Abstract 2312: Efficacy of targeted osmotic lysis is increased by cell cycle inhibition in M Phase

Abstract

Abstract Voltage-gated sodium channels (VGSCs) are upregulated in aggressive carcinomas, making these channels a target for novel clinical therapies. Targeted Osmotic Lysis (TOL) is a novel cancer therapy that combines pharmacologically blocking Na+,K+, ATPase (sodium pumps) while stimulating VGSCs with a pulsed electric field. The consequent increase in intracellular Na+ causes an osmotic lysis of the cells that overexpress VGSCs. Noncancerous cells, with fewer VGSCs do not lyse. We hypothesized that variability in efficacy of TOL is due to VGSC expression that varies across the cell cycle. We assessed cell surface expression of VGSCs and Na+,K+-ATPase during phases of the cell cycle in which there are single copies of DNA compared with phases in which DNA has doubled. For this, DNA was labeled with either propidium iodide or DAPI and VGSCs were labeled with a pan-specific VGSC antibody while Na+,K+-ATPases were labelled with a pan-specific Na+,K+-ATPase antibody in eight immortalized cancer and non-cancer cell lines. With flow cytometry we showed that VGSC expression doubled during phases of cell division (S-M phases) while Na+,K+-ATPase expression increased by 1.5-fold. To further elucidate the role of VGSCs and Na+,K+-ATPases throughout the cell cycle, S-Trityl-L-cysteine (STLC) was used to suspend the cell cycle in M phase. We hypothesized that treating cancer cells with TOL in the S-M phases would lead to increased cell death, compared to cells that were not suspended in M phase by STLC (G0-G1 phases). Cells were either treated with STLC or media without drug for 24 hours, then exposed to TOL treatment. The efficacy of the treatment was measured using a MTT assay revealing that cell death was greater in STLC-treated cells than control cells. By using cell cycle inhibitors, we may increase the efficacy of TOL for treating advanced carcinomas that overexpress VGSCs. Citation Format: Samantha Edenfield, Harry J. Gould, Dennis Paul. Efficacy of targeted osmotic lysis is increased by cell cycle inhibition in M Phase [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2312.