)无关。结论:MACC1可以作为预测腹膜转移、淋巴转移,评价胃癌进展的有效指标,可为胃癌患者的临床诊疗提供依据。     

沉默AQP-5表达对结肠癌细胞株HT-29凋亡影响机制探讨

目的 通过抑制内源性水通道蛋白(AQP-5)的表达,探讨AQP-5对HT-29细胞凋亡及凋亡抑制蛋白(inhibitaors of apoptosis proteins,IAPs)表达的影响.方法 体外常规培养人结肠癌HT-29细胞,通过siRNA技术抑制内源性AQP-5的表达,并经蛋白质印迹法检测AQP-5-siRNA转染效率;采用MTT法检测各组细胞增殖抑制率;流式细胞术检测细胞凋亡率;荧光实时定量RT-PCR和蛋白质印迹法检测转染AQP-5-siRNA的HT-29细胞IAPs家族成员c-IAP1、c-IAP2、XIAP、NAIP、Survivin和Livin表达水平.结果 蛋白质印迹法检测结果显示,转染AQP-5-siRNA的HT-29细胞AQP-5表达下调达90％.MTT分析结果显示,与转染NS-siRNA组细胞增殖抑制率(1.13±0.11)％相比,AQP-5-siRNA组的HT-29细胞增殖抑制率显著增加,高达(27.9±5.16)％,t=12.705,P＜0.001;流式细胞分析结果发现,与NS-siRNA组细胞凋亡率(0.99±0.18)％相比,AQP-5-siRNA组的HT-29细胞凋亡率显著增加,高达(10.81±1.32)％,t=-12.767,P＜0.001.荧光实时定量RT-PCR和蛋白质印迹法检测结果显示,与转染NS-siRNA组相比较,AQP-5-siRNA组c-IAP1(t=-3.232,P=0.018)、c-IAP2(t=-0.651,P=0.001)、XIAP(t=-9.296,P＜0.001)和Livin(t =-8.07,P＜0.001)的mRNA表达水平下降,AQP-5-siRNA组c-IAP1(t=-0.591,P=0.007)、c-IAP2(t=-4.889,P=0.008)、XIAP(t=-6.487,P=0.003)和Livin(t=-6.216,P=0.003)蛋白表达水平也下降,其中以XIAP下降最明显;Survivin和NAIP表达变化不明显.结论 AQP-5-siRNA可体外促进HT-29细胞凋亡,其机制可能与下调c-IAP1、c-IAP1、XIAP和Livin mRNA及蛋白表达有关.     

TRAF6表达与胃癌患者营养状况及预后的关系

目的 目前有关肿瘤坏死因子受体相关因子6(tumor necrosis receptor-associated factor 6,TRAF6)在胃癌相关领域的研究仍有限.本研究通过检测胃癌患者组织中TRAF6表达,探讨其与患者营养状况和预后的关系,为胃癌治疗提供新思路.方法 采用逆转录-聚合酶链反应、蛋白质印迹法、酶联免疫吸附试验检测2008-01-01-2013-06-30浙江省人民医院102例胃癌患者及53例腹腔良性疾病患者组织(腹直肌、血清)中TRAF6 mRNA和蛋白的表达情况,并结合临床资料分析其对胃癌患者营养状况及预后的影响.结果 胃癌患者腹直肌中TRAF6 mRNA的相对表达量(3.89±0.09)较腹腔良性疾病患者(1.77±1.08)明显升高,t=13.050,P<0.001.蛋白质印迹法结果显示,胃癌患者腹直肌中TRAF6蛋白表达较腹腔良性疾病患者明显升高,P<0.05.胃癌患者血清中TRAF6蛋白的相对表达量(4.89±1.09)较腹腔良性疾病患者(2.78±1.18)明显升高,t=14.595,P<0.001.胃癌患者血清中TRAF6蛋白表达水平与患者体质量丢失(χ2=12.901,P<0.001)、血清白蛋白(χ2=17.422,P<0.001)及血红蛋白水平(χ2=4.886,P=0.027)有关.胃癌患者血清中TRAF6蛋白表达水平与患者胃癌病理类型(χ2=6.154,P=0.046)、淋巴结转移(χ2=10.237,P=0.001)及TNM分期(χ2=7.727,P=0.005)有关.胃癌患者血清中TRAF6蛋白表达水平与患者生存率有关,χ2=6.641,P=0.010.结论 胃癌患者腹直肌及血清中 TRAF6 mRNA 和蛋白表达升高,且血清中 TRAF6 蛋白表达水平患者的营养状况及预后存在关联.TRAF6 可能与胃癌患者癌性恶病质的发生发展有关.     

