Synergistic Effect of Digoxin and Cisplatin on Redox Imbalance in HeLa Cells

Our previous study demonstrated a potent synergistic antitumor effect between 1 nM digoxin and 1 μM cisplatin in cervical cancer cells, which was dependent on the modulation of the signaling pathway involving Na, K-ATPase/Src. Because of the relationship between Na, K-ATPase/Src and the modulation of oxidative stress, the aim of this study was to demonstrate the effect of combined treatment with digoxin and cisplatin on oxidative stress parameters in HeLa cells and the effect of treatment in non-tumor cell lines. Analysis of oxidative stress parameters revealed a significant reduction in cellular antioxidant defense mechanisms, SOD activity, and content of reduced total thiol groups. Additionally, there was an increase in H₂O₂ content within 24 h, confirming the elevated cellular oxidative stress during the combined treatment. Furthermore, lipid peroxidation and lipid droplet formation levels were evaluated, showing an increase in these parameters after 48 h of treatment, consistent with oxidative stress. Compared to the other tested cell lines, the combined treatment did not significantly alter cell viability compared to the control. Our data demonstrate that the synergistic antitumor effects of digoxin and cisplatin in HeLa cells are tightly associated with increased oxidative stress via activation of the Na, K-ATPase/Src/ROS signaling pathway, may resulting in antiproliferative and pro-apoptotic effects. These findings indicate that oxidative stress is a key component of the cellular response underlying the synergistic antitumor effects of digoxin and cisplatin.