PRMT5 is required for lymphomagenesis triggered by multiple oncogenic drivers

Protein arginine methyltransferase 5 (PRMT5) has been implicated as a key modulator of lymphomagenesis. Whether PRMT5 has overt oncogenic function in the context of leukemia/lymphoma and whether it represents a therapeutic target remains to be established. We demonstrate that inactivation of PRMT5 inhibits colony-forming activity by multiple oncogenic drivers, including cyclin D1, c-MYC, NOTCH1, and MLL-AF9. Furthermore, we demonstrate that PRMT5 overexpression specifi cally cooperates with cyclin D1 to drive lymphomagenesis in a mouse model, revealing inherent neoplastic activity. Molecular analysis of lymphomas revealed that arginine methylation of p53 selectively suppresses expression of crucial proapoptotic and antiproliferative target genes, thereby sustaining tumor cell self-renewal and proliferation and bypassing the need for the acquisition of inactivating p53 mutations. Critically, analysis of human tumor specimens reveals a strong correlation between cyclin D1 overexpression and p53 methylation, supporting the biomedical relevance of this pathway.