Role of Translational Control in Anti-Cancer Effects of PEITC

描述(由申请人提供)： 膳食中的异硫氰酸酯(ITC)，包括异硫氰酸苯乙酯(PEITC)，是十字花科蔬菜的主要生物活性成分。ITCs可能是十字花科蔬菜对结肠癌等多种癌症的防癌作用的重要原因。我们最近证实，PEITC抑制帽子依赖的翻译，抑制蛋白质翻译在PEITC诱导的细胞凋亡中起关键作用。我们的长期目标是确定ITCs化学保护作用的分子机制。我们的具体假设是，翻译调控的调节有助于PEITC介导的化学保护作用。在这项拟议的研究中，我们将重点确定PEITC介导的翻译抑制的潜在上游信号和下游靶点。我们还建议确定从体外研究中获得的机制信息是否可以扩展到体内。更具体地说，我们建议：目标1.研究参与eIF4E翻译启动可用性调节的信号通路。我们将：(A)确定PEITC介导的抑制4E-BP1磷酸化的信号事件；以及(B)确定PEITC是否通过靶向Mnk1/eIF4E磷酸化途径来抑制eIF4E的可获得性。目的2.分析PEITC介导的多聚核糖体的变化。多聚体图谱将被用来：A)评估总体翻译率；B)识别潜在的翻译目标mRNAs。目的3.验证eIF4E在PEITC抑制肿瘤生长中的作用。为了确定体内相关性，我们将检查eIF4E的过度表达是否克服了PEITC介导的异种移植生长抑制。将对肿瘤进行检查，以确定在细胞中观察到的PEITC诱导的翻译抑制(目标1和2)与其在体内的效果相关的程度。公共卫生相关性拟议的研究将提供关于翻译调控是否以及如何在PEITC的化学保护作用中发挥关键作用的深入机制信息。更好地了解翻译调控和PEITC对肿瘤生长的影响之间的联系可能最终导致发现有效的生物标记物来评估饮食制剂的癌症保护效果。

DESCRIPTION (provided by applicant): Dietary isothiocynates (ITC), including phenethylisothiocynate (PEITC), are major bioactive components of cruciferous vegetables. ITCs may greatly account for the cancer protective effect of cruciferous vegetables on various cancers such as colon cancer. We recently demonstrated that PEITC inhibits cap-dependent translation and inhibition of protein translation is critical for PEITC-induced apoptosis. Our long-term goal is to define the molecular mechanism of ITCs' chemoprotective actions. Our specific hypothesis is that the modulation of translational regulation contributes to PEITC-mediated chemoprotective effects. In this proposed study, we will focus on determining the potential upstream signaling and downstream target of PEITC-mediated translation inhibition. We also propose to determine whether the mechanistic information obtained from in vitro studies can be extended to in vivo. More specifically, we propose to: Aim 1. Examine the signaling pathways involved in the regulation of eIF4E availability for translation initiation. We will: (A) identify the signaling events responsible for PEITC-mediated inhibition of 4E-BP1 phosphorylation; and (B) determine whether PEITC inhibits eIF4E availability through targeting Mnk1/eIF4E phosphorylation pathway. Aim 2. Analyze PEITC-mediated changes in polyribosome profile. Polysome profile will be used to: A) Evaluate overall translation rate; B) Identify potential translational target mRNAs. Aim 3. Validate the role of eIF4E availability in PEITC-caused inhibition of tumor growth. To establish in vivo relevance, we will examine whether overexpression of eIF4E overcomes PEITC-mediated inhibition of xenograft growth. Tumors will be examined to determine the extent to which PEITC-induced inhibition of translation observed in cells (Aim 1 and 2) correlates with its effect in vivo. PUBLIC HEALTH RELEVANCE The proposed studies will provide in-depth mechanistic information regarding whether and how translational regulation plays a critical role in PEITC's chemoprotective effects. A better understanding of the linkage between translational regulation and PEITC's effects on tumor growth may ultimately result in discovery of effective biomarkers to assess dietary agent cancer protective effect.