Pharmacologic targeting of SUMOylation drives mitochondrial dysfunction and metabolic alterations in B cell Malignancies

Sumoylation is a post-translational modification process that is deregulated in cancer. We foundthat sumoylation machinery was overexpressed in diffuse large B-cell lymphoma (DLBCL).Treatment with TAK-981, a SUMO-activating enzyme (SAE) inhibitor, induced desumoylationof cytoplasmic and mitochondrial proteins, restricting growth of DLBCL and mantle celllymphoma (MCL) cell lines and primary cells. DLBCL cells treated with TAK-981 exhibitedDNA damage, G2 arrest and downregulation of DNA repair, MYC and OxPhos pathways. SAEinhibition disrupted mitochondrial integrity and function, accompanied by mitophagy and rapidaccumulation of ROS. Metabolomic profiling revealed decreases in Krebs cycle substrates, andSeahorse respirometry confirmed dramatic reduction in OxPhos upon SAE inhibition. CRISPR-Cas9 loss-of-function library screens implicated NFκB, TP53, DNA damage andcentromere/telomere gene pathways in resistance to SAE inhibition; knockout of TP53 or BAXrescued DLBCL cells from TAK-981-induced apoptosis. Treatment with TAK-981 prolongedsurvival of mice xenografted with DLBCL and MCL PDX tumors. Thus, sumoylation is apromising target in lymphoid malignancies. To investigate the impact of TAK981 in B cell malignancies, cultured cell lines (OCI-LY3, OCI-LY19, U2932, SU-DHL4) were treated with TAK981 at corresponding time points and collected for RNA sequencing and ATAC sequencing and compared against a 0 hr timepoint.