Molecular Mechanisms of Adverse Metabolic Events by Asparaginase.

描述(申请人提供)：天冬酰胺酶是治疗急性淋巴细胞性白血病不可或缺的一部分，急性淋巴细胞性白血病是最常见的儿童癌症。天冬酰胺酶产生肝脏毒性，导致与治疗相关的代谢并发症，包括脂肪肝、血浆蛋白减少以及导致血栓栓塞症和脑血管事件的凝血问题。我们的长期目标是提高天冬酰胺酶的安全性和有效性。这项建议的目的是发现天冬酰胺酶引起不良代谢影响的机制。为了实现这一点，我们建议确定通过天冬酰胺酶调节肝功能障碍的关键分子事件。我们的初步数据表明，天冬酰胺酶增加了翻译因子eIF2的磷酸化。GCN2的缺失阻止了对天冬酰胺酶的适应性反应，并增强了内质网(ER)应激，导致另一种eIF2激酶的诱导，称为PKR样ER驻留激酶(PERK)。中心假设是eIF2激酶的激活可以预防和/或减轻天冬酰胺酶所致的肝功能障碍。我们计划通过以下具体目标来验证我们的假设并实现这一应用的目标：目的1)确定GCN2在天冬酰胺酶治疗过程中在肝脏中的作用；目的2)确定PERK在天冬酰胺酶治疗过程中在肝脏中的作用；目的3)表征天冬酰胺酶在肝脏中eIF2激酶信号的年龄差异。为了实现上述目标，天冬酰胺酶将被给予野生型小鼠和eIF2激酶、GCN2和/或PERK缺失的小鼠。时间进程分析将集中在eIF2激酶信号的调节和内质网应激的激活如何与肝功能障碍的发展相关。此外，天冬酰胺酶将用于不同年龄的小鼠，并将评估对天冬酰胺酶的关键分子和代谢反应。这项建议的创新之处在于，它试图确定天冬酰胺酶在不同年龄导致肝功能障碍的分子事件的进展。这项拟议的工作意义重大，因为它将有助于确定在发育连续期间有天冬酰胺酶不良代谢事件风险的儿科患者。研究结果还将用于开发和测试新的预防和/或治疗方法。

DESCRIPTION (provided by applicant): Asparaginase is an integral part of the treatment for acute lymphoblastic leukemia, the most common childhood cancer. Asparaginase produces hepatotoxicity resulting in treatment-related metabolic complications that include fatty liver, reduced plasma proteins, and coagulation problems that lead to thromboembolism and cerebrovascular events. Our long-term goal is to increase the safety and efficacy of asparaginase. The objective of this proposal is to discover mechanisms by which asparaginase causes adverse metabolic effects. To accomplish this, we propose to identify key molecular events that modulate hepatic dysfunction by asparaginase. Our preliminary data demonstrate that asparaginase increases phosphorylation of the translation factor, eIF2, by GCN2. Deletion of GCN2 precludes adaptive responses to asparaginase and enhances endoplasmic reticulum (ER) stress, leading to induction of another eIF2 kinase called PKR-like ER- resident Kinase (PERK). The central hypothesis is that activation of eIF2 kinases prevent and/or mitigate hepatic dysfunction by asparaginase. We plan to test our hypothesis and accomplish the objective of this application by pursuing the following specific aims: Aim 1) Identify the role of GCN2 in liver during asparaginase treatment; Aim 2) Determine the role of PERK in liver during asparaginase treatment; Aim 3) Characterize age differences in eIF2 kinase signaling in liver by asparaginase. To accomplish the above aims, asparaginase will be administered to both wild-type mice and mice deleted for the eIF2 kinases, GCN2 and/or PERK. Time course analysis will focus on how modulation of eIF2 kinase signaling and activation of ER stress relates to development of liver dysfunction. In addition, asparaginase will be administered to mice of varying ages and key molecular and metabolic responses to asparaginase will be assessed. This proposal is innovative in that it seeks to identify the progression of molecular events that lead to liver dysfunction by asparaginase at different ages. The work proposed is significant as it will help identify pediatric patients at risk for adverse metabolic events by asparaginase during the developmental continuum. The results will also be used to develop and test new methods of prevention and/or treatment.