摘要
目的:将编码GGC肽(diglycylcysteine,双甘氨酰半胱氨酸)的基因序列与人生长抑素2a型受体(hSSTr2a)基因的膜外N端开放阅读框相连接,构建融合受体重组腺病毒载体Ad5-GGC-hSSTr2a-IRES-EGFP。通过体外受体结合试验、细胞摄取试验、核素报告基因显像等一系列体外与体内实验研究,探讨以GGC序列为报告基因进行核素报告基因显像的可行性,以期建立一种新型的核素报告基因显像系统。
方法:
1.重组腺病毒载体Ad5-GGC-hSSTr2a-IRES-EGFP的构建与表达鉴定。
采用RT-PCR方法扩增hSSTr2a基因全长cDNA序列,将GGC肽的基因序列(亲水序列P1,疏水序列P2)与hSSTr2a的膜外N端开放阅读框相连接,通过一系列基因工程技术构建同源重组腺病毒骨架质粒pAdEasy-1/GGC-hSSTr2a-IRES-EGFP (pAd-SIG-P1, P2)。提取pAd-SIG-P1和pAd-SIG-P2质粒并转化大肠杆菌DH5a感受态细胞,酶切线性化后经脂质体(Lipofectamine2000)介导转染HEK293细胞,同源重组产生融合受体重组腺病毒载体Ad5-GGC-hSSTr2a-IRES-EGFP ( Ad5-P1/STR ,Ad5-P2/STR)。经PCR鉴定后进行大量扩增和纯化,采用PCR、荧光显微术鉴定目的基因的表达,并测定病毒感染滴度。
2. Ad5-GGC-hSSTr2a-IRES-EGFP在人乳腺癌MCF-7细胞内的表达。
以MOI = 50的重组腺病毒(Ad5-P1/STR, Ad5-P2/STR)感染人乳腺癌细胞MCF-7后,分别在24h、48h、72h和96h采用荧光显微术与流式细胞术检测细胞内EGFP的表达。研究99mTc-HYNIC-TOCA与受感染MCF-7细胞的体外受体结合特性。并利用99mTc-GH放射性摄取实验研究GGC肽在MCF-7细胞的表达。
3. Ad5-GGC-hSSTr2a-IRES-EGFP在荷瘤裸鼠体内的报告基因显像。
建立荷人乳腺癌裸鼠模型(双侧上肢荷瘤),以重组腺病毒Ad5-P1/STR、Ad5-P2/STR、Ad5-EGFP及Ad5-TIS(Ad5-HSV1-TK-IRES-hSSTr2a)对照性注射于两侧瘤体内(1×109IU),于感染48h后分别进行以99mTc-GH和99mTc-HYNIC-TOCA为显像剂的核素报告基因SPECT显像以及GFP活体荧光显像。同时以1×108~3×109 IU梯度滴度的重组腺病毒分组感染两侧瘤体,48小时后进行核素报告基因SPECT显像。通过感兴趣区(region of interest, ROI)技术进行半定量分析,计算肿瘤/非肿瘤比值(T/NT)。显像完毕后进行生物学分布实验,测定离体肿瘤标本的放射性计数,计算显像剂在裸鼠体内各脏器及肿瘤组织的克组织百分摄取率(%ID/g)。分别取感染Ad5-P1/STR和Ad5-P2/STR两侧肿瘤组织固定保存,以免疫组织化学技术检测病毒感染后肿瘤组织内hSSTr2a蛋白的表达。
结果:
1.重组腺病毒载体Ad5-GGC-hSSTr2a-IRES-EGFP的构建与表达鉴定。
重组腺病毒载体Ad5-GGC-hSSTr2a-IRES-EGFP(Ad5-P1/STR,Ad5-P2/STR)构建正确,PCR可特异性扩增出hSSTr2a片段(1212bp),荧光显微镜下显示出绿色荧光蛋白EGFP (enhanced green fluorescent protein)的表达。测得Ad5-P1/STR和Ad5-P2/STR的TCID50值均为8.2×109/mL。
2. Ad5-GGC-hSSTr2a-IRES-EGFP在人乳腺癌MCF-7细胞内的表达。
重组腺病毒以MOI=50感染MCF-7后,细胞内EGFP的表达随时间的延长而逐渐增强,至感染后48h,显微镜下绿色荧光最强且集中,流式细胞术检测其EGFP表达率为99.6%。72h后荧光逐渐减弱,流式细胞术检测EGFP表达率亦逐渐减低。以MOI=50的重组腺病毒感染后,MCF-7细胞对99mTc-GH的摄取率随时间延迟而逐渐增高,30min后重组腺病毒感染组与Ad5-EGFP感染的对照组细胞的摄取率有显著性差异( Ad5-P1/STR vs Ad5-EGFP : t=4.267~39.728 , Ad5-P2/STR vs Ad5-EGFP :t=4.362~9.455 , P均<0.01 )。而Ad5-P1/STR组与Ad5-P2/STR组无显著性差异(Ad5-P1/STR vs Ad5-P2/STR:t=0.347~1.083,P>0.05)。以MOI=0~100的重组腺病毒感染MCF-7后,细胞对99mTc-GH的摄取率均随感染滴度的增加而逐渐增加,且细胞对99mTc-GH的摄取率与Ad-P1/STR或Ad-P2/STR的感染滴度之间存在良好的相关性,R2分别为0.8997和0.9242 (P均<0.01)。
3. Ad5-GGC-hSSTr2a-IRES-EGFP在荷瘤裸鼠体内的报告基因显像。
活体GFP荧光显像可见,感染Ad5-P1/STR、Ad5-P2/STR和Ad5-EGFP的肿瘤部位均可见绿色荧光,而感染Ad5-TIS的肿瘤部位未见绿色荧光。体内放射性核素显像可见,感染重组腺病毒Ad5-P1/STR和Ad5-P2/STR的肿瘤部位可被99mTc-GH显像,而感染Ad5-EGFP的肿瘤部位无明显显像剂浓聚,其5h的T/NT比值有显著性差异(tP1, EGFP=4.780, tP2, EGFP=8.981, P均<0.05)。感染Ad5-P1, P2/STR的肿瘤部位在99mTc-GH显像与99mTc-HYNIC-TOCA显像中均可见显影,而感染Ad5-TIS的肿瘤部位仅在99mTc-HYNIC-TOCA显像中显影。以不同滴度的重组腺病毒感染肿瘤后显像提示,肿瘤组织对显像剂的摄取随感染滴度的增高而逐渐增加,且平均% ID/g值与Ad5-P1/STR或Ad5-P2/STR感染滴度的对数值呈线性相关(相关系数R2分别为0.8458和0.8948,P均<0.05)。而感染Ad5-P1/STR和Ad5-P2/STR的两组肿瘤的平均% ID/g值之间无显著性差异(t=0.039~2.314,P均>0.05)。免疫组织化学检测显示,感染Ad5-P1/STR和Ad5-P2/STR的肿瘤组织内均可检测到hSSTr2a的表达。
结论:含有GGC肽和hSSTr2a基因序列的融合受体重组腺病毒载体Ad5-P1/STR和Ad5-P2/STR构建成功。重组腺病毒感染荷瘤裸鼠后,GGC肽在其体内的表达可被核素显像所显示,肿瘤组织对显像剂的摄取与病毒感染滴度具有良好的相关性。GGC序列有望作为新型报告基因用于核素报告基因显像。
