Rituximab induces ferroptosis and RSL3 overcomes rituximab resistance in diffuse large B-cell lymphoma cells.

Diffuse large B-cell lymphoma (DLBCL) is the most common malignant lymphoma in adults, and the use of rituximab has greatly improved the survival of DLBCL patients. Currently, the first-line treatment regimen for DLBCL is still rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP), which significantly improves outcomes for DLBCL patients. However, a percentage of patients still experience refractory or relapsed disease. Since Dr. Brent R Stockwell proposed ferroptosis in 2012, Roudkenar, M. H. Roushandeh, A. M. Valashedi, M. R. and others proved the importance of ferroptosis in cancer drug resistance. The purpose of this study was to elucidate whether rituximab could exert anticancer effects on DLBCL cells by promoting ferroptosis. Cell viability was assessed using the Cell Counting Kit-8. The results showed that rituximab exposure induced ferroptosis in OCI-LY1 cells. However, combination with ferroptosis inhibitor ferrostatin (Fer-1) rescued ferroptosis-induced injury, indicating that ferroptosis plays a key role in rituximab-induced cell death. Western blotting was performed to detect the levels of specific ferroptosis-associated proteins in DLBCL. Moreover, GSH depletion and MDA upregulation was assessed using GSH assays and MDA assay kits in rituximab-treated OCI-LY1 cells. In addition, rituximab failed to induce ferroptosis in rituximab-resistant cell lines. Treatment with RSL3 enhanced the effects of rituximab on DLBCL cells by inhibiting cell viability. In conclusion, we report for the first time that rituximab induces ferroptosis in lymphoma cells, at least partially through the SLC7A11/GPX4 axis. We also identify targeting ferroptosis as a promising therapeutic option for both sensitive cells and resistant cells in the treatment of DLBCL.