S. Zeng1, L. Du1, M. Wang1, D. Yang1, D. Tao1, Z. Tang1, W. Zhou1, and Y. Wu2; 1Department of Radiation Oncology, Chongqing University Cancer Hospital, Chongqing, China, 2Department of Radiation Oncology, Chongqing Cancer Hospital & Cancer Institute, Chongqing, China
Purpose/Objective(s): Poor radiation sensitivity is the main limiting factor of therapeutic efficacy and results in cancer recurrence in non-small cell lung cancer (NSCLC), but the underlying molecular mechanism remains unknown. In this study, we investigated the role of Early B-cell Factor 1 (EBF1) in modulating the radioresistance of NSCLC. Materials/
Methods: We subjected A549 and H1299 cells overexpressing EBF1 to gradient-dose irradiation followed by incubation. After 13 days, the number of cell colonies was observed. EBF1-overexpressing NSCLC cells were cultured using the hanging drop method under serum-free and non-adherent conditions to generate cell spheres, which were then evaluated for their morphological characteristics using scanning electron microscopy (SEM). Subsequently, the potential of sphere cell enrichment for cancer stem cells (CSCs) was compared by analyzing sphere-forming efficiency and the expression of key stemness genes using quantitative real-time PCR. The expression levels of key enzymes implicated in glutamine metabolism were assessed. Results: Both the A549 and H1299 cell lines overexpressing EBF1 formed a significantly higher number of colonies compared to the control group after radiation exposure. Despite varied morphologies, both cell lines with EBF1 overexpression showed enhanced sphere-forming capacity. Elevated expression of stemness-associated genes (SOX2, CD44, SLUG, BMI1, CD33, OCT4) and glutamine synthetase(GS), a key enzyme in glutamine metabolism, was observed in EBF1-overexpressing cells. Importantly, the knockdown of GS attenuated the sphere-forming ability and radiation resistance conferred by EBF1. Conclusion: Our research demonstrates that EBF1 upregulates GS expression in NSCLC, thereby enhancing cancer stemness and diminishing radiation sensitivity. These insights position EBF1 as a potential therapeutic target in the treatment of non-small cell lung cancer, offering a novel avenue for enhancing radiotherapy outcomes.
