ABSTRACT
PURPOSE: 5-iododeoxyuridine analogues have been exclusively developed for the potential antiviral and antitumor therapeutic agents. In this study, we synthesized carbocyclic radioiododeoxyuridineanalogue (ddIVDU) and carbocyclic intermediate as efficient carbocyclic radiopharmaceuticals. MATERIALS AND METHODS: The synthesis is LAH reduction, hetero Diels-Alder reaction as key reactions including Pd(0)-catalyzed coupling reaction together with organotin. MCA-RH7777 (MCA) and MCA-tk (HSV1-tk positive) cells were treated with various concentration of carbocyclic ddIVDU, and GCV. Cytotoxicity was measured by the MTS methods. For in vitro uptake study, MCA and MCA-tk cells were incubated with 1uCi of [(125)I]carbocyclic ddIVDU. Accumulated radioactivity was measured after various incubation times. RESULTS: The synthesis of ddIVDU and precursor for radioiodination were achieved from cyclopentadiene in good overall yield, respectively. The radioiododemetallation for radiolabeling gave more than 80% yield with > 95% radiochemical purity. GCV was more toxic than carbocyclic ddIVDU in MCA-tk cells. Accumulation of [(125)I]carbocyclic ddIVDU was higher in MCA-tk cells than MCA cells. CONCLUSION: Biological data reveal that ddIVDU is stable in vitro, less toxic than ganciclovir (GCV), and selective in HSV1-tk expressed cells. Thus, this new carbocyclic nucleoside, referred to in this paper as carbocyclic 2',3'-didehydro-2',3'-dideoxy-5- iodovinyluridine (carbocyclic ddIVDU), is a potential imaging probe for HSV1-tk.
Subject(s)
Cycloaddition Reaction , Ganciclovir , Herpesvirus 1, Human , Idoxuridine , Radioactivity , RadiopharmaceuticalsABSTRACT
PURPOSE: The herpes simplex virus type 1 thymidine kinase gene (HSV1-tk) is an attractive candidate as a reporter gene in noninvasive reporter gene monitoring system. The HSV1-tk gene was chosen as a reporter gene, because it has been extensively studied, and there are appropriate reporter probes, substrates of HSV1-tk gene product, to apply for HSV1-tk gene imaging. We used radiolabeled 5-iodovinyl-2'-deoxyuridine (IVDU) and 5-Iodovinyl-2'-fluoro-2'-deoxyuridine (IVFRU) as reporter probes for HSV1-tk gene monitoring system. MATERIALS AND METHODS: We prepared HSV1-tk gene transduced Morris hepatoma cell line using retroviral vector, MOLTEN containing HSV1-tk gene. And we confirmed the HSV1-tk gene expression by Northern blotting and Western blotting. We compared in vitro uptakes of radioiodinated IVDU and IVFRU to monitor HSV1-tk gene expression in Morris hepatoma cell line (MCA) and HSV1-tk gene tranduced MCA (MCA-tk) cells until 480 minutes. We also performed correlation analysis between percentage of HSV1-tk gene tranduced MCA cell % (MCA-tk%) and uptakes of radiolabeled IVDU or IVFRU. RESULTS: MCA-tk cell expressed HSV1-tk mRNA and HSV1-TK protein. Two compounds showed minimal uptake in MCA, but increased uptake was observed in MCA-tk. IVDU showed 4-fold higher accumulation than IVFRU at 480 min in MCA-tk (p 0.96) with increasing MCA-tk%. CONCLUSION: The radiolabeld IVDU and IVFRU showed higher specific accumulation in retrovirally HSV1-tk gene transfected Morris hepatoma cell line. Both IVDU and IVFRU could be used as good substrates for evaluation of HSV1-tk gene expression.
