Primary Cilia and Malignant Transformation

描述(由申请人提供)：我们的目标是探索依赖于初级纤毛完整性的新的肿瘤抑制机制。我们的初步数据显示，胆管癌细胞中没有纤毛；因此，纤毛功能障碍可能与癌症的发生有关。导致这些肿瘤细胞纤毛减少的机制以及这种丢失的后果尚不清楚。我们假设，胆管细胞初级纤毛的功能完整性是传递环境刺激所必需的，并产生起肿瘤抑制作用的细胞内信号。我们认为，在胆管细胞癌中，(I)microRNAs表达减少(即mir-433、mir-22、mir-141、mir-200)导致HDAC6的过度表达，HDAC6是一种细胞质脱乙酰酶，可诱导纤毛再吸收，从而导致胆管细胞初级纤毛减少；以及(Ii)纤毛丢失导致环境与细胞内部的脱节，导致致癌因素的抑制和癌症的发生。在特定的目标#1中，我们将描述纤毛丢失对正常胆管细胞表型的影响。我们的工作假设是，基于初步数据，初级纤毛及其多感官功能诱导的细胞内信号限制了Hedgehog和MAPK通路，这两个通路参与了癌症的发展。在特定的目标#2中，我们将表征CCA中下调的特定miRNAs对胆管细胞纤毛表达的影响。我们的工作假设是，CCA中mir-433、mir-22、mir-141和/或mir-200的下调导致HDAC6的过度表达和纤毛的吸收。最后，在具体目标#3中，我们将评估纤毛修复对肿瘤细胞的影响。我们的工作假设是，这种干预是减少细胞生长和胆管癌细胞去分化的潜在方法。本研究的结果将提供有关控制肿瘤细胞增殖的纤毛依赖机制的新信息，并将为基于挽救原发纤毛结构和功能的合理的抗癌治疗提供基础。

DESCRIPTION (provided by applicant): Our goal is to explore novel tumor suppressor mechanisms dependent on the integrity of primary cilia. Our preliminary data shows the absence of cilia in cholangiocarcinoma cells; therefore, ciliary dysfunction may be associated with cancer development. The mechanisms leading to ciliary reduction in these tumor cells as well as the consequences of such a lost remain unknown. We HYPOTHESIZE that the functional integrity of cholangiocyte primary cilia is required for the transduction of environmental stimuli, and generates intracellular signals that function as tumor suppressors. We propose that in cholangiocarcinoma, (i) decreased microRNAs expression (i.e. mir-433, mir-22, mir-141, mir-200) leads to overexpression of HDAC6, a cytoplasmic deacetylase that induces ciliary resorption, and the subsequent reduction of cholangiocyte primary cilia; and (ii) ciliary loss generates the disengagement between the environment and the cell interior resulting in derepression of tumorigenic factors and cancer development. In Specific Aim #1 we will characterize the effect of ciliary loss on the normal cholangiocyte phenotype. Our working hypothesis, based upon preliminary data, is that primary cilia and the intracellular signals induced by their multisensory functions are constraining Hedgehog and MAPK pathways, which are involved in cancer development. In Specific Aim #2 we will characterize the effect of specific miRNAs downregulated in CCA on cholangiocyte ciliary expression. Our working hypothesis is that the downregulation of mir-433, mir-22, mir-141, and/or mir-200 in CCA induces the overexpression of HDAC6 and the resorption of cilia. Finally, in Specific Aim #3 we will evaluate the effect of cilia restoration on tumor cells. Our working hypothesis is that this intervention isa potential approach for decreasing cell growth and dedifferentiation of cholangiocarcinoma cells. The results of the present proposal will provide novel information regarding the ciliary-dependent mechanisms controlling the proliferation of tumor cells; and will provide the foundation for a plausible anti-cancer therapeutic treatment based on the rescue of primary cilia architecture and function.