Isothiocyanates as specific antagonists of human SXR

异硫氰酸盐作为人类 SXR 的特异性拮抗剂

• 批准号: 7316015
• 负责人: David L Eaton
• 金额: $ 28.94万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7316015
• 关键词: Active Sites; Animal Model; Benefits and Risks; Biological Availability; Broccoli - dietary; CYP1A2 gene; Caffeine; Carcinogens; Cells; Characteristics; Chemicals; Chemopreventive Agent; Cysteine; Cytochrome P450 3A4; Development; Diet; Dietary Phytochemical; Dose; Down-Regulation; Drug Interactions; Drug Kinetics; Failure; Gene Expression; Gene Proteins; Genes; Genetic; Goals; Grant; Hepatic; Hepatocyte; Hormones; Human; Human Volunteers; In Vitro; Individual; Intestines; Isothiocyanates; Lead; Ligand Binding; Ligands; Literature; Measures; Mediating; Metabolism; Microarray Analysis; Midazolam; Modification; Molecular; Mus; Nuclear Receptors; Nutraceutical; Pathway interactions; Peptides; Pharmaceutical Preparations; Pharmacologic Substance; Public Health; Receptor Activation; Regulation; Rifampin; Rodent; SFN gene; SXR receptor; Series; Site-Directed Mutagenesis; Steroid Receptors; Steroids; Structure; Sulforaphane; Testing; Time; Transcriptional Activation; Transgenic Animals; Treatment Efficacy; Xenobiotics; adduct; analog; base; cancer risk; feeding; human SFN protein; in vivo; molecular modeling; mouse model; novel therapeutics; optical imaging; pregnane X receptor; receptor function; response; species difference; transcription factor; urinary

DESCRIPTION (provided by applicant): Adverse drug interactions (ADI), are a major public health problem in the US. A major contributor to both ADI and failure of therapeutic efficacy is genetic variability and/or environmentally-induced (incl. diet) changes in hepatic and intestinal drug disposition. Cytochrome P450 3A4 (CYP3A4) is responsible for the hepatic and intestinal metabolism of numerous xenobiotics, including pharmaceutical compounds, some carcinogens, and several important endogenous steroids. Constitutive and inducible expression of CYP3A4 is regulated by a variety of different transcription factors/pathways. Among the most important determinants of CYP3A4 activity is the hormone nuclear receptor, Steroid and Xenobiotic Receptor (SXR; also known as the Pregnane X-receptor, PXR). Numerous drugs and non-drug chemicals induce CYP3A4 activity by acting as SXR ligands, and can cause significant adverse drug-drug interactions and alter therapeutic efficacy. In studies initially investigating the chemopreventive actions of the dietary phytochemical, sulforaphane (SFN; an isothiocyanate found in broccoli), we found that SFN causes remarkable 'down-regulation of CYP3A4 in human hepatocytes. We then verified this effect in human-derived intestinal cells (LS-180), and then demonstrated that SFN acts as an effective antagonist of ligand binding to SXR at low micromolar concentrations. Additional studies demonstrated that this is a species (human)-specific effect, consistent with known differences in SXR ligands between rodents and humans. In this grant we propose to: 1) further elucidate the molecular mechanisms by which SFN blocks SXR function; 2) evaluate structural analogs of SFN to identify more potent and/or specific SXR antagonists; 3) utilize 'humanized' SXR mice and other in vivo approaches to establish an animal model for human response, and 4) conduct a series of human feeding studies to determine if SFN in broccoli sprouts lowers basal expression of human CYP3A4 and/or interferes with rifampicin-mediated induction of CYP3A4, measured by midazolam clearance. If the basic feeding study identifies an effect on CYP3A4, additional feeding studies are proposed to examine other SFN analogs and further characterize the dose and time course of effects. These results may lead to the development of important new therapeutic and dietary approaches that could reduce adverse drug responses. They could also help explain the large inter-individual variability in CYP3A4 that has been noted for decades. Finally, they could help to further elucidate the risks and benefits of sulforaphane, a potential dietary phytochemical that has been proposed as a safe 'nutraceutical' compound to reduce cancer risk.

描述（由申请人提供）：在美国，不良药物相互作用（ADI）是一个主要的公共卫生问题。导致ADI和治疗功效失败的主要贡献者是遗传变异性和/或环境诱导的（包括饮食）肝药物处置的变化。细胞色素P450 3A4（CYP3A4）负责众多异种生物的肝和肠道代谢，包括药物化合物，一些癌和几种重要的内源性类固醇。 CYP3A4的组成型和诱导表达受多种不同的转录因子/途径的调节。 CYP3A4活性最重要的决定因素之一是激素核受体类固醇和异种生物受体（SXR；也称为妊娠X受体PXR）。许多药物和非药物化学物质通过充当SXR配体诱导CYP3A4活性，并可能引起严重的不良药物相互作用并改变治疗功效。在最初研究饮食植物化学的化学预防作用的研究中，我们发现SFN在人肝细胞中引起了CYP3A4的显着下调。然后，我们在人类源自肠细胞（LS-180）中验证了这种作用，然后证明SFN是在低微摩尔浓度下与SXR结合的有效拮抗剂。其他研究表明，这是一种特定的物种（人），与啮齿动物和人类之间的SXR配体的已知差异一致。在这笔赠款中，我们建议：1）进一步阐明SFN阻断SXR功能的分子机制； 2）评估SFN的结构类似物，以鉴定更有效和/或特定的SXR拮抗剂； 3）利用“人源化” SXR小鼠和其他体内方法来建立人类反应的动物模型，4）进行一系列人类喂养研究，以确定西兰花芽芽中的SFN是否降低了人类CYP3A4的基础表达和/或对Rifampicin介导的CYP3A4诱导的诱导率，该剂量降低了CYP3A4，测量的MIDAZOAZOLAM透明度。如果基本喂养研究确定了对CYP3A4的影响，则提出了其他喂养研究来检查其他SFN类似物，并进一步表征了剂量和时间的影响。这些结果可能会导致重要的新治疗方法和饮食方法，从而减少不良药物反应。它们还可以帮助解释CYP3A4中数十年来的大型个体间变异性。最后，他们可以帮助进一步阐明Sulforaphane的风险和益处，Sulforaphane是一种潜在的饮食植物化学物质，被认为是一种安全的“营养”化合物，以降低癌症的风险。