Integrating multi-omics data revealing LIMK1 as a metastatic biomarker in LUAD patients with brain metastasis

Lung adenocarcinoma (LUAD) is a major subtype of lung cancer that frequently develops brain metastases. Tumor heterogeneity substantially complicates disease management, and reliable biomarkers for metastatic progression remain lacking. LIM domain kinase 1 (LIMK1), a key regulator of cytoskeletal dynamics, has been implicated in tumor progression; however, its role in regulating brain metastasis in LUAD remains unclear. Single-cell RNA sequencing data from 11 primary LUAD tumors and 10 brain metastases were analyzed to identify malignant epithelial subclusters associated with metastatic dissemination. Tumor evolutionary trajectories and gene regulatory networks were explored using pseudotime trajectory analysis and weighted gene co-expression network analysis. LIMK1 expression was validated using The Cancer Genome Atlas dataset, as well as RT–qPCR and Western blotting in LUAD tissues and cell lines. Functional assays, including cell proliferation, colony formation, migration, and invasion, were performed following LIMK1 knockdown in LUAD cell lines. Six malignant epithelial subclusters were identified, among which clusters 0 and 4 were significantly enriched in brain metastases and associated with poor survival outcomes. LIMK1 was identified as a hub gene within these metastasis-associated clusters. LIMK1 expression was markedly upregulated in LUAD tissues and cell lines, and elevated LIMK1 levels predicted an unfavorable prognosis. Functional experiments demonstrated that LIMK1 depletion significantly inhibited tumor cell proliferation, migration, and invasion, while partially reversing epithelial–mesenchymal transition (EMT). Mechanistically, LIMK1 was found to promote LUAD progression through activation of the PI3K/AKT/mTOR signaling pathway. LIMK1 represents a novel prognostic biomarker and metastasis-associated regulator in LUAD. By driving EMT and activating PI3K/AKT/mTOR signaling, LIMK1 facilitates malignant progression, highlighting its potential as a therapeutic target for LUAD patients with brain metastases.