miR-153对肺腺癌细胞增殖、侵袭、迁移和凋亡的影响及机制研究

目的 探讨miR-153对肺腺癌细胞增殖、迁移、侵袭及凋亡的影响及其相关作用机制。方法 构建SRC-3’UTR-WT和SRC-3’UTR-MUT载体,分别与miR-153 mimic,mimic control共转染至肺腺癌A549细胞,采用双荧光素酶报告基因实验验证miR-153与SRC的靶向关系。构建miR-153过表达、敲低miR-153和SRC表达的A549细胞系,采用Western Blot检测miR-153对SRC蛋白表达的影响。通过CCK-8法、细胞划痕实验、Transwell侵袭实验及流式细胞仪分别检测miR-153,SRC及miR-153+SRC共转染对A549细胞增殖、迁移、侵袭及凋亡的影响。结果 双荧光素酶报告基因实验证实SRC是miR-153的靶基因。25例临床肺腺癌组织中miR-153表达水平（13.251±4.256）较癌旁正常组织（25.312±6.527）显著降低（t=7.739,P <0.001）,SRC表达水平（28.574±6.438）较癌旁正常组织（15.206±5.117）显著升高,差异有统计学意义(t=8.128,P <0.001...     

微小RNA-320检测在体外循环所致急性呼吸窘迫综合征中的临床价值及其机制研究

目的研究微小RNA（microRNA）在体外循环（CPB）诱导的急性呼吸窘迫综合征（ARDS）患者中表达,并初步探讨其机制。 方法设定体外循环转流开始前（T1）、转流结束后4 h（T2）、术后8 h（T3）、术后16 h（T4）等4个时间点,采用microRNA微阵列芯片分析32例因CPB诱发ARDS患者microRNA变化,并通过实时荧光定量PCR（qRT-PCR）技术加以验证。酶联免疫分析法检测患者肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）在T1~T4等4个时间点的水平变化,同时计算呼吸指数和氧合指数。Pearson相关性分析研究microRNA-320（miR-320）与TNF-α、IL-6、呼吸指数、氧合指数、Murray急性肺损伤评分以及急性病生理学和长期健康评价（APACHE）Ⅱ评分的相关性。体外培养人肺腺癌A549细胞,并转染pcDNA3.1-miR-320,采用细胞增殖检测试剂盒8（CCK-8）法和流式细胞术分析pcDNA3.1-miR-320转染对A549细胞48 h存活和凋亡率的影响。 结果在T1与T4时间点,ARDS患者血液标本中共有8个microRNA表达差异有统计学意义（t=28.313、30.014、25.313、20.312、29.442、21.443、18.427、22.369,P均< 0.001）,其中5个出现降低,3个出现增高,其中miR-499的降低程度（0.28 ± 0.09）最为显著,而miR-320的增高程度（1.62 ± 0.12）最为显著（P均< 0.05）。qRT-PCR证实从T1至T4时间点,miR-320相对表达水平（1.00、1.14 ± 0.07、1.34 ± 0.06、1.71 ± 0.08）逐渐升高,差异有统计学意义（F=20.648,P < 0.05）。CPB诱发ARDS的患者T1与T4时间点相比,TNF-α[（110 ± 10）ng/L vs.（254 ± 16）ng/L]、IL-6[（86 ± 8）ng/L vs.（165 ± 11）ng/L]、呼吸指数[（0.182 ± 0.021）vs.（0.381 ± 0.032）]均增高,氧合指数[（350 ± 22）vs.（245 ± 18）]下降,差异均有统计学意义（P均< 0.05）。Pearson相关性分析发现,miR-320的表达水平与Murray急性肺损伤评分,APACHEⅡ评分,T4时间点TNF-α、IL-6、呼吸指数均呈正相关（r=0.685、0.744、0.737、0.711、0.846,P均< 0.05）,而与氧合指数呈负相关（r=-0.745,P < 0.05）。pcDNA3.1-miR-320转染的A549细胞组与对照组48 h细胞存活率[（82% ± 8%）vs. 100%]、凋亡率[（20.0% ± 1.1%）vs.（9.4% ± 0.8%）]相比,差异均具有统计学意义（P均< 0.05）。 结论miR-320水平与TNF-α、IL-6等肺部损伤指标具有相关性,miR-320的高表达可能介导CPB导致的ARDS,作用机制为诱导肺泡上皮细胞的凋亡,因此miR-320具有临床诊断、评估ARDS生物学指标的潜能。     

