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着重要作用。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至关重要。最近对β -catenin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 -catenin和BCL-9的相互作用是由β -catenin中一个明确的结合袋和几个聚集在一起的关键疏水残基介导的。因此，β -连环蛋白和BCL-9的相互作用可能被非肽性的小分子靶向。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测定这种相互作用。在这项R21拨款中，我们建议进行高通量筛选，以发现β -catenin- bcl -9相互作用的小分子拮抗剂。已确定的“命中”将进一步研究其特异性、作用机制以及细胞活性和特异性。预期成功进行；该项目将开发大量高通量筛选方法，以发现β -连环蛋白- bcl -9相互作用的真正小分子拮抗剂。

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.