Abstract 2366: Dynamic crosstalk between endothelial and epithelial cells drives tumor progression in lung adenocarcinoma

Background: Lung adenocarcinoma (LUAD) is a leading cause of cancer-related deaths, but the mechanisms driving its initiation and progression are not fully understood. This study investigates the interactions between epithelial and endothelial cells in LUAD and their roles in tumor progression. Methods: Single-cell RNA sequencing and spatial transcriptomics (Visium) were employed to explore LUAD carcinogenesis in two mouse models: a genetically engineered KrasG12D mouse model (GEMM) and a urethane-induced carcinogen model (CITM), both in the 129S4 background. LUAD and its precursors (normal lung, hyperplasia, adenoma, and adenocarcinoma) were classified by pathologists. Lung tissues collected at multiple time points were analyzed to characterize epithelial-endothelial crosstalk during LUAD initiation and progression. Results: As LUAD progressed, the proportion of epithelial cells gradually increased. In GEMM, tumor cells exhibited higher scores in KRAS signaling, hypoxia, apoptosis, and the P53 pathway compared to normal epithelial cells, indicating activation of these pathways during tumorigenesis. In endothelial cells (ECs), tip ECs were significantly upregulated during tumor progression, highly expressing Angpt2, Cxcr4, Pgf, Col4a1, Col4a2 and Insr, which are associated with EC migration, matrix remodeling, and vascular endothelial growth factor (VEGF) signaling. These cells were predominantly localized within tumor regions, as demonstrated by spatial transcriptomics, indicating their role in tumor angiogenesis. In contrast, aerocytes (aCap) decreased significantly over time, suggesting a shift from a quiescent to a more tumor-supportive phenotype. The upregulation of tip ECs and the downregulation of aCap cells suggest that tumor progression is accompanied by a dynamic reshaping of the endothelial compartment, which promotes the formation of a more permissive tumor microenvironment. We also observed enhanced crosstalk between tip ECs and epithelial tumor cells, particularly via the Col4a1-Cd44 and Mif-(Cd74+Cxcr4) ligand-receptor pairs, facilitating tumor cell adhesion, migration, and invasion. Notably, Cd44 and Mif expression in epithelial cells progressively increased, supporting further epithelial-endothelial interactions, and contributing to tumor cell survival and immune evasion. Furthermore, we observed a significant increase in BATF+ Tregs within the tumor microenvironment as LUAD progressed, indicating an evolving tumor-supportive immune environment. Conclusions: This study highlights the critical role of tip ECs and endothelial-epithelial interactions in LUAD progression. The expansion of BATF+ Tregs underscores the complex immune interplay involved in this process. Targeting endothelial-epithelial crosstalk could provide a promising strategy to treat LUAD precancers and prevent the development of invasive disease. Citation Format: Hong Chen, Bo Zhu, Junya Fujimoto, Yanhua Tian, Jian-Rong Li, Chenyang Li, Pingjun Chen, Alexandre Reuben, Monique Nilsson, Xiuning Le, Alissa Poteete, Shawna M. Hubert, Don L. Gibbons, Ignacio I. Wistuba, Jia Wu, Chao Cheng, John V. Heymach, Jianjun Zhang. Dynamic crosstalk between endothelial and epithelial cells drives tumor progression in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2366.