维拉帕米对体内外胰腺癌SW1990细胞侵袭转移影响及其机制探讨

目的探讨三磷酸腺苷结合转运蛋白G家族成员2(ATP-binding cassette superfamily G member 2,ABCG2)抑制剂维拉帕米对体内外胰腺癌SW1990细胞侵袭转移能力影响及其机制。方法以终浓度分别为0、12.5、25、50、100和200μmol/L维拉帕米处理SW1990细胞24、48和72h后,以CCK-8法检测维拉帕米对SW1990细胞增殖抑制影响;RT-PCR和蛋白质印迹法检测维拉帕米对体内外SW1990细胞ABCG2mRNA及蛋白表达水平的影响;Transwell小室侵袭迁移实验及划痕实验分析维拉帕米处理后细胞侵袭迁移能力的改变。将SW1990细胞接种至裸鼠皮下,对比观察维拉帕米干扰前后肿瘤细胞在裸鼠体内的成瘤情况;免疫组化分析裸鼠肿瘤组织中ABCG2的表达。结果 CCK-8检测结果显示,浓度为25~100μmol/L维拉帕米对胰腺癌SW1990细胞的抑制呈现明显的剂量及时间依赖性。划痕实验结果显示,细胞平均迁移率比较,划痕24h维拉帕米组为(19.2±2.04)%,对照组为(36.8±2.25)%,t=-17.23,P<0.001;48h维拉帕米组为(43.7±3.14)%,对照组为(78.4±2.67)%,t=-23.85,P<0.001。Transwell侵袭实验结果显示,维拉帕米组平均穿膜细胞数为46.6±3.3,明显少于对照组的90.2±2.7,t=-47.2,P<0.001;迁移实验结果显示,维拉帕米组平均穿膜细胞数为61.4±2.8,亦少于对照组的110.3±3.5,t=-39.5,P<0.001;蛋白质印迹法及RT-PCR结果显示,维拉帕米能够明显降低体内外SW1990细胞ABCG2蛋白及mRNA的表达水平。裸鼠成瘤实验结果显示,细胞接种后10d左右可见肿瘤结节,50d时维拉帕米组裸鼠肿瘤体积为(521.6±48.5)mm3,小于对照组的(1 496.6±73.1)mm3,t=-38.6,P<0.001;维拉帕米组瘤质量(0.53±0.18)g,明显低于对照组(1.61±0.45)g,t=-22.49,P<0.001。免疫组化结果显示,维拉帕米能明显降低SW1990细胞ABCG2的表达。结论维拉帕米能明显抑制胰腺癌SW1990细胞在体内外的侵袭和转移,其机制可能与维拉帕米下调ABCG2的表达有关。     

叉头盒蛋白A1过表达对SW480细胞增殖和凋亡及EMT形成影响

目的探讨叉头盒蛋白A1(fork-head box protein A1,FOXA1)过表达对结肠癌SW480细胞增殖、凋亡及上皮间质转化(epithelial-mesenchymal transition,EMT)形成的影响,为结肠癌发生发展机制研究提供一定参考。方法收集南京医科大学第一附属医院2014-03-01-2016-10-31结肠癌手术切除癌组织及其配对正常组织标本各50例。体外培养结肠癌细胞SW480、T84、DIFI及人正常结肠上皮细胞NCM460,以随机数字表法分成空白对照组(CK组)、转染含慢病毒载体对照液的阴性对照组(NC组)和转染含FOXA1过表达慢病毒载体的FOXA1过表达(FOXA1过表达组)3组。采用qRT-PCR法检测细胞中FOXA1mRNA表达水平,采用MTT法检测细胞增殖,采用AnnexinⅤ/PI双染法检测细胞凋亡,采用流式细胞术法检测细胞周期,采用蛋白质印迹法检测细胞中FOXA1蛋白及EMT过程相关蛋白的表达。结果结肠癌组织FOXA1mRNA及蛋白表达水平分别为0.42±0.12、0.28±0.07,低于正常组织的1.11±0.24、0.98±0.21,t值分别为18.183、22.361,均P<0.05。结肠癌SW480、T84、DIFI细胞中FOXA1mRNA分别为0.11±0.02、0.14±0.03和0.15±0.03,蛋白表达水平分别为0.34±0.07、0.38±0.09和0.37±0.08,均低于正常上皮细胞的0.27±0.06、0.67±0.09,F值分别为10.259、10.385,P值分别为0.004、0.004;与CK、NC组比较,FOXA1过表达组结肠癌SW480细胞凋亡率(F=32.511)、G0/G1期细胞比例(F=8.860)、FOXA1mRNA(F=325.500)及其蛋白(F=39.670)、E-cadherin(F=37.507)、Cytokeratin蛋白水平(F=14.957)均升高,均P<0.05;24(F=22.407)、48(F=65.290)和72h(F=46.778)的A值、S期细胞(F=11.042)、G2/M期细胞比(F=6.139)、N-cadherin(F=20.746)、Vimentin(F=26.493)、Twist(F=11.024)、β-catenin蛋白(F=29.359)表达水平均降低,均P<0.05。结论过表达FOXA1能够抑制结肠癌SW480细胞增殖,诱导其凋亡,可能抑制结肠癌细胞EMT过程。     

