Fludarabine Enhances Radiosensitivity by Promoting Ferroptosis in B-Cell Lymphoma

The objective of this study is to investigate the impact of fludarabine, a signal transducer and activator of transcription-1 (STAT1) inhibitor, on the radiosensitivity of B-cell lymphoma (BCL) and to explore the underlying mechanisms. Radiotherapy is one of the primary treatments for BCL, and STAT1 plays a critical role in the transcription of cell proliferation-related genes, which are associated with radiotherapy and ferroptosis. This study aims to determine whether fludarabine can enhance the radiosensitivity of BCL and to elucidate the molecular pathways involved. Various in vitro methodologies, including CCK-8 assays, clonogenic formation assays, immunohistochemistry, immunofluorescence, flow cytometry, qRT-PCR, and Western blot analyses, were employed in B-cell lymphoma cell models to thoroughly investigate the effects of fludarabine on radiosensitivity. Subsequently, the obtained results were further validated through in vivo animal models and by examining human diffuse large B-cell lymphoma (DLBCL) cancer samples. Our findings demonstrate that the combination of fludarabine and irradiation synergistically inhibits cell viability and colony formation, while inducing apoptosis and ferroptosis in B-cell lymphoma cell lines Raji and Su-DHL-10. Moreover, fludarabine was found to enhance the ferroptosis induced by radiation, thereby synergistically impeding the growth of BCL. In vivo experiments confirmed these findings, revealing that the intraperitoneal injection of fludarabine significantly enhanced the inhibitory effects of radiation on Raji cell xenograft models, leading to an increased percentage of ferroptosis compared to models without fludarabine. Additionally, the administration of liproxstatin-1, a ferroptosis inhibitor, attenuated the inhibition of xenograft growth caused by the combination of fludarabine and irradiation. Furthermore, our analysis of clinical data revealed that increased co-expression of STAT1 and GPX4 is associated with poor overall survival in patients with diffuse large B-cell lymphoma. These results highlight the potential of fludarabine to enhance radiosensitivity and ferroptosis induction as a promising therapeutic strategy for BCL. Our results demonstrated that fludarabine promoted radiation-induced BCL death through the ferroptosis pathway. We have identified a previously unrecognized mechanism in the fludarabine and radiation combination, indicating that it is necessary to conduct prospective clinical trials to verify this new treatment regimen in BCL.