Epigallocatechin Gallate Modulates the Cellular Response to Doxorubicin in HeLa Cervical Cancer Cells

Cervical cancer remains a major cause of cancer-related mortality worldwide, highlighting the need for strategies that may improve responses to conventional chemotherapeutics. Epigallocatechin gallate (EGCG), a green-tea polyphenol with diverse biological activities, has been investigated as a potential chemosensitizing agent. This study evaluated the interaction between EGCG and doxorubicin (DOX) in HeLa cervical cancer cells, with HaCaT keratinocytes included as a non-malignant comparator. Cell viability and drug interactions were assessed using the CCK-8 assay and Chou-Talalay combination index (CI) analysis. Complementary assays evaluated membrane integrity, wound closure, apoptosis, cell-cycle distribution, intracellular DCF-associated fluorescence with or without N-acetylcysteine (NAC) pretreatment, caspase-3 immunoreactivity, and EGFR, FOXP3, CASP3, and CASP7 mRNA expression. Network-based analyses were additionally used to identify candidate molecular associations and pathways. CI analysis demonstrated synergistic EGCG-DOX interactions in HeLa cells under the tested conditions, whereas additive or antagonistic interactions predominated in HaCaT cells. Combined treatment produced the greatest reduction in viable cells, increased apoptosis, altered cell-cycle distribution, and reduced wound closure. It also produced the highest viability-normalized DCF-associated fluorescence, which was attenuated by NAC pretreatment, indicating an antioxidant-sensitive change in intracellular oxidative status without establishing a causal role in cytotoxicity. Combined treatment was further associated with increased total caspase-3 immunoreactivity and altered EGFR, FOXP3, CASP3, and CASP7 transcript levels. Overall, EGCG and DOX exhibited synergistic interactions and multiple treatment-associated cellular and transcriptional responses in HeLa cells under the present in vitro conditions. These findings do not establish cancer-specific selectivity or a definitive molecular mechanism but provide a basis for validation in additional cervical cancer models and at clinically relevant exposures.