During the last 3 years, I have implemented and used an innovative technology called CRISPR/Cas9. This new technology exploits a bacterial system called CRISPR to inactivate genes in human cells revealing unsuspected genes and pathways required for the survival of tumor cells that we were not able to study before the CRISPR/Cas9 area. During the first report period, I have set-up and adapt tools to carry-out genome-wide CRISPR/Cas9 screens on t-FL cell lines. This includes briefly the engineering of a collection of single-cell GCB/t-FL- clonal cell lines carrying an inducible Cas9 expression, the functional testing of the efficiency of Cas9 editing in these cells and the completion of the genome-wide screens per se. By comparing CRISPR from multiple lymphoma types studied in parallel in the lab, we discovered genes that are essential only to the t-FL subtype. In particular, our initial CRISPR screen survey revealed that the BCR is, in fact, essential in several tFL and GC-derived B lymphoma lines, but in a fundamentally different fashion than in agressive Diffuse large B cell lymphoma of the ABC type. Indeed, tFL and GBC DLBCL subtypes are more akin to a tonic form of BCR signaling, engaging the BCR itself, its co-receptor CD19 and SYK and LYN kinase to trigger downstream activation of the PI3K/AKT survival pathway, without engaging BTK/NF-kB. Based on these compelling data, we propose that differences in oncogenic BCR signaling in the tFL vs. aggressive DLBCL subtype setting will likely necessitate a different suite of therapeutic approaches that we are currently investigating. Selected elements of this work have been recently included in a paper published in Nature on which I'm a co-author (Phelan et al. 2018).
