Genetic Polymorphism of Dihydropyrimidine Dehydrogenase

描述(申请人提供)：本研究的长期目标 该项目是为了更好地了解严重、潜在的 5-氟尿嘧啶(5-FU)治疗后继发的危及生命的毒性 具体地说，进一步刻画了药物遗传综合征的特征 二氢嘧啶脱氢酶(DPD)缺乏。在下一个授权期内 我们将进一步阐明基因调控的分子机制。 负责DPD(DPYD)的表达，泛素蛋白酶体的作用 DPD蛋白周转系统，发展表型和基因诊断 检测DPD缺乏，最后检查其他酶步骤的作用 在5-FU代谢中引起严重的5-FU毒性。在接近每一位 以下列出的具体目标，我们将继续获得和利用 生化和分子数据(例如，DPD酶活性、DPD mRNA水平和 IV级患者DPYD基因突变分析 5-FU治疗后的毒性反应。具体目标包括：规范。目标1)- 确定和阐明其他转录调控元件的作用 对DPYD基因表达的影响，包括对A。转录 因子(S)，与之前的 已确定的启动子，以及b)内含子1中的额外潜在调节区 和3‘非翻译区；Spec.目标2)-确定 泛素(Ub)蛋白酶体系统对DPD蛋白-a的调节 测定野生型和突变型DPD蛋白的半衰期，以及b) 鉴定DPD蛋白中可能的不稳定元件(S)。目标3)- 开发用户友好的DPD缺乏症诊断测试，包括) 适用于常规筛查的DPD缺乏症的表型试验，以及b) DPD缺乏症特定原因的基因分型检测；以及Spec。目标4)- 确定可能导致严重5-FU毒性的其他因素的作用 包括a)作用部位5-FU的基因表达改变-胸苷 合酶，b)改变合成代谢酶的基因表达，例如尿苷和 胸腺嘧啶核糖核糖基转移酶、胸苷磷酸化酶和胸腺嘧啶核糖转移酶，以及 C)改变了其他分解代谢酶的基因表达，例如 二氢嘧啶酶。这一研究项目的成功进展应该是 转化为改善对接受氟嘧啶药物治疗的患者的护理 未来。

DESCRIPTION (provided by applicant): The long-term objective of this research project is to better understand the genetic basis for severe, potentially life-threatening toxicity secondary to treatment with 5-Fluorouracil (5-FU) and in particular further characterize the pharmacogenetic syndrome of dihydropyrimidine dehydrogenase (DPD) deficiency. During the next grant period we will further clarify the molecular mechanisms of regulation of the gene responsible for expression of DPD (DPYD), the role of the ubiquitin-proteasome system in DPD protein turnover, develop phenotypic and genotypic diagnostic tests for DPD deficiency, and lastly examine the role of other enzymatic steps in 5-FU metabolism in the cause of severe 5-FU toxicity. In approaching each of the specific aims listed below, we will continue to obtain and utilize biochemical and molecular data (e.g., DPD enzyme activity, DPD mRNA level, and analysis for mutations in DPYD gene) from patients presenting with grade IV toxicity after 5-FU therapy. The specific aims will include: Spec. Aim 1) - Identify and clarify the role of additional transcriptional regulatory elements affecting DPYD gene expression including identification of a.) transcription factor(s) that bind to regulatory elements I and II in the previously identified promoter, and b) additional potential regulatory regions in intron 1 and the 3'-untranslated region; Spec. Aim 2) - Determine the role of the ubiquitin (Ub) proteasome system in the regulation of DPD protein - a) determine DPD protein half-life for wild type and mutant DPD protein, and b) identify putative destabilizing element(s) of DPD protein; Spec. Aim 3) - Develop user-friendly diagnostic tests for DPD deficiency including a) phenotypic tests of DPD deficiency suitable for routine screening, and b) genotypic tests for specific causes of DPD deficiency; and Spec. Aim 4) - Determine the role of other factors that may contribute to severe 5-FU toxicity including a) altered gene expression of the 5-FU site of action - thymidylate synthase, b) altered gene expression of anabolic enzymes, e.g. uridine and thymidine phosphorylases and kinases and orotate phosphoribosyltransferase, and c) altered gene expression of other catabolic enzymes, e.g. dihydropyrimidinase. Successful progress on this research project should translate into improved care for patients receiving fluoropyrimidine drugs in the future.