Mechanisms of Hydroxyurea Efficacy in Sickle Cell Disease

项目总结 镰状细胞病(Scd)是世界上最常见的遗传性血液疾病之一，每年有 仅在美国就花费了超过10亿美元。目前，只有一种FDA批准的药物可用于 管理SCD、羟基脲(HU)。HU的疗效在很大程度上归因于伽马珠蛋白的增强表达 在红系祖细胞中导致胎儿血红蛋白产生增加以改善许多并发症 SCD.然而，胎儿血红蛋白的增加对一些患者来说可能是不够的，他们可能不够 受益于这种疗法的原因不明。由于可用的替代疗法有限，有必要 提高HU的疗效，为这些患者开发新药。这个项目将提供新的信息 关于HU疗效机制的探讨可为HU个体化治疗提供药物遗传学靶点 为SCD的其他治疗提供新的胎儿血红蛋白诱导治疗靶点。 它的新概念与详细的培训计划和来自一支高度成功的 翻译和临床研究人员也将促进首席调查员的职业发展。 我们之前研究HU药理学调节剂的工作已经发现，细胞膜 转运体尿素转运体B(UTB)和有机阳离子/肉碱转运体1(OCTN1)调节 细胞内HU的积累。这些转运体控制着有多少药物到达细胞内的靶点和 与胎儿血红蛋白水平升高有关。我们还发现，细胞内miRNAs、miR-148A、- 151-3p和-494与HU疗法在镰状细胞患者的红细胞治疗中相关 胎儿血红蛋白水平升高。因此，我们已经确定了两种可能的机制，通过这些机制，HU可以 导致胎儿血红蛋白水平升高。到目前为止，模型的局限性阻碍了我们的研究 这些调节剂在SCD的活体模型中。考虑到这些先前的发现，我们假设诱导 胎儿血红蛋白受转运蛋白和miRNAs的调节。在丰富的研究环境中 在匹兹堡大学，使用红细胞生成的体外模型，我们将在以下方面验证我们的假设 两个目的：1)确定UTB和OCTN1转运体是否控制HU的摄取和诱导的有效性 2)确定miR-148A、-151-3P和-494是否控制HU诱导 胎儿血红蛋白。在第三个目标中，我们将开发一种新的体内模型来剖析这些和其他机制 羟基脲介导的胎儿血红蛋白在SCD中的表达。 在进行翻译研究的同时，应聘者还将参加课程，参与职业生涯 发展计划，学习病毒基因转导的技术技能，提高专业能力 与沟通、指导、教学、管理和领导力相关。在整个项目指导过程中 由一组高级血液学和干细胞研究人员组成的团队将帮助确保候选人 独立的研究生涯，实现改善SCD治疗的长期目标。

PROJECT SUMMARY Sickle cell disease (SCD) is one of the most commonly inherited blood disorders world-wide with an annual cost of over 1 billion dollars in the United States alone. Currently, there is only one FDA-approved drug for managing SCD, hydroxyurea (HU). HU efficacy is attributed largely to augmented expression of gamma-globin in erythroid progenitors leading to increased production of fetal hemoglobin to ameliorate many complications of SCD. However, the increase in fetal hemoglobin may not be sufficient for some patients, and they may not benefit this therapy for reasons that are unknown. With limited alternative therapies available there is a need to improve efficacy of HU and develop new drugs for these patients. This project will provide new information about the mechanisms of HU efficacy that can offer pharmacogenetic targets to help personalize HU therapy and offer new therapeutic targets of fetal hemoglobin induction for developing additional treatments for SCD. Its novel concepts combined with a detailed training plan and mentorship from a highly accomplished team of translational and clinical researchers will also facilitate the career development of the principle investigator. Our previous work investigating modulators of HU pharmacology has identified that the cell membrane transporters urea transporter B (UTB) and organic cation/carnitine transporter1 (OCTN1) regulate the intracellular accumulation of HU. These transporters govern how much drug reaches intracellular targets and are associated with augmented fetal hemoglobin levels. We also found that intracellular miRNAs, miR- 148a, - 151-3p, and -494 are associated with HU therapy in erythroid cells of sickle cell patients in association with increased fetal hemoglobin level. Thus, we have identified two potential mechanisms through which HU may elicit an increase in fetal hemoglobin levels. To date, model limitations have hindered our studies to investigate these modulators in an in vivo model of SCD. Given these previous findings, we hypothesize that induction of fetal hemoglobin by hydroxyurea is modulated by transporters and miRNAs. In the rich research environment at University of Pittsburgh, using an in vitro model of erythropoiesis, we will test our hypothesis in the following two aims: 1) to determine whether UTB and OCTN1 transporters control uptake and efficacy of HU to induce fetal hemoglobin and 2) to determine whether miR-148a, -151-3p, and -494 control the efficacy HU to induce fetal hemoglobin. In a third aim, we will develop a novel in vivo model to dissect these and other mechanisms of hydroxyurea-mediated fetal hemoglobin in SCD. While conducting the translational research, the candidate will also take classes, participate in career development programs, learn technical skills in viral gene transduction and improve professional competencies related to communication, mentoring, teaching, management and leadership. Throughout the project mentoring by a team of senior-level hematology and stem cell researchers will help ensure that the candidate launches an independent research career and realize the long-term goal of improving treatment for SCD.