Adenovirus Vector-mediated Overexpression of a Truncated Form of the p65 Nuclear Factor κB cDNA in Dendritic Cells Enhances Their Function Resulting in Immune-mediated Suppression of Preexisting Murine Tumors

Purpose: The purpose of this study was to evaluate the effect of the Rel homology domain (RHD) of the transcription factor, nuclear factor κB (NFκB), on proinflammatory gene expression in bone marrow-derived dendritic cells (BMDCs). Experimental Design: We used an adenovirus vector encoding only the RHD of the NFκB (p65 family member) cDNA (AdRHD) to transduce murine BMDCs ex vivo . Endpoints measured included BMDC expression of activation markers, cytokine secretion, peptide antigen presentation, and the ability of these transduced cells to induce antitumor immunity in vivo . Results: AdRHD-transduced BMDCs secreted higher levels of the cytokines interleukin (IL) 1β, IL-6, and IL-12 (p40) compared with sham-transduced BMDCs or those transduced with an empty vector. AdRHD induced heightened surface expression of the activation markers CD40, B7.1, B7.2, and MHC class II on BMDCs, and these cells were able to present a peptide antigen to a T-lymphocyte hybridoma more efficiently than controls in vitro . Growth of syngeneic, established tumors (CT26 and B16.F10) was inhibited, and survival was prolonged in the mice that received intratumoral AdRHD-modified BMDCs compared with controls. Splenocytes from CT26 tumor-bearing animals that received intratumoral AdRHD-modified BMDCs were able to lyse CT26 target cells more efficiently than controls. Similar experiments using host mice harboring targeted mutations in CD4 and CD8, as well as BMDCs from mice lacking MHC class I, MHC class II, or IL-12 revealed that this tumor immunity was dependent on the presence of CD4+ and CD8+ cells in the tumor-bearing host, as well as MHC class I, MHC class II, and IL-12 expression by the administered BMDCs. Furthermore, induction of IL-12 (p40) expression by AdRHD was completely abrogated in BMDCs lacking the c-Rel NFκB family member. Conclusions: We made the following conclusions: ( a ) gene transfer-mediated overexpression of the RHD of NFκB activates BMDCs; ( b ) AdRHD-transduced BMDCs induce antitumor immunity when administered intratumorally, an effect mediated by both the CD4+ T cell/MHC class II and the CD8+ T cell/MHC class I pathways, as well as IL-12; and ( c ) IL-12 (p40) up-regulation by the RHD transgene in BMDCs is dependent on the presence of the c-Rel NFκB family member.