Abstract: Objective To identify key mitochondrial genes closely associated with the progression and prognosis of lung adenocarcinoma (LUAD) through bioinformatics screening and to elucidate, through in vitro experiments, their roles in regulating malignant phenotypes of LUAD cells, including proliferation, migration, and invasion.Methods Genomic, transcriptomic, and clinical data of LUAD from the TCGA database were integrated, and the LASSO algorithm was employed to identify mitochondrial genes significantly correlated with prognosis. Through comprehensive analyses of genomic variations, differential expression, GSEA functional enrichment, and immune correlation, the key gene mitochondrial ribosomal protein L15 (MRPL15) was identified. RT-qPCR was used to detect the expression of MRPL15 in LUAD cell lines and normal lung epithelial cells. Furthermore, the role of MRPL15 in regulating the proliferation, migration, and invasion abilities of LUAD cells was evaluated by CCK-8, colony formation, and Transwell assays.Results A total of 7 mitochondrial genes significantly associated with LUAD progression and prognosis were identified. Multi-omics analysis revealed significant genomic alterations of MRPL15 in LUAD. GSEA enrichment analysis indicated that cell cycle, DNA replication, p53 signaling pathway, and the tricarboxylic acid (TCA) cycle pathways were significantly activated in patients with high MRPL15 expression. Immune correlation analysis demonstrated differences in the infiltration levels of multiple immune cell types between high and low MRPL15 expression, and MRPL15 expression was positively correlated with several immune checkpoint genes. Furthermore, MRPL15 was significantly upregulated in LUAD cell lines, while interference with its expression markedly suppressed the proliferation, migration, and invasion capabilities of LUAD cells.Conclusions The key mitochondrial gene MRPL15 is highly expressed in lung adenocarcinoma and promotes tumor cell proliferation, migration, and invasion, suggesting its potential as a prognostic biomarker and therapeutic target for LUAD.