Subject(s)
Animals , Blotting, Northern , Blotting, Western , Cell Line , Gene Expression , Genes, Reporter , Genetic Therapy , Herpes Simplex , Herpesvirus 1, Human , Liver Neoplasms, Experimental , RNA, Messenger , Simplexvirus , Thymidine Kinase , Thymidine , ZidovudineABSTRACT
PURPOSE: Thallous-201 chloride produced at Korea Cancer Center Hospital(KCCH) is used in detecting cardiovascular disease and cancer. Thallium impurity can cause emesis, catharsis and nausea, so the presence of thallium and other metal impurities should be determined. According to USP and KP, their amounts must be less than 2 ppm in thallium and 5 ppm in total. In this study, the detection method of trace amounts of metal impurities in [201Tl]TlCl injection with polarography was optimized without environmental contamination. MATERALS AND METHODS: For the detection of metal impurities, Osteryoung Square Wave Stripping Voltammetry method was used in Bio-Analytical System (BAS) 50W polarograph. The voltammetry was composed of Dropping Mercury Electrode (DME) as a working electrode, Ag/AgCl as a reference electrode and Pt wire as a counter electrode. Square wave stripping method, which makes use of formation and deformation of amalgam, was adopted to determine the metal impurities, and pH 7 phosphate buffer was used as supporting electrolyte. RESULTS: T1, Cu and Pb in thallous-201 chloride solution were detected by scanning from 300 mV to -800 mV. Calibration curves were made by using TlNO3, CuSO4 and Pb(NO3)2 as standard solutions. Tl was confirmed at -450 mV peak potential and Cu at -50 mV. Less than 2 ppm of Tl and Cu was detected and Pb was not detected in KCCH-produced thallous-201 chloride injection. CONCLUSION: Detection limit of thallium and copper is approximately 50 ppb with this method. As a result of this experiment, thallium and other metal impurities in thallous-201 chloride injection, produced at Korea Cancer Center Hospital, are in the regulation of USP and KP. Polarograph could be applied for the determination of metal impurities in the quality control of radiopharmaceuticals conveniently without environmental contamination.
Subject(s)
Calibration , Cardiovascular Diseases , Catharsis , Copper , Electrodes , Hydrogen-Ion Concentration , Korea , Limit of Detection , Metals, Heavy , Nausea , Polarography , Quality Control , Radiopharmaceuticals , Thallium , VomitingABSTRACT
PURPOSE: The aim of this sutdy was to evaluate the feasibility of 3-[131I]Iodo-O-methyl-L-a-methyltyrosine ([131I]OMINT) as an agent for tumor image. MATERIALS AND METHODS: After synthesis of 4-O-methyl-L-a-methyltyrosine (OMAMT), OMAMT was labeled with 131I using Iodogen method. In viro cellular uptake study was performed using 9 L gliosarcoma cells at various time points upto 4 hr. The biodistribution (five rats implanted with the 9 L gliosarcoma cells per group) was evaluated at 30 min, 2 hr, 24 hr after iv injection of 3.7 MBq [131I]OMIMT or L-3-[131I]iodo-a-methyltyrosine ([131I]IMT). Gamma camera images were obtained at 30min, 2 hr, and 24 hr. RESULTS: [131I]OMINT uptake was 3.3 times and 2.5 times higher than [131I]IMT uptake at 30 min and 60 min, respectively and same after 2 hr in in vitro sutdy using 9L gliosarcoma cells. Maximum accumulation in tumor occurred at 30 min for both [131IOMINT and [131I]IMT in tumor bearing rats. The tumor uptake of [131I]OMINT was significantly higher than that of [131I]IMT in tumor bearing rats. The tumor uptake of [131I]OMIMT was significantly higher than that of [131I]IMT at early time point studied (3.74 +/- 0.48 vs 0.38 +/- 0.17% ID/g at 30 min and 2.40 +/- 0.17 vs 0.24 +/- 0.03% ID/g at 2 hr, respectively, p<0.01). However, the tumor uptake of both radiolabels were not significantly different at 24 hr (0.04 +/- 0.01 vs 0.05 +/- 0.01% ID/g). Tumor was visualized as early as at 30 min in gamma camera images. CONCLUSION: These data suggested that [131I]OMIMT might be a useful tumor imaging agent and has more advantage for the tumor imaging compared to [131I]IMT.