低氧环境下肺腺癌A549细胞自噬及miR-155表达变化的研究

目的观察低氧环境下培养人肺腺癌A549细胞自噬及miR-155表达的变化,为探讨miR-155与自噬关系的研究奠定基础。方法分别在常氧（20%O2/5%CO2/75%N2）（常氧组）及低氧（1%O2/5%CO2/94%N2）（低氧组）环境下培养A549细胞,采用电镜检测自噬体变化,Western blot检测自噬标记蛋白LC3蛋白表达,分析LC3Ⅱ/LC3Ⅰ比值变化,Real-Time PCR检测miR-155表达变化。结果与常氧组相比,低氧组LC3Ⅱ/LC3Ⅰ增加（0.46±0.03）倍;低氧组miR-155表达上调,于24、48 h分别增加（1.45±0.23）倍及（2.10±0.32）倍。结论在低氧环境中,A549细胞中miR-155表达上调,保护性自噬增加。     

LncRNA SNHG15通过miR-483-3p/DDIT4轴调节非小细胞肺癌细胞的顺铂敏感性和上皮间质转化

目的 探究LncRNA SNHG15对非小细胞肺癌（NSCLC）细胞的顺铂（DDP）敏感性和上皮间质转化的影响以及miR-483-3p/DNA损伤诱导转录物4(DDIT4)轴在其中发挥的作用。方法 体外培养NSCLC细胞（A549）、NSCLC耐药细胞（A549/DDP），检测两种细胞对DDP的IC50及LncRNA SNHG15、miR-483-3p、DDIT4 mRNA与蛋白表达，将A549/DDP细胞随机分为A549/DDP组、si NC组、si SNHG15组、si SNHG15+inhibitor NC组、si SNHG15+miR-483-3p inhibitor组、si SNHG15+miR-483-3p inhibitor+si NC组、si SNHG15+miR-483-3p inhibitor+si DDIT4组；蛋白印迹分析法检测各组细胞E-cad、N-cad、DDIT4蛋白表达变化；双荧光素酶报告实验验证miR-483-3p与LncRNA SNHG15、DDIT4的靶向关系。结果 与A549细胞相比，A549/DDP细胞对DDP的IC50、LncRNA SNHG...     

反义T-STAR基因对A549细胞的调节作用

目的：观察反义T-STAR基因对肺腺癌细胞A549的T-STAR蛋白表达的调节作用。 方法：实验于2002-09／2004-03在西南医院中心实验室完成。①用双酶切定向克隆法．构建T-STAR反义核酸真核表达载体pneo-STAR。②A549细胞分4组用脂质体介导转染法分别转染：A549-STAR细胞组转入正义T-STAR基因真核表达载体pEGFP-C1／T-STAR，A549-asSTAR细胞组转入反义T-STAR基因真核表达载体pneo-STAR，A549-neo细胞组转入空载体质粒pcl-neo，A549细胞组为相同处理下不加任何载体的A549细胞。③用反转录-聚合酶链反应和western blot联合检测以上各组细胞的T-STAR表达情况。 结果：①A549-STAR细胞组的T-STAR蛋白和RNA表达量显著高于A549细胞组[（19434&;#177;219）和（1．280&;#177;0．018），（6922&;#177;113）和（0．323&;#177;0．015），P〈0．05]。②A549-asSTAR细胞组的T-STAR蛋白和RNA表达量[（1122&;#177;97），（0．133&;#177;0．005）]显著低于A549细胞组（P〈0．05）。③A549-neo细胞组的T-STAR蛋白和RNA表达量[（6295&;#177;143），（0．625&;#177;0．085）]与A549细胞组差异无显著性意义（P〉0．05）。 结论：导入正义T-STAR基因后的A549细胞中，T-STAR蛋白及RNA表达增加，导入反义T-STAR基因后的A5．9细胞中，T-STAR蛋白及RNA表达减少，说明反义核酸真核表达载体pneo-STAR可以特异性降低A549细胞中T-STAR基因的表达．为进一步研究T-STAR基因的功能奠定了基础。     

