Developing cancer therapies through targeting the Six1/Eya transcriptional complex

 描述（由申请人提供）：大多数抗癌药物靶向酶或蛋白质受体上的结合口袋。这些药物通常靶向可以削弱肿瘤的上游通路，但可能无法击中肿瘤的中心节点。一段时间以来，人们已经知道转录因子可以作为这些“中心节点”。事实上，去调控的转录已经与大多数（如果不是全部的话）对癌细胞至关重要的性质相关，包括不受控制的生长、无限的复制潜力、迁移和侵袭。然而，很少有研究人员 已经承担了更困难的靶向转录因子的任务。Six 1同源框基因编码一种对胚胎发育至关重要的转录因子。在大多数组织中，一旦发育完成，Six 1表达就会消失。然而，Six 1在多达50%的原发性乳腺肿瘤和90%的转移性病变以及许多其他肿瘤类型中被重新激活。Six 1在乳腺癌和其他癌症的肿瘤发生、肿瘤生长和转移中起着因果作用，并且其抑制显著降低了几种小鼠癌症模型中的上述特性。Six 1没有内在的激活或抑制结构域，因此需要辅因子来介导其转录作用。我们已经证明Six 1需要Eya辅因子来介导其在乳腺癌细胞中的促增殖和促转移作用。对公开的乳腺癌微阵列数据集的检查显示，Six 1和Eya的高表达水平与乳腺癌复发时间缩短、转移时间缩短和总生存期缩短相关，而不是单独的两个基因。重要的是，我们最近确定了Six 1/Eya 2复合物的晶体结构，这表明Six 1使用单个α螺旋与Eya相互作用，类似于两种众所周知的蛋白质-蛋白质相互作用（p53/HDM 2和巴克/Bcl-xL），这些相互作用已被小分子成功靶向。我们进一步证明了Six 1螺旋上的单个氨基酸突变废除了Six 1与Eya的结合，以及Six 1介导的肿瘤起始和转移。该项目的目标是通过使用高通量筛选（Aim 1）鉴定和优化命中化合物，鉴定和开发靶向Six 1/Eya复合物的新型抗癌药物。将在细胞培养物和动物模型中检测已鉴定的抑制剂抑制致瘤性和转移的能力（目的2）。由于Six 1/Eya复合物影响肿瘤发生和转移过程的多个阶段，并且在大多数成人组织中不表达，因此靶向这种从未靶向过的复合物具有在疾病的早期和晚期抑制乳腺癌和其他癌症的治疗潜力 副作用有限的进展，这是目前大多数疗法所做不到的。

 DESCRIPTION (provided by applicant): Most anti-cancer drugs target binding pockets in enzymes or on protein receptors. These drugs often target upstream pathways that can cripple tumors, but may fail to hit the central node of the tumor. For some time, it has been known that transcription factors can serve as these "central nodes". Indeed, de-regulated transcription has been associated with most, if not all, properties that are critical to the cancer cell, including uncontrolled growth, unlimited replicative potential, migration and invasion. Yet few investigators have taken on the more difficult task of targeting transcription factors. The Six1 homeobox gene encodes a transcription factor that is critical for embryonic development. In most tissues, Six1 expression is lost once development is complete. However, Six1 is re-activated in as many as 50% of primary breast tumors and 90% of metastatic lesions, as well as in many other tumor types. Six1 plays a causal role in tumor initiation, tumor growth, and metastasis of breast and other cancers, and its inhibition dramatically diminishes the aforementioned properties in several mouse models of cancer. Six1 has no intrinsic activation or repression domains, and thus requires cofactors to mediate its transcriptional effects. We have demonstrated that Six1 requires the Eya cofactor to mediate its pro-proliferative and pro-metastatic effects in breast cancer cells. Examination of public breast cancer microarray datasets reveals that high expression levels of Six1 and Eya together, but not either gene alone, correlate with shortened time to relapse, shortened time to metastasis, and shortened overall survival in breast cancer. Importantly, we recently determined the crystal structure of the Six1/Eya2 complex, which reveals that Six1 uses a single alpha helix to interact with Eya, resembling two well-known protein- protein interactions (p53/HDM2 and Bak/Bcl-xL) that have been successfully targeted by small molecules. We further demonstrated that a single amino acid mutation on the Six1 helix abrogates the binding of Six1 to Eya and Six1-mediated tumor initiation and metastasis. The goal of this project is to identify and develop novel anti- cancer agents that target the Six1/Eya complex through characterizing and optimizing hit compounds identified through the use of a high throughput screen (Aim 1). Identified inhibitors will be tested in both cell culture and animal models for their ability to inhibit tumorigenicity and metastasis (Aim 2). Since the Six1/Eya complex influences multiple stages of the tumorigenic and metastatic processes and is not expressed in most adult tissues, targeting this never before targeted complex has the therapeutic potential to inhibit breast and other cancers both at early and later stages of disease progression with limited side effects, something most current therapies do not do.