P5: Dissection of KMT9 biology in urothelial carcinoma

表观遗传因子如组蛋白甲基转移酶在生理和病理控制中起关键作用。我们的初步数据确定了组蛋白甲基转移酶KMT9的生物学相关性，并确定KMT9是膀胱癌治疗干预的一个有希望的靶点。我们解决了KMT9的晶体结构，实现了结构导向的KMT9抑制剂程序，并开发了类似药物的小分子KMT9抑制剂（KMT9i）。KMT9i对目前已知的所有SET-domain和7- β -链组蛋白甲基转移酶具有选择性，在生化和细胞实验中具有高效力，并严重损害膀胱癌细胞的生长。为了促进KMT9抑制膀胱癌的临床I期测试，我们建议将小鼠遗传学和小分子KMT9抑制剂的体内分析结合起来，在体内和类器官培养系统中询问膀胱癌遗传学的特定方面。这项详细的分析将大大提高我们对KMT9在膀胱癌中的功能的认识，并提供KMT9作用的全面观点。特别是，我们将揭示KMT9对致癌PTEN信号传导和TP53细胞周期调节的影响。因此，我们的目的是(1)在体外和体内评估KMT9 - α缺失（KMT9 KO）和抑制（KMT9i）在Pten/Trp53缺失（Pten/Trp53 KO）膀胱癌模型中的治疗潜力。此外，我们建议(2)剖析KMT9在正常膀胱和尿路上皮癌中作用的不同机制基础。与UcarE其他小组的合作将使我们能够将我们在小鼠研究中的发现转化为人类膀胱癌样本，类器官和细胞系，以及对我们的KMT9抑制剂进行广泛的临床前测试。这一建议将拓宽我们对KMT9抑制在治疗干预中的应用的知识和视角，并提供对KMT9生物学的先进机制理解。

Epigenetic writers such as histone methyltransferases play key roles in the control of physiology and pathology. Our preparatory data establish the biological relevance of the histone methyltransferases KMT9 and identify KMT9 as a promising target for therapeutic intervention of bladder cancer. We solved the crystal structure of KMT9, implemented a structure-guided KMT9 inhibitor programme and developed drug-like small molecule KMT9 inhibitors (KMT9i). KMT9i display selectivity against all currently known SET-domain and 7-beta-strand histone methyltransferases, high potency in biochemical and cellular assays, and severely impair growth of bladder cancer cells. To promote the path of KMT9 inhibition to clinical phase I testing in bladder cancer, we propose to combine in vivo analyses using mouse genetics and small-molecule KMT9 inhibitors to interrogate specific aspects of the genetics of bladder cancer in vivo and in organoid culture systems. This detailed analysis will greatly enhance our understanding of KMT9 function in bladder cancer and provide a comprehensive view of KMT9 action. In particular, we will uncover the impact of KMT9 on oncogenic PTEN signalling and cell cycle regulation by TP53. Consequently, we aim (1) to evaluate the therapeutic potential of Kmt9-alpha loss (KMT9 KO) and inhibition (KMT9i) in the Pten/Trp53 deletion (Pten/Trp53 KO) bladder cancer model in vitro and in vivo. Furthermore, we propose (2) to dissect and the different mechanistic underpinnings of KMT9 action in normal bladder and urothelial carcinoma. Collaborations with the other UcarE groups will allow us to translate the findings made in our mouse studies to human bladder cancer samples, organoids and cell lines, as well as to carry out extensive pre-clinical testing of our KMT9 inhibitors. This proposal will broaden our knowledge and the perspectives on the utility of KMT9 inhibition for therapeutic intervention and provide advanced mechanistic understanding of KMT9 biology.