Authors
1
Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
2
Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran and Department of Medical Laboratory Scinces, School of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, and Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
3
Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
4
Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, and Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Abstract
Background: Triple-negative breast cancer (TNBC) remains a therapeutic challenge due to its metastatic features and resistance to conventional therapies. This study investigated the synergistic potential of quercetin (QC), a natural flavonoid, and 5-fluorouracil (5-FU) in targeting epithelial-mesenchymal transition (EMT) to inhibit proliferation and migration of the MDA-MB-231 TNBC cell line.
Methods: Cytotoxicity and selectivity were assessed using the MTT assay in MDA-MB-231 cells and normal MRC-5 fibroblasts. Synergy was quantified using combination index (CI) values. Scratch assay was assessed for migration inhibition, while quantitative RT-PCR analyzed EMT-related gene expression (Vimentin, ZEB1, N-cadherin, and E-cadherin). Western blotting confirmed protein expression of ZEB1 and E-cadherin following treatment with QC (50 μM), 5-FU (25 nM), or their combination.
Results: QC and 5-FU demonstrated concentration- and time-dependent cytotoxicity in MDA-MB-231 cells, with QC being highly selective for cancer cells. Toxicity in normal MRC-5 fibroblasts occurred only at 800 µM (25% viability). The combination of 50 µM of QC and 25 nM of 5-FU exhibited the strongest synergy (CI = 0.08), reducing viability by 75% and migration by 87.8%. QC alone downregulated ZEB1, Vimentin, and N-cadherin, while
5-FU further reduced these markers. Combined treatment enhanced suppression (ZEB1: 0.46-fold; Vimentin: 0.47-fold; N-cadherin: 0.68-fold) and significantly upregulated E-cadherin (3.75-fold), indicating EMT reversal. Western blotting confirmed decreased ZEB1 and increased E-cadherin by over four-fold with QC + 5-FU, indicating a shift to an epithelial phenotype.
Conclusions: Combining QC and 5-FU effectively inhibited TNBC proliferation and migration while minimizing toxicity to normal cells. This dual-action strategy offers a promising low-toxicity therapeutic approach for aggressive TNBC.
Keywords
Iranian Biomedical Journal