m6A甲基转移酶METTL3介导miR-127调控非小细胞肺癌细胞系自噬的机制研究

目的　分析N6 甲基腺苷（m6A）甲基转移酶 3（methyltransferase-like 3, METTL3）和miR-127 在非小细胞肺癌（non small cell lung cancer cells, NSCLC）细胞系中的表达及其相关性,并探究METTL3 介导miR-127 调控非小细胞肺癌自噬的作用机制。方法　采用qRT-PCR 法检测正常肺上皮细胞BEAS-2B 与非小细胞肺癌细胞HCC827,A549 和H460 中METTL3 和miR-127 的表达水平;通过Linked Domics 数据库筛选出肺癌中与miR-127 共表达的基因,并分析METTL3 和miR-127 之间的相关性;选择H460 细胞传代培养至对数生长期后,将浓度接近的细胞随机分为三组,分别转染METTL3-siR,NC-siR 及Control,验证转染后H460 细胞中METTL3 和miR-127 表达;通过吖啶橙染色,Lyso-Tracker Red 染色观察METTL3 对细胞自噬的影响;利用Western blot 检测PTEN,AKT,mTOR,ULK1,Beclin-1等自噬相关蛋白的表达。结果　非小细胞肺癌细胞HCC827,A549,H460 中METTL3 相对表达分别为1.35±0.17,1.54±0.11 和1.78±0.21,明显高于正常肺上皮细胞BEAS-2B 中表达水平（0.91±0.11）,差异有统计学意义(F=34.037,P=0.002)。非小细胞肺癌细胞HCC827,A549,H460 中miR-127 相对表达分别为1.56±0.21,1.85±0.19 和2.11±0.25,较正常肺上皮细胞BEAS-2B 中表达（1.02±0.20）亦显著升高,差异有统计学意义（F=28.152,P=0.005）。肺癌中METTL3 与miR-127 共同表达呈正相关性（r=0.452,P ＜ 0.001）。METTL3-siR 组细胞中METTL3 表达水平（0.61±0.15）较Control 组（1.71±0.28） 和NC-siR 组（1.65±0.19） 显著降低, 差异有统计学意义（F=78.357,P ＜ 0.001）。METTL3-siR 组细胞中miR-127 表达水平（0.48±0.15）较Control 组（2.02±0.33）和NC-siR 组（1.97±0.25）亦显著下降,差异有统计学意义（F=105.216,P ＜ 0.001）;吖啶橙和Lyso-Tracker Red 染色分别观察到METTL3-siR 组细胞酸性自噬小泡增多,自噬溶酶体数量也明显增加。与Control 组和NC-siR 组相比,METTL3-siR 组细胞中PTEN,ULK1,Beclin1 蛋白表达水平显著升高,差异均有统计学意义（F=62.420~175.615,均P<0.001）;p-AKT 和p-mTOR 表达水平显著下降,差异均有统计学意义（F=148.781,87.147,均P<0.001）。结论　METTL3 和miR-127 在非小细胞肺癌细胞系中均呈高表达,且它们之间呈正相关性,沉默METTL3 基因可以抑制miR-127 表达,促进非小细胞肺癌H460 细胞发生自噬,其调控机制可能与PTEN/AKT/mTOR 通路有关。     

