Regulation of drug disposition by a novel microRNA-mediated pathway

通过新型 microRNA 介导的途径调节药物分布

• 批准号: 9005869
• 负责人: Taosheng Chen
• 金额: $ 33.25万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9005869
• 关键词: ABCB1 gene; Agonist; Biological Availability; Cells; Chemicals; Complex; Data; Development; Doxorubicin; Drug Regulations; Drug resistance; Ectopic Expression; Experimental Models; FDA approved; Feedback; Goals; HDAC1 gene; Health; Histones; In Vitro; Laboratories; Lead; Ligands; Literature; Mediating; MicroRNAs; Modeling; Outcome; Pathway interactions; Pharmaceutical Preparations; Positioning Attribute; RXR; Reagent; Regulation; Resistance; Role; Solid; Testing; Therapeutic; Treatment Efficacy; Treatment Failure; Vorinostat; Work; Xenobiotics; cell type; chemotherapeutic agent; constitutive androstane receptor; effective therapy; improved; in vivo; inhibitor/antagonist; innovation; knock-down; novel; novel therapeutic intervention; pregnane X receptor; promoter; receptor; screening; uptake

DESCRIPTION (provided by applicant): We propose to investigate and determine the effect of a novel microRNA (miRNA)-mediated pathway in drug disposition and drug resistance. Elevated expression of drug transporters such as ABCB1 (MDR1) contributes to drug resistance mediated by active drug export. Expression of these transporters is transcriptionally controlled by two major xenobiotic receptors, constitutive androstane receptor (CAR) and pregnane X receptor (PXR), both of which function as heterodimers with retinoid X receptor (RXR). Whereas PXR is ligand- activated, CAR is constitutively active in the absence of ligand, and its expression leads to that of its transcriptional targets. Recent studies have provided evidence of miRNA-mediated drug resistance. Our preliminary studies found that miR-137 is down-regulated in doxorubicin-resistant cells, while CAR and MDR1 are up-regulated. We found that miR-137 and CAR form an unusual negative feedback loop wherein miR-137 directly reduces CAR levels, and CAR negatively regulates miR-137 expression. We also found that CAR inverse agonists reduce MDR1 and increase miR-137 levels, and have developed a novel CAR inverse agonist (LTC27) that is potent and selective for CAR. Importantly, ectopically expressed miR-137 reduces CAR and MDR1, and re-sensitizes doxorubicin-resistant cells to doxorubicin both in vitro and in vivo; suggesting that drug resistance can be reversed. However synthetic miRNAs have limited bioavailability because of their low stability and cellular uptake. By screening, we identified vorinostat (or SAHA) that induces miR-137 expression and reduce MDR1 level. SAHA, a drug approved by FDA, is an inhibitor of histone deacetylases (HDACs); HDAC inhibition can disrupt the transcriptionally repressive CAR-HDAC1 complex. Our preliminary data lead us to hypothesize that increasing miR-137 levels or inhibiting CAR will reduce MDR1 in drug-resistant cells, thereby increasing intracellular drug accumulation and re-sensitizing the cells; that HDAC inhibitors induce miR-137 expression, at least partly by relieving the repressive effect of CAR, and can reverse drug resistance. To test these hypotheses, we will determine (1) the extent to which doxorubicin resistance is reversed by ectopic expression of miR-137; (2) the extent to which doxorubicin resistance is reversed by CAR inverse agonists; and (3) the mechanism by which miR-137 expression is induced, and the extent to which drug resistance is reversed by HDAC inhibitors, in our unique doxorubicin- resistant models. We will also examine the HDAC1-CAR-miR-137 promoter complex and determine the extent to which the complex is disrupted by HDAC inhibitors. These studies will illustrate how drug resistance is acquired and identify potential treatments to reverse resistance.

描述（由申请人提供）：我们建议研究并确定新型 microRNA (miRNA) 介导的途径对药物处置和耐药性的影响。 ABCB1 (MDR1) 等药物转运蛋白的表达升高有助于由活性药物输出介导的耐药性。这些转运蛋白的表达在转录上由两种主要的异生素受体组成型雄甾烷受体（CAR）和孕烷X受体（PXR）控制，这两种受体均与类视黄醇X受体（RXR）作为异二聚体发挥作用。 PXR 是配体激活的，而 CAR 在没有配体的情况下具有组成型活性，并且其表达导致其转录靶标的表达。最近的研究提供了 miRNA 介导的耐药性的证据。我们的初步研究发现，在阿霉素耐药细胞中，miR-137 下调，而 CAR 和 MDR1 上调。我们发现miR-137和CAR形成了一个不寻常的负反馈环，其中miR-137直接降低CAR水平，而CAR负调节miR-137表达。我们还发现 CAR 反向激动剂可降低 MDR1 并增加 miR-137 水平，并开发了一种对 CAR 有效且具有选择性的新型 CAR 反向激动剂 (LTC27)。重要的是，异位表达的 miR-137 可以减少 CAR 和 MDR1，并使多柔比星耐药细胞在体外和体内重新对阿霉素敏感。表明耐药性是可以逆转的。然而，合成的 miRNA 由于稳定性和细胞摄取较低，其生物利​​用度有限。通过筛选，我们鉴定出伏立诺他（或 SAHA）可诱导 miR-137 表达并降低 MDR1 水平。 SAHA是FDA批准的药物，是组蛋白脱乙酰酶（HDAC）的抑制剂； HDAC 抑制可以破坏转录抑制性 CAR-HDAC1 复合物。我们的初步数据使我们推测，增加miR-137水平或抑制CAR将减少耐药细胞中的MDR1，从而增加细胞内药物积累并使细胞重新敏感； HDAC 抑制剂至少部分通过缓解 miR-137 的表达来诱导 miR-137 表达 CAR的抑制作用，并能逆转耐药性。为了检验这些假设，我们将确定 (1) miR-137 异位表达逆转阿霉素耐药性的程度； (2) CAR反向激动剂逆转阿霉素耐药性的程度； (3) 在我们独特的阿霉素耐药模型中，诱导 miR-137 表达的机制，以及 HDAC 抑制剂逆转耐药性的程度。我们还将检查 HDAC1-CAR-miR-137 启动子复合物，并确定该复合物被 HDAC 抑制剂破坏的程度。这些研究将说明耐药性是如何获得的，并确定逆转耐药性的潜在治疗方法。