ANTIMETABOLITES AND NUCLEAR MATRIX-BOUND DNA

最近的证据支持这样一个概念，在真核细胞中 复制连接到核基质上的固定位置，并且 模板DNA在复制时会通过这些位置。因为有很多人 癌症化疗中使用的抗代谢药物会导致链断裂， DNA的片断和其他变化，这些似乎是合理的 药剂可能会对 核基质上的模板DNA和DNA复制酶。然而， 在很大程度上，这些抗代谢药物可能通过的潜在机制 抑制DNA复制仍未被探索。建议进行的研究包括 旨在揭示5-氟-2‘-脱氧尿苷(FdUrd)、5，8-脱氧尿苷 二氮杂异叶酸(IAHQ)或替尼平苷(VM-26)特异性抑制 人CCRF-CEM白血病细胞中核基质结合的DNA复制，以及 这种抑制是否由DNA结合受损所致 与核相关的新生DNA的聚合酶α和DNA启动酶 矩阵。将进行研究，以确定是否存在直接的 核基质结合DNA抑制程度之间的关系 复制、DNA单链断裂的形成和抑制 菌落形成软琼脂糖凝胶。这些抗癌药对人体健康的影响 核基质结合的DNA复制也将在以下条件下进行检查 其中所有脱氧核糖核苷的细胞内浓度 在未经处理的情况下，三磷酸盐被同等和饱和地用于DNA合成 L-溶血磷脂透膜后药物处理的CCRF-CEM细胞。 还计划进行更多研究，以确定FdUrd、IAHQ或VM-26 通过干扰DNA合成抑制新生DNA的伸长 DNA干扰在新生DNA伸长过程中的定位 在核基质上的固定位置合成。各种方法将是 用来检验这些抗癌剂最终阻止 通过干扰核基质结合的DNA复制 DNA复制酶与核基质。在这些阿尔法和DNA中 核基质组分中的Primase及其与DNA聚合酶的结合 在对照组和药物组中，α-DNA引物酶复合体与新复制的DNA- 处理过的细胞。对这一假设的进一步检验将涉及到量化 这些抗代谢药物对RNA诱导的比活性的影响 核矩阵上新生的DNA。这些结果可能会有新的和 通过以下方式更清楚地理解这些机制的重要意义 哪些抗代谢药物能抑制DNA复制。

Recent evidence supports the concept that in eucaryotic cells DNA replication are attached to fixed sites on the nuclear matrix, and that template DNA passes through these sites as it is replicated. Since many antimetabolites used in cancer chemotherapy induce strand-breaks, fragmentations, and other alterations in DNA, it seems reasonable that these agents might have direct and important effects on the interactions of template DNA and DNA replication enzymes on the nuclear matrix. However, for the most part these potential mechanisms by which antimetabolites might inhibit DNA replication have remained unexplored. The proposed studies are designed to reveal if either 5-fluoro-2'-deoxyuridine (FdUrd), 5,8- dideazaisofolic acid (IAHQ),or teniposide (VM-26) specifically inhibit nuclear matrix-bound DNA replication in human CCRF-CEM leukemia cells, and whether or not this inhibitation results from impaired binding of DNA polymerase alpha and DNA primase to nascent DNA associated with the nuclear matrix. Studies will be carried out to determine if there is a direct relationship among the degree of inhibition of nuclear matrix-bound DNA replication, the formation of DNA single-strand breaks, and the inhibition of colony formation soft agarose. The effects of these anticancer agents on nuclear matrix-bound DNA replication will also be examined under conditions in which the intracellular concentrations of all the deoxyribonucleoside triphosphates are made equal and saturating for DNA synthesis in untreated and drug-treated CCRF-CEM cells following L-lysolecithin permeabilization. Additional studies are planned to determine if either FdUrd, IAHQ, or VM-26 inhibit the elongation of nascent DNA by interfering with DNA synthesis at fixed sites on the elongation of nascent DNA by interfering with DNA synthesis at fixed sites on the nuclear matrix. Various approaches will be taken to test the hypothesis that these anticancer agents ultimately block nuclear matrix-bound DNA replication by interfering with the association of DNA replication enzymes with the nuclear matrix. In these alpha and DNA primase in the nuclear matrix fraction, and on the binding of DNA polymerase alpha - DNA primase complexes to newly replicated DNA in control and drug- treated cells. Further testing of this hypothesis will involve quantitating any effects of these antimetabolites on the specific activity of RNA-primed nascent DNA on the nuclear matrix. These results could have novel and important implications for more clearly understanding the mechanisms by which antimetabolites inhibit DNA replication.