HyTK基因用于膀胱癌基因放射治疗的实验研究

目的　了解放射治疗协同单纯疱疹病毒 胸苷激酶 (HSV TK) /更昔洛韦 ( gancyclovir,GCV)对膀胱癌细胞的联合杀伤作用。方法　通过逆转录病毒介导 ,将潮霉素磷酸转移酶和HSV TK的融合基因 (HyTK)基因转入膀胱肿瘤细胞株EJ中并获得表达 ,联合应用放射治疗及低剂量GCV ,了解基因 放射治疗对转基因细胞EJ/HyTK的杀伤作用。 结果　SouthernBlot、DotBlot检测证实HyTK在转基因细胞的表达 ,联合应用低剂量GCV可使转入HyTK基因的膀胱癌细胞株对放疗的敏感性明显增高 (SER =1.3 6)。结论　放疗协同HSV TK/GCV系统可作为膀胱癌基因治疗的一种有效方法。     

γ射线联合HSV-tk/GCV基因治疗系统抗肿瘤体外实验研究

目的研究γ射线与人单纯疱疹病毒胸苷激酶（HSV-tk）／丙氧鸟苷（GCV）基因治疗系统联合应用对Lewis肺癌细胞的杀伤作用及其可能机制。方法以脂质体介导法将含HSV—tk基因的真核表达质粒体外转染小鼠Lewis肺癌细胞，建立稳定表达的细胞株；RT-PCR检测细胞tk基因表达；Hoechst33258/PI荧光活染、流式细胞术检测γ射线与HSV-tk／GCV系统单独及联合作用下的细胞凋亡；集落形成法检测细胞存活曲线，反映放射敏感性变化；同时检测旁观者效应及γ射线对该效应的影响。结果HSV-tk／GCV系统对转染基因的Lewis细胞（Lewis-Hytk细胞）具有选择性杀伤作用。γ射线与HSV-tk／GCV系统联合应用可使Lewis-Hytk细胞的凋亡和坏死率显著高于二者单独作用之和。0．1μg/ml GCV可使Lewis-Hytk细胞的放射敏感性明显增高（SER=1．47）。γ射线可增强HSV-tk/GCV系统的旁观者效应，二者联合作用后的Lewis-Hytk细胞的培养液对未处理过的Lewis细胞具有杀伤作用。结论γ射线与HSV-tk／GCV系统联合应用对Lewis肺癌细胞具有协同杀伤效应。γ射线增强HSV—tk／GCV系统的旁观者效应可能是其协同效应产生的机制之一．     

TK基因慢病毒载体质粒的构建及慢病毒表达系统的建立

目的:构建人单纯疱疹病毒胸苷激酶(HSV-TK)基因的慢病毒载体质粒,并建立其慢病毒表达系统.方法:利用酶切分别获取目的基因TK片段及慢病毒pLenti6/V5载体片段,将目的基因插入载体相应酶切位点,构建pLenti6/V5-TK质粒.构建的重组质粒经PCR、酶切及测序鉴定.利用慢病毒表达系统(ViraPowerTM Lentiviral Expression Systems),将重组质粒与包装系统质粒(pLP1,pLP2,pLP/VSVG) 4质粒共转染293T细胞,48 h后收集培养上清并感染大鼠胶质瘤细胞9L,抗稻瘟菌素(blasticidin, BSD)筛选9L/TK细胞.MTT方法测试更昔洛韦(ganciclovir GCV)对体外培养的9L/TK细胞杀伤效果.结果与结论:构建的质粒经PCR、酶切及测序鉴定正确;该质粒与包装质粒共转染293T细胞获取的慢病毒滴度达2.7×105转导单位(transducing units,TU)/ml.经BDS筛选的9L/TK细胞对GCV杀伤敏感.成功构建了TK基因慢病毒载体质粒pLenti6/V5-TK,并建立了其慢病毒表达系统.     