Objective To construct the recombinant adenoviral vectors Ad5-GGC-hSSTr2a-IRES-EGFP by fusing the GGC (diglycylcysteine) motifs on the open reading frame of extracellular N-terminus of human somatostatin receptor subtype 2a gene. A series of experiments in vitro and in vivo such as characteristics of receptor-binding, uptake kinetics and radionuclide reporter rene imaging were performed to investigate the feasibility of GGC motifs used for radionuclide reporter gene imaging as a reporter gene.
Methods
1. Construction and the expression of recombinant adenoviral vectors encoding GGC and human somatostatin receptor subtype 2a
The full length of hSSTr2a cDNA was amplified from plasmid pGEM-T/hSSTr2a by RT-PCR, and its open reading frame of extramembranous N-terminal was combined with the GGC motifs (hydrophilic motif P1, or hydrophobic motif P2). A series of gene engineering techniques were performed to construct homologous recombinant adenovirus plasmids pAdEasy-1/GGC-hSSTr2a-IRES-EGFP (pAd-SIG-P1, P2). The recombinant plasmids pAd-SIG-P1 and pAd-SIG-P2 were extracted and transformed into competent E coli DH5α. After been linearized, the recombinant plasmids were transfected into HEK 293 cells by lipofectamine 2000 to generate recombinant adenoviral vectors Ad5-GGC-hSSTr2a- IRES-EGFP (Ad5-P1/STR, Ad5-P2/STR). After the amplification and purification of the recombinant adenovirus, PCR and fluorescence microscopy detection were performed to confirm the expression of hSSTr2a and enhanced green fluorescent protein (EGFP). TCID50 of Ad5-P1/STR and Ad5-P2/STR were detected.
2. Expression of the recombinant adenovirus Ad5-GGC-hSSTr2a-IRES-EGFP in MCF-7 cells.
The human breast cancer cells MCF-7 were infected with the recombinant adenovirus (Ad5-P1/STR, Ad5-P2/STR) at a wide range multiplicity of infection (MOI) from 0 to 100 infectious units (IU/per cell). The fluorescence microscopy and flow cytometry were used to validate the expression of enhanced green fluorescent protein (EGFP) at 24h, 48h, 72h and 96h after infection. Then the characteristics of receptor-binding of 99mTc- hydrazinonicotinyl-Tyr3-octreotate (99mTc-HYNIC-TOCA) to MCF-7 cells infected with the recombinant adenovirus were studied. And the protein expression of GGC motifs in MCF-7 cells was determined by experiments of the radioactive uptake rate of 99mTc-GH in MCF-7 cells.
3. Reporter gene imaging using the recombinant adenovirus
Ad5-GGC-hSSTr2a-IRES-EGFP in nude mice bearing MCF-7 tumors. BALB/c A nude mice bearing MCF-7 tumor (both upper limbs) were injected with 1×109 IU of Ad5-P1/STR, Ad5-P1/STR or Ad5-TIS (Ad5-HSV1-TK-IRES-hSSTr2a). 48 hours later, the whole-body GFP fluorescence tomography and radionuclide reporter gene SPECT imaging were performed using 99mTc-GH and 99mTc-HYNIC-TOCA. On the other hand, we infected both MCF-7 tumors of nude mice with recombinant adenovirus at a multiplicity infection from 1×108 to 1×109 IU, and then performed reporter gene SPECT imaging. Semiquantitative analysis was studied to evaluate the tumor/non-tumor ratios (T/NT) with region of interest (ROI). Bio-distribution of the probe in each organ and tumor of mice was analyzed withγcounter ex vivo. Immunohistochemistry technique was used to validate the expression of hSSTr2a in tumors infected with Ad5-P1/STR and Ad5-P2/STR, separately.
