DRUG SYNERGY WITH ANTIFOLATE COMBINATIONS

拟议的研究针对的是一种生长抑制和 抗叶酸类化合物组合的机理评价 对体外培养的肝癌细胞表现出协同作用。 初步研究表明，二氢叶酸还原酶 (DHFR)抑制剂可以与以叶酸为基础的 胸苷合成酶(TS)抑制剂(N10-丙基-5，8- 以产生协同的肿瘤细胞生长 抑制和毒性。目前最有效的dhfr 与PDDF联合使用的抑制剂是脂溶的抗滤泡药物。 如甲氧菊酯或曲美他酯。我们打算做一件 对其他DHFR抑制剂的评估以确定哪些是 最有效以及哪种用药时机最有效。这个 协同组合的通用性将在 其他肿瘤细胞系统。实验方法将是 通过测量协同作用的效果来评价抑制作用 结合生长和克隆试验。新陈代谢 协同组合的抑制作用将通过以下方式进行评估 在处理的细胞中测量新的胸腺嘧啶生物合成。这个 胸腺嘧啶核苷对联合用药的保护作用观察 生长抑制表明，轻度抑制浓度的 DHFR抑制剂使细胞对PDDF敏感。这可能是 归因于5，10-亚甲基四氢叶酸的减少和 转储的增加，这有利于形成抑制的 PDDF-TS-Dump三元络合物。详细的机械原理 这两类企业之间的协同作用分析 将会制造出反叶酸。当前阶段的做法 这项研究将检验DHFR和TS的影响 TS底物水平上的抑制剂。此外， 目标酶的功能量和目标酶的 将检测在协同抑制过程中与TS结合的PDDF。 这种独特的药物相互作用的其他原因似乎是合理的 这些将根据会议结果予以考虑。 拟议的机械论研究。希望通过对 此机制将使您更多地了解 抗叶酸在肿瘤治疗中的应用及其进展 这些药物组合的可能性。

The proposed study is directed at a growth inhibitory and mechanistic evaluation of combinations of antifolates which exhibit synergy with each other against hepatoma cells in culture. The preliminary studies have shown the dihydrofolate reductase (DHFR) inhibitors can be combined with a folate based thymidylate synthase (TS) inhibitor (N10-propartyl-5,8- dideazafolate, PDDF) to yield synergistic tumor cell growth inhibition and toxicity. Currently the most effective DHFR inhibitors in combination with PDDF are the lipid soluble antifols such as metoprin or trimetrexate. We propose to make evaluations of other DHFR inhibitors to determine which are the most effective and which drug timing is the most effective. The generality of the synergistic combinations are to be tested in other tumor cell systems. The experimental approach will be to evaluate the inhibition by measuring the effects of synergistic combination with outgrowth and clonal assays. Metabolic inhibition by the synergistic combinations will be evaluated by measuring de novo thymidylate biosynthesis in treated cells. The observation that thymidine can protect against combination based growth inhibition suggests that mildly inhibitory concentrations of DHFR inhibitors are sensitizing the cells to PDDF. This could be accounted by a reduction in 5,10-methylenetetrahydrofolate and increase in dUMP, which favors the formation of an inhibited PDDF-TS-dUMP ternary complex. A detailed mechanistic analysis of the synergistic interaction of the two classes of antifolates will be made. The approach in the current phase of the study will be to examine the effects of the DHFR and TS inhibitors on levels of substrates for TS. In addition the functional amounts of the target enzymes and the amounts of PDDF bound to TS during synergistic inhibition will be examined. Other causes for the unique drug interaction are plausible and these will be considered depending upon the outcome of the proposed mechanistic studies. It is hoped that an understanding of this mechanism will result in more knowledge about the use of the antifolates in treatment of neoplasms and the development of the potential for combination of these agents.