乏氧照射双敏感启动子HRE.CArG调控HSVtk基因对肺癌细胞的杀伤效应

 目的 观察乏氧照射后HRE.CArG融合性启动子诱导增强的绿色荧光蛋白(EGFP)在SPCA1和A549肺癌细胞株中的表达变化及乏氧照射诱导下该启动子驱动自杀基因HSVtk对肺癌细胞的杀伤作用.方法 用聚乙烯亚胺转染法转染SPCA1和A549细胞,乏氧照射后24 h测EGFP表达强度;乏氧照射后24 h加入GCV,48 h后用MTT法测定细胞存活率.结果 乏氧照射后转染pDNA.HRE.CArG.EGFP质粒的SPCA1和A549细胞EGFP表达强度分别是对照组的(3.37±0.23)倍和(3.10±0.28)倍(P＜0.01);转染pDNA.HRE.CArG.HSVtk质粒的SPCA1和A549细胞存活率较对照组分别降低(63.23±2.31)%和(76.58±2.19)%(P＜0.01).结论 质粒载体中包含的HRE.CArG元件对乏氧照射敏感,乏氧照射后通过诱导下游的HSVtk基因大量表达,使转染细胞对GCV的敏感性增高,而大大增加对SPCA1和A549细胞的杀伤效应.     

hTERT启动子调控TK基因靶向性杀伤鼻咽癌移植瘤的实验研究

目的 研究人端粒酶反转录酶(hTERT)基因核心启动子调控的单纯疱疹病毒胸苷激酶基因/更昔洛韦(HSV-TK/GCV)系统对鼻咽癌移植瘤的体内杀伤作用. 方法 采用培养细胞移植法,将人鼻咽癌细胞系C666-1接种于裸鼠腋部皮下,建立裸鼠人鼻咽癌移植瘤模型.将40只裸鼠随机分为5组:hTERTp/HSV-TK/PGL3/GCV组、CMV/HSV-TK/PGL3/GCV组、HSV-TK/PGL3/GCV组、GCV组及生理盐水组,每组8只.采用脂质体介导,进行瘤内直接注射,同时经腹腔给予GCV治疗,观察各组裸鼠生存状况及肿瘤相对体积、抑瘤率,并进行荷瘤裸鼠肝肾组织的常规病理检查. 结果 成功构建了 C666-1裸鼠皮下移植瘤动物模型,hTERTp/HSV-TK/PGL3/GCV组移植瘤被明显抑制,抑瘤率达到45.51%,与HSV-TK/PGL3/GCV组、GCV组及生理盐水组(抑瘤率分别为5.52%、14.31%、0.03%)比较有显著性差异(P＜0.01),肝肾病理检查发现,该组裸鼠肝肾均无明显病理学变化.CMV/HSV-TK/PGL3/GCV组的抑瘤率亦达到51.56%,但病理检查发现裸鼠出现肝肾毒性. 结论 hTERT启动子调控TK基因靶向治疗系统能够在体内特异性杀伤鼻咽癌移植瘤,而无明显全身毒副作用,是一种安全、有效的肿瘤靶向基因治疗系统,将为鼻咽癌临床基因治疗开辟新领域.     

VEGFP-CDglyTK系统诱导肝癌细胞凋亡的实验研究

目的 探讨腺病毒介导血管内皮生长因子(VEGF)启动子驱动的CD/TK双自杀基因体系(Ad-VEGFP-CDglyTK)对肝癌细胞HepG2的体外杀伤作用.方法 用重组腺病毒Ad-VEGFP-CDglyTK体外感染表达VEGF的HepG2细胞,荧光显微镜观察其感染效率,然后给予前药更昔洛韦(GCV)和5-氟胞嘧啶(5-FC),在光镜、透射电镜下观察,用流式细胞术等方法 观察细胞凋亡、细胞周期及细胞内DNA含量的变化.结果 腺病毒对HepG2细胞的感染率随病毒滴度的增高而递增.在感染复数为100时,前药GCV和5-FC在一定范围(GCV 5-FC分别为:1mg/L 20mg/L,10mg/L 40mg/L,100mg/L 60mg/L)内呈剂量依赖性地诱导HepG2细胞凋亡;中浓度下(GCV:10mg/L,5-FC:40mg/L)作用细胞72h,透射电镜下可见HepG2细胞发生典型凋亡改变:空泡形成,染色质浓缩、沿核膜排列,甚至出现核碎裂现象.流式细胞仪测定见用药组出现典型的凋亡峰;随着药物浓度的增加,凋亡细胞所占的比例逐渐增加,实验组凋亡细胞数与对照组比较有显著性差异(P＜0.01);细胞周期分析显示前药能明显抑制HepG2/CD-TK细胞的增殖,主要作用在细胞G2-M期.结论 VEGF启动子可调控双自杀基因系统选择性杀伤表达VEGF的HepG2细胞,其机制与诱导细胞凋亡有关.     

