Abstract 3985: Immune-competent “NoGlow” transgenic mice overcome restrictive tolerance to multiple xenoantigens and simultaneously permit identification, tracking, and temporal gene expression in tumor cells

Abstract

Abstract The ability to temporally regulate gene expression and track labeled cells make animal models powerful biomedical tools. However, sudden exposure to xenobiotic genes (e.g. GFP, luciferase (luc), or rtTA3) triggers inadvertent immune responses that can significantly suppress foreign gene expression or result in complete rejection of transplanted cells. Although germline expression of foreign genes somewhat addresses these challenges, native fluorescence and bioluminescence abrogates their utility as cellular reporters and spatiotemporally restricted expression can lead to suboptimal xenoantigen tolerance. Even in endogenous cancer models, we find that the means of tissue-directed expression of the same foreign gene yield significant differences in overall tolerance. Thus, the degree of tolerance to foreign genes strongly impacts the utility of different genetic modification and can strongly influence experimental outcomes and interpretations. To overcome these unwanted immune responses and enable reliable cell tracking/gene regulation, we developed a novel mouse model that selectively expresses antigen-intact but non-functional forms of GFP, luc, and rtTA3. These "NoGlow" mice possess no detectable background fluorescence or luminescence and mount limited adaptive immune responses against transgenic xenoantigens even after vaccination. Furthermore, we demonstrate that NoGlow mice allow tracking and tetracycline inducible gene regulation of triple-transgenic cells expressing GFP/luc/rtTA3, in contrast to transgene-negative immune competent mice which completely eliminate these cells. Notably, this model enables de novo metastasis from orthotopically implanted, triple-transgenic tumor cells, despite high xenoantigen expression. Finally, we observed model and sex-based differences in immune tolerance to the encoded xenoantigens after activation by different tissue-specific CREs, illustrating the obstacles of tolerizing animals to foreign genes and validating the utility of NoGlow mice to dissect the mechanisms of central and peripheral tolerance. Altogether, the NoGlow model provides a critical resource for in vivo studies across multiple disciplines, including oncology, developmental biology, infectious disease, autoimmunity, and transplantation. Citation Format: Timothy N. Trotter, Andrea Wilson, Jason McBane, Carina Dagotto, Xiao Yang, Junping Wei, Gangjun Lei, Hannah Thrash, H. Kim Lyerly, Zachary Hartman. Immune-competent “NoGlow” transgenic mice overcome restrictive tolerance to multiple xenoantigens and simultaneously permit identification, tracking, and temporal gene expression in tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3985.