Enhancing lung cancer growth inhibition with calcium ions: Role of mid- and high-frequency electric field pulses

Abstract

Calcium electroporation (CaEP) involves the combination of calcium ions with electroporation, which is induced by pulsed electric fields (PEFs). This study explores the application of high-frequency unipolar nanosecond pulsed electric fields (nsPEFs: 8–14 kV/cm, 200 ns, 10 kHz, 100 kHz, 1 MHz repetition frequency pulse bursts, n = 100) and their potential in inhibiting lung cancer cell growth. As a reference, standard microsecond range parametric protocols were used (100 µs x 8 pulses). Methods included cell permeability quantification through Yo-Pro-1 uptake, cell viability assays, immunofluorescence studies for apoptosis and EMT markers, analysis of cell death types depending on repetition frequency pulse bursts. We determined the susceptibility of human lung cancer to electric pulses, characterized the efficacy of CaEP, and investigated cell death types depending on repetition frequency pulse bursts. We have shown that adding calcium ions to the applied nsPEF protocol increases cytotoxicity. Additionally, the use of these electroporation parameters can modulate key cellular processes, such as the epithelial-mesenchymal transition and apoptosis, as indicated by changes in the expression of markers such as E-cadherin, N-cadherin, BCL-2, and p53. Changes in cell morphology over time were observed using holotomographic microscopy. The study provides insights into the modulation of key cellular processes, indicating that nsPEF technology could improve the outcomes of conventional cancer treatments through enhanced efficacy and potentially mitigating drug resistance mechanisms. The promising results advocate for further research to optimize nsPEF protocols for clinical application, highlighting the potential of electrical fields in advancing cancer therapy.

Keywords

• High frequency
• Calcium electrochemotherapy
• Tumors
• Lung cancer, 3D cell culture, spheroids