Abstract 4831: Inducible models of EMT reveal dynamic changes in the tumor-immune microenvironment

Abstract Epithelial-to-mesenchymal transition (EMT) drives tumor cell plasticity, stemness, and metastasis, yet the dynamic consequences of EMT activation on the tumor microenvironment remain poorly defined. Doxycycline-regulated EMT-inducible systems offer a powerful strategy to study reversible EMT programs with precise temporal control in both in vitro and in vivo settings. In this study, we developed doxycycline-inducible miR-200 and ZEB1 models in the D2A1 and EMT6 breast cancer cell lines to interrogate EMT regulation across diverse contexts. Doxycycline treatment produced robust EMT inhibition in miR-200 models and EMT activation in ZEB1 models, accompanied by expected morphological changes. In vivo, doxycycline-induced miR-200 expression suppressed EMT marker expression and reshaped the tumor immune microenvironment. Specifically, miR-200 induction increased intratumoral CD8+ T cells, reduced Arg1+ macrophages, and decreased platelet accumulation, as confirmed by immunohistochemistry. Cytokine profiling revealed shifts in inflammatory and immune-recruiting signals, and single-cell RNA sequencing showed enhanced MHC-I antigen presentation pathways and altered immune activation states upon EMT inhibition. Together, these results demonstrate that doxycycline-inducible EMT models faithfully recapitulate epithelial-mesenchymal plasticity and uncover key EMT-dependent changes in stemness and immune composition. Ongoing studies aim to define the mechanisms through which miR-200-mediated EMT suppression drives these immune shifts. These inducible systems provide a powerful framework for dissecting how EMT dynamics shape tumor-immune interactions and may offer insight into therapy responsiveness. Citation Format: Breanna Demestichas, Tanvi Visal, Petra den Hollander, Nick Kuburich, Sendurai A. Mani. Inducible models of EMT reveal dynamic changes in the tumor-immune microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4831.