Dimethyl fumarate induces ferroptosis and impairs NF-?B/STAT3 signaling in DLBCL

Multi-agent chemotherapy still represents the first-line standard-of-care treatment for diffuse large B-cell lymphoma (DLBCL), the most common form of lymphoma in adults. However, the clinicopathological and molecular heterogeneity of DLBCLs poses a major challenge in their successful therapy. At least two major subtypes, i.e. germinal center B-cell-like (GCB) and the aggressive activated B-cell-like (ABC) DLBCL, which differ both in their gene expression profile and in their mutation patterns, have been identified. Here we demonstrate a broad inhibitory effect of dimethyl fumarate (DMF) on the outgrowth of both DLBCL subtypes, even though the molecular basis for its efficacy differs between GCB and ABC DLBCL. Due to high expression of arachidonate 5-lipoxygenase in concert with low glutathione and glutathione peroxidase 4 levels, DMF induced lipid peroxidation and thus ferroptotic cell death in GCB DLBCL. In contrast, in ABC DLBCL inhibition of NF-?B and STAT3 activity essentially contributed to DMF-dependent cytotoxicity. Interestingly, the BCL-2 specific BH3 mimetic ABT-199 or an inhibitor of the ferroptosis suppressor protein 1 synergized with DMF treatment in inducing cell death in DLBCL cell lines. Collectively, our findings identify the established and approved drug DMF as a promising novel therapeutic option in the treatment of both GCB and ABC DLBCL. Overall design: Gene expression profiling was performed in HBL-1 cells after 6, 12, 24 and 48h of treatment with 20µM DMF, compared to control. Each time point was measured in triplicate, resulting in 24 samples in total.