Regulation of drug metabolizing enzymes by miRNAs

描述(由申请人提供)：可变药物处置是公认的改变药物疗效和损害安全性的原因。虽然这种变异性的一些原因是已知的，但大部分原因仍不清楚；因此，许多药物不良反应和药物疗效决定因素仍然不可预测。由于药物代谢是药物动力学的主要决定因素，而大多数临床上严重的药物相互作用是药物代谢改变的结果，我们希望评估其他调节药物代谢酶表达的机制。导致药物代谢变化的一个重要因素是细胞色素P450(CYP450)酶表达的发育变化；这是在婴幼儿中需要考虑的一个特别重要的因素。这一建议的中心假设是，内源性microRNAs(MiRNAs)调节关键药物代谢酶表达的发育变化，从而改变药物暴露。内源性miRNAs是调节基因和蛋白质表达的非编码小RNA；这包括组织特异性基因表达的发育调节的重要作用。我们的假设是基于我们的初步数据，这些数据表明miRNAs也调节关键的CYP药物代谢酶。我们的长期目标是通过更好地了解并减少个体间的药代动力学变异性来提高治疗药物的有效性和安全性。我们将通过以下具体目标来验证我们的假设：1)识别被预测控制肝脏药物代谢的miRNAs。这一生物信息学努力的结果将对理解这一重要类别的酶具有广泛的生物学意义。2)确定肝脏细胞色素P450活性发展过程中的整体miRNA表达模式的变化。这些研究将集中在人类胎儿、新生儿/儿科和成人期。3)确定与已记录的发育变化相关的miRNA表达模式，该酶是一种关键的药物代谢酶：CYP2D6。4)采用体外miRNA生物检测方法，对预测的miRNA对细胞色素P450 2D6表达的调控进行功能验证。该项目具有很高的创新性，因为它利用由miRNA控制的新的分子机制解决了药物代谢中的发育变化。这些努力也可能对儿童和成人的个体间转运体、受体和信号变异性产生重要影响。我们组建了一支在临床药理学、分子生物学和生物信息学方面拥有公认专业知识的研究团队。作为这个团队的一部分，我们可以获得大量经过适当同意的临床样本，这些样本将使我们能够将我们的发现直接转化为人体研究。更好地理解人类肝脏细胞色素P450酶的发育控制机制可能会提高我们对人类药物代谢中发生的发育变化的理解。最终，这将导致改善治疗性药物剂量策略，特别是在发育变化的关键时期。 与公共卫生相关：我们将研究导致药物不良反应和药物疗效不佳的潜在机制。我们将确定小的内源性microRNAs在调节肝脏药物代谢酶中的作用。这些研究应该有助于我们更好地了解药物反应的个体间变异性，从而改进药物治疗。

DESCRIPTION (provided by applicant): Variable drug disposition is a well recognized cause of altered drug efficacy and impaired safety. While some of the causes of this variability are known, much of it is still unexplained; consequently, many of the adverse drug reactions and drug efficacy determinants are still unpredictable. Since drug metabolism is a primary determinant of pharmacokinetics and most clinically serious drug-interactions are the result of alterations in drug metabolism, we wish to evaluate additional mechanisms that regulate the expression of the drug metabolizing enzymes. One important factor that contributes to variable drug metabolism is developmental change in the expression of the cytochrome P450 (CYP450) enzymes; this is a particularly important factor to consider in infants and young children. The central hypothesis of this proposal is that endogenous microRNAs (miRNAs) regulate developmental changes in the expression of key drug metabolizing enzymes, and thereby, altering drug exposure. Endogenous miRNAs are small non-coding RNAs that regulate gene and protein expression; this includes the important role of developmental regulation of tissue-specific gene expression. Our hypothesis is based on our preliminary data that suggest that miRNAs also regulate key CYP drug metabolizing enzymes. Our long-range goal is to improve the efficacy and safety of therapeutic drugs by better understanding and then reducing interindividual pharmacokinetic variability. We will test our hypotheses through the following specific aims: 1) To identify miRNAs that are predicted to control hepatic drug metabolism. The results of this bioinformatic effort will have broad biological relevance to the understanding of this important class of enzymes. 2) To determine the changes in global miRNA expression patterns that occur during the development of hepatic CYP450 activity. These studies will focus on the human fetal, neonatal/pediatric, and adult periods. 3) To identify miRNA expression patterns that are associated with the documented developmental changes in a single, but critical drug-metabolizing enzyme: CYP2D6. 4) To use in vitro miRNA bioassays to functionally test the predicted miRNA regulation of CYP2D6 expression. This project is highly innovative because it addresses the developmental variation seen in drug metabolism using new molecular mechanisms inherent in control by miRNA. These efforts may also have important implications for interindividual transporter, receptor, and signaling variability in children and adults. We have assembled a team of investigators that have well-recognized expertise in clinical pharmacology, molecular biology and bioinformatics. As part of this team, we have access to a wealth of appropriately consented clinical samples that will enable us to translate our findings directly into human studies. A better understanding of the developmental control mechanisms of the human hepatic CYP450 enzymes will likely improve our understanding of the developmental changes that occur in human drug metabolism. Ultimately, this should lead to improved therapeutic drug dosing strategies, particularly during critical times of developmental change. PUBLIC HEALTH RELEVANCE: We will be studying the underlying mechanisms that contribute to adverse drug reactions and poor drug efficacy. We will determine the role of small endogenous microRNAs in the regulation of liver drug metabolizing enzymes. These studies should help us better understand the interindividual variability in drug responses, and consequently improve drug therapies.