三氧化二砷诱导人肺腺癌细胞凋亡形态学及数量变化

目的观察三氧化二砷（arsenic trioxide,As2O3）诱导人肺腺癌A549细胞增殖和凋亡的形态学改变及计数变化。方法体外培养A549细胞至对数生长期后随机分为实验组和空白对照组。实验组加入As2O3药液,光学显微镜（光镜）和电子显微镜（电镜）扫描观察细胞凋亡情况,使用流式细胞仪定量计数凋亡细胞比例变化,并与空白对照组比较。结果实验组A549细胞光镜下表现为细胞缩小、变圆,透光度降低,胞体呈空泡样改变;经吖啶橙荧光染色后,贴壁细胞荧光强度降低,密度下降,部分细胞破碎、胞核消失,出现凋亡细胞;电镜下可见细胞核固缩、破裂,无核膜包被,核染色质边集胞膜,出现凋亡小体。计数结果表明,实验组凋亡细胞比例（14.497%）明显多于空白对照组（0.027%）,差异有统计学意义（χ2=18.447,P〈0.0001）。结论经As2O3诱导后,A549细胞发生了明确的增殖和凋亡改变,且凋亡细胞计数增加,故As2O3有可能成为临床治疗肺癌的一种新方法。     

肿瘤组织中细胞间粘附分子-1表达的PET/近红外荧光跨模态靶向成像表征

目的验证基于双标记细胞间粘附分子-1（ICAM-1）单抗示踪剂，进行胰腺癌组织中ICAM-1的正电子发射断层（PET）/近红外荧光（NIRF）跨模态靶向成像的可行性。方法采用流式细胞术测定2种胰腺癌细胞系BxPC-3、MIA PaCa的ICAM-1表达水平。通过生物耦联和配位反应制备NIRF荧光团和[89Z]锆核素双标记示踪剂。在上述细胞系构建的裸鼠皮下移植瘤模型（简称模型鼠）中，测试示踪剂的特异性、跨模态成像性能和生物分布特性；尝试在BxPC-3模型鼠中进行解剖前/后离体组织器官NIRF光学成像。最后采用组织病理学方法确认ICAM-1在移植瘤组织中的分布。结果BxPC-3与MIA PaCa细胞系的ICAM-1表达水平有显著差异（P < 0.05）。PET/NIRF跨模态成像和放射性生物分布实验显示，在2种模型鼠中，肿瘤的示踪剂摄取峰值的差异也有统计学意义（P < 0.05）。PET/NIRF成像所显示的肿瘤位置相互吻合。解剖切除瘤体前后，荧光信号随瘤体转移，周围组织几乎无残留信号。免疫组织化学染色显示，这2种移植瘤组织的ICAM-1表达水平差异与其示踪剂浓聚水平差异正相关（P < 0.05）。结论本研究确认了以ICAM-1为靶标的双标记单抗示踪剂，用于胰腺癌组织临床前靶向跨模态成像是可行的，这为同时实现肿瘤活体全身成像和肿瘤组织原位可视化提供了例证，揭示了基于ICAM-1靶向成像的病灶检测、手术导航等临床转化应用的潜力。      

miR-26a靶向调控AP-2γ表达对神经母细胞瘤细胞增殖的影响

[目的]探讨miR-26a是否可通过靶向调控AP-2γ表达而抑制神经母细胞瘤细胞增殖.[方法]通过双荧光素酶基因分析检测miR-26a对AP-2γ 3＇非编码区（3＇UTR）-荧光素酶的影响;采用Western blot方法检测miR-26a模拟物转染神经母细胞瘤细胞中AP 2γ表达水平;将AP-2γ shRNA转染SK-N AS细胞,MTS细胞增殖活性检测分析干扰AP-2γ表达对神经母细胞瘤细胞增殖能力.[结果]双荧光素酶活性检测显示miR-26a特异性地与AP-2γ的3＇UTR结合,抑制其荧光素酶活性.过表达miR-26a的神经母细胞瘤细胞AP2γ蛋白表达水平降低;shRNA干扰AP-2γ表达能抑制SK-N-AS细胞的增殖能力.[结论]miR-26a通过靶向调控AP-2γ表达而抑制神经母细胞瘤细胞的增殖.     

