Reactive Oxygen and Nitrogen Species Release of Single Pancreatic Cancer Cells Subjected to Pulsed Electric Field Ablation: Concentration and Dynamics

Pancreatic cancer, recognized for its extreme lethality, is normally diagnosed at an advanced stage, leaving only a minority of patients eligible for surgical resection. Pulsed electric field (PEF) ablation, an ablative technique for clinical treatment of locally advanced pancreatic cancer, causes tumor cell death by disrupting cellular redox balance, resulting in the overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In situ monitoring of the dynamic changes in ROS/RNS levels of pancreatic cancer cells under PEF ablation is important for understanding its mechanism for pancreatic cancer treatment. Here, we constructed an in vitro pancreatic cancer cell model via culturing PANC-1 cells on polyacrylamide gels with a stiffness of 4.0 kPa to simulate the mechanical microenvironment of advanced pancreatic cancer stage. We then established a theoretical model and simulated the electric field strengths of PEF ablation used for the clinical treatment of pancreatic cancer. After applying PEF ablation with these electric field strengths on the in vitro pancreatic cancer cell model, we in situ monitored the dynamic releasing processes of hydrogen peroxide (H₂O₂) and nitric oxide (NO) from PANC-1 cells by employing scanning electrochemical microscopy (SECM). Through quantitative analysis of SECM results, we found that the electric field strengths of PEF ablation over 1.5 kV cm^-1 caused cells to exhibit periodic bursts of H₂O₂ and NO effluxes during the initial 5 min and then reduced to their initial values within 6 min after treatment, while mitochondrial dysfunction persisted. It demonstrates a prolonged impact of electric field strength on disrupting cellular redox balance, offering valuable insights into the mechanism of electric field strength-dependent redox imbalance of pancreatic cancer under electric ablation.