Discovery of small-molecule inhibitors of the beta-catenin/BCL-9 interaction

描述（由申请人提供）：Wnt信号通路的组成性激活在癌细胞对当前治疗剂的抗性中起主要作用。β-连环蛋白和BCL-9的相互作用对于Wnt信号通路的组成性激活是关键的。最近对β-连环蛋白和BCL-9的高分辨率晶体结构的测定表明，与大多数其他蛋白质-蛋白质相互作用不同，β-连环蛋白和BCL-9相互作用是由β-连环蛋白中的明确定义的结合口袋和聚集在一起的几个关键疏水残基介导的。因此，β-连环蛋白和BCL-9的相互作用可以被非肽小分子靶向。为此，我们对BCL-9进行了广泛的突变研究，并确定了关键的结合残基。此外，我们已经开发了强大的荧光偏振和FRET检测这种相互作用。在这项R21资助中，我们建议进行高通量筛选，以发现β-连环蛋白-BCL-9相互作用的小分子拮抗剂。将进一步研究鉴定的“命中”的特异性、作用机制及其细胞活性和特异性。预计该项目将成功实施;该项目将导致开发许多用于高通量筛选的检测方法，以发现β-连环蛋白-BCL-9相互作用的真正小分子拮抗剂。 公共卫生相关性：癌症是美国第二大死亡原因。迫切需要更有效的治疗方法来改善数百万癌症患者的预后。本研究项目旨在开发β-连环蛋白-BCL-9蛋白-蛋白相互作用的高通量筛选方法，并发现这种相互作用的非肽类小分子抑制剂。这些小分子抑制剂将作为重要的先导化合物进行进一步优化，这可能导致开发一类新的小分子抗癌药物用于治疗人类癌症，包括但不限于乳腺癌和前列腺癌。

DESCRIPTION (provided by applicant): The constitutive activation of the Wnt signaling pathway plays a major role in the resistance of cancer cells to current therapeutic agents. The interaction of beta- catenin and BCL-9 is critical for the constitutive activation of the Wnt signaling pathway. Recent determination of a high-resolution crystal structure of beta-catenin and BCL-9 suggests that unlike most other protein-protein interactions, the beta-catenin and BCL-9 interaction is mediated by a well-defined binding pocket in beta-catenin and several key hydrophobic residues that are clustered together. Thus, the beta-catenin and BCL-9 interaction may be targeted by non-peptidic, small-molecules. To this end, we have carried out extensive mutational studies on BCL-9 and have defined the key binding residues. Furthermore, we have developed robust fluorescence-polarization and FRET assays for this interaction. In this R21 grant, we propose to carry out high throughput screening for the discovery of small-molecule antagonists of the beta-catenin-BCL-9 interaction. Identified "hits" will be further investigated for their specificity, their mechanism of action and for their cellular activity and specificity. It is expected that successfully carried out; this project will lead to the development of a number of assays for high throughput screening for the discovery of bona fide small-molecule antagonists of the beta-catenin-BCL-9 interactions. PUBLIC HEALTH RELEVANCE: Cancer is the second leading cause of death in the United State of America. More effective treatments are urgently needed to improve the outcome of millions of cancer patients. This research project aims at development of high throughput screening assays for the beta-catenin-BCL-9 protein-protein interaction and discovery of non-peptide, small-molecule inhibitors of this interaction. These small-molecule inhibitors will serve as important lead compounds for further optimization, which can lead to the development of a new class of small-molecule anti-cancer drugs for the treatment of human cancer, including but not limited to breast cancer and prostate cancer.