Developing a Dre-rox Recombination-Based Genetically Engineered Mouse Model (GEMM) for NUT Carcinoma - Title: Developing a Dre-rox Recombination-Based Genetically Engineered Mouse Model (GEMM) for NUT Carcinoma. Project Summary: NUT-rearranged neoplasm is an emerging group of poorly characterized aggressive cancers caused by fusion genes, formed by chromosome translocations, involving the testis-specific gene NUTM1, including NUT Carcinoma (BRD4::NUTM1), undifferentiated small round cell sarcoma (CIC::NUTM1), Porocarcinoma (YAP::NUTM1) and other poorly understood cancers (caused by fusion genes such as MGA-NUTM1 and MXD4- NUTM1). Because each NUT-rearranged neoplasm is a rare entity that presents an aggressive disease course, with an uncertain cell type of origin and is generally resilient to therapies, investigations using preclinical animal models can provide critical insight into their oncogenic mechanisms and facilitate the development of life-saving treatments. By inducing an endogenous chromosome translocation forming the Brd4::Nutm1 using the cre-lox mediated site- specific recombination (SSR) technology, we have developed the first GEMM recapitulating the syntenic chromosome translocation event (in contrast to the other reported model that relies on FLEx-mediated ectopic expression) in NUT Carcinoma (NC) - the most aggressive entity within NUT-rearranged neoplasm. This innovative GEMM faithfully recapitulated the tissue spectrum, histopathological and molecular features of NCs and provided a critical preclinical model for this rare but devastating disease. Using this model, we have identified crucial factors, such as YAP/TAZ, cMYC, and ETV4, that may be required for the initiation and progression of NC and intriguing putative cancer stem cell populations such as the Sox2-positive cells that may facilitate the survival and invasion of NC. Conditional genetic manipulations such as conditional knockout (KO), lineage tracing, and cell ablations are required to functionally dissect the roles of these promising candidate pathways and cell populations in NC and develop new treatments based on these new understandings. However, because the NC model is cre-lox-based, it prohibited the application of the inducible cre-lox-based genetic manipulation technology and the rich resources of floxed alleles and synthetic tools for lineage tracing and cell ablation. This R03 project proposes to develop and characterize a dre-rox recombination-based GEMM of NC (Aim 1), and use the model to unravel the critical functions of YAP/TAZ mediated signals in NC progression (Aim 2). Overall Impact. Our new model will liberate inducible cre-lox recombination and allow conditional knockout, lineage tracing, and cell ablation in NC GEMM. The dual recombinase system will deepen our understanding of the fundamental mechanism of NC oncogenesis and facilitate the effective testing of therapeutic target pathways for this devastating disease. Furthermore, because chromosome translocation models are modular, by simply moving one rox site, novel models for other NUT-rearranged neoplasms can be generated and significantly expand the toolset for understanding emerging and devastating NUT-rearranged neoplasm.
