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Stimulation of Cytoplasmic DNA Sensing Pathways In Vitro and In Vivo
Published on: September 18, 2014
Cytosolic DNA Sensor Upregulation Accompanies DNA Electrotransfer in B16.F10 Melanoma Cells
Katarina Znidar1, Masa Bosnjak2, Maja Cemazar1,2
1Faculty of Health Sciences, University of Primorska, Izola, Slovenia.
Abstract:
In several preclinical tumor models, antitumor effects occur after intratumoral electroporation, also known as electrotransfer, of plasmid DNA devoid of a therapeutic gene. In mouse melanomas, these effects are preceded by significant elevation of several proinflammatory cytokines. These observations implicate the binding and activation of intracellular DNA-specific pattern recognition receptors or DNA sensors in response to DNA electrotransfer. In tumors, IFNβ mRNA and protein levels significantly increased. The mRNAs of several DNA sensors were detected, and DAI, DDX60, and p204 tended to be upregulated. These effects were accompanied with reduced tumor growth and increased tumor necrosis. In B16.F10 cells in culture, IFNβ mRNA and protein levels were significantly upregulated. The mRNAs for several DNA sensors were present in these cells; DNA-dependent activator of interferon regulatory factor (DAI), DEAD (Asp-Glu-Ala-Asp) box polypeptide 60 (DDX60), and p204 were significantly upregulated while DDX60 protein levels were coordinately upregulated. Upregulation of DNA sensors in tumors could be masked by the lower transfection efficiency compared to in vitro or to dilution by other tumor cell types. Mirroring the observation of tumor necrosis, cells underwent a significant DNA concentration-dependent decrease in proliferation and survival. Taken together, these results indicate that DNA electrotransfer may cause the upregulation of several intracellular DNA sensors in B16.F10 cells, inducing effects in vitro and potentially in vivo.
Insights
Intratumoral electroporation of plasmid DNA triggers antitumor responses by activating intracellular DNA sensors. This process upregulates DNA sensors and reduces tumor cell proliferation and survival, indicating potential therapeutic applications.
Area of Science:
- Immunology
- Molecular Biology
- Oncology
Background:
- Intratumoral electroporation (electrotransfer) of plasmid DNA without a therapeutic gene shows antitumor effects in preclinical models.
- These effects are linked to elevated proinflammatory cytokines and suggest activation of intracellular DNA sensors.
Purpose of the Study:
- To investigate the role of intracellular DNA sensors in the antitumor effects of DNA electrotransfer.
- To examine the impact of DNA electrotransfer on DNA sensor expression and cellular responses in vitro and in vivo.
Main Methods:
- Preclinical tumor models (mouse melanomas) and B16.F10 melanoma cells in culture were used.
- DNA electrotransfer was performed, followed by analysis of cytokine and DNA sensor mRNA and protein levels.
- Cell proliferation, survival, and tumor necrosis were assessed.
Main Results:
- DNA electrotransfer significantly increased IFNβ mRNA and protein levels in tumors and B16.F10 cells.
- Upregulation of DNA sensors, including DNA-dependent activator of interferon regulatory factor (DAI), DEAD (Asp-Glu-Ala-Asp) box polypeptide 60 (DDX60), and p204, was observed.
- Cells showed a DNA concentration-dependent decrease in proliferation and survival, and tumors exhibited increased necrosis.
Conclusions:
- DNA electrotransfer induces the upregulation of intracellular DNA sensors in melanoma cells.
- Activation of these sensors contributes to the observed antitumor effects, including reduced cell proliferation and increased tumor necrosis.
- DNA electrotransfer shows potential as a therapeutic strategy by harnessing innate immune responses.