HSV-TK/GCV自杀基因系统联合γ射线放射治疗宫颈癌的实验研究

目的 探讨HSV-TK／GCV自杀基因系统协同^60Coγ射线放射治疗对人宫颈癌细胞系的体内外联合杀伤作用，以及HSV-TK／GCV对放射治疗的增敏作用。方法 分别以HSV-TK／GCV、^60Coγ射线放射治疗及两者联合治疗人宫颈癌HeLa细胞系和裸鼠宫颈癌移植瘤模型，比较治疗效果；利用增敏效应比值（E／O）、克隆形成实验评价体内外HSV-TK／GCV对放射敏感性的影响。结果 在体外实验中，自杀基因对宫颈癌HeLa细胞生长的抑制率为45．8％，单纯放疗的抑制率为42．4％，而基因治疗与放疗联用的抑制率为87．5％，与前两者比较，差异有统计学意义（P〈0．01）；且联合治疗组对射线敏感性较单独治疗组明显增加，克隆形成率明显下降（P〈0．05）；在体内实验中，单纯基因治疗与放疗对HeLa细胞裸鼠皮下移植瘤生长的抑瘤率分别为39．5％和35．8％，而基因治疗放疗联用的抑瘤率达到87．9％，与前两者比较，差异均有统计学意义（P〈0．01）；增敏效应比值（E／O）为3．2（〉1．4），提示HSV-TK／GCV对放疗具有增敏作用。结论 HSV-TK／GCV自杀基因系统具有放射增敏作用，二者联合治疗可作为宫颈癌综合治疗的有效补充方法。     

H-2半相合CD34+和TK+T细胞移植建立急性移植物抗宿主病模型及丙氧鸟苷疗效观察

目的　探讨HSV TK/GCV对H 2半相合CD34 细胞和TK T细胞混合移植急性移植物抗宿主病 (GVHD)的疗效。方法　从亲代雄性供鼠骨髓分离CD34 细胞 ,同时取脾脏T细胞转染tk基因。4 8只受鼠随机分为 6组 ,第 1组输入CD34 细胞 (1× 10 5) ;第2、3组输入CD34 细胞和T细胞 (1× 10 7) ;第 4～ 6组输入CD34 细胞和TK T细胞 (1× 10 7)。第 1组不予任何处理 ;第 2、4组于d0～d14给予PBS 0 2ml/d;第 3、5、6组于d7、d0、d7开始给予丙氧鸟苷(GCV)治疗 ,剂量为 5 0mg/ (kg·d)× 7天腹腔注射。结果　第 1组受鼠全部长期存活 ,无急性GVHD发生。 2～ 6组均发生急性GVHD ,病理表现典型。 2～ 4组 3周内均死于急性GVHD ,第 5、6组生存时间分别为 2 6 6± 4 8天和 4 0 5± 8 4天 ,与 2～4组相比差异显著 (P <0 0 1) ,第 6组生存时间长于第 5组(P <0 0 5 )。结论　H 2半相合CD34 和TK T细胞移植能够建立急性GVHD模型 ;TK/GCV系统对急性GVHD有较好治疗作用 ;GCV给予时间不同则疗效有差异。     

