Activation of the Cancer Preventive Nrf2-ARE Pathway by Seaweed

描述(由申请人提供)： 项目摘要/摘要海藻(海藻)是亚洲国家，特别是日本的主要饮食来源。海藻消费的许多有益影响已有报道，但只有部分归因于个别化学成分。海藻促进健康作用的一个明显的共同点是抗氧化活性，它可能会抵消导致癌症的氧化应激诱导的损害。随之而来的是，日本几种癌症的发病率极低，而且据报道，海藻的摄入量与癌症的发病率呈负相关。在日本，前列腺癌的风险几乎可以忽略不计。前列腺癌的特征是谷胱甘肽-S-转移酶(GST)基因沉默，这是一种II相解毒酶。第二阶段和其他抗氧化酶通常由抗氧化反应元件(ARE)调节，该元件由转录因子Nrf2激活。激活NRF2-ARE途径是一种有效的癌症预防策略，而西兰花的一种成分萝卜硫素就是通过这一机制发挥作用的防癌天然产物的最著名的例子。初步数据表明，某些海藻提取物激活了IMR-32人神经母细胞瘤细胞中的ARE-荧光素酶报告基因。这里假设一些海藻能够激活NRF2-ARE癌症预防信号通路，一些有益的，特别是抗氧化特性，可能是通过激活ARE来调节的。首先，将在佛罗里达州沿海栖息地进行小规模的海藻采集。然后，将准备各种提取物，并进行短暂的分级。粗提物和组分排列在96孔板中，然后在细胞模型中使用ARE报告基因分析进行氧化应激和癌症预防的筛选。通过引起氧化应激或毒性而激活ARE的天然产品混合物将在柜台屏幕上被消除。将使用各种二级生化分析进一步确定HITS的优先顺序。在重新收集最有希望的海藻物种后，相应的提取物或部分将使用ARE报告鼠在体内测试它们激活ARE的能力，这是优先排序的额外一层。将执行生物测定引导的分级，以从体内活性混合物中分离出纯的ARE激活剂。然后，活性成分(S)将通过分析技术，主要是核磁共振进行结构鉴定。这项拟议的研究得到了PI实验室正在进行的研究的补充，该研究旨在表征Nrf2-ARE途径，并一直在为通过这一机制作用的癌症预防和抗退化剂产生潜在的分子靶点。这一应用与NIH确定有效的疾病预防策略的目标是一致的。与公共健康相关氧化应激导致致癌的细胞损伤，这种损伤可以通过增强内源性防御系统来减轻或预防。海藻是一种饮食来源，这里假设是通过一种特定的信号通路来提高人类抗氧化和解毒因子的水平。识别防癌海藻和个体活性成分可能成为制定新的健康促进战略的基础。

DESCRIPTION (provided by applicant): Project Summary/Abstract Seaweed (marine algae) is a major dietary source in Asian countries, particularly in Japan. Numerous beneficial effects of seaweed consumption have been reported, but only some of which have been attributed to individual chemical components. An apparent common denominator of seaweed's health-promoting effects is the antioxidant activity which may counteract cancer-causing oxidative stress induced damage. Concomitantly, the incidence of several types of cancer is extremely low in Japan and inverse correlations with seaweed consumption have been reported. Prostate cancer risk in particular is almost negligible in Japan. Prostate cancer is characterized by the silencing of one glutathione-S-transferase (GST) gene, a phase II detoxification enzyme. Phase II and other antioxidant enzymes are commonly regulated by the antioxidant response element (ARE) which is activated by transcription factor Nrf2. The activation of the Nrf2-ARE pathway is a valid cancer preventive strategy, and sulforaphane, a constituent of broccoli, is the best known example of a cancer preventive natural product that acts through this mechanism. Preliminary data indicate that certain seaweed extracts activate the ARE-luciferase reporter in IMR-32 human neuroblastoma cells. It is hypothesized here that some seaweeds are able to activate the Nrf2-ARE cancer preventive signaling pathway and that some of the beneficial, particularly antioxidant properties, may be mediated through ARE activation. First, small-scale collections of seaweed will be carried out in Florida coastal habitats. Various extracts will then be prepared and briefly fractionated. Crude extracts and fractions are arrayed in 96-well plates and then screened in cellular models for oxidative stress and cancer prevention using an ARE reporter gene assay. Natural product mixtures that activate the ARE by causing oxidative stress or toxicity will be eliminated in counter screens. Hits will be further prioritized using a variety of secondary biochemical assays. Following re- collections of most promising seaweed species, the corresponding extracts or fractions will then be tested for their ability to activate the ARE in vivo using ARE reporter mice, which serves as an additional layer of prioritization. Bioassay-guided fractionation will be executed to isolate pure ARE activators from in vivo active mixtures. The active principle(s) will then be structurally identified by analytical techniques, primarily NMR. The proposed study is complemented by ongoing research in the PI's laboratory which aims in characterizing the Nrf2-ARE pathway and which has been yielding potential molecular targets for cancer preventive and anti- degenerative agents acting through this mechanism. This application is in line with NIH's goal to identify effective disease-preventive strategies. PUBLIC HEALTH RELEVANCE Oxidative stress results in cancer-causing cellular damage which can be attenuated or prevented by boosting the endogenous defense system. Seaweed is a dietary source that is hypothesized here to enhance levels of humans' antioxidant and detoxification factors through a specific signaling pathway. The identification of cancer-preventing seaweeds and of individual active components may become the basis for the development of new health-promoting strategies.