不同麻醉方式对腹腔镜前列腺癌根治术患者围术期细胞免疫功能的影响

目的探讨不同麻醉方式对腹腔镜前列腺癌根治术患者围术期细胞免疫功能的影响。方法选择18例腹腔镜前列腺癌根治术患者, 随机分为两组:全凭静脉麻醉组（A组）和静脉全麻复合腰硬联合麻醉组（B组）,每组9例。分别于麻醉前1 h（T0）、麻醉后1 h（T1）、术后24 h（T2）及术后7 d（T3）抽取外周静脉血,测定两组各时间段T淋巴细胞亚群（CD3+、CD4+、CD8+、CD4+/CD8+值）及NK细胞（CD16+56+）水平,分析两组麻醉手术后各时间点、各指标与T0时相比的变化。结果两组患者T1时与T0时比较,T淋巴细胞（CD3+、CD4+、CD4+/CD8+）及NK细胞（CD16+56+）水平均有所降低,其中A组降低水平有统计学意义（P < 0.05）;两组患者T2时与T0时比较T淋巴细胞（CD3+、CD4+、CD4+/CD8+）及NK细胞（CD16+56+）水平均明显降低,差异均有统计学意义（A组P < 0.01,B组P < 0.05）,组间比较A组下降程度较B组更显著（P < 0.05）;两组患者T3时各指标均接近T0水平（P>0.05）;各时间点两组患者CD8+变化均无统计学意义（P>0.05）。结论全凭静脉麻醉与静脉全麻复合腰硬联合麻醉对腹腔镜前列腺癌根治术患者均有一过性不同程度的细胞免疫功能抑制,而静脉全麻复合腰硬联合麻醉的抑制作用较轻。      

Indirect monitoring of endogenous gene expression by positron emission tomography (PET) imaging of reporter gene expression in transgenic mice.

PURPOSE: Repetitive imaging with microPET of endogenous albumin gene expression by using transgenic mice in which the Herpes Simplex Virus Type 1 thymidine kinase (HSV1-tk) reporter gene is driven by the albumin promoter (AL-HSV1-tk). METHODS: Transgenic mice were imaged repeatedly on a microPET scanner with approximately 200 microCi of 9-[4-[18F]fluoro-3-(hydroxymethyl)butyl]guanine (FHBG) (a substrate for HSV1-TK enzyme). Four transgenic mice were monitored for body weight, serum albumin, and imaged at the end of each of three dietary phases (17%, 0%, and 25% protein diet). Each phase last 14-21 days. The 0% protein diet has been reported previously to reduce albumin gene expression in rats. Twenty non-transgenic mice of the same strain followed a similar feeding schedule and were monitored for serum albumin, body weight, and sacrificed at various time points for determination of their GAPDH normalized albumin mRNA levels. RESULTS: Transgenic mice showed a relatively high FHBG signal from the liver region as expected. Variation of the mean FHBG signal in two mice with a fixed 17% protein diet over a four-month period was <19% s.d. The mean +/- s.e. FHBG liver standardized uptake value (SUV) in four transgenics went from 4.49 +/- 0.32 to 2.17 +/- 0.52 to 6.21 +/- 0.72 as the mice went through the three diets of 17%, 0%, and 25% sequentially. Non-transgenic mice showed GAPDH normalized albumin mRNA that went from 37.68 +/- 6.04 to 26.41 +/- 4.29 to 52.42 +/- 4.09. The FHBG SUV from transgenics was well correlated with GAPDH normalized albumin mRNA from non-transgenics (r(2) = 0.97) supporting that endogenous gene expression of albumin can be indirectly imaged with FHBG. CONCLUSION: Measuring correlated changes in albumin expression in wild type mice and HSV1-TK expression by microPET in transgenic mice in which the reporter gene is driven by the albumin promoter demonstrates that the HSV1-tk gene can be used to monitor, in living animals, modulated expression of transgenes.     

