Synthesis and evaluation of 99mTc-labeling thymidine derivatives as potential tumor proliferation probes

• Main Authors: Jia-Guo Chen, 陳嘉國
• Other Authors: Chuan-Lin Chen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/82839367622348526185

碩士 === 國立陽明大學 === 生物醫學影像暨放射科學系暨研究所 === 99 === Abstract Objective: The purpose was to synthesize four radioactive technetium-labeled thymidine analogues with different spacer length at C-3’ and N-3 position, and to evaluate them as potential tumor detection or HSV1-tk gene expression traces. Methods: These bis(S-trityl)-protected 3’-MAMA-propyl- thymidine 21、3’-MAMA-hexanyl-thymidine 22、3’-MAMA- decanyl- thymidine 23 , and N3-MAMA-decanyl-thymidine 27 precursors were prepared and confirmed with 1H and 13C-NMR and high resolution mass spectrometry. After S-trityl deprotection and 99mTc radiolabeling, these 99mTc -labeled compounds (99mTc-3’-MAMA-propyl-thymidine 28, 99mTc 3’-MAMA-hexanyl-thymidine 29, 99mTc-3’-MAMA-decanyl-thymidine 30 and 99mTc-N3-MAMA-decanyl-thymidine 31) were accomplished and purified with high-performance liquid chromatography, and their log P were determined. The cellular uptake studies of these four nucleoside analogues were performed in NG4TL4-TK (tk(+))and NG4TL4-WT (tk(-)) sarcoma cells at designed time points (0.5, 1, 2, 4, and 8 h post-incubation) , and compared with pretreatment with 5-fluorodeoxy- uridine (FUdR), which is known to induce upregulation of nucleoside transporter. Results: All radioactive technisium-labeled thymidine analogues were obtained with acceptable radiochemical yield(>70%) and high radiochemical purity (≧95%). The log P of compound 28, 29, 30 and 31 were 0.55、0.60、1.67 and 1.76, respectively. The cellular accumulation (% total dose/106 cells) of 99mTc-N3- MAMA-decanyl-thymidine 31 in tk(-) and tk(+) cells were 7.3% and 2.8% , respectively, while those of 99mTc -3’-MAMA-propyl-thymidine 28, 99mTc -3’-MAMA- hexanyl-thymidine 29 and 99mTc -3 ’-MAMA- decanyl-thymidine 30 were only 0.1~0.2%, no matter in tk(-) or tk(+) cells. In the following study the internalization of compound 31 was determined with pretreatment with 5-fluorodeoxyuridine (FUdR). The retention amount of compound 31 actually elevated from 7.34±0.23 to 27.35±0.49 and the C-3’ modified compound 30 only led to the lower cellular uptake(0.12% to 0.2%) after 0.5 h incubation in the cells. This result suggesting that the cellular accumulation level of compound 31 was correlated with the nucleoside transporter. Conclusions: This study discovered that the modification site on thymidine is important to tumor accumulation (N3 modification is better than 3’-modification), and these results may provide a hint for further experiments.