Cyclin D as a Retinoid Differentiation Molecular Target

描述（由申请人提供）：此NIH RO1-CA111422的修订竞争性续期申请：“Cyclin D as a Retinoid Differentiation Molecular Target”继续深入研究Cyclin D1作为全反式维甲酸（RA, Retinoid）反应的主要靶点的重要作用，现在研究了它如何也是hedgehog （Hh）途径的靶点，也是类维甲酸调节的，但以一种以前未被认识的方式对生殖细胞肿瘤（gct）的分化和自我更新至关重要，gct是人类胚胎干细胞（ES）的恶性对照。有趣的是，我们的研究揭示了一种独特的类维生素a反应：诱导patch -1 （Ptch1）受体，该受体驱动自我更新的丧失并调节分化。Ptch1是Hh通路的靶基因，被用作Hh激活的读出基因。我们的假设是RA通过一种新的机制来抑制Hh信号，Ptch1诱导，独立于smoothened (Smo)，这是Hh抑制剂（如环巴胺）唯一公认的靶点。认识到这一点的重要性来自于我们团队成功地利用基因分析研究来识别胚胎癌（ECs）中独特的类维生素a靶点。本研究探索了一种独特的调节内皮细胞和其他肿瘤自我更新的药理学机制。我们渴望追求的具体目标是：(1)发现RA诱导Ptch1是否是独立于Smo的EC细胞参与的一般机制，以及这是否是触发多能EC细胞最终分化的药物的共同途径；(2)通过对影响Hh靶点、调节细胞凋亡、自我更新或分化反应的Ptch1表达的增加和减少的研究，探讨该通路的功能重要性；(3)通过了解RA是否在胚胎干细胞（或其他癌症或干细胞）以及Ptch1报告小鼠中诱导Ptch1，并通过确认Ptch1及其靶点在独特的肿瘤库中差异表达，从而阐明体内和临床相关性，从而全面分析分化（成熟畸胎瘤）与未分化（EC） gct。这已经成功地揭示了d型细胞周期蛋白是人类EC生长、化疗反应和分化的关键调节因子。这些独特的体外、体内和临床资源，结合药理学、细胞和分子生物学方法，将为Hh通路调节GCT或其他肿瘤的凋亡、自我更新或分化提供重要见解。

DESCRIPTION (provided by applicant): This revised competing renewal application of NIH RO1-CA111422: "Cyclin D as a Retinoid Differentiation Molecular Target" continues in depth studies of the important role of cyclin D1 as a major target of all-trans- retinoic acid (RA, retinoid) response by now examining how this is also a target of the hedgehog (Hh) pathway, also retinoid regulated, but in a previously unrecognized manner critical for differentiation and self- renewal of germ cell tumors (GCTs), the malignant counterparts of human embryonal stem (ES) cells. Intriguingly, our studies uncovered a unique retinoid response: induction of the Patched-1 (Ptch1) receptor which drives loss of self-renewal and regulates differentiation. Ptch1 is a target gene of the Hh pathway and is used as a read-out of Hh activation. The hypothesis explored is RA represses Hh signaling by a novel mechanism, Ptch1 induction, independent of smoothened (Smo), the only recognized target of Hh inhibitors, such as cyclopamine. Recognizing importance of this came from mining gene profiling studies successfully used by our team to identify unique retinoid targets in embryonal cancers (ECs). This proposal explores a distinct pharmacologic mechanism regulating self-renewal of ECs and likely other tumors. We are eager to pursue the Specific Aims that: (1) discover whether RA induction of Ptch1 is a general mechanism engaged by EC cells independent of Smo and if this is a common pathway of agents that trigger terminal differentiation of pluripotent EC cells; (2) probe the functional importance of this pathway by gain and loss of Ptch1 expression studies that affect Hh targets and regulate apoptosis, self-renewal or differentiation response; and (3) elucidate in vivo and clinical relevancy by learning whether RA induces Ptch1 in ES cells (or other cancer or stem cells) as well as in Ptch1 reporter mice and by confirming Ptch1 and its targets are differentially expressed in a unique tumor bank enabling comprehensive analyses of differentiated (mature teratoma) versus undifferentiated (EC) GCTs. This has successfully uncovered D-type cyclins as key regulators of human EC growth, chemotherapy response and differentiation. These unique in vitro, in vivo, and clinical resources with pharmacologic, cell and molecular biologic approaches will provide critical insights into the Hh pathway in regulating apoptosis, self-renewal or differentiation of GCT or other tumors.