Results
1. Construction and the expression of recombinant adenoviral vectors encoding GGC and human somatostatin receptor subtype 2a
The recombinant adenoviral vectors Ad5-GGC-hSSTr2a-IRES-EGFP (Ad5-P1/STR, Ad5-P2/STR) were constructed correctly. The expression of hSSTr2a could be identified by PCR, and the expression of EGFP could be identified by fluorescence microscopy. TCID50 of both Ad5-P1/STR and Ad5-P2/STR were 8.2×109/mL.
2. Expression of the recombinant adenovirus Ad5-GGC-hSSTr2a-IRES-EGFP in MCF-7 cells.
After infected with the recombinant adenovirus at a MOI of 50, the expression level of EGFP in MCF-7 cells increased gradually with time. At 48 hours after infection, the green fluorescent in MCF-7 was detected strongest and localized by fluorescence microscopy, and the expression rate was determined 99.6% by flow cytometry. 72 hours later, the green fluorescent in MCF-7 tapered, and its expression rate also decreased. After infected with the recombinant adenovirus at a MOI of 50 infectious units, the radioactive uptake rate of 99mTc-GH in MCF-7 cells increased gradually with time. There was significant difference between experimental group (infected with Ad5-P1/STR or Ad5-P2/STR) and control group (infected with Ad5-EGFP) after 30 min (Ad5-P1/STR vs Ad5-EGFP: t=4.267~39.728, P<0.01; Ad5-P2/STR vs Ad5-EGFP: t=4.362~9.455, P <0.01). But there was no significant difference between Ad5-P1/STR and Ad5-P2/STR (Ad5-P1/STR vs Ad5-P2/STR:t=0.347~1.083,P>0.05). Infected with the recombinant adenovirus at a wide range MOI from 0 to 100 infectious units, the radioactive uptake rate of 99mTc-GH increased gradually with increasing viral titer. Furthermore, the uptake rate of 99mTc-GH correlated significantly with the viral titer (R2=0.8997 for Ad5-P1/STR; R2=0.9242 for Ad5-P2/STR, P both<0.01).
3. Reporter gene imaging using the recombinant adenovirus
Ad5-GGC-hSSTr2a-IRES-EGFP in nude mice bearing MCF-7 tumors. Green fluorescence could be shown in tumors that infected with Ad5-P1/STR, Ad5-P2/STR and Ad5-EGFP in the whole-body GFP fluorescence tomography, but there was no green fluorescence in tumors that infected with Ad5-TIS. Radionuclide reporter gene imaging in vivo showed tumors that infected with Ad5-P1/STR or Ad5-P2/STR. However, tumors infected with Ad5-EGFP could not be shown. There was significant difference between their T/NT at 5h (tP1, EGFP=4.780, P<0.05; tP2, EGFP=8.981, P<0.05). Tumors infected with Ad5-P1, P2/STR could be shown in the SPECT imaging with 99mTc-GH or 99mTc-HYNIC-TOCA. However, tumors infected with Ad5-TIS only could be shown in the SPECT imaging with 99mTc-HYNIC-TOCA. Radioactivity uptake of 99mTc-GH in tumors increased with increasing infection titer of adenovirus. The mean %ID/g of tumors positively correlated with the logarithm of infection titer of Ad5-P1/STR or Ad5-P2/STR (R2P1=0.8458, P<0.05; R2P2=0.8948, P<0.05). There was no significant difference between %ID/g of tumors that infected with Ad5-P1/STR and Ad5-P2/STR respectively (t=0.039~2.314, P both>0.05). The expression of hSSTr2a could be detected in tumors infected with Ad5-P1/STR or Ad5-P2/STR.
Conclusions: The recombinant adenovirus vectors Ad5-P1/STR and Ad5-P2/STR were constructed successfully. Infected with the recombinant adenovirus, the expression of GGC peptide in nude mice could be clearly imaged with radionuclide imaging in vivo. The GGC motifs could be used in radionuclide reporter imaging as a new reporter gene.
引文
1 Blasberg RG, Gelovani-Tjuvajev J. In vivo molecular-genetic imaging. J Cell Biochem Suppl, 2002, 39: 172-183.
2 Doubrovin M, Serganova I, Mayer-Kuckuk P, et al. Multimodality in vivo molecular-genetic imaging. Bioconjug Chem, 2004, 15(6): 1376-1388.
3 Blasberg RG, Tjuvajev JG. Molecular-genetic imaging: current and future perspectives. J Clin Invest, 2003, 111(11): 1620-1629.
4 Gelovani Tjuvajev J, Blasberg RG. In vivo imaging of molecular-genetic targets for cancer therapy. Cancer Cell, 2003(4), 3: 327-332.
5 Belmar C, So PW, Vassaux G, et al. Non-invasive genetic imaging for molecular and cell therapies of cancer. Clin Transl Oncol, 2007, 9(11): 703-714.
6 Tost H, Meyer-Lindenberg A, Ruf M, et al. One decade of functional imaging in schizophrenia research. From visualisation of basic information processing steps to molecular-genetic oriented imaging. Radiologe, 2005, 45(2): 113-118, 120-123.