CD/5-FC自杀基因系统治疗胰腺癌的实验研究

为探讨自杀基因CD/5-FC系统对胰腺癌的杀伤作用及作用机制,应用细菌内同源重组法构建含大肠杆菌胞嘧啶脱氨酶（cytosine deaminase, CD）基因的腺病毒载体,经293细胞包装、扩增,氯化铯密度梯度离心制备纯化CD腺病毒液,体外转染人胰腺癌细胞,并给予前药5-FC,观察其体外杀伤效果;并建立胰腺癌裸鼠皮下移植瘤模型,瘤内直接注入CD腺病毒液,随后腹腔内注入5-FC,观察CD基因的原位治疗效应。含CD基因腺病毒载体经酶切鉴定正确,包装纯化后,检测病毒滴度为2×1011pfu/ml,将重组腺病毒转染胰腺癌细胞株后,可见5-FC对转导入CD基因的胰腺癌细胞有明显细胞毒性作用,而对未导入CD基因的人胰腺癌细胞毒性较低,体内实验显示CD基因原位转导对裸鼠胰腺癌疗效较明显。腺病毒介导CD基因,不仅转染效果强,而且加用5-FC后,可直接或通过旁观者效应杀伤胰腺癌细胞或抑制移植瘤的生长,可作为胰腺癌基因治疗的有效方法。     

p16基因转染对胰腺癌细胞生长及辐射敏感性的研究

目的 探索p16基因转染对胰腺癌细胞生长辐射敏感性的作用。方法 将外源野生型p16基因连接到pCDNA3.1^＋载体构建pCDNA3.16＋ -p16重组质粒,利用Lipofectamine^TM介导转染胰腺癌JF305细胞,筛选阳性克隆。照射后,RT-PCR检测p16基因表达,Western blot检测蛋白表达;用MTT法测定细胞生长曲线和肿瘤细胞杀伤率。结果 转染p16基因的JF305细胞有外源p16基因的整合及表达,生长速度明显减少,对辐射的敏感性增强。结论 导入外源野生型p16基因可抑制胰腺癌细胞恶性增殖,提高胰腺癌细胞对辐射的敏感性。     

Assessment of treatment response by autoradiography with (14)C-aminocyclopentane carboxylic acid, (67)Ga-DTPA, and (18)F-FDG in a herpes simplex virus thymidine kinase/ganciclovir brain tumor model.

Assessments of herpes simplex virus 1 thymidine kinase (HSV-tk)/ganciclovir (GCV) treatment response, early in the course of therapy, are important in the evaluation and clinical management of patients. This study addresses whether imaging amino acid transport, glucose utilization, and passive vascular permeability provides an early indication of treatment response and can predict long-term outcome. METHODS: Fischer 344 rats with intracerebral HSV-tk transduced RG2TK+ xenografts were studied. GCV-treated (50 mg/kg twice daily) and saline-treated control animals were compared; triple-label quantitative autoradiography was performed 3 d after initiating treatment, and long-term survival was determined. Autoradiograms of (18)F-FDG, (67)Ga-diethylenetriaminepentaacetic acid ((67)Ga-DTPA), and (14)C-aminocyclopentane carboxylic acid ((14)C-ACPC) were obtained; measurements of (14)C-ACPC and (67)Ga-DTPA plasma clearance (K(1)), (14)C-ACPC transport ( partial differential K(1)), relative glucose utililization (R), and normalized radioactivity (% dose/g) were obtained in tumor and brain tissues. Adjacent sections were stained to detect apoptotic cells, microvessels, and type L neutral amino acid transporter in tumor and normal brain. RESULTS: GCV treatment reduced partial differential K(1) and % dose/g of (14)C-ACPC in RG2TK+ xenografts to approximately 30% of that in nontreated animals (from 34 +/- 9 [mean +/- SD] to 9.5 +/- 2.7 microL/min/g and from 0.28 +/- 0.09 to 0.11 +/- 0.04 % dose/g, respectively). GCV had a significant but substantially smaller effect than toxicity on glucose utilization and little or no effect on passive vascular permeability of RG2TK+ xenografts. These differences could not be explained by differences in plasma amino acid or glucose concentration at the time of the study. Histology revealed a large fraction of dead tumor cells and only a sparse distribution of apoptotic cells in GCV-treated tumors. Many CD34-positive endothelial cells in GCV-treated tumors showed only weak or marginal LAT1 staining, whereas CD98 staining remained unchanged. Survival was significantly increased by GCV treatment from 18 +/- 4 to 56 +/- 17 d. CONCLUSION: (14)C-ACPC influx, K(1)(ACPC), facilitated transport, partial differential K(1)(ACPC), and % dose/g (ACPC) are good indicators of early treatment response after HSV-tk/GCV gene therapy. The parametric images and changes in K(1)(ACPC), partial differential K(1)(ACPC), and % dose/g (ACPC) are substantial and are better than the corresponding measures obtained in the same animals and in the same tissue (tumor) regions with (67)Ga-DTPA and (18)F-FDG. Amino acid transport imaging may be a good surrogate paradigm to monitor treatment response of brain tumors.     

