Targeting protein-protein interactions of Bmi1 oncoprotein

项目摘要 Bmi 1（B细胞特异性莫洛尼鼠病毒插入位点1）基因已被鉴定为一种致癌基因， 多种癌症，诱发B细胞和T细胞白血病。Bmi 1是一种干细胞基因，它决定了细胞的增殖能力。 正常和白血病干细胞的能力和自我更新。多项研究确定Bmi 1蛋白诱导 在多种体外和体内模型中致癌转化并促进肿瘤生长。因此，我们认为， 靶向Bmi 1活性代表了一种非常有前途的开发新疗法的方法， 有吸引力的药物来根除癌症干细胞。 Bmi 1蛋白是多梳抑制复合物1（PRC 1）的组分，并且已被证明 通过作为INK 4a/ARF基因座编码的转录抑制因子在细胞周期调控中起关键作用 两个重要的肿瘤抑制因子p16 Ink 4a和p14 Arf。Bmi 1是一种相对较小的37 kDa蛋白质，由 具有E3泛素连接酶活性的N-末端RING结构域和第二结构域（B2 D，Bmi 1第二结构域 结构域），其代表蛋白质-蛋白质相互作用基序。B2 D结构域的蛋白质-蛋白质相互作用 对Bmi 1活性至关重要。已经表明，B2 D参与与多同源异型的相互作用， PRC 1复合物内的蛋白质以及锌指转录因子E4 F1、Zfp 277和PLZF-1。 RARA融合蛋白。 在这个项目中，我们建议开发针对B2 D蛋白质的小分子抑制剂， Bmi 1的B2 D结构域作为新的化学探针，以进一步研究Bmi 1的B2 D结构域的作用， 鉴定新的潜在抗癌剂。我们已经描述了B2 D结构域的相互作用， Bmi 1与PHC 2的结合，并开发了适用于筛选小分子的高质量生化测定法。 图书馆.我们将在化学基因组学中心（CCG）进行高通量筛选， 密歇根大学，以确定这种蛋白质-蛋白质相互作用的小分子抑制剂。我们会委聘 结合生物化学分析、生物物理实验和结构生物学的跨学科方法 验证HTS命中和鉴定高质量Bmi 1小分子抑制剂的方法。活动最 有效的抑制剂将在一组基于细胞的实验中进行评估，以评估它们抑制 白血病细胞的自我更新特性。我们的项目代表了一种非常新颖和创新的方法， Bmi 1通过阻断蛋白质-蛋白质相互作用，因为目前没有Bmi 1的抑制剂。总的来说， 我们希望能够鉴定出非常有价值的化合物，这些化合物可以作为适用于机械的化学探针， 研究和进一步开发成致癌Bmi 1的有效体内抑制剂。

Project Summary Bmi1 (B-cell specific Moloney murine virus insertion site 1) gene has been identified as an oncogene in multiple cancers, inducing B- and T-cell leukemias. Bmi1 is a stem cell gene, which determines the proliferative capacity and self-renewal of normal and leukemic stem cells. Multiple studies identified Bmi1 protein to induce oncogenic transformation and promote tumor growth in a variety of in vitro and in vivo models. Therefore, targeting Bmi1 activity represents a very promising approach for development of novel therapeutics and attractive agents to eradicate cancer stem cells. Bmi1 protein is a component of the polycomb suppressive complex 1 (PRC1), and has been shown to play a critical role in cell cycle regulation by acting as a transcriptional repressor of INK4a/ARF locus encoding two important tumor suppressors p16Ink4a and p14Arf. Bmi1 is a relatively small, 37 kDa protein composed of N-terminal RING domain which has E3 ubiquitin ligase activity and the second domain (B2D, the Bmi1 2nd domain) which represents a protein-protein interaction motif. Protein-protein interactions of the B2D domain are essential for Bmi1 activity. It has been shown that B2D is involved in the interactions with polyhomeotic proteins within the PRC1 complex as well as with the zinc-finger transcription factors E4F1, Zfp277 and PLZF- RARA fusion protein. In this project we propose to develop small molecule inhibitors targeting the B2D protein-protein interaction domain of Bmi1 as new chemical probes to further study the role of B2D domain of Bmi1 and to identify new potential anti-cancer agents. We have already characterized the interaction of B2D domain of Bmi1 with PHC2 and developed high quality biochemical assays suitable for screening of small molecule libraries. We will carry out high-throughput screening at the Center for Chemical Genomics (CCG) at the University of Michigan to identify small molecule inhibitors of this protein-protein interaction. We will employ interdisciplinary approach combining biochemical assays, biophysical experiments and structural biology methods to validate HTS hits and identify high quality small molecule inhibitors of Bmi1. Activity of the most potent inhibitors will be evaluated in a panel of cell-based experiments to assess their capability to inhibit the self-renewal properties of leukemic cells. Our project represents a very novel and innovative approach to target Bmi1 through blocking the protein-protein interactions as currently there are no inhibitors of Bmi1. In summary, we expect to identify highly valuable compounds that can serve as chemical probes suitable for mechanistic studies and for further development into potent in vivo inhibitors of the oncogenic Bmi1.