Synthesis and Characterization of 9-(4-[18F]Fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)-6-oxopurine as a Novel PET Agent for Mutant Herpes Simplex Virus Type 1 Thymidine Kinase Reporter Gene Imaging

Molecular Imaging and Biology - [18F]FHBG has been used as a positron emission tomography (PET) imaging tracer for the monitoring of herpes simplex virus type 1 thymidine kinase (HSV1-tk), a...     

A fully automated one pot synthesis of 9-(4-[18F]fluoro-3-hydroxymethylbutyl) guanine for gene therapy studies.

PURPOSE: To develop a new fully-automated method for the synthesis of 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) amenable for its routine use in gene therapy monitoring studies.PROCEDURES: A nuclear interface commercial synthesizer was substantially modified and adapted to the synthesis of the referred compound. After the fluorination reaction of the tosylate precursor, the intermediate product was purified by Solid Phase Extraction (SPE) before the hydrolysis. The final product was purified by semi-preparative high performance liquid chromatography (HPLC).RESULTS: [18F]FHBG was obtained in 10-15% yield in 65 minutes including HPLC purification. The radiotracer was > 99% chemically and radiochemically pure, sterile and free from pyrogens. The synthesized compound was shown to accumulate in thymidine kinase (tk) expressing cells both in cell culture, and in laboratory animals infected with an adenoviral vector containing the herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene.CONCLUSIONS: This new procedure facilitates the compliance with the applicable regulatory guidelines for positron emission tomography (PET) radiopharmaceuticals and will assist the clinical application of [18F]FHBG-PET as a noninvasive way to monitor gene therapy in humans.     

Noninvasive imaging of ex vivo intracoronarily delivered nonviral therapeutic transgene expression in heart.

We developed a clinically applicable approach for noninvasive monitoring of reporter-therapeutic linked gene expression in the whole heart of large animals using PET imaging and further validated the efficacy and cardiac adverse effects of reporter-therapeutic linked gene transfer in a rabbit cervical heterotopic functional heart transplant model. Cationic liposome complexed with a vector containing a herpes simplex virus type 1 mutant thymidine kinase (HSV1-sr39tk) as the reporter gene and a recombinant human immunosuppressive cytokine, interleukin-10 (hIL-10), as the therapeutic gene was ex vivo intracoronarily delivered into cardiac allografts before implantation. Long-term HSV1-sr39tk and hIL-10 transgene and protein overexpression associated with myocardial PET reporter probe 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) accumulation was observed in the allografts. The expression of the HSV1-sr39tk gene was significantly correlated with the hIL-10 gene expression and the total myocardial [18F]FHBG accumulation quantified as a percentage of intravenously injected [18F]FHBG dose. A homogeneous distribution of [18F]FHBG accumulation was seen in the whole heart similar to the distribution of [18F]fluorodeoxyglucose, a PET glucose metabolism probe. The immunosuppressive therapeutic efficacy remained the same in allografts treated with reporter-therapeutic linked gene and therapeutic gene only. No cardiac adverse effect was found. Our results demonstrate for the first time that PET reporter-therapeutic linked gene imaging is applicable for noninvasively monitoring ex vivo intracoronarily delivered therapeutic transgene expression in the whole heart.     

Semiautomated Radiosynthesis and Biological Evaluation of [<Superscript>18</Superscript>F]FEAU: A Novel PET Imaging Agent for <Emphasis Type="Italic">HSV1-tk/sr39tk</Emphasis> Reporter Gene Expression

