Abstract
BACKGROUND: Mitochondrial dysfunction critically impacts lung adenocarcinoma (LUAD) progression and tumor microenvironment (TME) remodeling, highlighting the urgent need to identify predictive biomarkers with clinical utility. METHODS: RNA-seq data sourced from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were analyzed to identify mitochondrial-related (MTR) genes associated with LUAD progression. A three-gene prognostic signature, consisting of SFXN1, CPS1, and MTFR2, was developed through univariate, Least Absolute Shrinkage and Selection Operator (LASSO), and multivariate Cox regression analyses. Functional enrichment, immune infiltration, and tumor mutation burden (TMB) analyses were performed to characterize the TME. Experimental studies were conducted in LUAD cell lines via siRNA-mediated knockdown, assessing mitochondrial dynamics, mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) levels, and mitochondrial DNA (mtDNA) stability. RESULTS: The signature stratified patients into high-risk and low-risk groups with significant survival differences (TCGA: HR = 1.476, P < 0.001; GSE31210: P < 0.001; GSE30219: P = 0.001). High-risk patients exhibited features of immunosuppressive TME, including elevated tumor purity, higher TIDE scores, increased TMB, and immune checkpoint expression (CD274, CD276, PDCD1, RELT). Functional analyses revealed that siRNA-mediated knockdown of CPS1 triggered mitochondrial fission, as evidenced by ΔΨm↓/ROS↑. Conversely, SFXN1 knockdown induced mitochondrial fusion accompanied by hyperpolarization (ΔΨm↑/ROS↓). Notably, MTFR2 knockdown promoted mitochondrial fusion, contributing to ΔΨm↑/ROS↓. All three siRNA treatments compromised mtDNA integrity, with CPS1 knockdown uniquely inducing the release of cytosolic mtDNA. CONCLUSION: This study has successfully established a mitochondrial-related prognostic signature that predicts survival outcomes and immune phenotypes of LUAD patients, providing a clinically relevant predictive tool and laying the foundation for developing mitochondrial-targeted therapeutic strategies.