(PQ9) Developing EZH2 Degraders for Treating Triple-Negative Breast Cancer

项目摘要 EZH 2（enhancer of zeste homolog 2）是PRC 2（polycomb repressive complex）的主要酶亚基 2)催化组蛋白H3赖氨酸27（H3 K27）的甲基化。EZH 2在广泛的肿瘤细胞中过表达， 癌症，包括三阴性乳腺癌（TNBC）和高表达与不良预后相关。 然而，EZH 2抑制剂在抑制具有EZH 2的乳腺癌细胞系的增殖方面无效 包括TNBC细胞系的过表达，即使它们有效地抑制TNBC细胞系的酶活性。 EZH2/PRC 2.还已经显示，EZH 2的敲低显著阻断乳腺癌细胞的生长， 包括TNBC细胞。总之，这些结果表明，EZH 2的过表达，而不是EZH 2的过表达。 EZH 2的甲基转移酶活性对于驱动乳腺癌细胞增殖至关重要。因此我们 假设EZH 2降解剂，是指选择性降低EZH 2蛋白水平的小分子， 将是用EZH 2治疗TNBC和其他乳腺癌亚型的有效治疗剂 过度表达为了检验这一治疗假设，我们提出通过使用 二价抑制剂技术如PROTAC（蛋白水解靶向嵌合体）和疏水标记， 其已成功地应用于多种蛋白质靶的选择性降解。在我们的初步调查中 通过研究，我们使用二价抑制剂技术生产了一流的EZH 2降解剂。我们 原型EZH 2降解剂显著降低EZH 2蛋白水平，并显示出稳健的抗增殖活性。 在TNBC细胞和异种移植小鼠模型中的作用。基于有希望的初步结果，我们建议， （1）优化EZH 2降解剂，使其具有体外和细胞效力、选择性和药代动力学 性质与体内化学探针一致，以及（2）评估TNBC中改进的EZH 2降解剂 细胞和小鼠模型。我们希望拟议的研究将验证我们的假设， EZH 2的药理学降解将为治疗TNBC提供新的治疗策略。的 这里产生的化学探针可以进一步优化为候选药物，用于在临床中翻译， TNBC患者这些EZH 2降解剂也是评估EZH 2潜力的有价值的化学工具 在其他癌症中的降解，如前列腺癌、淋巴瘤、骨髓瘤和其他乳腺癌亚型 EZH 2过表达的癌症。

Project Summary EZH2 (enhancer of zeste homolog 2) is the main enzymatic subunit of PRC2 (polycomb repressive complex 2) that catalyzes methylation of histone H3 lysine27 (H3K27). EZH2 is overexpressed in a broad spectrum of cancers including triple-negative breast cancer (TNBC) and high expression correlates with poor prognosis. However, EZH2 inhibitors are ineffective at inhibiting proliferation of breast cancer cell lines with EZH2 overexpression including TNBC cell lines even though they effectively inhibit the enzymatic activity of EZH2/PRC2. It has also been shown that knockdown of EZH2 significantly blocks growth of breast cancer cell lines including TNBC cells. Together, these results suggest that overexpression of EZH2, but not the methyltransferase activity of EZH2, is critical for driving breast cancer cell proliferation. We therefore hypothesized that EZH2 degraders, which refer to small molecules that selectively reduce EZH2 protein levels, would be effective therapeutics for treating TNBC and other subtypes of breast cancer with EZH2 overexpression. To test this therapeutic hypothesis, we propose to develop EZH2 degraders by using the bivalent inhibitor technologies such as PROTACs (proteolysis targeting chimeras) and hydrophobic tagging, which have been successfully applied to selective degradation of multiple protein targets. During our preliminary studies, we have generated first-in-class EZH2 degraders using the bivalent inhibitor technologies. Our prototype EZH2 degraders significantly reduced EZH2 protein levels and displayed robust antiproliferative effects in TNBC cellular and xenograft mouse models. Based on the promising preliminary results, we propose to: (1) optimize EZH2 degraders so that they have in vitro and cellular potency, selectivity, and pharmacokinetic properties consistent with an in vivo chemical probe, and (2) evaluate improved EZH2 degraders in TNBC cellular and mouse models. We expect that the proposed research will validate our hypothesis that pharmacological degradation of EZH2 would provide a novel therapeutic strategy for treating TNBC. The chemical probes generated here can be further optimized into a drug candidate for translating in the clinic for TNBC patients. These EZH2 degraders are also valuable chemical tools for assessing the potential of EZH2 degradation in other cancers such as prostate cancer, lymphoma, myeloma and other subtypes of breast cancer with EZH2 overexpression.