A novel CRISPR activation mouse enables modelling of aggressive lymphoma and interrogation of venetoclax resistance

CRISPR technologies have advanced cancer modelling in mice, but CRISPR activation (CRISPRa) methods have not been exploited in this context. We establish a CRISPRa mouse (dCas9a-SAMKI/+ 38 ) for inducing gene expression in vivo and in vitro. Using dCas9a-SAMKI 39 primary lymphocytes, we induced B cell restricted genes in T cells and vice versa, demonstrating the power of this system. There are limited models of aggressive double hit lymphoma. Therefore, we transactivated pro-survival BCL-2 in Eµ-MycT/+;dCas9a-SAMKI/+ 42 haematopoietic stem and progenitor cells. Mice transplanted with these cells rapidly developed lymphomas expressing high BCL-2 and MYC. Unlike standard Eµ-Myc lymphomas, BCL-2 expressing lymphomas were highly sensitive to the BCL-2 inhibitor venetoclax. We performed genome-wide activation screens in these lymphoma cells and found a dominant role for the BCL-2 protein A1 in venetoclax resistance. Here we show the power of our CRISPRa model for mimicking disease and providing insights into resistance mechanisms towards targeted therapies. Comparative gene expression profiling analysis of RNA-seq data for Mouse Embryonic Fibroblast (MEF) cell lines.