靶向沉默CXCR4基因抑制肝细胞癌侵袭体外研究

目的:采用RNAi技术构建CXCR4shRNA干扰载体,探讨靶向沉默CXCR4基因表达后对人肝细胞癌增殖和侵袭作用的影响及可能机制。方法:通过蛋白质印迹法和RT-PCR,检测不同分化程度的肝癌细胞株CXCR4表达程度。通过RNAi技术,将CXCR4shRNA干扰载体转染CXCR4高表达的肝癌细胞HepG2,并采用G418筛选出稳定表达株,蛋白质印迹法和RT-PCR验证shRNA对CXCR4基因的靶向沉默效率。以转染空载体细胞为阴性对照组,MTT法检测CXCR4基因沉默后肝癌细胞的增殖能力,Transwell小室侵袭试验检测CXCR4基因沉默后肝癌细胞的侵袭能力,蛋白质印迹法检测MMP-2和MMP-9蛋白表达水平,免疫荧光检测MMP-2在细胞内表达。结果:CXCR4靶向沉默的细胞CXCR4表达受到显著抑制。HepG2、HepG2-Vector和HepG2-CXCR4-细胞CXCR4蛋白相对表达量分别为0.56±0.07、0.54±0.04和0.14±0.05,F=57.42,P<0.001。正常HepG2、HepG2-Vector和HepG2-CXCR4-细胞的CXCR4mRNA相对表达量分别为1.04±0.05、1.05±0.11和0.19±0.03,P<0.001。MTT结果显示,CXCR4基因沉默能明显抑制HepG细胞的增殖。72h时正常HepG2、HepG2-Vector和HepG2-CXCR4-细胞的相对增殖速度分别为1.34±0.05,1.32±0.03和1.14±0.03。Transwell试验显示,10%FBS趋化作用下,HepG2、HepG2-Vector和HepG2-CXCR4-穿膜细胞数分别为85±13、89±17和23±6,差异有统计学意义,F=63.91,P<0.001;SDF-1趋化作用下,HepG2、HepG2-Vector和HepG2-CXCR4-穿膜细胞数分别为168±20、171±24和30±9。蛋白质印迹法显示,相对于正常HepG2细胞(0.83±0.04),HepG2-CXCR4-细胞MMP-2相对表达量(0.31±0.06)明显下降,P<0.001;而HepG2-Vector细胞MMP-2相对表达量(0.85±0.07)改变不明显,P=0.75。HepG2、HepG2-Vector和HepG2-CXCR4-细胞MMP-9相对表达量分别为0.35±0.04、0.33±0.07和0.32±0.06,差异无统计学意义,F=0.23,P=0.79。结论:通过RNAi技术成功靶向干扰CXCR4基因表达,可抑制肝癌细胞增殖和侵袭,可能与其抑制侵袭相关分子MMP-2表达有关。     

EphA8在结肠癌组织中的表达和临床意义

目的 探讨EphA8在结肠癌组织中的表达情况和临床意义.方法 采用实时定量RT-PCR和Western blot检测EphA8 mRNA和蛋白在1种正常结肠黏膜细胞株和2种结肠癌细胞株中的表达情况.采用免疫组织化学法检测98例结肠癌组织和12例正常结肠组织中EphA8和血管内皮生长因子(VEGF)的蛋白表达情况,同时使用CD31染色检测肿瘤微血管密度(MVD)情况,并分析EphA8与VEGF和MVD的关系及其与病理分期、预后的关系.结果 EphA8的mRNA在结肠癌细胞株的表达明显高于正常结肠黏膜细胞株(t=11.98,13.54,均P＜0.001).EphA8蛋白在结肠癌细胞株的表达也明显高于正常结肠黏膜细胞株(=4.63,P=0.006;t =4.92,P=0.004).免疫组织化学结果表明EphA8蛋白在结肠癌组织高表达,且癌组织中EphA8的蛋白表达与肿瘤大小(X2=22.97,P＜0.001)、分期(P＜0.001)、分化程度(P=0.007)、淋巴结转移(P ＜0.001)、远处转移(x2=6.97,P=0.008)以及患者生存率(x2=17.3,P＜0.001)存在显著相关性,而与患者的性别和年龄没有明显相关性(X2=1.36,P=0.30;0=0.83,P=0.44).此外,EphA8与VEGF和MVD的表达呈正相关(r=0.434,P＜0.001;r=0.584,P＜0.001).结论 EphA8在结肠癌的恶性发展和转移中有重要作用,因此,EphA8对于结肠癌的治疗干预和预后判断具有潜在的临床应用价值.     