2′-Deoxy-2′-[¹⁸F]fluoro-5-ethyl-1-β-d-arabinofuranosyluracil ([¹⁸F]FEAU) is a promising radiolabeled nucleoside designed to monitor Herpes Simplex Virus Type 1 thymidine kinase (HSV1-tk) reporter gene expression with positron emission tomography (PET). However, the challenging radiosynthesis creates problems for being able to provide [¹⁸F]FEAU routinely. We have developed a routine method using a commercial GE TRACERlab FX-FN radiosynthesis module with customized equipment to provide [¹⁸F]FEAU. All radiochemical yields are decay corrected to end-of-bombardment and reported as means ± SD. Radiofluorination (33 ± 8%; n = 4), bromination (85 ± 8%; n = 4), coupling reaction (83 ± 6%; n = 4), base hydrolysis steps, and subsequent high-performance liquid chromatography purification afforded purified [¹⁸F]FEAU β-anomer in 5 ± 1% overall yield (n = 3 runs) after ~5.5 h and a β/α-anomer ratio of 7.4. Radiochemical/chemical purities and specific activity exceeded 99% and 1.3 Ci/μmol (48 GBq/μmol), respectively. In cell culture, [¹⁸F]FEAU showed significantly (P < 0.05) higher accumulation in C6 cells expressing HSV1-tk/sr39tk as compared to wild-type C6 cells. Furthermore, [¹⁸F]FEAU showed slightly higher accumulation than 9-[4-[¹⁸F]fluoro-3-(hydroxymethyl)butylguanine ([¹⁸F]FHBG) in cells expressing HSV1-tk (P < 0.05), whereas [¹⁸F]FHBG showed significantly higher (P < 0.05) accumulation than [¹⁸F]FEAU in HSV1-sr39tk-expressing cells. micro-PET imaging of mice carrying tumor xenografts of C6 cells stably expressing HSV1-tk or HSV1-sr39tk are consistent with the cell uptake results. The [¹⁸F]FEAU mouse images also showed very low gastrointestinal signal with predominant renal clearance as compared to [¹⁸F]FHBG. The routine radiosynthesis of [¹⁸F]FEAU was successfully semiautomated using a commercial module along with customized equipment to provide the β-anomer in modest yields. Although further studies are needed, early results also suggest [¹⁸F]FEAU is a promising PET radiotracer for monitoring HSV1-tk reporter gene expression.     

Quantitation of cell number by a positron emission tomography reporter gene strategy.

PURPOSE: An important potential of positron emission tomography (PET) is the capacity for quantitation of cell signals in an anatomic regions of interest. However, little is known about the constraints and parameters for using PET signal detection to establish cell numbers in regions of interest. In this study, we determined the correlation of PET signal to cell number, and characterized the cellular limit of detection for PET imaging. PROCEDURES: Cells expressing the herpes simplex virus type I thymidine kinase PET reporter gene (HSV1-sr39TK) were detected following accumulation of [(18)F]FHBG (9-[4-[(18)F]-fluoro-3-(hydroxymethyl) butyl]guanine) by microPET scanning and quantitation. RESULTS: When cells were cultured with [(18)F]FHBG in vitro, and then transferred to a model vascularized site, 73% retention was observed one hour post-transfer. Using this information, and the measured attenuation of PET signal in whole mouse scans, we assessed the per-cell uptake of [(18)F]FHBG in the vascularized site following standard parenteral administration of the substrate. We observed a cell number-dependent signal, with a limit of detection calculated as 10(6) cells in a region of interest of 0.1 mL volume. Quantitatively similar parameters were observed with stably tranfected N2a glioma cells and retrovirally transduced primary T lymphocytes. CONCLUSION: These methods and findings provide a strategy for quantitation of cellularity using PET imaging that has implications for both experimental models and clinical diagnosis.     

MicroPET imaging of Cre-loxP-mediated conditional activation of a herpes simplex virus type 1 thymidine kinase reporter gene

