Molecular Determinants for the Bioactivity of the Flavonoid Quercetin

说明(申请人提供)：黄酮类化合物由一组多酚化合物组成，主要以其抗氧化性能而闻名。对类黄酮的研究表明，它们在预防和治疗各种癌症、炎症性疾病和心脏病方面具有广阔的应用前景。栎素是一种天然存在的生物活性类黄酮，广泛存在于水果、蔬菜和其他植物中。多项研究表明，栎素具有抗多种肿瘤细胞和血管生成的生物活性。然而，其他几项研究也表明了Qercetin的致癌潜力。此外，槲皮素被认为是一些有毒植物的主要分子之一。因此，栎素作为抗肿瘤药物或致癌物质具有生物活性的条件还不是很清楚。了解栎素和其他类黄酮在分子水平上的功能对公共健康至关重要，因为它将帮助我们建立特定的生物活性类黄酮化合物可能有益于治疗目的或可能不利于治疗目的的条件。 在这项研究中，我们建议确定在特定的细胞信号调节蛋白已被去除的条件下，槲皮素的生物活性机制。我们的具体目标是研究：(1)哪些基因被Quercetin表达或抑制；(2)Quercetin是如何通过细胞信号调节蛋白调节细胞存活或细胞死亡的。为了解决这些目标，首先，我们将研究细胞的整体和差异基因的表达谱，对P53蛋白完整或缺失的细胞，通过用栎素处理它们。我们还将研究Quercetin对P53调控的细胞周期和凋亡蛋白的表达和功能的影响。其次，我们将通过检测ATM/ATR蛋白和下游事件来分析DNA损伤反应途径。第三，我们将检测其他关键的细胞周期和细胞凋亡调节蛋白的水平和活性。为了检验通过最初的治疗实验确定的关键蛋白质的作用，我们将使用敲除的细胞来寻找蛋白质，或者我们将通过短干扰RNA来敲除蛋白质。这一结果将有助于我们了解是否用栎素治疗会影响细胞周期、细胞凋亡和细胞中的DNA损伤调节蛋白。在未来的研究中，我们将利用这些目标的知识来评估Qercetin在体内肿瘤细胞中发挥的作用。

DESCRIPTION (provided by applicant): Flavonoids constitute a group of polyphenolic compounds primarily known for their anti-oxidant properties. Studies on flavonoids show their promising use for the prevention and treatment of a variety of cancer, inflammatory and heart diseases. Quercetin is a naturally occurring bioactive flavonoid ubiquitously available in fruits, vegetables and other plants. Several studies have shown the bioactivity of Quercetin against a variety of tumor cells and angiogenesis. However, several other studies have also indicated the carcinogenic potential of Quercetin. Moreover, Quercetin has been described as one of the principal molecules of some toxic plants. Therefore, the conditions under which Quercetin is bioactive as an anti-tumor agent or as a carcinogen are not well known. Understanding how Quercetin and other flavonoids function at the molecular level is of paramount importance to public health because it will help us establish the conditions under which specific bioactive flavonoid compounds may or may not be beneficial for therapeutic purposes. In this study, we propose to determine the mechanisms of Quercetin bioactivity under conditions where specific protein regulators of cell signaling have been ablated. Our specific aims are to examine: (1) what genes are expressed or inhibited by Quercetin; (2) how Quercetin modulates cell survival or cell death through cell signaling regulatory proteins. To address these aims, firstly, we will study the global and differential gene expression profiles of cells, which are intact or null for the p53 protein, by treating them with Quercetin. We will also examine the effect of Quercetin on the expression and function of cell cycle and apoptosis proteins regulated by p53. Secondly, we will analyze the DNA-damage response pathway through examination of the ATM/ATR proteins and downstream events. Thirdly, we will examine the levels and activities of other key cell cycle and apoptosis regulatory proteins after treatment with Quercetin. To examine the role of key proteins identified through the initial treatment experiments, we will use cells knocked out for the proteins or we will knock down the proteins by short interfering RNAs. The results will help us understand if treatment with Quercetin influences cell cycle, apoptosis, and DNA-damage regulatory proteins in cells. In future studies, we will utilize knowledge from these aims to evaluate the effect that Quercetin exerts in tumor cells in vivo.