NUR77 Agonists: New Targets for Pancreatic Cancer Chemotherapy

描述（由申请人提供）：孤儿受体的神经生长因子I-B（NGFI-B）家族包括NGFI-B？（Nur77，TR3），NGFI-B？（Nurr 1）和NGFI-B？（Nor 1）和NGFI-B蛋白的配体尚未报道。细胞凋亡/分化诱导剂通过核（反式激活）途径或通过Nur 77的核-线粒体或核-胞质易位激活Nur 77依赖性细胞凋亡。我们现在已经首次确定了至少三种化合物，激活野生型Nur 77的反式激活试验，这种反应需要Nur 77的配体结合结构域（LBD）。Nur 77活性的1，1-二（3 '-吲哚基）-1-（对位取代苯基）甲烷含有CF 3（DIM-C-pPhCF 3）、H（DIM-C-Ph）和OCH 3（DIM-C-pPhOCH 3）取代基。这些C-取代的二吲哚甲烷（DIM）诱导胰腺癌细胞凋亡通过核途径，我们假设，C-取代的DIM代表一类独特的配体，激活Nur 77和诱导胰腺癌细胞凋亡。在目的1中，将在表达Nur 77蛋白的六个胰腺癌细胞系中确定通过一系列C-取代的DIM的环和苯基取代的衍生物对Nur 77的结构依赖性活化。最具活性的化合物（至少3种）将用作原型Nur 77激动剂，用于研究电泳迁移率变动试验中的配体依赖性Nur 77-DNA结合以及配体诱导的Nur 77-辅激活因子相互作用和增强的反式激活。目的2将集中于Nur 77激动剂诱导凋亡途径，并将这些反应与在选定的胰腺癌细胞系中观察到的凋亡诱导剂（TPA，丁酸盐和类维生素A CD 437）进行比较。这种方法将解决以前的报告中的明显差异，并区分配体激活的Nur 77（核）与非核途径诱导细胞凋亡。此外，还将研究Nur 77激动剂诱导促凋亡基因表达的分子机制。在目的3中，将测定Nur 77激动剂的体内抗肿瘤活性。拟议的研究将确定Nur 77激活的作用机制，所选的C-取代的DIM是这种孤儿受体的第一个已知配体。这些研究将有助于突出选择性Nur 77调节剂作为治疗胰腺癌的新型化疗药物的潜在作用。

DESCRIPTION (provided by applicant): The nerve growth factor I-B (NGFI-B) family of orphan receptors include NGFI-B? (Nur77, TR3), NGFI-B? (Nurr1), and NGFI-B? (Nor1), and ligands for NGFI-B proteins have not been reported. Apoptosis/differentiation inducing agents activate Nur77-dependent apoptosis via nuclear (transactivation) pathways or by nuclear-mitochondrial or nuclear-cytosolic translocation of Nur77. We have now identified for the first time at least three compounds that activate wild-type Nur77 in transactivation assays, and this response requires the ligand binding domain (LBD) of Nur77. The Nur77-active 1,1-bis(3'-indolyl)-1-(p-substitutedphenyl)methanes contain CF3 (DIM-C-pPhCF3), H (DIM-C-Ph), and OCH3 (DIM-C-pPhOCH3) substituents. These C-substituted diindolylmethanes (DIMs) induce apoptosis in pancreatic cancer cells through a nuclear pathway, and we hypothesize that C-substituted DIMs represent a unique class of ligands that activate Nur77 and induce apoptosis in pancreatic cancer cells. In Aim 1, the structure-dependent activation of Nur77 by a series of ring- and phenyl-substituted derivatives of C-substituted DIMs will be determined in six pancreatic cancer cell lines that express Nur77 protein. The most active compounds (at least 3) will be used as prototypical Nur77 agonists for investigating ligand-dependent Nur77-DNA binding in electrophoretic mobility shift assay and ligand-induced Nur77-coactivator interactions and enhanced transactivation. Aim 2 will focus on induction of apoptotic pathways by Nur77 agonists and compare these responses to those observed for apoptotic inducing agents (TPA, butyrate and the retinoid CD437) in selected pancreatic cancer cell lines. This approach will resolve apparent differences in previous reports and distinguish between ligand-activated Nur77 (nuclear) vs. extranuclear pathways for induction of apoptosis. Moreover, the molecular mechanisms of Nur77 agonist-induced expression of pro-apoptotic genes will also be investigated. In Aim 3, the in vivo antitumorigenic activity of Nur77 agonists will be determined. The proposed studies will define the mechanism of action of Nur77 activation by selected C-substituted DIMs that are the first known ligands for this orphan receptor. These studies will serve to highlight the potential role of selective Nur77 modulators as a new class of chemotherapeutic drugs for treatment of pancreatic cancer.