Regulation of immune-recognition molecules following delivery of plasmid backbone

Abstract

Abstract Local intratumor delivery with electroporation of low levels of plasmids encoding molecules, such as IL-12, IL-15, induces an antitumor effect without causing systemic toxicity. However, previous studies have predominately focused on the function of the delivered molecule encoded within the plasmid, and ignored the plasmid backbone. In this study, we found backbones pUMVC3 and pVax1 induced up-regulation of MHC class I (MHC-I), PD-L1, CD95 (Fas) and CD155 on tumor cell surface. These molecules participate in a considerable number of immunoregulatory functions through their interactions with activating and inhibitory immune cell receptors. MHC molecules are well-known for their role in antigen (cross-) presentation, thereby functioning as key players in the communication between immune cells and tumor cells. Increased PD-L1 expression on tumor cells is an important monitor of tumor growth and effectiveness of immune inhibitor therapy. During cancer progression CD95 is frequently downregulated, raising the possibility that loss of CD95 is part of a mechanism for tumor evasion. Due to its prominent endogenous and immune functions, CD155 has been gaining interest as a therapeutic target in the field of tumor immunology. Results from flow cytometry confirmed increased expression of MHC-I and PDL-1 on B16F10, 4T1 and KPC tumor cell lines. Preliminary animal data from tumor-bearing models, B16F10 melanoma, 4T1 breast cancer and KPC pancreatic cancer mouse models showed that tumor growth was attenuated after pUMVC3 intratumoral electroporation. Our data also documented pSTAT1-NF-κB signaling pathway might be associated with plasmid backbones’ function of up-regulating MHC-I, PD-L1, CD95 (Fas) and CD155 on tumor cells. R01 CA186730