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: 8670437
• 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 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8670437
• 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; 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; novel; novel therapeutic intervention; pregnane X receptor; promoter; public health relevance; 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）：我们建议调查和确定新型microRNA（miRNA）介导的途径在药物处置和耐药性中的影响。药物转运蛋白（例如ABCB1（MDR1））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由两个主要的异种生物受体（构成雄激素受体（CAR）和妊娠X受体（PXR））在转录上控制，这两者都充当带有类维生素X受体（RXR）的异二聚体。尽管PXR是配体激活的，但在没有配体的情况下，CAR具有组成性活性，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被下调，而CAR和MDR1被上调。我们发现miR-137和汽车形成了一个不寻常的负反馈回路，其中miR-137直接降低了汽车水平，而汽车会负调节miR-137的表达。我们还发现，汽车反向激动剂降低了MDR1并增加了miR-137水平，并开发了一种新型的汽车逆激动剂（LTC27），对CAR有效且有选择性。重要的是，异位表达的miR-137降低了CAR和MDR1，并将抗霉素耐药细胞重新敏感为阿霉素的体外和体内。表明耐药性可以逆转。然而，合成miRNA由于其稳定性低和细胞摄取而具有有限的生物利用度。通过筛选，我们确定了诱导miR-137表达并降低MDR1水平的Vorinostat（或SAHA）。 SAHA是FDA批准的一种药物，是组蛋白脱乙酰基酶（HDACS）的抑制剂； HDAC抑制会破坏转录抑制的CAR-HDAC1复合物。我们的初步数据使我们假设增加了miR-137水平或抑制汽车会减少耐药细胞中的MDR1，从而增加细胞内药物的积累并重新敏感细胞。 HDAC抑制剂诱导miR-137表达，至少部分通过缓解 汽车的抑制作用，并可以逆转耐药性。为了检验这些假设，我们将确定（1）miR-137的异位表达逆转阿霉素抗性的程度； （2）汽车反激动剂逆转阿霉素的耐药性程度； （3）在我们独特的阿霉素耐药模型中，HDAC抑制剂诱导miR-137表达的机制以及耐药性逆转的程度。我们还将检查HDAC1-CAR-MIR-137启动子复合物，并确定HDAC抑制剂破坏该复合物的程度。这些研究将说明如何获得耐药性，并识别潜在的抗抗性。