Abstract 6782: ACADS as a novel target of selinexor activity in diffuse large B cell lymphoma

Abstract Background: Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL), with poor outcomes in the relapsed/refractory (R/R) setting. Recent years have identified nuclear export protein Exportin-1 (XPO1) as a negative prognostic factor in several cancer types such as DLBCL. Selinexor is an orally available inhibitor of XPO1 with activity in R/R DLBCL, but knowledge gaps in understanding how XPO1 drives DLBCL are preventing the drug’s effective use in the clinic. Here, we analyzed selinexor’s effects on DLBCL metabolism and conducted a mass spectrometry analysis of mitochondrial proteins to determine which proteins and pathways relevant to bioenergetics are modulated by selinexor in DLBCL. Methods: DLBCL cell lines (HBL-1, OCI-Ly2, OCI-Ly8) were treated with selinexor for 24 hours and an XFe96 bioanalyzer was used to measure changes in mitochondrial and glycolytic ATP production. To identify factors driving changes in cellular metabolism, mitochondria were purified from DLBCL cell lines with and without treatment with selinexor. The mitochondrial preparations were digested with proteases and the resulting peptides were identified by mass spectrometry (MS). The sequences of metabolic proteins of interest were analyzed using the LocNES nuclear export sequence identifier (Xu et al., 2014) to determine which of these proteins might be canonical XPO1 cargo molecules. Additional validation of potential XPO1 cargo was performed via nuclear-cytoplasmic fractionation. Results: Selinexor significantly reduced both glycolytic and mitochondrial ATP production in all cell lines, as measured by extracellular acidification rate and oxygen consumption rate. MS analysis identified 4224 proteins, of which 92 showed a statistically significant change in mitochondrial abundance with selinexor treatment; 61 of these were downregulated, while 31 were upregulated. Several metabolic proteins were affected by selinexor treatment, most notably short-chain acyl-CoA dehydrogenase (ACADS), which catalyzes lipid metabolism via short-chain fatty acid oxidation. ACADS showed a decreased mitochondrial abundance in response to selinexor treatment, suggesting a mechanism by which the drug exerts its metabolic effects via the inhibition of short-chain fatty acid oxidation. Upon further analysis, the primary sequence of the protein was predicted to contain a nuclear export sequence, and subcellular fractionation analysis showed nuclear accumulation of ACADS following selinexor treatment, identifying it as a potential novel XPO1 cargo molecule in DLBCL. Conclusion: Selinexor inhibits glycolytic and mitochondrial metabolism in DLBCL, in part by blocking the nuclear export of enzymes involved in metabolism such as ACADS, which catalyzes short-chain fatty acid oxidation. Future work will further validate these targets of interest to reveal how selinexor exerts its cytotoxic effects in DLBCL. Citation Format: Kyla L. Trkulja, Will Tong, Daisy V. Tran, Lily Meng, Evelyn Teh, Susanne Penny, Devanand M. Pinto, Armand Keating, John Kuruvilla, Rob C. Laister. ACADS as a novel target of selinexor activity in diffuse large B cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6782.