ANTICANCER ACTIVITY OF EPIGALLOCATECHIN GALLATE AGAINST MDA-MB-231 TRIPLE-NEGATIVE BREAST CANCER CELLS THROUGH OXIDATIVE STRESS-INDUCED APOPTOSIS

Abstract

Background: Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer characterized by the absence of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 (HER2). Owing to the lack of specific molecular targets, conventional chemotherapy remains the principal treatment modality, although therapeutic outcomes are often limited by recurrence and drug resistance. Epigallocatechin-3-gallate (EGCG), the predominant polyphenolic catechin found in green tea, has shown considerable promise because of its ability to inhibit tumour growth through multiple molecular mechanisms. Objective: To investigate the cytotoxic effect of EGCG on MDA-MB-231 triple-negative breast cancer cells and to elucidate its mechanism of action by assessing oxidative stress, apoptosis, and membrane damage. Materials and Methods: MDA-MB-231 cells were exposed to EGCG at concentrations ranging from 0 to 50 μM for 24 hours. Cell viability was determined using a colorimetric cytotoxicity assay. Intracellular reactive oxygen species (ROS) levels were quantified using the DCFH-DA fluorescence assay, while activation of caspase-3/7 was measured using a fluorometric assay. Membrane integrity was evaluated by estimating lactate dehydrogenase (LDH) release. Data were expressed as mean ± standard deviation and analyzed using one-way analysis of variance followed by Tukey's post hoc test. A p-value <0.05 was considered statistically significant. Results: Exposure to EGCG resulted in a marked concentration-dependent reduction in the viability of MDA-MB-231 cells. Growth inhibition increased progressively from 6.37% in untreated cells to 78.06% following treatment with 50 μM EGCG. Intracellular ROS generation increased substantially, with fluorescence intensity rising from 220.5 in the control group to 4491.5 at the highest concentration tested. Caspase-3/7 activity also increased markedly, indicating activation of the apoptotic pathway, while LDH release showed a parallel increase, reflecting progressive loss of membrane integrity. These findings collectively indicate that EGCG suppresses tumour cell proliferation by promoting oxidative stress mediated apoptosis. Conclusion: EGCG demonstrated potent anticancer activity against MDA-MB-231 triple-negative breast cancer cells by reducing cell viability and inducing oxidative stress, caspase-dependent apoptosis, and membrane damage in a concentration-dependent manner. These findings support the potential role of EGCG as a promising natural therapeutic candidate for TNBC. Further preclinical and in vivo studies are warranted to establish its therapeutic efficacy and clinical applicability.