7 Wang ZZ, Qu W, Wang F, et al. Expression of somatostatin receptor reporter gene and its correlation with targeted imaging in vivo for detection of pancreas carcinoma. Zhonghua Zhong Liu Za Zhi, 2005, 27(11): 663-666.
8 Zhang ZW, Zhang XM, Wu H. Radionuclide reporter gene imaging. Zhongguo Yi Xue Ke Xue Yuan Xue Bao, 2003, 25(6): 728-730.
9 Iyer M, Barrio JR, Namavari M, et al. 8-[18F] Fluoropenciclovir: an improved reporter probe for imaging HSV1-tk reporter gene expression in vivo using PET. J Nucl Med, 2001, 42(1): 96-105.
10 Hu SY, Chen ZX, Zhao Y, et al. Application of EGFP as reporter gene in study of WT1 regulation elements. Zhongguo Shi Yan Xue Ye Xue Za Zhi,2007,15(3):599-602.
11 Tsakiridis A, Tzouanacou E, Larralde O, et al. A novel triple fusion reporter system for use in gene trap mutagenesis. Genesis, 2007, 45(6): 353-360.
12 Cho ZH, Son YD, Kim HK, et al. A fusion PET-MRI system with a high-resolutionresearch tomograph-PET and ultra-high field 7.0 T-MRI for the molecular-genetic imaging of the brain. Proteomics, 2008, 8(6): 1302-1323.
13 Glunde K, Bhujwalla ZM. Will magnetic resonance imaging (MRI)-based contrast agents for molecular receptor imaging make their way into the clinic? J Cell Mol Med, 2008, 12(1): 187-188.
14 Massoud TF, Gambhir SS. Molecular imaging in living subjects: seeing fundamental biological processes in a new light. Genes Dev, 2003, 17(5): 545-580.
15 Young Kim J, Jun Oh S, Sook Ryu J, et al. Synthesis of 99mTc(CO)3-deoxyuridine derivatives as potential HSV1-tk gene expression imaging agents. Appl Radiat Isot, 2008, 66(4): 489-496.
16 Chin FT, Namavari M, Levi J, et al. Semiautomated radiosynthesis and biological evaluation of [18F]FEAU: a novel PET imaging agent for HSV1-tk/sr39tk reporter gene expression. Mol Imaging Biol, 2008, 10(2): 82-91.
17 Cai H, Yin D, Zhang L, et al. Preparation and biological evaluation of 2-amino-6-[18F] fluoro-9-(4-hydroxy-3-hydroxy-methylbutyl) purine (6-[18F] FPCV) as a novel PET probe for imaging HSV1-tk reporter gene expression. Nucl Med Biol, 2007, 34(6): 717-725.
18 Yaghoubi SS, Gambhir SS. PET imaging of herpes simplex virus type 1 thymidine kinase (HSV1-tk) or mutant HSV1-sr39tk reporter gene expression in mice and humans using [18F] FHBG. Nat Protoc, 2006, 1(6): 3069-3075.
19 Cho SY, Ravasi L, Szajek LP, et al. Evaluation of (76)Br-FBAU as a PET reporter probe for HSV1-tk gene expression imaging using mouse models of human glioma. J Nucl Med, 2005, 46(11): 1923-1930.
20 Alauddin MM, Shahinian A, Gordon EM, et al. Direct comparison of radiolabeled probes FMAU, FHBG, and FHPG as PET imaging agents for HSV1-tk expression in a human breast cancer model. Mol Imaging, 2004, 3(2): 76-84.
21 Gambhir SS, Bauer E, Black ME, et al. A mutant herpes simplex virus type 1thymidine kinase reporter gene shows improved sensitivity for imaging reporter gene expression with positron emission tomography. Proc Natl Acad Sci U S A, 2000, 97(6): 2785-2790.
22 Tjuvajev JG, Doubrovin M, Akhurst T, et al. Comparison of radiolabeled nucleoside probes (FIAU, FHBG, and FHPG) for PET imaging of HSV1-tk gene expression. J Nucl Med, 2002, 43(8): 1072-1083.
23 Aung W, Okauchi T, Sato M, et al. In-vivo PET imaging of inducible D2R reporter transgene expression using [11C] FLB 457 as reporter probe in living rats. Nucl Med Commun, 2005, 26(3): 259-268.
24 Patel YC, Srikant CB. Subtype selectivity of peptide analogs for all five cloned human somatostatin receptors (hsstr 1-5). Endocrinology, 1994, 135(6): 2814-2817.
25 Tagliati F, Zatelli MC, Bottoni A, et al. Role of complex cyclin d1/cdk4 in somatostatin subtype 2 receptor-mediated inhibition of cell proliferation of a medullary thyroid carcinoma cell line in vitro. Endocrinology, 2006, 147(7): 3530-3538.
26 Kumar M, Liu ZR, Thapa L, et al. Mechanisms of inhibition of growth of human pancreatic carcinoma implanted in nude mice by somatostatin receptor subtype 2. Pancreas, 2004, 29(2): 141-151.
27 Kumar M, Liu ZR, Thapa L, et al. Anti-angiogenic effects of somatostatin receptor subtype 2 on human pancreatic cancer xenografts. Carcinogenesis, 2004, 25(11): 2075-2081.
28 Verwijnen SM, Sillevis Smith PA, Hoeben RC, et al. Molecular imaging and treatment of malignant gliomas following adenoviral transfer of the herpes simplex virus-thymidine kinase gene and the somatostatin receptor subtype 2 gene. Cancer Biother Radiopharm, 2004, 19(1): 111-120.
