Exploratory Evaluation of Resveratrol-Thymoquinone Cytotoxic Interactions and Apoptotic Responses in MDA-MB-231 Triple-Negative Breast Cancer Cells.

INTRODUCTION Diet-derived bioactive antioxidants have attracted increasing attention due to their potential role in modulating cancer-related pathways. This study aimed to investigate the cytotoxic and apoptotic effects of resveratrol and thymoquinone, individually and in combination, and to evaluate their potential synergistic interaction in aggressive MDA-MB-231 breast cancer cells.

Methods

The cytotoxic effects of resveratrol and thymoquinone were evaluated in MDA-MB-231 cells using the MTT assay, and IC50 values were calculated. Combination doses were determined based on the cytotoxic concentrations obtained from single treatments. Drug interaction analysis was performed using the Chou- Talalay method to calculate combination indices (CI) from the MTT results. Each experiment was performed in three independent biological replicates. Apoptotic effects were assessed by Annexin V staining analysis.

Results

Combination index values of resveratrol and thymoquinone were found to be <1, indicating a synergistic interaction between the two compounds. Annexin V staining analysis revealed that the proportion of late apoptotic cells was significantly higher in the combination treatment than in the individual treatments.

Discussion

The present findings indicate that the combined administration of resveratrol and thymoquinone enhances cytotoxic effects in MDA-MB-231 cells through synergistic interactions at the tested concentration pairs. The higher proportion of late apoptotic cells observed with the combined treatment indicates that apoptosis contributes to the cellular response associated with reduced metabolic viability. However, the molecular pathways underlying this response were not directly investigated. Therefore, potential involvement of oxidative stress, mitochondrial dysfunction, and apoptosis-related signaling requires direct molecular validation. Because no non-malignant breast epithelial cell line was included, the cancer-cell selectivity of these effects could not be determined.

Conclusion

The combination of resveratrol and thymoquinone was associated with a greater apoptotic response than the individual treatments and demonstrated synergistic cytotoxic interactions at the tested concentration pairs in MDA-MB-231 cells. These preliminary findings require confirmation in non-malignant breast epithelial cells, additional breast cancer models, and molecularly characterized experimental systems.