Abstract 2670: Understanding cell-of-origin influence on cancer-associated fibroblasts in lung adenocarcinoma

Abstract Lung cancer remains the top cause of cancer mortality worldwide, with lung adenocarcinoma (LUAD) representing the most common and heterogeneous subtype of non-small cell lung cancer (NSCLC). This heterogeneity lies in cell of origin, histological presentation, therapeutic response and clinical outcome, posing challenges for precision in diagnosis, prognosis and effective therapeutics. Our previous research in mouse models determined that GRAM domain containing-2 (Gramd2)-positive alveolar epithelial type 1 (AT1) cells can give rise to LUAD, exhibiting histological, cellular and molecular characteristics that are distinct from LUAD derived from surfactant-secreting type 2 (AT2) cells, which are a widely regarded cell of origin for LUAD. Additionally, we recently leveraged single-nucleus RNA sequencing (snRNA-seq) to dissect the composition of the tumor microenvironment (TME) of the Gramd2+ AT1 cell-derived LUAD and Sftpc+ AT2 cell-derived LUAD, demonstrating a distinct immune landscape of LUAD based on cell-of-origin. Significantly, immunosuppressive myeloid cells, such as myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), dominated the TME of Sftpc+ AT2 cell-derived LUAD, whereas immunoreactive macrophages and pro-inflammatory monocytes were highly enriched in Gramd2+ AT1 cell-derived LUAD. These findings may partly answer why only a subset of LUAD patients respond to immunotherapy. However, the role of mesenchymal cells in the TME and how they influence LUAD progression are unknown. To address this, snRNA-seq data of cancer-associated fibroblasts (CAF/M) cells from both cell of origin models was analyzed. We identified a distinct Lcn2+, Mmp2+, Cxcl14+ CAF/M cell population specifically enriched in Sftpc+ AT2-derived LUAD TME. These CAF/M cells exhibited upregulated mitochondrial activity, oxidative phosphorylation, and extracellular matrix remodeling, supporting tumor development and invasion. In contrast, fibroblasts in the TME of Gramd2+ AT1-derived LUAD showed elevated RNA processing, mRNA metabolism, and DNA damage repair. To further investigate the aberrations of cancer cells, we employed InferCNV, an R package to infer genomic alterations associated with cancer, to analyze large-scale copy number variations (CNVs) of LUAD cells between two models. The results reveal significantly higher CNV scores in Sftpc+ AT2-LUAD compared to Gramd2+ AT1-LUAD, suggesting a more pronounced genomic instability and an aggressive tumor phenotype. These significant variations may interact with CAF/M cells and thereby impact survival outcomes. This study demonstrates that it is critical to stratify properties of the LUAD TME and establish how LUAD evolves based on cell-of-origin, yielding knowledge for elucidating LUAD heterogeneity and consequently boost development of precision medicine strategies in the clinic. Citation Format: Minxiao Yang, Tawfeeq Al-Mansur, Chunli Yan, Zea Borok, Crystal Marconett. Understanding cell-of-origin influence on cancer-associated fibroblasts 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 2670.