Targeted Approach for Prevention and Therapy of Colorectal Cancer

描述(申请人提供)：结直肠癌(CRC)是美国癌症发病率和死亡率的主要原因之一。从正常肠上皮组织到转移性肿瘤的多步骤进展是多种调节机制受损的结果，这些调节机制涉及调节正常的增殖、分化、迁移和凋亡模式的关键信号通路。其中，Wnt和RAS信号通路在调节肠道细胞增殖中起着至关重要的作用，也是最常受到干扰的 在结直肠癌方面。尽管有这些知识，但很少有治疗策略被开发出来专门针对这些特定途径的组件，而且没有一种获得FDA的批准。本课题组已发现Kr？ppel-like factor5(KLF5)是肠上皮细胞增殖的重要调节因子，在肠道肿瘤发生过程中经常过度表达。最近，我们已经将KLF5与结直肠癌发生中的RAS和WNT信号通路联系起来。我们的团队还观察到，KLF5表达的减少会导致携带肿瘤抑制基因APC胚系突变的小鼠肠道肿瘤形成减少，APC是Wnt途径的关键组成部分，或者APC和KRAS联合突变。利用超高通量筛选(UHTS)方法，通过靶向KLF5的表达来确定具有潜在治疗作用的新的先导化合物，然后对生成的HITS进行结构活性研究，我们确定了一种新的小分子ML264，它有效和选择性地阻断KLF5的表达并降低结直肠癌细胞系的增殖。我们建议进一步研究ML264抑制KLF5表达的机制，并评估其作为结直肠癌治疗剂的疗效。这项研究计划的长期目标是开发和表征用于预防和/或治疗结直肠癌的新型治疗剂。基于我们的结果，我们提出了中心假设，即化合物ML264通过降低体内KLF5的表达来防止结直肠癌的发生和发展。为了验证这一假说，我们提出了三个具体目标：1)研究ML264调节KLF5在CRC细胞中表达的机制；2)评估化合物ML264在预防结直肠癌小鼠模型中的临床前疗效；以及3)产生具有完全合适的药代动力学特性的优化的ML264类似物，用于抗癌治疗。本申请中提出的实验将对ML264及其优化模拟的结构和功能提供明确的改进。这一努力的目的是获得耐受性好、寿命长的生物可用化合物，适用于结直肠癌的治疗。

DESCRIPTION (provided by applicant): Colorectal cancer (CRC) is one of the leading causes of cancer morbidity and mortality in the United States. The multistep progression from normal intestinal epithelial tissue to metastatic neoplasm results from impairment of multiple regulatory mechanisms involving critical signaling pathways that regulate normal patterns of proliferation, differentiation, migration, and apoptosis. Among these, the Wnt and RAS signaling pathways play crucial roles in governing intestinal cell proliferation and are the most frequently perturbed in colorectal cancer. Despite this knowledge, few therapeutic strategies have been developed to specifically target components of these particular pathways, and none have gained FDA approval. Our group has identified Kr¿ppel-like factor 5 (KLF5) as an important regulator of intestinal epithelial cell proliferation that is frequently overexpressed during intestinal tumorigenesis. Recently, we have linked KLF5 to both the RAS and Wnt signaling pathways in colorectal carcinogenesis. Our group has also observed that reduction in KLF5 expression leads to reduced intestinal tumor formation in mice harboring a germline mutation in the tumor suppressor gene, APC, a crucial component of the Wnt pathway, or combined APC and KRAS mutations. Using an ultrahigh-throughput screening (uHTS) approach to identify novel lead compounds with potential therapeutic benefits by targeting KLF5 expression, followed by structure-activity studies on the resultant hits, we identified a novel small molecule, ML264, which potently and selectively blocks KLF5 expression in and decreases proliferation of colorectal cancer cell lines. We propose to further characterize the mechanisms by which ML264 inhibits KLF5 expression and evaluate its efficacy as a therapeutic agent for colorectal cancer. The Long-Term Goal of this research proposal is to develop and characterize novel therapeutic agents for the prevention and/or treatment of colorectal cancer. Based on our results we propose the Central Hypothesis that the compound ML264 prevents colorectal cancer development and progression by decreasing KLF5 expression in vivo. To test this hypothesis we propose three Specific Aims: 1) To investigate the mechanism by which ML264 regulates KLF5 expression in CRC cells; 2) To evaluate the preclinical efficacy of compound ML264 in preventing colon cancer formation in mouse models of colorectal cancer; and 3) To generate optimized analogs of ML264 with fully appropriate pharmacokinetic properties for anticancer therapy. The experiments proposed in this application will provide a definitive refinement of the structure and function of ML264 and its optimized analogs. The intent of this effort is to obtain well-tolerated, long-lived bioavailable compounds suitable for therapeutic use in colorectal cancer.