Research is supported by the National Cancer Institute of the National Institutes of Health under award number R01CA196796.
Principal investigator at the Institute of Oncology Ljubljana: Maja Čemažar PhD
In vivo electroporation is a rapidly expanding molecular delivery platform. Although it has enormous clinical utility and many clinical trials are ongoing, it is an evolving technology. For clinical applications of in vivo DNA electroporation, molecular mechanisms at a cellular as well as the organism level should be elucidated.
In our studies we observed that after electroporation of non-coding backbone plasmid DNA (pDNA), a percentage of mouse melanoma and sarcoma tumors completely regress. Both pulses and DNA are necessary to produce this regression; however, an encoded therapeutic gene is not necessary. The regression level is dependent on the both pDNA concentration and the electric pulse protocol used. We then demonstrated that increases in inflammatory protein levels accompany this regression, suggesting that inflammation may be a contributing factor.
Since electroporation delivers DNA to both the endosomes and the cytosol of the cell, this inflammation may be a product of activation of the well-described endosomal pattern recognition receptor (PRR) TLR9 or of the more recently described cytosolic DNA sensors.
Our research goals are designed to determine if PRRs are activated after DNA electroporation in non-immune cells, and if so, which PRRs or combinations of PRRs are activated. Most of the research in the field of DNA electroporation is focused either on the elucidation of the mechanisms of DNA entry into the cell, trafficking through the cytoplasm and entering the nucleus, or into the therapeutic effectiveness of different therapeutic genes. Our studies are designed to clarify currently unexpected in vivo findings that may have significant clinical consequences. Since most research utilizing DNA electroporation is directed toward clinical applications, it is important and significant to completely understand these unpredicted effects. Variable induction of inflammation affects cancer-directed immune modulation, vaccine induction of immune responses, and therapies for simple transgene expression in cases where an immune response is not desirable. With a full understanding, this activation can be harnessed or controlled during therapeutic design, thus leading to improved gene therapies.