29 Li Y, Si JM, Zhang J, et al. Somatostatin receptor subtype 2-mediated scintigraphy and localization using (99m)Tc-HYNIC-Tyr(3)-octreotide in human hepatocellular carcinoma-bearing nude mice. World J Gastroenterol, 2005, 11(25): 3953-3957.
30 Burggasser G, Hurtl I, Hauff W, et al. Orbital scintigraphy with the somatostatin receptor tracer 99mTc-P829 in patients with Graves' disease. J Nucl Med, 2003, 44(10): 1547-1555.
31 Zinn KR, Chaudhuri TR, Buchsbaum DJ, et al. Detection and measurement of in vitro gene transfer by gamma camera imaging. Gene Ther, 2001, 8(4): 291-299.
32 Moresco RM, Colombo C, Fazio F, et al. Effects of fluvoxamine treatment on the in vivo binding of [F-18]FESP in drug naive depressed patients: a PET study. Neuroimage, 2000, 12(4): 452-465.
33 MacLaren DC, Gambhir SS, Satyamurthy N, et al. Repetitive, non-invasive imaging of the dopamine D2 receptor as a reporter gene in living animals. Gene Ther, 1999, 6(5): 785-791.
34 Saji H, Iida Y, Kawashima H, et al. In vivo imaging of brain dopaminergic neurotransmission system in small animals with high-resolution single photon emission computed tomography. Anal Sci, 2003, 19(1): 67-71.
35 Perez V, Catafau AM, Corripio I, et al. Preliminary evidence of striatal D2 receptor density as a possible biological marker of prognosis in naive schizophrenic patients. Prog Neuropsychopharmacol Biol Psychiatry, 2003, 27(5): 767-770.
36 Lewis MR. A "new" reporter in the field of imaging reporter genes: correlating gene expression and function of the sodium/iodide symporter. J Nucl Med, 2006, 47(1): 1-3.
37 Bogdanov A Jr, Simonova M, Weissleder R. Design of metal-binding green fluorescent protein variants. Biochim Biophys Acta, 1998, 1397(1): 56-64.
38 Northrop JP, Bednarski M, Barbieri1 SO, et al. Cell surface expression of single chain antibodies with applications to imaging of gene expression in vivo. Eur J Nucl Med Mol Imaging, 2003; 30(9): 1292-1298.
39 Luker GD, Luker KE, Sharma V, et al. In vitro and in vivo characterization of a dual-function green fluorescent protein--HSV1-thymidine kinase reporter gene driven by the human elongation factor 1 alpha promoter. Mol Imaging, 2002, 1(2): 65-73.
1 Zatelli MC, Piccin D, Vignali C, et al. T Pasireotide, a multiple somatostatin receptor subtypes ligand, reduces cell viability in non-functioning pituitary adenomas by inhibiting vascular endothelial growth factor secretion. Endocr Relat Cancer, 2007, 14(1): 91-102.
2 Florio T, Thellung S, Corsaro A, et al .Characterization of the intracellular mechanisms mediating somatostatin and lanreotide inhibition of DNA synthesis and growth hormone release from dispersed human GH-secreting pituitary adenoma cells in vitro. Clin Endocrinol (Oxf), 2003, 59 (1): 115-128.
3 Wenger FA, Kilian M, Jacobi CA, et al. Effects of octreotide on liver metastasis and intrametastatic lipid peroxidation in experimental pancreatic cancer. Oncology, 2001, 60(3): 282-288.
4 Rivera JA, Alturaihi H, Kumar U. Differential regulation of somatostatin receptors 1 and 2 mRNA and protein expression by tamoxifen and estradiol in breast cancer cells. Journal of carcinogenesis, 2005, 4(1): 10.
5 Yamada Y, Post SR, Wang K, et al. Cloning and functional characterization of a family of human and mouse somatostatin receptors expressed in brain, gastrointestinal tract, and kidney. Proc Natl Acad Sci USA, 1992, 89(1): 251-255.
6 Gr?tzinger C, Wiedenmann B. Somatostatin receptor targeting for tumor imaging and therapy. Ann N Y Acad Sci, 2004, 1014: 258-264.
7 Ginj M, Chen J, Walter MA, et al. Preclinical evaluation of new and highly potent analogues of octreotide for predictive imaging and targeted radiotherapy. Clin Cancer Res, 2005, 11(3): 1136-1145.
8 Kwekkeboom DJ, Mueller-Brand J, Paganelli G, et al. Overview of results of peptide receptor radionuclide therapy with 3 radiolabeled somatostain analogs. J Nucl Med, 2005, 46(Suppl 1): 62-66.
9 Ferone D, van Hagen MP, Kwekkeboom DJ, et al. Somatostatin receptor subtypes in human thymoma and inhibition of cell proliferation by octreotide in vitro. J Clin Endocrinol Metab, 2000, 85(4): 1719-1726.
10 O′Byrne KJ , Dobbs N , Propper D J , et al. PhaseⅡstudy of RC-160 (vapreotide), an octapeptide analogue of somatostatin, in the treatment of metastatic breast cancer. Br J Cancer, 1999, 79 (9-10): 1413-1418.
11 Dolan JT, Miltenburg DM, Granchi TS, et al. Treatment of metastatic breast cancer with somatostatin analogues--a meta-analysis. Ann Surg Oncol, 2001, 8 (3): 227-233.
12 Casini Raggi C, Pinzani P, Gelmini S, et al. Somatostatin receptors in non-endocrine tumours. Minerva Endocrinol, 2001, 26(3): 149-158.