反义胶原纤维酸性蛋白逆转录病毒对胶质瘢痕增生的影响

研究抑制胶原纤维酸性蛋白基因表达对在体胶质瘢痕形成的影响。方法构建反义ＧＦＡＰ逆转录病毒表达载体,经过病毒包装后,将获得的病毒上清液浓缩并通过微量注射的方法,引入大鼠脑穿刺损伤灶内,采用免疫组化及形态学观察的方法,研究重组反义ＧＦＡＰ逆转录病毒对脑损伤后胶质瘢痕形成的影响。     

Molecular imaging with 123I-FIAU, 18F-FUdR, 18F-FET, and 18F-FDG for monitoring herpes simplex virus type 1 thymidine kinase and ganciclovir prodrug activation gene therapy of cancer.

The ability to monitor tumor responses during prodrug activation gene therapy and other anticancer gene therapies is critical for their translation into clinical practice. Previously, we demonstrated the feasibility of noninvasive in vivo imaging with 131I-5-iodo-2'-fluoro-1-beta-D-arabinofuranosyluracil (131I-FIAU) for monitoring herpes simplex virus type 1 thymidine kinase (HSV1-tk) cancer gene expression in an experimental animal model. Here we tested the efficacy of SPECT with 123I-FIAU and PET with 5-18F-fluoro-2'-deoxyuridine (18F-FUdR), 2-18F-fluoroethyl-L-tyrosine (18F-FET), and 18F-FDG for monitoring tumor responses during prodrug activation gene therapy with HSV1-tk and ganciclovir (GCV). METHODS: In the flanks of FVB/N female mice, 4 tumors per animal were established by subcutaneous injection of 1 x 10(5) cells of NG4TL4 sarcoma cells, HSV1-tk-transduced NG4TL4-STK cells, or a mixture of these cells in different proportions to model different efficacies of transfection and HSV1-tk gene expression levels in tumors. Ten days later, the animals were treated with GCV (10 mg/kg/d intraperitoneally) for 7 d. Gamma-Imaging with 123I-FIAU and PET with 18F-FUdR, 18F-FET, and 18F-FDG were performed before and after initiation of therapy with GCV in the same animal. RESULTS: Before GCV treatment, no significant difference in weight and size was found in tumors that expressed different HSV1-tk levels, suggesting similar in vivo proliferation rates for NG4TL4 and NG4TL4-STK sarcomas. The accumulation of 123I-FIAU at 24 h after injection was directly proportional to the percentage of NG4TL4-STK cells in the tumors. The 123I-FIAU accumulation at 4 and 7 d of GCV therapy decreased significantly compared with pretreatment levels and was proportional to the percentage of HSV1-tk-positive tumor cells. Tumor uptake of 18F-FUdR in all HSV1-tk-expressing tumors also decreased significantly compared with pretreatment levels and was proportional to the percentage of HSV1-tk-positive tumor cells. The accumulation of 18F-FET decreased minimally (about 1.5-fold) and 18F-FDG decreased only 2-fold after 7 d of GCV therapy, and the degree of reduction was proportional to the percentage of HSV1-tk-positive tumor cells. CONCLUSION: We have shown that gamma-camera imaging with 123I-FIAU was the most reliable method for prediction of tumor response to GCV therapy, which was proportional to the magnitude of HSV1-tk expression in tumor tissue. 123I-FIAU imaging can be used to verify the efficacy of elimination of HSV1-tk-expressing cells by therapy with GCV. PET with 18F-FUdR reliably visualizes proliferating tumor tissue and is most suitable for the assessment of responses in tumors undergoing HSV1-tk plus GCV prodrug activation gene therapy. PET with 18F-FDG or 18F-FET can be used as additional "surrogate" biomarkers of the treatment response, although these radiotracers are less sensitive than 18F-FUdR for monitoring tumor responses to prodrug activation gene therapy with HSV1-tk and GCV in this sarcoma model.     

