Molecular Determinants for the Bioactivity of the Flavonoid Quercetin

说明（由申请人提供）：黄酮类化合物是一组多酚类化合物，主要以其抗氧化性能而闻名。对黄酮类化合物的研究表明，它们有希望用于预防和治疗各种癌症、炎症和心脏病。槲皮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。几项研究表明槲皮素对多种肿瘤细胞和血管生成具有生物活性。然而，其他几项研究也表明了槲皮素的致癌潜力。此外，槲皮素已被描述为一些有毒植物的主要分子之一。因此，槲皮素作为抗肿瘤剂或作为致癌物具有生物活性的条件尚不清楚。了解槲皮素和其他黄酮类化合物在分子水平上的功能对公共卫生至关重要，因为它将帮助我们建立特定生物活性黄酮类化合物可能或可能不有益于治疗目的的条件。 在这项研究中，我们建议确定槲皮素的生物活性的条件下，细胞信号传导的特定蛋白质调节剂已被消融的机制。我们的具体目标是研究：（1）槲皮素表达或抑制哪些基因;（2）槲皮素如何通过细胞信号调节蛋白调节细胞存活或细胞死亡。为了解决这些问题，首先，我们将研究的整体和差异的基因表达谱的细胞，这是完整的或无效的p53蛋白，通过处理他们与槲皮素。我们还将研究槲皮素对p53调控的细胞周期和凋亡蛋白的表达和功能的影响。其次，我们将通过检查ATM/ATR蛋白和下游事件来分析DNA损伤反应途径。第三，我们将检测槲皮素处理后其他关键细胞周期和凋亡调节蛋白的水平和活性。为了检查通过初始治疗实验鉴定的关键蛋白质的作用，我们将使用敲除蛋白质的细胞，或者我们将通过短干扰RNA敲除蛋白质。这些结果将帮助我们了解槲皮素治疗是否会影响细胞周期，细胞凋亡和细胞中的DNA损伤调节蛋白。在未来的研究中，我们将利用这些目的的知识来评估槲皮素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.