Sleeping Beauty Screen Identifies RREB1 and Other Genetic Drivers in Human B-cell Lymphoma.

Follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) are the most common non-Hodgkin lymphomas distinguishable by unique mutations, chromosomal rearrangements and gene expression patterns. Here it is demonstrated that early B cell progenitors express 2',3'-Cyclic-nucleotide 3' phosphodiesterase (CNP) and that when targeted with Sleeping Beauty (SB) mutagenesis, Trp53R270H mutation or Pten loss gave rise to highly-penetrant lymphoid diseases, predominantly FL and DLBCL. In efforts to identify genetic drivers and signaling pathways that are functionally important in lymphomagenesis, SB transposon insertions were analyzed from splenomegaly specimens of SB-mutagenized mice (n=23) and SB-mutagenized mice on a Trp53R270H background (n=7) and identified 48 and 12 sites with statistically recurrent transposon insertion events, respectively. Comparison to human data sets revealed novel and known driver genes for B cell development, disease and signaling pathways: PI3K-AKT-mTOR, MAPK, NF-κB and BCR. Lastly, functional data indicates that modulating Ras responsive element binding protein 1 (RREB1) expression in human DLBCL cell lines in vitro alters KRAS expression, signaling, and proliferation; thus, suggesting that this proto-oncogene is a common mechanism of RAS-MAPK hyperactivation in human DLBCL. Implications: A forward genetic screen identified new genetic drivers of human B-cell lymphoma and uncovered a RAS/MAPK activating mechanism not previously appreciated in human lymphoid disease. Overall, these data support targeting the RAS/MAPK pathway as a viable therapeutic target in a subset of human DLBCL patients.