Title: Tumor cell death after electrotransfer of plasmid DNA is associated with cytosolic DNA sensor upregulation
Abstract: // Katarina Znidar 1 , Masa Bosnjak 2 , Nina Semenova 3 , Olga Pakhomova 3 , Loree Heller 3, 4 and Maja Cemazar 1, 2 1 Faculty of Health Sciences, University of Primorska, Izola, Slovenia 2 Department od Experimental Oncology, Institute of Oncology Ljubljana, Ljubljana, Slovenia 3 Frank Reidy Research Center of Bioelectrics, Old Dominion University, Norfolk, Virginia, USA 4 School of Medical Diagnostic and Translational Sciences, Collage of Health Sciences, Old Dominion University, Norfolk, Virginia, USA Correspondence to: Maja Cemazar, email: [email protected] Loree Heller, email: [email protected] Keywords: plasmid DNA; pattern recognition receptors; mammary adenocarcinoma cells; fibrosarcoma cells; electroporation; Immunology Received: December 26, 2017 Accepted: February 27, 2018 Published: April 10, 2018 ABSTRACT Cytosolic DNA sensors are a subgroup of pattern recognition receptors (PRRs) and are activated by the abnormal presence of the DNA in the cytosol. Their activation leads to the upregulation of pro-inflammatory cytokines and chemokines and can also induce cell death. The presence of cytosolic DNA sensors and inflammatory cytokines in TS/A murine mammary adenocarcinoma and WEHI 164 fibrosarcoma cells was demonstrated using real time reverse transcription polymerase chain reaction (RT-PCR), western blotting and enzyme-linked immunosorbent assay (ELISA). After electrotransfer of plasmid DNA (pDNA) using two pulse protocols, the upregulation of DNA-depended activator of interferon regulatory factor or Z-DNA binding protein 1 (DAI/ZBP1), DEAD (Asp-Glu-Ala-Asp) box polypeptide 60 (DDX60) and interferon-inducible protein 204 (p204) mRNAs was observed in both tumor cell lines, but their expression was pulse protocol dependent. A decrease in cell survival was also observed; it was cell type, DNA concentration and pulse protocol dependent. Furthermore, the different protocols of electrotransfer led to different cell death outcomes, necrosis and apoptosis, as indicated by an annexin V and 7AAD assays. The obtained data provide new insights on the presence of cytosolic DNA sensors in tumor cells and the activation of different types of cells death after electrotransfer of pDNA. These observations have important implications on the planning of gene therapy or DNA vaccination protocols.