Allosteric Modulators of Polycomb Repressive 2 Gene Repression as Potential Therapeutics for the Development of Novel Epigenetic Cancer Therapies

新的有效的抗癌疗法仍然是非常需要的，因为它们具有降低死亡率的潜力 患者的死亡率、复发率和更好的生活质量。癌症是一种遗传性疾病，但它的发展也 涉及多个表观遗传改变。表观遗传学通过调节染色质来调节转录 架构通过不同的机制。因此，这种机制的失调可能会导致异常 基因表达或沉默，进而可能导致癌症的发生。最相关的表观遗传学之一 修饰是组蛋白3(H3K27)上赖氨酸27的甲基化，这是一种广为人知的抑制性组蛋白标记。 H3K27甲基化被多梳抑制复合体2(PRC2)结合，多聚体蛋白 由四个核心成分组成的复合体：EZH2，EED，SuZ12和RbAp46/48，所有这些都是 它的催化活性。PRC2蛋白的过度表达，特别是EZH2蛋白的过度表达，导致了 复杂和高水平的H3K27M3，与无数人类癌症有关。几个PRC2 到目前为止，已经发现了一些抑制剂，其中一些目前正在临床开发中。 这些化合物 以EZH2或EED的催化集结构域为靶点。尽管他们已经交付了一些 有希望的结果是，最近的报告表明，延长给药时间会导致EZH2继发突变 对治疗产生抗药性的人。因此，新的PRC2功能的抑制剂非常有兴趣，因为这样 化合物可以提供 解决上述耐药问题的替代解决方案。最近，我们的 实验室报告发现了一种有效的、细胞可渗透的装订多肽， GN-ZW11，作为一种强有力的 肾癌细胞中H3K27me3的选择性抑制剂。这种化合物的设计目标是SANT2 因此，它很可能是迄今为止描述的第一类EZH2变构抑制剂。这个 目前的提案旨在扩大我们与GN-ZW11的初步研究，首先，开展结构性活动 关系研究，以了解其结合的分子决定因素，以及收集有价值的数据 用于GN-ZW11类似物的设计，具有更高的效力和稳定性。第二，我们建议开展 进一步对转移性肾癌细胞进行生物学检测，以更好地了解其作用机制 目的：探讨GN-ZW11对肾透明细胞癌的治疗潜力。最后， 我们计划将我们的初步研究扩展到其他癌细胞株，在这些癌细胞中，PRC2蛋白已经被 研究GN-ZW11在体内对PRC2的抑制作用。 在小鼠异种移植模型中诱导肿瘤消退的能力。总之，拟议的研究项目将 结果制备和验证了一个新的PRC2功能变构抑制剂家族。我们期待着 从这些研究中获得的知识将有助于提高我们对 EZH2在肿瘤学中的应用，并将指导确定用于治疗人类的靶向化疗药物 未来。

Novel and effective anticancer therapies are still of great need since they hold the potential for lower mortality rates, reoccurrence and better quality of life for patients. Cancer is a genetic disease, but its development also involves multiple epigenetic alterations. Epigenetics regulates transcription by modulating chromatin architecture through different mechanisms. Hence, dysregulation of such mechanisms can result in aberrant gene expression or silencing, which in turn can lead to carcinogenesis. One of the most relevant epigenetic modifications is the methylation of lysine 27 at histone 3 (H3K27), a broadly known repressive histone mark. H3K27 methylation is incorporated by the polycomb repressive complex 2 (PRC2), a multimeric protein complex formed by four core components: EZH2, EED, SUZ12 and RbAp46/48, all of which are essential for its catalytic activity. Overexpression of PRC2 proteins, particularly of EZH2, results in hyperactivation of the complex and high levels of H3K27m3, which are associated to a myriad of human cancers. Several PRC2 inhibitors have been discovered to date, some which are currently in clinical development. These compounds target either the catalytic SET domain of EZH2 or EED allosterically. Although they have delivered some promising results, recent reports indicate that extended dosing with them leads to secondary EZH2 mutants that become resistant to treatment. Hence, novel inhibitors of PRC2 function are of great interest, since such compounds could offer an alternative solution to address the above-mentioned resistant profiles. Recently, our laboratory has reported the discovery of a potent, cell permeable stapled peptide, GN-ZW11, as a potent and selective inhibitor of H3K27me3 in renal carcinoma cells. This compound was designed to target the SANT2 domain in EZH2, and thus it may well be the first-in class EZH2 allosteric inhibitor described to date. The current proposal aims to expand our preliminary studies with GN-ZW11 by carrying out, first, structural-activity relationship studies to understand the molecular determinants of its binding, as well as to gather valuable data for the design of GN-ZW11 analogs with improved potency and stability. Secondly, we propose to carry out further biological assays in metastatic renal carcinoma cells to better understand the mechanism of action of GN-ZW11 and to evaluate its therapeutic potential for the treatment of clear cell renal cell carcinoma. Finally, we plan on expanding our preliminary studies to other cancer cell lines in which PRC2 proteins have been found overexpressed and to investigate the impact of PRC2 inhibition by GN-ZW11 in vivo, by measuring its ability to induce tumor regression in mouse xenografts models. In summary, the proposed research project will result in the preparation and validation of a new family of allosteric inhibitors of PRC2 function. We expect that the knowledge gained from these studies will help to improve our overall understanding surrounding the role of EZH2 in oncology, and will also guide the identification of targeted chemotherapeutics for treating humans in the future.