MECHANISM OF CYTOTOXICITY OF DEOXYADENOSINE AND ANALOGS

脱氧腺苷(An)的生物化学机制 腺苷脱氨酶抑制剂)、2-氯脱氧腺苷和 2-溴脱氧腺苷对细胞的细胞毒作用将被 进一步调查和比较。这些核苷明显 对人T淋巴母细胞、B淋巴母细胞和髓系细胞的细胞毒作用 培养和生产对小鼠肿瘤的治疗反应和 对抗人类血液系统恶性肿瘤的药物。 该项目的一个部分将旨在确定抑制 核苷三联体核糖核苷二磷酸还原酶 是细胞毒性的主要机制。其中一些实验将 涉及与完整细胞的工作，为此，人类 将使用T淋巴母细胞系CCRF-CEM。其他研究将 使用L1210细胞的部分纯化的还原酶和高纯度的 小牛胸腺中的还原酶。 在项目的第二部分，将获得证据，以确定是否 这些核苷对DNA合成的抑制涉及到另一个方面 意义重大的机制。我们会特别注意 DNA聚合酶α被抑制的可能性，或者掺入 类似物进入DNA会抑制链的延长。纯化的DNA聚合酶 阿尔法将被用于这些实验。 也将使用对类似物具有抵抗力的电池 在项目的两个部分。

The biochemical mechanisms by which deoxyadenosine (in the prsence of an adenosine deaminase inhibitor), 2-chlorodeoxyadenosine and 2-bromodeoxyadenosine exert their cytotoxic effects on cells will be further investigated and compared. These nucleosides are markedly cytotoxic to human T-lymphoblastoid, B-lymphoblastoid and myeloid cell lines in cutlure and produc therapeutic responses against murine tumors and against human hemaologic malignancies. One part of the project will be aimed at determining whether inhibition of ribonucleoside diphosphate reductase by tripyhospahtes of the nucleosides is the main mechanism of cytotoxicity. Some of these experiments will involved work with intact cells, and for this purpose the human T-lymphoblastoid cell line CCRF-CEM will be used. Other studies will employ partially purified reductase from L1210 cells and highly purified reductase from calf thymus. In the second part of the project evidence will be obtained as to whether inhibition of DNA synthesis by these necleosides involves another signifiicant mechanism. Particular attention will be given to the possibility that DNA polymerase Alpha is inhibited, or that incorporation of analogue into DNA inhibits chain elongation. Purified DNA polymerase Alpha will be used for these experiments. The use of cells selected for resistance to the analogues will also be used in both parts of the project.