腺病毒介导VEGF启动子驱动的TK及CD融合基因系统与碘油混合栓塞治疗兔肝癌的实验研究

目的 评价携带血管内皮生长因子(VEGF)启动子调控的TK及CD融合双自杀基因重组腺病毒系统(AdVEGF-CDglyTK)与超液化碘油混合栓塞兔肝癌后的治疗效果及安全性. 资料与方法 36只荷VX2瘤兔随机分4组,LP组(单纯超液化碘油栓塞组);LP AdVEGF-CDglyTK组(超液化碘油 AdVEGF-CDglyTK栓塞混合栓塞,介入术后腹腔注射GCV 5-FC治疗组);AdVEGF-CDglyTK组(单纯灌注AdVEGF-CDglyTK,介入术后腹腔注射GCV 5-FC治疗组);NS组(生理盐水治疗组).于术前及术后第10、15天行MRI检查观察肿瘤的体积,免疫组织化学法检测肿瘤组织VEGF的表达及微血管密度(MVD). 结果 4组兔术前肿瘤体积在统计学无显著差异(P>0.05);介入治疗后10天、15天的各组之间肿瘤增长率均有显著性差异(P<0.05),LP AdVEGF-CDglyTK肿瘤增长率最小.VEGF表达方面:LP组表达较其他三组高(P<0.05).MVD:LP AdVEGF-CDglyTK组较其他组低(P<0.05). 结论 在对兔肝癌的治疗中,与单纯碘油栓塞以及单纯灌注AdVEGF-CDglyTK相比,AdVEGF-CDglyTK与碘油混合肝动脉栓塞可以明显降低肿瘤的生长率,减少肿瘤组织VEGF的表达及减少肿瘤新生血管生成.     

Evaluation of (76)Br-FBAU as a PET reporter probe for HSV1-tk gene expression imaging using mouse models of human glioma.

The utility of 5-(76)Br-bromo-2'-fluoro-2'-deoxyuridine ((76)Br-FBAU), a uracil analog, as a PET reporter probe for use with the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene system for gene expression imaging was evaluated in vivo and in vitro using human and rat glioma cells. METHODS: Human glioma cell lines U87 and U251 were transduced with replication-defective adenovirus constitutively expressing HSV1-tk (Ad.TK) or a control expressing green fluorescent protein (Ad.GFP). These cells were incubated with (76)Br-FBAU for 20-120 min to determine the percentage of total dose uptake. In vitro uptake of equimolar concentrations (1.8 x 10(-8) mol/L) of (76)Br-FBAU and 2'-fluoro-2'-deoxy-5-iodouracil-beta-d-arabinofuranoside ((14)C-FIAU) was also determined in RG2-TK rat glioma cells stably expressing HSV1-tk and in control RG2 cells at 30-120 min. In vivo uptake of (76)Br-FBAU was determined in subcutaneous U87 tumor intratumorally transduced with Ad.TK by ex vivo biodistribution. Uptake in intracranial U87 tumors transduced with Ad.TK expressing HSV1-tk was measured by brain autoradiography. In vivo PET was performed on subcutaneous and intracranial U87 tumors transduced with Ad.TK and on subcutaneous and intracranial stably expressing RG2-TK tumors. RESULTS: U87 and U251 cells transduced with Ad.TK had significantly increased uptake of (76)Br-FBAU compared with cells transduced with Ad.GFP over 20-120 min. In stably expressing cells at 120 min, (14)C-FIAU uptake in RG2-TK tumor cells was 11.3 %ID (percentage injected dose) and in RG2 control cells was 1.7 %ID, and (76)Br-FBAU uptake in RG2-TK tumor cells was 14.2 %ID and in RG2 control cells was 1.5 %ID. Ex vivo biodistribution of subcutaneous U87 tumors transduced with Ad.TK accumulated (76)Br-FBAU significantly more than in the control Ad.GFP transduced tumor and normal tissue, with the lowest uptake in brain. Autoradiography showed localized uptake in intracranial U87 and U251 cells transduced with Ad.TK. PET image analyses of mice with RG2-TK tumors resulted in an increased tumor-to-background ratio of 13 and 26 from 2 to 6 h after injection, respectively, in intracranial tumors. CONCLUSION: (76)Br-FBAU accumulates in glioma cells constitutively expressing HSV1-tk by either adenoviral transduction or in stably expressing cell lines both in vitro and in vivo. (76)Br-FBAU shows promise as a PET reporter probe for use with the HSV1-tk in vivo gene expression imaging system.     

