XPO1 Inhibition enhances sensitivity to platinum-based chemotherapy in germinal-center B-cell-like-DLBCL cells

Platinum-based chemotherapy is considered as salvage therapy to relapsed/refractory diffuse large B-cell lymphoma (DLBCL) patients. However, treatment failure due to drug resistance occurs in some patients, particularly those with Exportin 1 (XPO1) overexpression. This study investigates whether XPO1 inhibition enhances platinum sensitivity in DLBCL subtypes. XPO1 expression in DLBCL was predicted using online datasets. Cell lines representing DLBCL subtypes were treated with varying concentrations of the XPO1 inhibitor selinexor (XPO1i), cisplatin (CDDP), and oxaliplatin (OXA), alone or in combination. Cellular viability was assessed via CCK-8 assay, while apoptosis rates and reactive oxygen species (ROS) levels were measured by flow cytometry. Protein levels of XPO1 and pro-apoptotic cytokines were evaluated using Western blotting. Bioinformatic analysis revealed elevated XPO1 expression in DLBCL. Both XPO1i and platinum-based therapy inhibited cellular viability and promoted apoptosis across DLBCL subtypes in a dose-dependent fashion. The combination of XPO1i at its IC50 and CDDP synergistically suppressed cell viability across both activated B-cell-like- and germinal-center B-cell-like (GCB)-DLBCL subtypes compared to CDDP monotherapy. The combination of XPO1i at its IC30 and OXA synergistically led to a greater reduction in cell viability, along with enhanced induction of apoptosis and ROS accumulation in GCB-DLBCL cells. In OCI-Ly8 and OCI-Ly1 cells, OXA alone inhibited phosphorylation of AKT and mTOR while increasing phosphorylation of JNK, ATM, and p53, and expression of γH2AX; these effects were potentiated by the combination of XPO1i and OXA. XPO1 inhibition enhances platinum-induced cytotoxicity in GCB-DLBCL, supporting clinical evaluation of XPO1i-platinum combinations as salvage therapy.