非病毒载体系统在基因治疗中的应用

非病毒载体系统具有低毒、低免疫原性和相对靶向性等优点,是新兴发展起来的基因转移系统.本文综述了目前基因治疗中所用的几种非病毒载体系统及其研究进展.     

HSV1-tk基因在肿瘤报告基因显像与治疗中的研究进展

自杀基因疗法是一种有潜在临床应用价值的肿瘤治疗策略。HSV1-tk基因兼具治疗基因和报告基因的功能，可用于基因显像、基因治疗及其疗效监测。近年来，无创伤性的肿瘤HSV1-tk基因显像发展很快，核素标记的显像底物有FIAU、FMAU、FHBG和FHPG等，使用的显像设备有PET、SPECT或γ照相机等，这些显像方法具有不同的敏感性和特异性，但均能监测动物体内表达HSV1-tk肿瘤部位的增殖情况和治疗效果，更复杂的HSV1-tk报告基因显像方案正在探索中。HSV1-tk基因治疗联合靶向治疗、放射治疗、药物治疗、免疫生物治疗、热疗及其他基因治疗具有疗效相加或协同效应，增强了对肿瘤的杀伤作用。     

MLL-mediated transcriptional gene regulation investigated by gene expression profiling

The human mixed lineage leukemia (MLL) gene is involved in about 50 different chromosomal translocations, associated with the disease phenotype of acute leukemia. However, the normal function of MLL is less understood. Homozygous knockouts of murine Mll were embryonal lethal, while heterozygous disruption led to aberrant hox gene expression associated with skeletal malformations, growth retardation, and impaired hematopoiesis. To understand MLL functions on the molecular level, gene expression profiling experiments were performed with a pair of murine cell lines (MLL(+/+) and MLL(-/-)). Microarray hybridization experiments revealed 197 potential target genes that are differentially expressed, providing new and important clues about MLL functions.     

Light-induced adenovirus gene transfer, an efficient and specific gene delivery technology for cancer gene therapy

A main issue for further clinical progress of cancer gene therapy is to develop technologies for efficient and specific delivery of therapeutic genes to tumor cells. In this work, we describe a photochemical treatment that substantially improves gene delivery by adenovirus, one of the most efficient gene delivery vectors known. Transduction of two different cell lines was studied by microscopy, flow cytometry, and an enzymatic assay, employing a beta-galactosidase-encoding adenovirus. The photochemical treatment induced a >20-fold increase in gene transduction, compared with conventional adenovirus infection, both when measured as the percentage of cells transduced, and when measured as the total beta-galactosidase activity in the cell population. The effect was most pronounced at lower virus doses, where in some cases the same transduction efficiency could be achieved with a 20 times lower virus dose than with conventional infection. Photochemical treatments are already in clinical use for cancer therapy, and generally are very specific and have few side effects. The photochemical internalization technology described thus has a clear potential for improving both the efficiency and the specificity of gene delivery in cancer gene therapy, making it possible to achieve efficient site-specific in vivo gene delivery by adenoviral vectors.     

bcr-abl和白介素-7共表达基因疫苗诱导小鼠免疫保护作用

目的探讨小鼠白介素-7（IL-7）基因对bcr-abl融合基因疫苗诱导机体免疫应答的影响。方法采用pVbcr-abl／mIL-7质粒免疫BALB／c小鼠,检测小鼠血清中bcr-abl特异性抗体水平。以转染bcr-abl融合基因片段的SF2／0细胞为靶细胞,用LDH释放实验检测免疫小鼠脾细胞特异性细胞毒活性。结果pVbcr-abl／mIL-7质粒能诱导小鼠产生血清特异性抗bcr-abl抗体,pVbcr-abl／mIL-7免疫组的血清特异性抗体滴度高于pVbcr-abl免疫组,脾细胞杀伤SP2／0／bcr-abl靶细胞的细胞毒活性明显增强。结论共表达bcr-abl和mIL-7的基因疫苗能在小鼠体内诱导较高的特异性体液免疫和细胞免疫水平,为慢性粒细胞白血病基因疫苗的临床前实验研究提供了依据。     

