Genetic dissection and inhibitor targeting of Rac signaling in pancreatic cancer.

描述（由申请人提供）：胰腺癌（PDAC）是一种致命疾病，5年生存率为4%，目前的治疗选择很少且无效。因此，对这种癌症的新型靶向治疗仍然是迫切需要的。最近的研究暗示了激活Rac小GTPase的信号通路在PDAC致瘤生长和侵袭中的重要性。因此，我们假设Rac信号抑制剂将是PDAC治疗的有效策略。然而，尽管Rac和其他小gtp酶（如Ras）已被证实是关键的疾病驱动因素，但目前尚未被认为是有吸引力的或可用于癌症治疗的靶点。虽然最近已经建立了合成致死性遗传筛选来确定Ras致癌的关键成分，但尚未确定Rac的此类哺乳动物细胞测定。因此，需要新的方法。我们已经建立、验证并执行了一种新的基于秀丽隐杆线虫的正选择功能筛选，用于(a)鉴定功能对Rac活性至关重要的基因，(b)高通量化学文库筛选，以鉴定Rac致死率的小分子抑制剂。在我们的模型中，秀丽隐杆线虫的Rac同源物CED-10的组成激活导致100%的致死率，从而为我们的遗传和药理学筛选提供了积极的选择。该模型结合了遗传适应性、低成本和与全基因组遗传和高通量化学筛选相容的培养条件。我们将秀丽隐杆线虫模型与哺乳动物细胞培养和小鼠模型相结合进行验证和进一步分析，可能会发现阻断PDAC中Rac的新方法。如果成功，我们的概念验证研究将表明，基于秀丽隐杆线虫的模型可以有效地用于药物发现，并将激发人们对靶向小gtpase和开发其他基于生物的药物发现功能筛选的新兴趣。我们提出了三个目标来实现这一目标：(1)确定其破坏特异性抑制活化CED-10/Rac的基因，(2)确定抑制CED-10/Rac致死率的小分子抑制剂，以及(3)应用基于细胞和小鼠的遗传定义的Rac信号成分和小分子抑制剂的验证。相关性：胰腺癌是一种5年生存率为4%的致命疾病，有效的治疗方案很少且无效。传统的药物发现方法并不能有效地解决这一问题。我们建议应用一种创新的新模型系统，专注于这种致命疾病的有效新治疗靶点的药物发现

DESCRIPTION (provided by applicant): Pancreatic cancer (PDAC) is a lethal disease with 5-year survival of 4% and current therapeutic options are few and ineffective. Therefore, there remains a dire need for novel targeted therapies for this cancer. Recent studies have implicated the importance of signaling pathways that activate the Rac small GTPase in PDAC tumorigenic growth and invasion. We therefore hypothesize that inhibitors of Rac signaling will be an effective strategy for PDAC treatment. However, while well validated as key disease drivers, Rac and other small GTPases (e.g. Ras) are not currently considered to be attractive or druggable targets for cancer treatment. While recent synthetic lethality genetic screens have been established to identify key components of Ras oncogenesis, no such mammalian cell assay has been identified for Rac. Therefore, novel approaches are needed. We have established, validated and performed a novel C. elegans-based positive-selection functional screen for (a) identifying genes whose functions are critical for Rac activity and (b) high-throughput chemical library screening to identify small molecule inhibitors of Rac lethality. In our model, constitutive activation of the Rac ortholog in C. elegans, CED-10, causes 100% lethality, thus providing positive selection for our genetic and pharmacologic screens. This model combines genetic amenability, low cost and culture conditions compatible with genome wide genetic and high-throughput chemical screening in a whole animal context. Our application of this C. elegans model, when coupled with mammalian cell culture and mouse models for validation and further analyses, may identify novel approaches for blocking Rac in PDAC. If successful, our proof-of-concept studies will show that C. elegans-based models can be effective for drug discovery and will stimulate renewed interest both in targeting small GTPases and in development of other organism-based functional screens for drug discovery. We propose three aims to accomplish this goal: (1) identify the genes whose disruption specifically suppressed activated CED-10/Rac, (2) identify small molecule inhibitors that suppress CED-10/Rac lethality, and (3) apply cell- and mouse-based validation of genetically defined Rac signaling components and small molecule inhibitors. Relevance: Effective therapeutic options for pancreatic cancer, a lethal disease with 5-year survival of 4%, are few and ineffective. Traditional drug discovery approaches have not been effective in addressing this problem. We propose our application of an innovative new model system for drug discovery focused on a validated new therapeutic target for this deadly disease