Using Drosophila for in vivo drug screens to selectively target cancer stem cells

描述（由申请人提供）：越来越多的证据支持这样一种观点，即恶性肿瘤是由一群与正常成体干细胞具有相似生物学特性的肿瘤细胞引发和维持的。癌症干细胞（CSCs）能够在特定的癌症样本中产生所有类型的细胞。这些细胞被认为作为一个独特的群体存在于肿瘤中，并通过产生新的肿瘤引起复发和转移。针对这些癌症的一个合乎逻辑的治疗角度是针对干细胞本身。然而，这种方法需要能够反映csc的生物学和背景的筛选范例。协调干细胞增殖和分化的信号通路的复杂部署强调了肿瘤生物学的复杂性。因此，细胞系模型中传统的高通量细胞筛选不太可能提供最合适的检测，因为细胞脱离了其复杂的细胞环境（即生态位）。理想情况下，人们希望在整个动物中进行小分子筛选，以增加鉴定出的小分子在穿透组织时有效的机会，表现出很小的毒性，并特异性地影响csc。在这个应用中，我们建议在果蝇肠道中使用我们验证的人源化肿瘤模型来对影响CSCs的小分子进行大规模筛选（目的1）。我们已经开发出一种筛选方法，可以让我们在两年内筛选200,000个小分子。除了筛选外，我们还将进行一些验证研究，以表征它们的作用模式。我们的目标是专注于特异性影响CSCs而非野生型干细胞的生长抑制剂，以及特异性靶向Notch通路的药物，因为很明显这类药物可以有益于治疗哺乳动物结直肠癌（Aim 2）。总之，这些研究的结果将使我们能够确定一些对CSCs有效的小分子，特别是Notch活性的抑制剂。

DESCRIPTION (provided by applicant): There is a growing body of evidence that supports the idea that malignant tumors are initiated and maintained by a population of tumor cells that share similar biological properties to normal adult stem cells. Cancer stem cells (CSCs) have the ability to give rise to all cell types found in a particular cancer sample. Such cells are proposed to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors. A logical therapeutic angle to target these cancers is to target the stem cells themselves. This approach, however, requires the availability of screening paradigms that reflect the biology and context of the CSCs. The intricate deployments of signaling pathways that orchestrate the proliferation and differentiation of stem cells underscore the complexity of the biology of tumors. Thus, traditional high-throughput cell-based screens in cell line models are unlikely to provide the most appropriate assays as cells are out of their complex cellular context (i.e., the niche). Ideally, one would like to perform small molecule screens in whole animals to increase the chances that the small molecules identified are effective at penetrating tissues, show little toxicity, and affect the CSCs specifically. In this application, we propose to use our validated humanized-tumorogenic model in the Drosophila gut to perform a large-scale screen for small molecules that affect CSCs (Aim 1). We have developed a screening method that will allow us to screen 200,000 small molecules within two years. In addition to the screen, we will perform a number of validation studies to characterize their modes of action. Our goal is to focus on growth inhibitors that specifically affect the CSCs and not wildtype stem cells, and drugs that specifically target the Notch pathway, as it is clear that this class can be beneficial for treating mammalian colorectal cancers (Aim 2). In summary, results from these studies will allow us to identify a number of small molecules effective on CSCs, and in particular inhibitors of the Notch activity. PUBLIC HEALTH RELEVANCE: We propose to perform a large scale in vivo screen for small molecules that will be effective on Cancer Stem Cells. The screens will in particular identify inhibitor of Notch activity.