Buthionine sulfoximine acts synergistically with doxorubicin as a sensitizer molecule on different tumor cell lines

The chemotherapeutic drug doxorubicin (DOX) has been widely used for treating solid tumors attributed to its antiproliferative effectiveness; however, its clinical use is limited due to side effects, including cardiotoxicity, myelosuppression, and drug resistance. Combining DOX with buthionine sulfoximine (BSO), a glutathione (GSH) synthesis inhibitor, showed promising results in overcoming these adverse effects, potentially reducing the required DOX dose while maintaining efficacy. The aim of the present study was to examine the effects of different concentrations of BSO and DOX, both individually and in combination, utilizing B16/F10 (murine melanoma), SNB-19 (human glioblastoma), S180 (murine sarcoma), and SVEC4-10 (murine endothelial) cell lines. Cell viability, migration, and clonogenicity were assessed using the following assays MTT, scratch, and colony formation. Antioxidant levels of GSH, as well as activities catalase (CAT), and superoxide dismutase (SOD) were measured. BSO alone exhibited minimal cytotoxic effects, while DOX alone reduced cell viability significantly. The combination of BSO+DOX decreased IC₅₀ values for most cell lines, demonstrating a synergistic effect, especially in B16/F10, S180, and SVEC4-10 cells. BSO+DOX combination significantly inhibited cell migration and clonogenicity compared to DOX alone. While GSH levels were decreased with BSO+DOX treatment activities of CAT and SOD increased following DOX administration but remained unchanged by BSO. These results suggest that BSO may be considered a valuable tool to improve DOX therapeutic efficacy, particularly in cases of chemotherapy-resistant tumors, as BSO enhances DOX activity while potentially reducing systemic chemotherapeutic drug toxicity.