Site-specific recombination tools such as the Cre-loxP system are used to create animal models where conditional gene deletion/activation studies are required. In the current proof of principle study, we have demonstrated that a PET reporter gene (PRG), the herpes simplex virus type 1 thymidine kinase (HSV1-tk), can be made to remain silent and can be activated by Cre-loxP-mediated recombination in cell culture and in living mice. An adenovirus carrying a silent HSV1-tk was tail-vein injected (1 x 10(9) PFU) in six transgenic mice that express Cre recombinase in their liver (Cre+) and in four control mice (Cre-). The liver-specific expression of the PRG in Cre+ mice was detected in the microPET following injection of the reporter probe, 9-[4-fluoro-3-(hydroxymethyl)butyl]guanine ([(18)F]-FHBG). The [(18)F]-FHBG accumulation in the liver in terms of percent-injected dose per gram of tissue was 7.72+/-1.13 for the Cre+ mice and 0.10+/-0.02 for the Cre- mice (P<0.05) 48 h after adenoviral injection. These results were further validated by quantitative RT-PCR, western blotting and by in vitro assays for herpes simplex virus type 1 thymidine kinase enzyme activity. Thus by using the Cre-loxP system it is possible to modulate a PRG and noninvasively monitor the extent of Cre-loxP-mediated gene activation by imaging in a microPET scanner.     

[18F]FHBG PET/CT Imaging of CD34-TK75 Transduced Donor T Cells in Relapsed Allogeneic Stem Cell Transplant Patients: Safety and Feasibility

Described herein is a first-in-man attempt to both genetically modify T cells with an imagable suicide gene and track these transduced donor T cells in allogeneic stem cell transplantation recipients using noninvasive positron emission tomography/computerized tomography (PET/CT) imaging. A suicide gene encoding a human CD34-Herpes Simplex Virus-1-thymidine kinase (CD34-TK75) fusion enabled enrichment of retrovirally transduced T cells (TdT), control of graft-versus-host disease and imaging of TdT migration and expansion in vivo in mice and man. Analysis confirmed that CD34-TK75-enriched TdT contained no replication competent γ-retrovirus, were sensitive to ganciclovir, and displayed characteristic retroviral insertion sites (by targeted sequencing). Affinity-purified CD34-TK75⁺-selected donor T cells (1.0–13 × 10⁵)/kg were infused into eight patients who relapsed after allogeneic stem cell transplantation. Six patients also were administered 9-[4-(¹⁸F)fluoro-3-hydroxymethyl-butyl]guanine ([¹⁸F]FHBG) to specifically track the genetically modified donor T cells by PET/CT at several time points after infusion. All patients were assessed for graft-versus-host disease, response to ganciclovir, circulating TdT cells (using both quantitative polymerase chain reaction and [¹⁸F]FHBG PET/CT imaging), TdT cell clonal expansion, and immune response to the TdT. This phase 1 trial demonstrated that genetically modified T cells and [¹⁸F]FHBG can be safely infused in patients with relapsed hematologic malignancies after allogeneic stem cell transplantation.     

Monitoring adenoviral DNA delivery,using a mutant herpes simplex virus type 1 thymidine kinase gene as a PET reporter gene

Current gene therapy protocols often suffer from an inability to monitor the site, level and persistence of gene expression following somatic DNA delivery. Herpes simplex virus 1 thymidine kinase (HSV1-tk) is currently under intensive investigation as a reporter gene for in vivo imaging of reporter gene expression. The presence of the HSV1-tk reporter gene is repetitively and non-invasively monitored by systemic injection of positron-emitting, radionuclide-labeled thymidine analogues or acycloguanosine HSV1-TK substrates and subsequent detection, by positron emission tomography, of trapped, phosphorylated product. To improve the efficacy of the HSV1-tk PET reporter gene system, both alternative substrates and mutations in the HSV1-tk gene have been described. We used a replication defective adenovirus to deliver the HSV1-sr39tk mutant enzyme and the wild-type HSV1-tk enzyme to mice. HSV1-sr39TK demonstrates greater sensitivity than wild-type HSV1-TK enzyme in vivo, using 9-[(4-[(18)F]fluoro-3-hydroxymethylbutyl)guanine as probe, following adenovirus-mediated hepatic expression in mice. Using this adenoviral delivery system, the location, magnitude and duration of HSV1-sr39tk PET reporter gene expression could be non-invasively, quantitatively and repetitively monitored for over 3 months by microPET.