KDR启动子驱动双自杀基因诱导胃癌细胞凋亡的实验研究

目的探讨KDR启动子驱动双自杀基因体系对胃癌细胞凋亡的诱导作用。方法以重组腺病毒AdEasy-KDR-CDglyTK体外感染表达KDR的SCG7901细胞株和不表达KDR的HepG2细胞株,并给予不同浓度的前药GCV和（或）5-FC,观察该体系对SCG7901细胞的杀伤效应。分别应用透射电镜、Hoechest33258／PI染色、流式细胞仪观察细胞超微结构、细胞凋亡率和细胞周期的变化。结果携带双自杀基因（CDglyTK）和报告基因（GFP）的重组腺病毒载体转染后,95％以上SCG7901和HepG2细胞中有GFP表达。表达KDR的SCG7901细胞对前药具有较高的敏感性,不表达KDR的HepG2细胞对前药不敏感（P〈0．01）。两种前药联合应用优于任一前药单独应用的疗效（P〈0．01）。流式细胞术检测表明该体系可抑制SCG7901细胞DNA的合成,表现为s期细胞比例增高及G2期细胞减少。同时,Hoechest33258／PI染色和电镜下可见SCG7901有凋亡改变。结论KDR启动子可以调控融合基因体系选择性地杀伤人胃癌SCG7901细胞,并且该体系可以诱导胃癌细胞凋亡。     

Tumor-specific in vivo transfection with HSV-1 thymidine kinase gene using a Sindbis viral vector as a basis for prodrug ganciclovir activation and PET.

One type of gene therapy of tumors, gene-directed enzyme-prodrug therapy (GDEPT), holds considerable promise, although practical considerations limit its clinical applicability. These include the lack of acceptable noninvasive methods that are adaptable to humans for selective tumor targeting of the therapeutic genetic material. Sindbis virus is an oncolytic, alpha-virus that selectively targets tumors through the 67-kDa laminin receptor (LAMR). In this report we describe a novel approach that permits tumor-selective tumor targeting and quantitative in vivo monitoring using PET of a commonly applied GDEPT, based on herpes simplex virus thymidine kinase type 1 (HSVtk) and ganciclovir (GCV). METHODS: Sindbis/tk vectors were harvested from the supernatant of in vitro cultures of a packaging cell produced by electroporation of both replicon RNA (SinRep5/tk) and helper RNA (DH-BB) into baby hamster kidney (BHK) cells. The therapeutic effect of GCV was determined by incubation of transfected tumor cells with increasing concentrations of GCV. BHK tumors growing as xenografts in severe combined immunodeficiency disease (SCID) mice were transfected by parenteral administration of the vector. Imaging was performed using small-animal PET at 2 h after injection of 18F fluoro-ethyl-arabinosyluridine (18F-FEAU) and 24 h after the final parenteral injection of Sindbis/tk viral vector. RESULTS: The vector efficiently expresses the HSVtk enzyme in infected tumor cells, both in vitro and in vivo. High levels of HSVtk expression ensure sufficient prodrug GCV conversion and activation for bystander effects that kill the surrounding untransduced tumor cells. Tumor localization of intravenously administered 18F-FEAU after 2 and 3 parenteral vector treatments of Sindbis/tk demonstrated uptake of 1.7 and 3.1 %ID/g (percentage injected dose per gram), respectively. CONCLUSION: The vector efficiently targets the HSVtk enzyme gene into Sindbis-infected tumor cells. High levels of HSVtk expression ensure sufficient prodrug GCV conversion and activation for bystander effects that killed many surrounding untransduced tumor cells. In addition, the HSVtk activities in tumors can be noninvasively monitored using PET after systemic Sindbis/tk treatments as a basis for determining the levels and tissue distribution of vector, noninvasively in living animals, and for optimizing in vivo transfection rates of tumor.     

