Development of Nuclear Medicine Technique for the Evaluation of Cell Proliferation Kinetics, Directry Contributing to Cancer Treatment

我们优化了用^ 3h -胸苷和抗BrdUrd抗体测定动物肿瘤潜在倍增时间（Tpot）的双标记方法。然后，我们测量了照射后小鼠肿瘤的生长动力学，发现在分次照射期间肿瘤内的Tpot值是不均匀的，并且一些群体的生长速度与未照射的肿瘤一样快。我们可以证明在辐照过程中加速了种群的再生。这类信息对放射治疗计划非常重要。应发展核医学人体Tpot测量技术。作为评价细胞增殖的示踪剂，碘标记尿苷衍生物和^< 11b> c -胸腺嘧啶从血清和组织的稳定性和代谢的角度进行了评价。这些示踪剂被证明不适合我们的目的，因为前者在血液和组织中被去碘化，后者在组织中被代谢，因此估计DNA结合分数将非常困难。而据报道，^<18>F-3'-脱氧-3'-氟胸苷（[^<18>F]FLT）在血液中是稳定的，并被困在增殖组织中。我们认为[^<18>F]FLT是观察肿瘤体内增殖活性的最佳示踪剂。然后，我们测试了[^<18>F]FLT的放射性合成，并评估了其临床应用的疗效。根据文献进行放射性合成；[^<18>F]氟与溶解于乙腈中的底物在100℃下反应15 min。粗产物经添加硝酸铯铵脱保护后，经短柱纯化，最后经高效液相色谱分离。在100分钟内获得了放射化学纯度[^<18>F]的FLT，总放射化学产率为6-8%。我们的结论是，尽管我们的产率与报道的13%相比较低，但该方法具有可重复性。大鼠生物分布研究表明[^<18>F]FLT在骨髓中有明显的积累。我们已经从美国的一个前期研究组获得了暴露剂量和急性毒性的数据，从而完成了[^<18>F]FLT临床使用的准备。但是，需要指出的是，我们基于人工操作的方法必须在日常实践中实现自动化，并且需要另外的投资。我们也开始基于与肿瘤增殖密切相关的微管和基质金属蛋白酶抑制剂的类似设计，开发新的^<18 bb0 f标记肿瘤显像剂。少

We optimized a double labeling method using ^3H-thymidine and anti BrdUrd antibodies for measuring potential doubling time (Tpot) of animal tumors. Then, we measured growth kinetics of a mouse tumor after irradiation and found that Tpot values were inhomogeneous within a tumor during fractionated irradiation and that some population grew as rapid as un-irradiated tumors. We could demonstrate the accelerated re-population during irradiation . Such kind information is very important for radiotherapy planning. Tpot measurement in humans by nuclear medicine should be developed.As tracers for the evaluation of cell proliferation, iodine-labeled uridine derivatives and ^<11>C-thymidines were evaluated from the view point of stability and metabolism in the serum and tissues. These tracers proved not o be suitable for our purposes, because the former is de-iodinated in the blood and tissues and latter is metabolized in the tissues and thus estimation of DNA binding fraction will be very diffic … More ult. While ^<18>F-3'-deoxy-3'- fluorothymidine ([^<18>F]FLT) was reported to be stable in the blood and trapped in the proliferating tissues. We decided [^<18>F]FLT is the best tracer for visualizing proliferative activity of tumors in vivo. Then, we tested radiosynthesis of [^<18>F]FLT and evaluated its efficacy for clinical application.The radiosynthesis was performed according to the literature ; [^<18>F]Fluoride was reacted with the substrate dissolved in acetonitrile at 100℃ for 15 min. After deprotection by addition of cesium ammonium nitrate the crude product was purified by passing through a short column and finally by HPLC separation. The radiochemically pure [^<18>F]FLT was obtained in overall radiochemical yields of 6-8% within 100 min. We concluded that the method was reproducible despite our lower yields compared to the reported value of 13%. Biodistribution studies with rats showed that [^<18>F]FLT was remarkably accumulated in bone marrow as expected. We have already obtained data for exposure dose and acute toxicity from a preceding research group in USA and thus finished the preparation for clinical use of [^<18>F]FLT.However, it should be pointed out that our method based on manual operation must be automated for routine practice and that it requires another investment.We have also started to develop new ^<18>F-labeled tumor imaging agents, based on analogous design of microtubular and matrix metalloproteinase inhibitors which are closely related to tumor proliferation. Less