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）：该提案是CA57629的扩展，其重点是了解核苷类似物的代谢、作用机制和相互作用。随着白血病类似物的成功率，包括我们在内的几个实验室已经研究了这些药物导致细胞死亡的机制。步骤包括类似物的三磷酸形成，并入复制DNA，抑制核糖核苷酸还原酶（与较新的类似物），最后抑制DNA合成。DNA合成的持续抑制通过细胞凋亡导致细胞死亡。当在积极循环和复制DNA的细胞系中进行测试时，这种情况似乎是正确的。然而，当一个人试图在治疗过程中验证这一过程时，结果是矛盾的和有趣的。人体内白血病细胞的生物学特性与培养的细胞系非常不同。外周血中的白血病细胞通常是非循环或慢循环，s期细胞的比例很小（0-5%）。尽管如此，在有效的核苷类似物治疗5天后，细胞大量减少（1至3对数减少）。我们的假设是围绕这些前提建立的，表明除了传统的s期介导途径外，可能还有其他途径导致治疗期间非s期细胞死亡。为了验证这一假设，我们想要追求三个特定的目标，这些目标集中在不同的类似物细胞死亡模式上。首先，我们计划确定在治疗过程中由传统DNA合成抑制途径引起的细胞死亡的因素。利用奈拉宾和氯法拉滨这两种临床上最成功的新型核苷类似物，我们计划研究细胞药代动力学和细胞药效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死亡。核苷类似物可能直接和/或间接影响线粒体，诱导循环白血病细胞在治疗期间死亡。直接影响，如线粒体呼吸功能涉及ATP合成酶，腺苷核苷酸转运器（ANT），和早期降低线粒体膜电位，以阐明线粒体诱导细胞凋亡的作用。间接影响包括细胞色素c的释放和对膜电位的后期影响。最后，我们将探讨受体介导的白血病细胞死亡在治疗过程中的作用。我们在细胞系中率先发现，类似物掺入导致fas配体诱导，随后fas介导的非相群体细胞死亡，我们计划在治疗期间继续研究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设计核苷类似物治疗白血病的最佳方法。