Bioflavonoids as DNA Topoisomerase II Poisons

描述(由申请人提供)：生物类黄酮是一种有效的拓扑异构酶II毒药，被认为对成年人具有化学预防作用。然而，它们也与子宫内急性髓系白血病(AML)的启动有关。这项建议的总体目标是进一步确定生物类黄酮改变人类拓扑异构酶II的催化活性的机制以及它们在启动癌症发生中的潜在作用。这一建议的具体目的是：(1)通过用于检测DNA切割和连接的体外酶学研究，描述生物类黄酮改变人类II型拓扑异构酶催化功能的机制。突变和核磁共振研究将被用来确定生物类黄酮在酶上相互作用的位置。(2)利用siRNA技术检测拓扑异构酶IIα和β在生物黄酮类化合物对人细胞的细胞毒性和遗传毒性作用中的作用。我们将通过克隆和聚合酶链式反应的方法来研究每一种异构体在生物类黄酮诱导的人类细胞MIL基因易位中的作用。这个项目将进一步加深我们对生物黄酮类化合物的化学预防和细胞毒性的理解，并可能导致这些化合物作为化学治疗药物的使用。

DESCRIPTION (provided by applicant): Bioflavonoids are potent topoisomerase II poisons and are believed to be chemopreventative in adults. However, they have also been implicated in the initiation of acute myeloid leukemia's (AMLs) in utero. The overall goal of this proposal is to further define the mechanism by which bioflavonoids alter the catalytic activity of human topoisomerase II and their potential role in the initiation of carcinogenesis. The specific aims for this proposal are to: (1) Delineate the mechanism by which bioflavonoids alter the catalytic function of human type II topoisomerases via in vitro enzymological studies that are used to examine DNA cleavage and ligation. Mutagenesis and NMR studies will be employed to define the site of interaction of bioflavonoids on the enzyme. (2) Determine the role of topoisomerase II alpha and beta in mediating the cytotoxic and genotoxic effects of bioflavonoids in human cells by using siRNA. The role of each isoform in the initiation of bioflavonoid-induced MIL gene translocations in cultured human cells will be examined via cloning and PCR approaches. This project will further our understanding of the chemopreventative and cytotoxic properties of bioflavonoids and potentially lead to the utilization of these compounds as chemotherpeutic agents.