The Cholangiocyte Primary Cilium as a Tumor Suppressor Organelle

 描述(申请人提供)：胆管癌(CCA)是一种致命的恶性肿瘤，具有胆道分化的特点，治疗选择有限。因此，该计划的长期目标是了解CCA的发病机制，并为其治疗开发新的治疗方法。目前的总体目标是探讨胆管细胞降解在CCA的发生和发展中的重要性。中心假说是，在CCA中，由Exportin-5/miRNA/HDAC6失调引起的原发纤毛吸收破坏了正常的、纤毛依赖的、肿瘤抑制信号，这些信号保护胆管细胞免受恶性转化。具体目标#1将通过检验一种假说来描述CCA中纤毛丢失的机制，该假说认为核质到细胞质的转运蛋白exportin-5的失调会导致肿瘤抑制miRNAs的减少，如mir-433和mir-22，从而导致HDAC6蛋白水平上调和纤毛丢失。具体目标#2将通过测试这一假说来评估纤毛丢失的后果，该假说促进正常的、纤毛依赖的、肿瘤抑制因子外部信号的脱离，导致持续的MAPK和Hedgehog信号、P53下调和细胞生长。最后，在具体目标#3中，我们将评估纤毛挽救在CCA动物模型中的结果。我们的工作假设是，通过靶向HDAC6(shRNAs或药理学)或mir433和mir-22(miR模拟物)恢复初级纤毛，通过挽救胆管细胞传递纤毛依赖肿瘤抑制物外部信号的能力来改善肿瘤进展。该方法是创新的，因为它提出利用胆管细胞初级纤毛的感觉功能诱导的信号通路作为一种肿瘤抑制机制。纤毛最近才成为密集研究的对象，由于纤毛发生可能是可逆的，因此针对纤毛的研究是重要的。这项拟议的研究具有重要意义，因为为了开发更好的治疗方法，必须确定调控疾病启动和进展的细胞网络。本提案的结果将揭示控制恶性细胞增殖的纤毛依赖的基本机制的新的和普遍的信息，并为基于恢复原发纤毛完整性的看似合理的新的抗癌治疗提供基础。

 DESCRIPTION (provided by applicant): Cholangiocarcinoma (CCA) is a lethal malignancy with features of biliary tract differentiation with limited therapeutic options. Thus, the long-ter goals of this program are to understand the pathogenesis of CCA and develop new therapies for its treatment. The current overall objective is to explore the importance of cholangiocyte deciliation, a potential pathologic process recently discovered by us, in the pathogenesis and progression of CCA. The CENTRAL HYPOTHESIS is that in CCA, primary cilia resorption resulting from exportin-5/miRNA/HDAC6 dysregulation disrupts the normal, ciliary dependent, tumor-suppressor signals that protect cholangiocytes from malignant transformation. Specific Aim #1 will characterize the mechanisms of ciliary loss in CCA by testing the hypothesis that the dysregulation of the nuclear-to-cytoplamic transporter, exportin-5, results in a decrease in tumor suppressing miRNAs, such as mir-433 and mir-22, inducing the upregulation of HDAC6 protein levels and ciliary loss. Specific Aim #2 will assess the consequences of ciliary loss by testing th hypothesis that promotes the disengagement of the normal, ciliary-dependent, tumor- suppressor external cues resulting in persistent MAPK and Hedgehog signaling, p53 downregulation, and cell growth. Finally, in Specific Aim #3 we will evaluate the outcomes of cilia rescue in CCA animal models. Our working hypothesis is that the restoration of primary cilia by targeting HDAC6 (shRNAS or pharmacologically), or mir433 and mir-22 (miR-mimetics), ameliorates tumor progression by rescuing the cholangiocyte ability to transmit ciliary dependent tumor suppressor external cues. The approach is innovative because it proposes to utilize the signaling pathways induced by the sensory functions of primary cilia in cholangiocytes as a tumor suppressive mechanism. Cilia have only recently become the subject of intense investigation, and since ciliogenesis is potentially reversible, studies directed at cilia are important. The proposed research is significant because it is imperative to identify the cellular networks regulating disease initiation and progression in order to develop better therapies. The results of the present proposal will uncover novel and generalizable information on fundamental, ciliary-dependent mechanisms controlling the proliferation of malignant cells and provide the foundation for plausible, novel anti-cancer therapies based on the restoration of primary cilia integrity.