Combined RNA interference of adenine nucleotide translocase-2 and ganciclovir therapy in hepatocellular carcinoma

PurposeThe purpose of this study was to investigate the anticancer effects of combined RNA interference (RNAi) of the adenine nucleotide translocase-2 (ANT2) gene and ganciclovir (GCV) therapy for treatment of hepatocellular carcinoma cells (Huh 7) in an animal model.MethodsThe Huh 7/NTG stable cell line was established by transfection of a vector with the human sodium iodide symporter (hNIS), HSV1-sr39 thymidine kinase (tk), and enhanced green florescent protein (EGFP) fusion gene into Huh 7 cells. mRNA expressions of these genes were evaluated by RT-PCR analysis. The functions of hNIS and HSV1-sr39tk were verified with ¹²⁵I uptake and ³H-penciclovir (PCV) uptake tests. EGFP and hNIS expression was confirmed with confocal microscopy after immunocytochemical staining. We treated the tumor cells with ANT2 shRNA or GCV or both ANT2 shRNA and GCV and treated the in vivo mouse model with a Huh 7/NTG tumor xenograft. The therapeutic effects of the in vivo study were assessed with caliper measurements and gamma camera imaging using ^99mTc-pertechnetate.ResultsHuh 7/NTG cells showed a cell number-dependent increase in ¹²⁵I uptake and a 24-fold higher ³H-PCV uptake compared to parent Huh 7 cells. Huh 7/NTG cells transfected with ANT2 shRNA had lower ANT2 mRNA expression and more impaired proliferation activity than cells transfected with scramble shRNA. Proliferation of Huh 7/NTG cells was also inhibited by GCV treatment. Combined GCV and ANT2 shRNA therapy further inhibited cell proliferation in the in vitro study. The combined therapy with GCV and ANT2 shRNA showed a further decrease in tumor growth in the mouse model.ConclusionsOur results suggest that the combined RNA interference with ANT2 and GCV therapy inhibited hepatocellular carcinoma cell proliferation more than single GCV therapy or ANT2 shRNA therapy in vitro and in vivo. Therefore it could be applied treating incurable hepatocellular carcinoma.     

Induction and loss of a TP53-dependent radioadaptive response in the human lymphoblastoid cell model TK6 and its abrogation by BCL2 over-expression

PURPOSE: To characterize the radioadaptive response in the human lymphoblastoid cell model TK6, and determine: (i) Whether repeated low dose exposures are more effective than single acute exposures in inducing resistance, (ii) the time-course for induction and loss of resistance following chronic exposures, and (iii) the effect of TP53 deletion or BCL2 over-expression on the induction of an adaptive response. MATERIALS AND METHODS: TK6, a human B-lymphoblastoid cell line, TK6-BCL2, a TK6 line that over-expresses BCL2 and is resistant to radiation-induced apoptosis, and NH32, a TP53 knockout of TK6 that is also resistant to apoptosis were studied. Cells were exposed to chronic, daily doses of 10 cGy given over 1 -21 days before being challenged with 1 -5 Gy exposures. Cell survival and chromatid break induction following high dose challenge were used to evaluate adaptive radiation responses. RESULTS: Exposure to 10 cGy gamma rays induced resistance to killing and chromosome break induction in TK6 cells, but not in either TK6-BCL2 or NH32 cells. Resistance in TK6 was observed 4 h after exposure, and cells remained resistant for about 48 h. Maximal resistance was induced by a single 10 cGy dose. Repeated 10 cGy exposures had no additional effect on radiation sensitivity, except to maintain the induced radioresistance. CONCLUSION: An adaptive response is maximally and rapidly induced by a single low dose exposure in TK6 cells, and it has a limited lifespan. Induction of an adaptive response in TK6 cells can be abrogated by either TP53 loss or BCL2 over-expression. The characteristics of induced resistance in TK6 cells suggest that alterations in TP53-dependent apoptotic responses may be one mechanism for resistance.