ROLE OF TOPOISOMERASE II IN NBQ MEDIATED TUMOR CELL DIFFERENTIATION

3-硝基苯并噻唑并[3，2-a]喹啉(NBQ)嵌入DNA和DNA中 显示出作为抗肿瘤药物的强大潜力。在我们实验室进行的关于 其作用机制表明，NBQ的细胞毒性与 拓扑异构酶II介导的DNA链断裂。此外，NBQ显著地 促进成年Newt Notophtalmus的体内晶状体再生 并在体外诱导HL-60和DFaDu细胞分化 肿瘤细胞系。NBQ，以非致命性剂量刺激分化， 在体外将拓扑异构酶II与纯化的DNA结合。 拓扑异构酶II在细胞毒性和分化中的作用 NBQ的活性，使人们对拓扑异构酶的作用产生了疑问 II在NBQ诱导分化中。关于分子的知识 NBQ诱导分化的机制(S)与其 细胞毒作用，将进一步发展一种潜在的新癌症模式 化疗。为了探索这个问题，我们将研究NBQ的影响 以及使用分子和细胞方法相结合的八个类似物。 因为可切割复合体的DNA序列定位，由 NBQ和各种类似物，与拓扑异构酶II应该是相同的， 药物效应的比较更容易解释。我们建议 为了表征8个NBQ类似物的细胞毒活性， 评价对拓扑异构酶活性的抑制作用。差异化 将每种模拟物的能力与NBQ(80-90%HL-60细胞)进行比较 分化成粒细胞系)。要了解这一机制 对NBQ和类似物的作用，我们将进行评估；蛋白质的形成 完整细胞中连接的链断裂，拓扑异构酶的抑制 体外活性，并促进染色体异常。其影响 细胞周期中NBQ类似物的浓度将被检测到 与细胞毒浓度相比，诱导分化。这种模式 NBQ刺激的拓扑异构酶II介导的DNA切割 与NBQ类似物刺激的切割模式和 拓扑异构酶II毒害阿霉素、VP-16和m-AMSA。最后， NBQ类似物将在耐药的HL-60和m-AMSA中进行研究。 最后，将研究NBQ类似物在抗药性HL-60中的作用 细胞系(HL-60/NBA)，这使我们能够研究差异的基础 在活性方面，特别是分化的诱导。

3-nitrobenzothiazolo[3,2-a] quinolinium (NBQ) intercalates in DNA and shows a strong potential as antitumor agent. Studies in our laboratory on its mode of action revealed that the cytotoxicity of NBQ is associated with topoisomerase II- mediated DNA strand breaks. Moreover, NBQ significantly enhances in vivo lens regeneration in the adult newt Notophtalmus viridescens, and induces in vitro the differentiation of HL-60 and DFaDu tumor cell lines. NBQ, at non-lethal doses that stimulate differentiation, binds in vitro topoisomerase II to purified DNA. The involvement of topoisomerase II in the cytotoxic and differentiation activities of NBQ, brings into question what is the role of topoisomerase II in the NBQ-induced differentiation. Knowledge of the molecular mechanism(s) through which NBQ induces differentiation, in contrast to its cytotoxic effect, will further a potentially new mode of cancer chemotherapy. To explore this question, we will study the effects of NBQ and eight analogs using a combination of molecular and cellular approaches. Because the DNA sequence localization of the cleavable complex, formed by NBQ and the various analogs, with topoisomerase II should be identical, the comparison of drug effects is more amenable to interpretation. We propose to characterize the cytotoxic activity of the eight NBQ analogues and evaluate athe inhibition f topoisomerase activity. The differentiation ability of each analog will compared to NBQ (80 - 90% HL-60 cells differentiated into the granulocytic series). To understand the mechanism of action of NBQ and analogs, we will evaluate; the formation of protein linked strand breaks in intact cells, the inhibition of topoisomerase activity i vitro, and promotion of chromosomal abnormalities. The effects of NBQ analogs on the cell cycle will be detected at concentration that induce differentiation compared with cytotoxic concentrations. The pattern of topoisomerase II-mediated DNA cleavage stimulated by NBQ will be compared to the cleavage pattern stimulated by NBQ analogs and the topoisomerase II poisons doxorubicin, VP-16 and m-AMSA. Finally, the effects of NBQ analogs will be studied in the resistant HL-60 and m-AMSA. Finally, the effects of NBQ analogs will be studied in the resistant HL-60 cell line (HL-60/NBA), which allows us to study the basis for differences in activity, specially, the induction of differentiation.