The origins of cancer immunotherapy date back to the late 19th century, when William B. Coley introduced the approach of intratumoral injection with heat-inactivated toxin-producing bacteria. One of the most promising immunotherapeutic strategies is in situ vaccination, which relies on local tumor ablation to trigger a tumor-specific immune response by releasing tumor antigens from dying cancer cells. As part of this master's thesis, we evaluated the basic functionality of plasmids encoding bacterial toxins as potential candidates for in situ antitumor vaccination by gene electrotransfer (GEP). Using an EGFP (enhanced green fluorescent protein) reporter system, we compared the efficiency of secretion signals from the interleukin 2 and perforin 1 genes and determined the expression of plasmids for the expression of pore-forming toxins and superantigenic toxins. The plasmid was transfected into the B16F10 mouse melanoma cell line, and EGFP expression was determined by fluorescence imaging, toxin expression by quantitative PCR, and cytotoxicity by the PrestoBlueTM assay. The results showed efficient secretion in the construct with the PRF1 secretion signal and successful transcription of all analyzed toxins in transfected cells. The findings confirm the suitability of the prepared plasmids for further studies of therapeutic efficacy in in situ antitumor vaccination.
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