Anti-tumor gene therapy

Gene therapy as an anti-tumor strategy is becoming a powerful tool for cytokine delivery to inhibit the growth of many tumors. Several delivery systems are being utilized and designed for the expression of specific genes to achieve a therapeutic result. Liposomes, retroviral vectors, and adenoviral vectors have all been used and eventual clinical application may depend on the type of tumor, the location, the specific gene carried, and the patients health status. Novel expression vectors may eventually achieve tissue-specific targeting and low immuno-reactivity. Inactivation of mutated oncogenes, such as ras, or re-expression of inactive suppressor genes, such as p53 have been used as strategies for anti-tumor therapy. Additionally, exogenous genes, su ch as viral thymidine kinase that metabolize chemotherapeutic agents to achieve local cytotoxicity have also been employed. Neuro-endocrine tumors are targets of these genetic strategies since they are often difficult to treat by conventional methods bec ause of their location (brain tumors) or because they have spread from the primary tumor (melanoma). Further advances in the design of these vectors may achieve safe targeting of a variety of malignant tumors.     

Viral gene therapy

Cancer is a multigenic disorder involving mutations of both tumor suppressor genes and oncogenes. A large body of preclinical data, however, has suggested that cancer growth can be arrested or reversed by treatment with gene transfer vectors that carry a single growth inhibitory or pro-apoptotic gene or a gene that can recruit immune responses against the tumor. Many of these gene transfer vectors are modified viruses. The ability for the delivery of therapeutic genes, made them desirable for engineering virus vector systems. The viral vectors recently in laboratory and clinical use are based on RNA and DNA viruses processing very different genomic structures and host ranges. Particular viruses have been selected as gene delivery vehicles because of their capacities to carry foreign genes and their ability to efficiently deliver these genes associated with efficient gene expression. These are the major reasons why viral vectors derived from retroviruses, adenovirus, adeno-associated virus, herpesvirus and poxvirus are employed in more than 70% of clinical gene therapy trials worldwide. Because these vector systems have unique advantages and limitations, each has applications for which it is best suited. Retroviral vectors can permanently integrate into the genome of the infected cell, but require mitotic cell division for transduction. Adenoviral vectors can efficiently deliver genes to a wide variety of dividing and nondividing cell types, but immune elimination of infected cells often limits gene expressionin vivo. Herpes simplex virus can deliver large amounts of exogenous DNA; however, cytotoxicity and maintenance of transgene expression remain as obstacles. AAV also infects many non-dividing and dividing cell types, but has a limited DNA capacity. This review discusses current and emerging virus-based genetic engineering strategies for the delivery of therapeutic molecules or several approaches for cancer treatment. Supported by an unrestricted educational grant from AstraZeneca.     

抗肿瘤基因疫苗

肿瘤基因疫苗的发展逐渐趋于成熟,常见基因疫苗主要有细胞因子类基因疫苗、多基因联合疫苗,转染基因的树突状细胞疫苗等.近些年肿瘤基因疫苗的发展逐渐趋向于寻找基凶疫苗佐剂或探索不同基凶的联合从而达到更加有效地治疗目的.     

Saporin as a novel suicide gene in anticancer gene therapy

We used a non-viral gene delivery approach to explore the potential of the plant saporin (SAP) gene as an alternative to the currently employed suicide genes in cancer therapy. Plasmids expressing cytosolic SAP were generated by placing the region encoding the mature plant ribosome-inactivating protein under the control of cytomegalovirus (CMV) or simian virus 40 (SV40) promoters. Their ability to inhibit protein synthesis was first tested in cultured tumor cells co-transfected with a luciferase reporter gene. In particular, SAP expression driven by CMV promoter (pCI-SAP) demonstrated that only 10 ng of plasmid per 1.6 x 10(4) B16 cells drastically reduced luciferase activity to 18% of that in control cells. Direct intratumoral injection of pCI-SAP complexed with either lipofectamine or N-(2,3-dioleoyloxy-1-propyl) trimethylammonium methyl sulfate (DOTAP) in B16 melanoma-bearing mice resulted in a noteworthy attenuation of tumor growth. This antitumor effect was increased in mice that received repeated intratumoral injections. A SAP catalytic inactive mutant (SAP-KQ) failed to exert any antitumor effect demonstrating that this was specifically owing to the SAP N-glycosidase activity. Our overall data strongly suggest that the gene encoding SAP, owing to its rapid and effective action and its independence from the proliferative state of target cells might become a suitable candidate suicide gene for oncologic applications.