Electrotransfer of Different Control Plasmids Elicits Different Antitumor Effectiveness in B16.F10 Melanoma.

Masa Bosnjak,Tanja Jesenko,Maja Cemazar,Gregor Sersa,Urska Kamensek,Loree Heller,Jaka Lavrencak

doi:10.3390/cancers10020037

Masa Bosnjak, Tanja Jesenko + Show 5 more

Open Access

https://doi.org/10.3390/cancers10020037

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Journal: Cancers	Publication Date: Jan 29, 2018
Citations: 23	License type: CC BY 4.0

Affiliation: Institute of Oncology Ljubljana, Old Dominion University

Abstract

Several studies have shown that different control plasmids may cause antitumor action in different murine tumor models after gene electrotransfer (GET). Due to the differences in GET protocols, plasmid vectors, and experimental models, the observed antitumor effects were incomparable. Therefore, the current study was conducted comparing antitumor effectiveness of three different control plasmids using the same GET parameters. We followed cytotoxicity in vitro and the antitumor effect in vivo after GET of control plasmids pControl, pENTR/U6 scr and pVAX1 in B16.F10 murine melanoma cells and tumors. Types of cell death and upregulation of selected cytosolic DNA sensors and cytokines were determined. GET of all three plasmids caused significant growth delay in melanoma tumors; nevertheless, the effect of pVAX1 was significantly greater than pControl. While DNA sensors in vivo were not upregulated significantly, cytokines IFN β and TNF α were upregulated after GET of pVAX1. In vitro, the mRNAs of some cytosolic DNA sensors were overexpressed after GET; however, with no significant difference among the three plasmids. In summary, although differences in antitumor effects were observed among control plasmids in vivo, no differences in cellular responses to plasmid GET were detected in tumor cells in vitro. Thus, the tumor microenvironment as well as some plasmid properties are most probably responsible for the antitumor effectiveness.

Highlights

Gene electrotransfer (GET) is a non-viral delivery method for transfection of cells and tissues [1,2,3].The transfer of genetic material across the cell membrane is enabled by a transient increase in the permeability of cell membrane achieved by exposing the cells to short high voltage electric pulses.Cancers 2018, 10, 37; doi:10.3390/cancers10020037 www.mdpi.com/journal/cancersThis process is referred to as electroporation (EP) [4,5]
Expression of the mRNAs of selected DNA sensors and cytokines that we previously demonstrated to be overexpressed in tumor cells were quantified
Tumor growth delay was more pronounced when pVAX1 was used than when pControl or pENTR/U6 scr were used in combination with the EP

Summary

Introduction

Gene electrotransfer (GET) is a non-viral delivery method for transfection of cells and tissues [1,2,3].The transfer of genetic material across the cell membrane is enabled by a transient increase in the permeability of cell membrane achieved by exposing the cells to short high voltage electric pulses.Cancers 2018, 10, 37; doi:10.3390/cancers10020037 www.mdpi.com/journal/cancersThis process is referred to as electroporation (EP) [4,5]. While GET is an efficient, reliable and safe in vivo transfection method, one of its shortcoming is the high cell mortality that particular pulse protocols can induce. Whereas in intratumoral GET, when targeting cancer cells, high cell mortality induced by pulse protocol and/or plasmid backbone could potentially contribute to overall effectiveness, in other GET applications such as vaccination this phenomenon is undesirable. Cytosolic DNA sensors can detect foreign DNA as pathogen-associated molecular patterns (PAMPs) or as damage-associated molecular patterns (DAMPs). Activation of these sensors mediates the activation of proinflammatory molecules that can trigger an innate and potentiate an adaptive immune response [16,17,18,19]

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