Single-Cell RNA Sequencing Identifies Stem-Like Subpopulations and Their Gene Signature in Lung Adenocarcinoma Progression

Lung adenocarcinoma (LUAD) exhibits substantial intra-tumor heterogeneity (ITH), contributing to disease progression and therapeutic challenges. This study utilized single-cell RNA sequencing (scRNA-seq) to profile cells from stage I and III LUAD tumors and matched normal tissues, aiming to delineate malignant cell states and identify tumor-propagating subpopulations. Unsupervised clustering revealed eight major cell lineages, with epithelial cells dominating in tumors and a shift toward immunosuppressive niches in advanced stages, including elevated T cell exhaustion and pro-angiogenic macrophages. Malignant cells formed 11 subclusters, with stage III tumors enriched for invasive and immunosuppressive states. Pseudotime analysis suggested evolutionary trajectories from alveolar-like to squamous and stress-responsive lineages. Using CytoTRACE to infer stemness without predefined markers, we identified sub-cancer stem cells (sub-CSCs) predominantly in stage III, characterized by high transcriptional diversity and a core signature involving cytoskeleton motility, immune modulation, metabolic reprogramming, and protein homeostasis. A four-gene panel demonstrated strong prognostic value in independent cohorts. These findings provide insights into stemness-driven progression in LUAD and nominate potential targets for addressing heterogeneity.