Inhibition of Wnt/B-Catenin Signaling in Colorectal Cancer Therapy

描述（由申请人提供）：Wnt信号转导通路，以调节参与细胞增殖、迁移、自我更新和存活的基因而闻名，在许多类型的癌症中被失调，特别是结直肠癌（CRC），其中超过80%的散发性结直肠癌中发生该通路的激活突变。因此，抑制该途径的药物作为新一代创新治疗剂的基础受到高度追捧。不幸的是，用类似药物的小分子靶向这一途径的能力存在差距，这一差距是发现靶向这一途径缺陷的药物的障碍。作为我们从床到床的努力的一部分，我们最近报告了fda批准的药物niclosamide通过一种涉及内化卷曲受体和下调disheveled和ß-catenin的新机制抑制Wnt/ß-catenin信号。随后的研究表明，氯硝柳胺有望治疗结直肠癌。具体来说，我们证明了氯硝胺选择性地抑制结直肠癌细胞系和新切除的人类结直肠癌肿瘤中的肿瘤细胞增殖，包括APC和ß-catenin突变的细胞。重要的是，在小鼠异种移植模型中，氯硝胺还能抑制Wnt/ß-catenin信号传导和体内结直肠癌肿瘤生长，而没有明显的毒性迹象。基于我们的发现，拟议的临床试验正在进行中，在结肠镜检查前的磨合期后，将对氯硝沙胺在息肉中的Wnt抑制活性进行组织化学评估。鉴于长期以来在生物化学靶点上的努力和空白，fda批准的药物氯硝柳胺抑制这一途径的发现具有重要意义，并为开发创新的临床药物提供了机会。然而，重新利用氯硝柳胺治疗转移性结直肠癌可能受到其驱虫作用机制和次优全身生物利用度的限制。具有更好效力、选择性和药代动力学特性的生化靶点和抑制剂的鉴定为改善结直肠癌的治疗提供了潜力。我们的工作提出了一个假设，即通过氯硝柳胺和优化的衍生物调节Wnt信号传导对治疗结直肠癌是有用的，并且通过结合可用于药物开发的特定蛋白质靶点发生抑制。本提案的目的是确定尼科罗胺介导的Wnt信号抑制的靶点和机制，以便为尼科罗胺的临床试验设计提供信息，并为未来的临床研究开发更有效和选择性的具有适当PK特性的同类最佳Wnt信号抑制剂。该提案的具体目标是：(1)定义结构-活性

DESCRIPTION (provided by applicant): The Wnt signal transduction pathway, known for regulating genes involved in cell proliferation, migration, self- renewal, and survival, is dysregulated in many types of cancers, particularly colorectal cancer (CRC) where activating mutations in this pathway occur in over 80% of sporadic colorectal cancers. As a result, drugs that inhibit the pathway are highly sought-after as the basis of a new generation of innovative therapeutic agents. Unfortunately, a gap exists in the ability to target the pathway with small, drug-like molecules, a gap that is the barrier to discovering drugs targeting defects in this pathway. As part of our bed-to-bedside effort, we recently reported the FDA-approved drug niclosamide inhibits Wnt/ß-catenin signaling via a novel mechanism involving internalization of Frizzled receptors and downregulation of Dishevelled and ß-catenin. Subsequent studies showed that niclosamide holds promise to treat colorectal cancer. Specifically, we demonstrated that niclosamide selectively inhibited tumor cell proliferation in colorectal cancer cell lines and freshly resected human colorectal tumors, including cells harboring mutations in APC and ß-catenin. Importantly, niclosamide also inhibited Wnt/ß-catenin signaling and colorectal tumor growth in vivo without obvious signs of toxicity in mouse xenograft models. Based on our discovery, proposed clinical trials are being developed, in which the Wnt inhibitory activity of niclosamide in polyps will be evaluated histochemically after a run-in phase prior to colonoscopy. Given the long-standing efforts and gap in biochemical targets amenable to drug discovery, the finding that a FDA-approved drug niclosamide inhibits the pathway is highly significant and offers an opportunity to develop innovative clinical agents. Nonetheless, repurposing niclosamide to treat metastatic CRC may be limited by its anthelmintic mechanism of action and suboptimal systemic bioavailability. Identification of the biochemical target and inhibitors with better potency, selectivity and pharmacokinetic properties offer the potential to improve treatment of CRC. Our work led to the hypothesis that modulating Wnt signaling by niclosamide and optimized derivatives are useful to treat CRC and that inhibition occurs by binding a specific protein target that can be exploited for drug discovery. The objective of this proposal is to identify the target and define the mechanism of niclosamide-mediated inhibition of Wnt signaling in order to inform clinical trial designs with niclosamide, and to develop more potent and selective best-in-class Wnt signaling inhibitors with appropriate PK properties for future clinical studies. The specific aims of the proposal are to: (1) To define Structure-Activity Relationships (SAR) of niclosamide driving Wnt inhibitory activity and to identify more potent and selective inhibitors of Wnt signaling; (2) To delineate the molecular mechanism underlying niclosamide-mediated inhibition of Wnt signaling and to identify the molecular target of niclosamide; and (3) To determine the tumor inhibitory effect of novel niclosamide derivatives in vivo. Funding of this proposal will enable us to identify the biological target and identify inhibiors to progress toward clinical studies to overcome a barrier in the discovery of Wnt/ß-catenin inhibitors. Thus accelerate the translational application of niclosamide and its derivatives to improve patient survival.