Regulation of a Tumor Target Through Steroid Receptors

通过类固醇受体调节肿瘤靶点

• 批准号: 7007740
• 负责人: Manohar Ratnam
• 金额: $ 26.48万
• 依托单位: UNIVERSITY OF TOLEDO HEALTH SCI CAMPUS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7007740
• 关键词: amidohydrolases; androgen receptor; apical membrane; biological signal transduction; chromatin immunoprecipitation; corticosteroid receptors; estrogen receptors; female reproductive system neoplasm; gel mobility shift assay; polymerase chain reaction; progesterone receptors; receptor expression; steroid hormone receptor; transcription factor

DESCRIPTION (provided by applicant): In the limited number of normal tissues in which the folate receptor (FR) type alpha is expressed, the receptor is restricted to apical (luminal) surfaces, where it is inaccessible via the circulation. As a consequence, FR-alpha is regarded as a promising tumor target, particularly in major subtypes of gynecological cancers, for the selective delivery of a broad range of diagnostic and therapeutic agents through the blood stream. Even though a large and growing body of evidence from pre-clinical and clinical studies supports the feasibility of developing such diagnostics/therapies, translating the success obtained in animal models to human cancer is confounded by variability and heterogeneity in the expression levels of FR-alpha in the tumors. We have previously shown that antiestrogens will up-regulate the FR-alpha gene in estrogen receptor (ER)-positive tumors. We now show that the FR-alpha gene can be transcriptionally modulated by the progesterone receptor (PR), the glucocorticoid receptor (GR) and the androgen receptor (AR), greatly expanding the histologic range of FR-alpha+ tumors in which the receptor expression may be optimized for effective targeting. Agonists of PR, GR and AR enhance FR-alpha transcription by apparently distinct mechanisms and in the absence of classical hormone response elements and further, trichostatin A, a histone deacetylase (HDAC) inhibitor, appears to potentiate these effects, overcoming cell context-dependent co-regulator limitations. The actions of PR, GR and AR on the FR-alpha gene will be studied in sufficient mechanistic detail in vitro and in the physiologic milieu of animal tumor xenograft models to establish the biological contexts and clinical conditions in which FR-alpha expression may be controlled through these nuclear receptors. The specific aims are: (i) Mechanistic studies of nuclear receptor modulation of FR-alpha: Elucidate the individual modes of action (direct vs. indirect) of the nuclear receptors, establish co-regulator requirements/limitations, map the sites of action of PRa, PRb, GR and AR in the FR-alpha promoter, identify and relate the dynamics of the relevant transcription factors, examine the effects of well tolerated HDAC inhibitors and test various synthetic agonists; (ii) Develop and study stable recombinant cell lines that will express the steroid receptors individually and in combination, together with FR-alpha to reflect their in vivo (co)expression patterns in tumors and characterize individual and combined nuclear receptor mediated modulation of FR-alpha in these cells in vitro and mechanisms of potential cross-talk; (iii) Test the effects of the appropriate steroid receptor agonists and antagonists and HDAC inhibitors in animal tumor xenograft models using representative model cell lines developed in Aim ii and FR-targeted imaging agents. It is anticipated that the proposed studies will systematically establish a foundation for clinical trials of this concept of manipulating tumor tissues to enhance the sensitivity of whole body imaging and the therapeutic efficacy of FR-targeted agents.

描述（由申请人提供）：在表达叶酸受体（FR）型α型的正常组织中，受体仅限于顶端（腔）表面，在该表面上，通过循环无法访问它。结果，FR-α被视为有前途的肿瘤靶标，尤其是在妇科癌的主要亚型中，可以选择性地通过血流递送广泛的诊断和治疗剂。即使来自临床前和临床研究的大量证据支持了开发此类诊断/疗法的可行性，但将动物模型中的成功转化为人类癌症的成功还是被肿瘤中FR-Alpha表达水平的可变性和异质性混淆。我们先前已经表明，抗雌激素将上调雌激素受体（ER）阳性肿瘤中的FR-α基因。现在，我们表明，可以通过孕酮受体（PR），糖皮质激素受体（GR）和雄激素受体（AR）在转录调节FR-α基因，从而大大扩展了FR-Alpha+肿瘤的组织学范围，其中可以优化受体表达的有效靶向。 PR，GR和AR的激动剂通过明显不同的机制以及在没有经典的激素反应元件的情况下增强了FR-Alpha转录，此外，Trichostatin A（一种组蛋白脱乙酰基酶（HDAC）抑制剂）似乎可以促进这些影响，从而克服了这些效应，克服了基于细胞的环境相关的共同调节器的限制。 PR，GR和AR对FR-α基因的作用将在体外和动物肿瘤异种移植模型的生理环境中以足够的机械细节进行研究，以建立可以通过这些核受体控制FR-α表达的生物学环境和临床条件。具体目的是：（i）FR-ALPHA的核受体调制的机理研究：阐明核受体的各个作用模式（直接与间接），建立共同调节剂的需求/限制，绘制PRA，PRB，PRB，GR和AR在FR-Alpha启动子中的各种验证和相关效果的动态，并将其验证的各种验证的动态验证，绘制pra，PRB，GR和AR的作用部位，并将其映射。合成激动剂； （ii）开发和研究稳定的重组细胞系，这些细胞系将单独和结合表达类固醇受体，并与FR-Alpha一起反映其在肿瘤中的体内（CO）表达模式，并表征了这些细胞中的FR-Alpha的个体和联合核受体介导的在这些细胞中的FR-Alpha的调节。 （iii）使用在AIM II和FR靶向成像剂中开发的代表性模型细胞系中，适当的类固醇受体激动剂和拮抗剂和HDAC抑制剂在动物肿瘤异种移植模型中的影响。预计拟议的研究将系统地为操纵肿瘤组织的临床试验建立基础，以增强全身成像的敏感性和靶向FR靶向药物的治疗功效。