Non-cancer gene addition as anticancer strategy

描述（由申请人提供）：癌症治疗在过去十年中发生了根本性的变化。基于驱动每个患者肿瘤发生的特定分子变化的新疗法正在成为传统治疗的低毒和更有效的替代方案。因此，靶向生长因子受体、EGFR-1和ErbB2、雌激素核受体或BCR-ABL融合蛋白已经是完善的临床方案的一部分。然而，即使是这些理想的量身定制的治疗方法也不能提供长期治愈，只能延缓疾病的进展。除了真正的癌症基因的改变，在肿瘤细胞中，多个正常的调节网络已经被重新排列，以适应致瘤状态。由于这种差异，癌细胞的存活也依赖于维持肿瘤稳态所必需的非癌基因。这种依赖性产生了正常细胞中不存在的肿瘤特异性脆弱性，这为治疗干预提供了机会。因此，我们假设干扰这些非癌症依赖性将导致系统失效，即致瘤状态的停止。由于正常细胞中靶点的非必需性质，攻击非癌性淋巴结的潜在治疗剂将有一个很大的治疗窗口。此外，与针对癌症基因的治疗相比，为了避免致命效应，肿瘤细胞可以去除/减弱致瘤性原发病变（例如，激活癌基因），而这本身会影响肿瘤的适应性。尽管肿瘤之间的表面相似，但每种肿瘤的特异性改变极大地影响了其内在特征。因此，每种癌症基因型都有一系列不同的非癌症依赖性，构成“基因合成致死性”（GSL）。在这个应用中，我们计划识别非癌症基因，这些基因对于维持携带特定癌症改变的肿瘤细胞的活力至关重要，并探索它们作为量身定制治疗的肿瘤靶点的潜在用途。系统地消除基因组中的每个基因以寻找GSL是揭示肿瘤特异性脆弱性的一种有吸引力的方法。虽然这一过程已经成功地应用于酵母来解剖细胞途径，但它在哺乳动物中的应用非常有限，主要是因为缺乏适当的遗传工具。然而，最近RNA干扰（RNAi）技术已经消除了这一障碍。我们率先开发了基于rnai的遗传工具，极大地促进了全基因组水平上功能丧失的研究。因此，我们计划使用我们最先进的rnai筛选技术作为一种扰动方法来寻找基因，当被阻断时，由于真正的癌症基因的存在，在乳腺癌细胞中产生GSL效应。在这里，我们建议使用“非癌加法”的新概念来识别乳腺癌细胞的“阿喀琉斯之踵”。我们的工作假设完全颠覆了寻找治疗癌症靶点的标准策略，该策略几乎完全专注于癌细胞中激活的途径的失活。因此，我们相信这项研究计划的成功完成将对下一代癌症治疗方法的设计产生相当大的影响。

DESCRIPTION (provided by applicant): Cancer therapy has radically changed during the last decade. Novel therapies based on the specific molecular changes that drive tumorigenesis in every patient are emerging as low toxic and more efficient alternatives to classical treatments. Thus, the targeting of the growth factor receptors, EGFR-1 and ErbB2, the estrogen nuclear receptor, or the BCR-ABL fusion protein is already part of well established clinical protocols. However, even these ideal tailored therapies fail to provide a long-term cure and can only delay the progression of the disease. Additionally to alterations in bona-fide cancer genes, in a tumor cell, multiple normal regulatory networks have been rearranged in order to adapt to the tumorigenic state. As consequence of this divergence, survival of cancer cells also depends on non-cancer genes that are essential to maintain the tumor homeostasis. This dependency generates tumor specific vulnerabilities that do not exist in normal cells and that represent opportunities for therapeutic intervention. Therefore, we postulate that interfering with these non-cancer dependencies will result in system failure, that is, the cessation of the tumorigenic state. Potential therapeutic agents attacking non-cancer nodes would have a large therapeutic window because of the non-essential nature of the targets in normal cells. Furthermore, in contrast to therapies directed against cancer genes, to escape the lethal effect tumors cells could remove/attenuate the tumorigenic primary lesion (ex. activation of an oncogene) which by itself will affect tumor fitness. Despite the relative superficial similitude among tumors, the specific alterations present in each tumor greatly influence its intrinsic characteristics. Therefore, each cancer genotype will have a distinct series of non- cancer dependencies constituting "genetic synthetic lethals" (GSL). In this application, we plan to identify non- cancer genes that are essential to maintain the viability of tumor cells that carry specific cancer alterations and to explore their potential use as tumor targets for tailored therapies. The systematic elimination of every gene in the genome to search for GSL represents an attractive approach to unveil tumor specific vulnerabilities. Although this process has been successfully applied in yeast to dissect cellular pathways, its use in mammals has been very limited, mainly because of the lack of proper genetic tools. However, recently RNA interference (RNAi) technology has eliminated this handicap. We have pioneered the development of RNAi-based genetic tools that greatly facilitate loss-of-function studies at a genome wide level. Thus, we plan to use our state-of-the-art RNAi-screen technology as a perturbation method to find genes that, when blocked, produce GSL effects in breast cancer cells due to the presence of bona-fide cancer genes. Here, we propose to identify the "Achilles' heel" of breast cancer cells using the novel concept of the "non- cancer addition". Our working hypothesis completely reverses the standard strategy for finding therapeutic cancer targets which has almost exclusively focused in the inactivation of pathways activated in cancer cells. Thus, we are convinced that the successful completion of this research plan will have a considerably impact in the design of the next generation of cancer treatments. PUBLIC HEALTH RELEVANCE: One of the major challenges of modern cancer treatments is the ability to eliminate tumor cells without affecting normal ones. Cancer therapy has radically changed during the last decade. Novel therapies based on the specific molecular changes that drive tumorigenesis in every patient are emerging as low toxic and more efficient alternatives to classical treatments. However, current tailored therapies are suboptimal and, despite some exceptions, their impact in the survival of cancer patients is still modest. Here, we propose to identify this exclusive "Achilles' heel" of breast cancers by eliminating one by one every gene in the human genome to search for genes that, when blocked, exclusively reduce the viability of tumor cells. The successful completion of this research plan will provide us with novel targets for more efficient and less harmful breast cancer therapies and it may impact the design of future generation of cancer treatments.