13 Bogdanov A Jr, Petherick P, Marecos E, et al. In vivo localization of diglycylcysteine-bearing synthetic peptides by nuclear imaging of oxotechnetate transchelation. Nucl Med Biol, 1997, 24(8): 739-742.
14 Begent RH, Verhaar MJ, Chester KA, et al. Clinical evidence of efficient tumor targeting based on single-chain Fv antibody selected from a combinatorial library. Nat Med, 1996, 2(9): 979-984.
15 Forsberg AJ, Pavitt GD, Higgins CF, et al. Use of transcriptional fusions to monitor gene expression: A cautionary tale. J Bacteriol, 1994, 176(7): 2128- 2132.
16 Jacobs A, Dubrovin M, Hewett J, et al. Functional coexpression of HSV-1 thymidine kinase and green fluorescent protein: implications for noninvasive imaging of transgene expression. Neoplasia, 1999, 1(2): 154-161.
17 Loimas S, Wahlfors J, Janne J. Herpes simplex virus thymidine kinase-green fluorescent protein fusion gene: new tool for gene transfer studies and gene therapy. Biotechniques, 1998, 24(4): 614-618.
18 Strathdee CA, McLeod MR, Underhill TM. Dominant positive and negative selection using luciferase, green fluorescent protein and beta-galactosidase reporter gene fusions. Biotechniques, 2000, 28(2): 210-212, 214.
19 Cobbold LC, Spriggs KA, Haines SJ, et al. Identification of internal ribosome entry segment (IRES)-trans-acting factors for the Myc family of IRESs. Mol Cell Biol, 2008, 28(1): 40-49.
20 Toyoda H, Franco D, Fujita K, et al. Replication of poliovirus requires binding of the poly(rC) binding protein to the cloverleaf as well as to the adjacent C-rich spacer sequence between the cloverleaf and the internal ribosomal entry site. J Virol, 2007, 81(18): 10017-10028.
21 Siddappa NB, Kashi VP, Venkatramanan M, et al. Gene expression analysis from human immunodeficiency virus type 1 subtype C promoter and construction of bicistronic reporter vectors. AIDS Res Hum Retroviruses, 2007, 23(10): 1268-1278.
22 Vagner S, Galy B, Pyronnet S. Irresistable IRES: attracting the translation machinery to internal ribosome entry sites. EMBO Rep, 2001, 2(10): 893-898.
23 Kamoshita N, Tsukiyama-Kohara K, Kohara M, et al. Genetic analysis of internal ribosomal entry site on hepatitis C virus RNA: implication for involvement of the highly ordered structure and cell type-specific transacting factors. Virology, 1997, 233(1): 9-18.
24 Baron U, Freundlieb S, Gossen M, et al. Co-regulation of two gene activities by tetracycline via a bidirectional promoter. Nucleic Acids Res, 1995, 23(17): 3605-3606.
25 Yaghoubi SS, Wu L, Liang Q, et al. Direct correlation between positron emission tomographic images of two reporter genes delivered by two distinct adenoviral vectors. Gene Ther, 2001, 8(14): 1072-1080.
26 Sun X, Annala AJ, Yaghoubi SS, et al. Quantitative imaging of gene induction in living animals. Gene Ther, 2001, 8(20): 1572-1579.
27 Boerman OC, Oyen WJ, Corstern FH. Progress in gene therapy: seeing is believing. J Nucl Med, 2001, 42(8): 1235-1237.
28 Xiong Z, Cheng Z, Zhang X, et al. Imaging chemically modified adenovirus for targeting tumors expressing integrin alphavbeta3 in living mice with mutant herpessimplex virus type 1 thymidine kinase PET reporter gene. J Nucl Med, 2006, 47(1): 130-139.
29 Groot-Wassink T, Aboagye EO, Glaser M, et al. Adenovirus biodistribution and noninvasive imaging of gene expression in vivo by positron emission tomography using human sodium/iodide symporter as reporter gene. Hum Gene Ther, 2002, 13(14): 1723-1735.
30 Singh RS, Chaudhuri A. Single additional methylene group in the head-group region imparts high gene transfer efficacy to a transfection-incompetent cationic lipid. FEBS Lett, 2004, 556(1-3): 86-90.
31 Hosseinkhani H, Azzam T, Tabata Y, et al. Dextran-spermine polycation: an efficient nonviral vector for in vitro and in vivo gene transfection. Gene Ther, 2004, 11(2): 194-203.
32 Suzuki K, Murtuza B, Brand NJ, et al. Enhanced effect of myocardial gene transfection by VP22-mediated intercellular protein transport. J Mol Cell Cardiol, 2004, 36(4): 603-606.
33 Xiang JJ, Nie XM, Tang JQ, et al. In vitro gene transfection by magnetic iron oxide nanoparticles and magnetic field increases transfection efficiency. Zhonghua Zhong Liu Za Zhi, 2004, 26(2): 71-74.
1 Guggenberg EV, Mikolajczak R, Janota B, et al. Radiopharmaceutical development of a freeze-dried kit formulation for the preparation of [99mTc-EDDA-HYNIC-D-Phe1, Tyr3]-octreotide, a somatostatin analog for tumor diagnosis. J Pharm sci, 2004, 93(10): 2497-2506.
2 Gabriel M, Muehllechner P, Decristoforo C, et al. 99mTc-EDDA/HYNIC- Tyr(3)-octreotide for staging and follow-up of patients with neuroendocrine gastro-entero-pancreatic tumors. Q J Nucl Med Mol Imaging, 2005, 49(3): 237-244.
