Cyclin D as a Retinoid Differentiation Molecular Target

描述(由申请人提供)：NIH RO1-CA111422：“Cyclin D作为维甲酸分化分子靶点”的修订竞争更新申请继续深入研究细胞周期蛋白D1作为全反式维甲酸(RA，维甲酸)反应的主要靶点的重要作用，现在研究了这也是Hedgehog(HH)途径的靶标，该通路也受维甲酸调节，但对于生殖细胞肿瘤(GCTS)的分化和自我更新至关重要，而生殖细胞肿瘤(GCTS)是人类胚胎干细胞(ES)细胞的恶性对应分子。有趣的是，我们的研究揭示了一种独特的维甲酸反应：诱导Patted-1(Ptch1)受体，它驱动自我更新的丧失并调节分化。Ptch1是HH途径的靶基因，被用来读出HH的激活。研究的假设是RA通过一种新的机制ptch1诱导抑制HH信号，而不依赖于平滑(Smo)，Smo是环胺等HH抑制剂唯一识别的靶点。认识到这一点的重要性来自于挖掘基因图谱研究，我们的团队成功地使用这些研究来识别胚胎癌症(ECs)中独特的维甲酸靶点。这项建议探索了一种独特的药理学机制，调节内皮细胞和可能的其他肿瘤的自我更新。我们急于追求的具体目标是：(1)发现RA诱导ptch1是否是EC细胞独立于Smo参与的一般机制，以及这是否是触发多能EC细胞终末分化的共同途径；(2)通过影响HH靶点并调节细胞凋亡、自我更新或分化反应的ptch1表达的获得和丧失来探讨该途径的功能重要性；以及(3)通过了解RA是否在ES细胞(或其他癌症或干细胞)以及ptch1报告小鼠中诱导ptch1，并确认ptch1及其靶点在一个独特的肿瘤库中差异表达，从而全面分析分化(成熟畸胎瘤)和未分化(EC)GCTS，阐明体内和临床的相关性。这成功地发现了D-型细胞周期蛋白作为人类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途径调控GCT或其他肿瘤的凋亡、自我更新或分化提供关键的见解。

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.