MECHANISM OF CYTOTOXICITY OF DEOXYADENOSINE AND ANALOGS

脱氧腺苷（在存在一种 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是 进一步研究和比较。 这些核苷明显是 对人T-淋巴母细胞、B-淋巴母细胞和骨髓细胞有细胞毒性 细胞系，并产生针对小鼠肿瘤的治疗反应， 对抗人类血液恶性肿瘤。 该项目的一部分将旨在确定是否禁止 核苷三磷酸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 涉及完整细胞的工作，为此， 将使用T淋巴母细胞样细胞系CCRF-CEM。 其他研究将 使用来自L1210细胞的部分纯化的还原酶和高度纯化的 小牛胸腺还原酶。 在项目的第二部分，将获得证据，以证明 这些核糖苷对DNA合成的抑制涉及另一个 重要机制 将特别注意 DNA聚合酶α被抑制的可能性，或掺入 类似物进入DNA抑制链延长。 纯化DNA聚合酶 Alpha将用于这些实验。 还将使用选择的对类似物具有抗性的细胞 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.