3 Decristoforo C, Melendez-Alafort L, Sosabowski JK, et al. 99mTc-HYNIC-[Tyr3]- octreotide for imaging somatostatin-receptor-positive tumors: preclinical evaluation and comparison with 111In-octreotide. J Nucl Med, 2000, 41(6): 1114-1119.
4 Hubalewska-Dydejczyk A, Fross-Baron K, Mikolajczak R, et al. 99mTc- EDDA/HYNIC-octreotate scintigraphy, an efficient method for the detection and staging of carcinoid tumours: results of 3 years' experience. Eur J Nucl Med Mol Imaging, 2006, 33(10): 1123-1133.
5 Clemens D, Stephen JM. Preparation, 99mTc labelling, and in vitro characterization of HYNIC and N3S modifide RC-160 and [Tyr3]-octreotide. Bioconjug Chem, 1999, 10(3): 431-438.
6 von Guggenberg E, Penz B, Kemmler G, et al. Comparison of different methods for radiochemical purity testing of [99mTc-EDDA-HYNIC-D-Phe1, Tyr3]-octreotide. Appl Radiat Isot, 2006, 64(2): 194-200.
7 Dabasi G, Hauser P, Kertész GP, et al. Imaging of pediatric brain tumors using somatostatin analogue 111In-DTPA-D-Phe1-octreotide. Magy Onkol, 2007, 51(3): 229-234.
8 Bodei L, Cremonesi M, Grana C, et al. Receptor radionuclide therapy with 90Y-[DOTA]-Tyr3-octreotide (90Y-DOTATOC) in neuroendocrine tumours. Eur J Nucl Med Mol Imaging, 2004, 31(7): 1038-1046.
9 Bernhardt P, Oddstig J, K?lby L, et al. Effects of treatment with (177)Lu-DOTA -Tyr(3)-octreotate on uptake of subsequent injection in carcinoid-bearing nude mice. Cancer Biother Radiopharm, 2007, 22(5): 644-653.
10 Hubalewska-Dydejczyk A, Fr?ss-Baron K, Go?kowski F, et al. 99mTc-EDDA/HYNIC -octreotate in detection of atypical bronchial carcinoid. Exp Clin Endocrinol Diabetes, 2007, 115(1): 47-49.
11 Buchmann I, Henze M, Engelbrecht S, et al. Comparison of 68Ga-DOTATOC PET and
111In-DTPAOC (Octreoscan) SPECT in patients with neuroendocrine tumours. Eur J Nucl Med Mol Imaging, 2007, 34(10): 1617-1626.
12 Wester HJ, Schottelius M, Scheidhauer K, et al. Comparison of radioiodinated TOC, TOCA and Mtr-TOCA: the effect of carbohydration on the pharmacokinetics. Eur J Nucl Med Mol Imaging, 2002, 29(1): 28-38.
13 Lee YS, Jeong JM, Kim HW, et al. An improved method of 18F peptide labeling: hydrazone formation with HYNIC-conjugated c (RGDyK). Nucl Med Biol, 2006, 33(5): 677-683.
14 Rennen HJ, Boerman OC, Koenders EB, et al. Labeling proteins with Tc-99m via hydrazinonicotinamide (HYNIC): optimization of the conjugation reaction. Nucl Med Biol, 2000, 27(6): 599-604.
15 King RC, Surfraz MB, Biagini SC, et al. How do HYNIC-conjugated peptides bind technetium? Insights from LC-MS and stability studies. Dalton Trans, 2007, 21(43):4998-5007.
16 Blankenberg FG, Backer MV, Levashova Z, et al. In vivo tumor angiogenesis imaging with site-specific labeled (99m)Tc-HYNIC-VEGF. Eur J Nucl Med Mol Imaging, 2006, 33(7): 841-848.
17 Rennen HJ, Laverman P, van Eerd JE, et al. PET imaging of infection with a HYNIC-conjugated LTB4 antagonist labeled with F-18 via hydrazone formation. Nucl Med Biol, 2007, 34(6): 691-695.
18 Agha NH, Al-Hilli M, Karim HM, et al. Instant 99mTc-labelled glucoheptonate kit for kidney imaging. Nuklearmedizin, 1983, 22(5): 246-250.
19 Vorne M, Alanko K, J?rvi K, et al. Comparison of gallium-67 citrate and technetium-99m glucoheptonate in the evaluation of pulmonary malignancies. J Nucl Med, 1987, 28(4): 442-446.
20 Ziessman HA, Balseiro J, Fahey FH, et al. 99mTc-glucoheptonate for quantitation of differential renal function. AJR Am J Roentgenol, 1987, 148(5): 889-893.
21 Barai S, Rajkamal , Bandopadhayaya GP, et al. Thallium-201 versus Tc99m-glucoheptonate SPECT for evaluation of recurrent brain tumours: a within-subject comparison with pathological correlation. J Clin Neurosci, 2005, 12(1): 27-31.
22 Ji SD, Fang W, Zhou JD, et al. Preparation and biodistribution of new apoptosis imaging regent 99mTc-FM-2. Nucl Tech, 2007, 30(8): 679-682.
23 Bogdanov A Jr, Petherick P, Marecos E, et al. In vivo localization of diglycylcysteine-bearing synthetic peptides by nuclear imaging of oxotechnetate transchelation. Nucl Med Biol, 1997, 24(8): 739-742.
