Biochemical Strategies to Increase Leukemia Response

提高白血病反应的生化策略

• 批准号: 6784584
• 负责人: VARSHA GANDHI
• 金额: $ 26.43万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-15 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6784584
• 关键词: CD95 molecule; DNA replication; acute myelogenous leukemia; adenosine triphosphate; antileukemic agent; apoptosis; cell cycle; clinical research; combination cancer therapy; cytochrome c; cytotoxicity; drug interactions; drug metabolism; drug screening /evaluation; flow cytometry; human subject; human therapy evaluation; membrane potentials; mitochondrial membrane; neoplastic cell; nucleoside analog; oxidative phosphorylation; pharmacokinetics; polymerase chain reaction; ribonucleotide reductase

DESCRIPTION (provided by applicant): This proposal is an extension of CA57629 that has been focused on understanding the metabolism, mechanism of action, and interaction of nucleoside analogs. With the success rate of analogs in leukemias, several laboratories including ours have investigated the mechanisms of cell death by these agents. The steps include formation of triphosphate of the analog, incorporation into replicating DNA, inhibition of ribonucleotide reductase (with newer analogs) and finally inhibition of DNA synthesis. Continued inhibition of DNA synthesis proceeds to cell death through apoptosis. When tested in cell lines, which are actively cycling and replicating DNA, such scenario seems to be in place. However, when one tries to validate this process during therapy, the outcome is conflicting and intriguing. The biology of leukemia cells in the body is very different from cell lines in culture. Leukemia cells in peripheral blood are generally non- or slow- cycling and with a very small percent of cells in S-phase (0-5%). Nonetheless after 5-days of effective nucleoside analog therapy, there is a massive cytoreduction (1 to 3-log decrease). Our hypothesis is built around these premises to suggest that in addition to conventional S-phase mediated pathway, there may he additional pathways that result in non-S-phase cell death during therapy. To test this hypothesis, we want to pursue three specific aims that are focused toward different mode of cell death by analogs. First, we plan to define the elements of cell death caused by conventional DNA synthesis inhibition pathway during therapy. Using nelarabine and clofarabine, two of the most successful new nucleoside analogs in the clinic, we plan to investigate the role of cellular pharmacokinetics and cellular pharmacodynamics in cell death. These parameters will be compared with clinical response to these therapies. Second, we plan to identify mitochondria induced cell death of leukemia cells during therapy. Nucleoside analogs may affect mitochondria directly and/or indirectly to induce cell death in circulating leukemia cells during therapy. Direct effect such as mitochondrial respiratory function involving ATP synthase, adenosine nucleotide translocator (ANT), and early decrease in mitochondnal membrane potential will be accessed to elucidate the role of mitochondria induced apoptosis. Indirect effect will include release of cytochrome c, and late effect on membrane potential. Finally, we will investigate the role of receptor-mediated cell death of leukemia cells during therapy. Following our lead in cell lines that analog incorporation results in induction of fas ligand followed by fas-mediated cell death of non-Sphase population, we plan to pursue the role of fas in cell death during therapy. We feel that knowledge gained through these aims will assist us in designing optimal therapy of leukemia with nucleoside analogs.

描述（由申请人提供）：该建议是CA57629的扩展，该延伸集中在理解核苷类似物的代谢，作用机理和相互作用上。随着白血病中类似物的成功率，包括我们在内的几个实验室研究了这些药物的细胞死亡机制。这些步骤包括形成类似物的三磷酸，掺入复制DNA，抑制核糖核苷酸还原酶（具有较新的类似物）以及最终抑制DNA合成。持续抑制DNA合成通过凋亡导致细胞死亡。当在积极循环和复制DNA的细胞系中进行测试时，这种情况似乎就位了。但是，当人们试图在治疗过程中验证这一过程时，结果是矛盾和吸引人的。体内白血病细胞的生物学与培养细胞系有很大不同。外周血中的白血病细胞通常是非或慢速循环的，并且S相中的细胞很小（0-5％）。但是，在有效的核苷类似物治疗的5天后，仍有大量的细胞减少（1至3型降低）。我们的假设是在这些前提周围建立的，以表明除了传统的S相介导的途径外，还可能会导致治疗过程中非S相细胞死亡的其他途径。为了检验这一假设，我们要追求三个特定目标，这些目标集中在类似物的不同细胞死亡方式上。首先，我们计划定义由常规DNA合成抑制途径在治疗过程中引起的细胞死亡元素。我们使用尼拉滨和克洛法拉滨（诊所中最成功的两个新核苷类似物），我们计划研究细胞药代动力学和细胞药物学在细胞死亡中的作用。这些参数将与对这些疗法的临床反应进行比较。其次，我们计划在治疗过程中鉴定线粒体诱导的白血病细胞的细胞死亡。核苷类似物可能直接影响线粒体和/或间接诱导治疗过程中循环白血病细胞中的细胞死亡。直接效应，例如涉及ATP合酶，腺苷核苷酸易位剂（ANT）以及线粒体膜电位的早期降低的直接效应，以阐明线粒体诱导的凋亡的作用。间接效应将包括细胞色素C的释放，以及对膜电位的晚期作用。最后，我们将研究受体介导的白血病细胞在治疗过程中的作用。跟随我们在细胞系中的领导，模拟掺入会导致FAS配体诱导，然后是FAS介导的非相群体的细胞死亡，我们计划在治疗过程中追求FAS在细胞死亡中的作用。我们认为通过这些目标获得的知识将有助于我们使用核苷类似物设计白血病的最佳治疗。