Abstract A012: Kmt2c/d Loss Primes Urothelium for Tumorigenesis and Redistributes Menin to Bivalent Promoters

Abstract Urothelial carcinoma arises from a “field” of precancerous but histologically normal urothelium. The KMT2C/D-KDM6A complexes known to bind and activate enhancers are frequently mutated in urothelial carcinoma and in histologically normal urothelium. Here, using a genetically engineered mouse model, we demonstrate that knockout of Kmt2c and/or Kmt2d induced a histologically normal, pre-tumorigenic state characterized by impaired differentiation from basal state and by augmented responses to growth and inflammatory stimuli. This sensitized the urothelium to transformation by known oncogenic drivers in urothelial carcinoma. Mechanistically, Kmt2d localized to both active enhancers and a small group of CpG-poor promoters and Kmt2c/d knockout led to diminished H3K4me1, H3K27ac and nascent RNA transcription at these sites, which together led to downregulation of the urothelial differentiation program. We further observed that Menin distributed extensively to Kmt2d localized enhancers and Kmt2c/d knockout led to redistribution of Menin to CpG-high and particularly bivalent promoters, resulting in transcriptional de-repression of bivalent genes. Blockade of Kmt2a/b-Menin interaction partially rescued the transcriptional changes that induced by Kmt2c/d deletion. Therapeutically, Kmt2c/d knockout maintained a basal state that upregulated EGFR signaling and conferred vulnerability to EGFR inhibitors. Together, our data posits that functional loss of Kmt2c/d licenses a molecular “field effect” priming histologically normal urothelium for oncogenic transformation and leading to therapeutic vulnerabilities to EGFR signaling pathway inhibition. Citation Format: Naitao Wang, Mohini Pachai, Dan Li, Cindy Lee, Sarah Warda, Makhzuna Khudoynazarova, Woo Hyun Cho, Guojia Xie, Fengshen Kuo, Sagar Shah, Li Yao, Cheng Qian, Elissa Wong, Juan Yan, Fanny Tomas, Wenhuo Hu, Sizhi Gao, Alison Smith, Ming Han, Dong Gao, Kai Ge, Haiyuan Yu, Sarat Chandarlapaty, Gopakumar Iyer, Jonathan Rosenberg, David Solit, Hikmat AI-Ahmadie, Ping Chi, Yu Chen. Kmt2c/d loss primes urothelium for tumorigenesis and redistributes Menin to bivalent promoters [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr A012.