1 Iyer M, Barrio JR, Namavari M, et al. 8-[18F] Fluoropenciclovir: an improved reporter probe for imaging HSV1-tk reporter gene expression in vivo using PET. J Nucl Med, 2001, 42(1): 96-105.
2 Nanda D, de Jong M, Vogels R, et al. Imaging expression of adenoviral HSV1-tk suicide gene transfer using the nucleoside analogue FIRU. Eur J Nucl Med Mol Imaging, 2002, 29(7): 939-947.
3 Min JJ, Iyer M, Gambhir SS. Comparison of [18F] FHBG and [14C]FIAU for imaging of HSV1-tk reporter gene expression: adenoviral infection vs stable transfection. Eur J Nucl Med Mol Imaging, 2003, 30(11): 1547-1560.
4 Soghomonyan SA, Doubrovin M, Pike J, et al. Positron emission tomography (PET) imaging of tumor-localized Salmonella expressing HSV1-TK. Cancer Gene Ther, 2005,12(1): 101-108.
5 Yaghoubi SS, Gambhir SS. PET imaging of herpes simplex virus type 1 thymidine kinase (HSV1-tk) or mutant HSV1-sr39tk reporter gene expression in mice and humans using [18F] FHBG. Nat Protoc, 2006, 1(6): 3069-3075.
6 Chin FT, Namavari M, Levi J, et al. Semiautomated radiosynthesis and biological evaluation of [18F] FEAU: a novel PET imaging agent for HSV1-tk/sr39tk reporter gene expression. Mol Imaging Biol, 2008, 10(2): 82-91.
7 Yaghoubi SS, Gambhir SS. Measuring herpes simplex virus thymidine kinase reporter gene expression in vitro. Nat Protoc, 2006, 1(4): 2137-2142.
8 Gambhir SS, Bauer E, Black ME, et al. A mutant herpes simplex virus type 1 thymidine kinase reporter gene shows improved sensitivity for imaging reporter gene expression with positron emission tomography. Proc Natl Acad Sci USA, 2000, 97(6): 2785-2790.
9 Rogers BE, Chaudhuri TR, Reynolds PN, et al. Non-invasive gamma camera imaging of gene transfer using an adenoviral vector encoding an epitope-tagged receptor as areporter. Gene Ther, 2003, 10(2): 105-114.
10 Zinn KR, Chaudhuri TR. The type 2 human somatostatin receptor as a platform for reporter gene imaging. Eur J Nucl Med Mol Imaging, 2002, 29(3): 388-399.
11 Chaudhuri TR, Rogers BE, Buchsbaum DJ, et al. A noninvasive reporter system to image adenoviral-mediated gene transfer to ovarian cancer xenografts. Gynecol Oncol, 2001, 83(2): 432-438.
12 Liang Q, Satyamurthy N, Barrio JR, et al. Noninvasive, quantitative imaging in living animals of a mutant dopamine D2 receptor reporter gene in which ligand binding is uncoupled from signal transduction. Gene Ther, 2001, 8(19): 1490-1498.
13 MacLaren DC, Gambhir SS, Satyamurthy N, et al. Repetitive, non-invasive imaging of the dopamine D2 receptor as a reporter gene in living animals. Gene Ther, 1999, 6(5): 785-791.
14 Aung W, Okauchi T, Sato M, et al. In-vivo PET imaging of inducible D2R reporter transgene expression using [11C]FLB 457 as reporter probe in living rats. Nucl Med Commun, 2005, 26(3): 259-268.
15 Serganova I, Ponomarev V, Blasberg R. Human reporter genes: potential use in clinical studies. Nucl Med Biol, 2007, 34(7): 791-807.
16 Shin JH, Chung JK, Kang JH, et al. Feasibility of sodium/iodide symporter gene as a new imaging reporter gene: comparison with HSV1-tk. Eur J Nucl Med Mol Imaging, 2004, 31(3): 425-432.
17 Groot-Wassink T, Aboagye EO, Glaser M, et al. Adenovirus biodistribution and noninvasive imaging of gene expression in vivo by positron emission tomography using human sodium/iodide symporter as reporter gene. Hum Gene Ther, 2002, 13(14): 1723-1735.
18 Dingli D, Russell SJ, Morris JC 3rd. In vivo imaging and tumor therapy with the sodium iodide symporter. J Cell Biochem, 2003, 90(6): 1079-1086.
19 Niu G, Gaut AW, Ponto LL, et al. Multimodality noninvasive imaging of gene transferusing the human sodium iodide symporter. J Nucl Med, 2004, 45(3): 445-449.
20 Bacolod MD, Basu AK. Mutagenicity of a single 1-nitropyrene-DNA adduct N-(deoxyguanosin-8-yl)-1-aminopyrene in Escherichia coli located in a GGC sequence. Mutagenesis, 2001, 16(6): 461-465.
21 Simonova M, Shtanko O, Sergeyev N, et al. Engineering of technetium-99m-binding artificial receptors for imaging gene expression. J Gene Med, 2003, 5(12): 1056-1066.
22 Bogdanov A Jr, Simonova M, Weissleder R, et al. Design of metal-binding green fluorescent protein variants. Biochim Biophys Acta, 1998, 1397(1): 56-64.
23 Liapakis G, Fitzpatrick D, Hoeger C, et al. Indentifcation of ligand binding determinants in somatostatin receptor subtypes 1 and 2. J Biol Chem, 1996, 271(34): 20331-20339.