Differential Effects of Carboplatin, Metformin, and Boric Acid on Cell Viability, Migration, and Oxidative Stress in MCF-7 Breast Cancer and CRL-4010 Normal Mammary Epithelial Cells

Background/Objectives: Oxidative stress is a key contributor to breast cancer (BC) progression and therapeutic response. Although carboplatin is widely used in BC treatment, the effects of combining carboplatin with metformin and boric acid (BA) on cellular redox homeostasis remain poorly understood. This study investigated the effects of these agents on cell viability, migration, and oxidative stress in BC and normal mammary epithelial cells. Methods: Human BC MCF-7 cells and normal mammary epithelial CRL-4010 cells were treated with carboplatin, metformin, BA, and selected combination regimens. Cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay following 24, 48, and 72 h of treatment. Cell migration was evaluated using a scratch wound-healing assay, and intracellular oxidative stress responses were assessed by measuring superoxide dismutase (SOD) activity. Statistical analyses were performed using one-way ANOVA followed by Fisher’s least significant difference (LSD) post hoc test. Results: Treatment responses were both time- and treatment-dependent in MCF-7 and CRL-4010 cells. Combination regimens significantly reduced cell viability after 48 and 72 h (all p < 0.0001) and generally exhibited greater inhibitory effects than single-agent treatments. Metformin- and BA-containing combinations also produced more pronounced inhibition of cell migration. Significant treatment-related alterations in SOD activity were observed in both cell lines, indicating treatment-associated changes in antioxidant enzyme activity. While several combination regimens decreased SOD activity, others induced increased SOD activity, suggesting differential oxidative stress responses between malignant and non-malignant cells. Conclusions: Carboplatin, metformin, and BA significantly modulated cell viability, migration, and antioxidant responses in both BC and normal mammary epithelial cells. Combination treatments generally produced greater inhibitory effects on cell viability and migration than selected single-agent treatments, particularly in MCF-7 cells. These findings demonstrate treatment-dependent changes in cell viability, migration, and SOD activity and provide a basis for further investigation of the molecular mechanisms underlying carboplatin-based combination treatments.