Modulation of Cancer-Associated Fibroblasts via the miR-624-5p/FAP Axis Drives Progression and Metastasis in Non-Small Cell Lung Cancer.

BACKGROUND: Cancer-associated fibroblasts (CAFs) are key mediators of metastatic progression in non-small cell lung cancer (NSCLC). Fibroblast activation protein (FAP) serves as the hallmark of CAF activation. However, the upstream regulation of FAP remains elusive, limiting stroma-targeted therapy development. METHODS: (68)Ga-FAP inhibitor (FAPI)-04 PET/CT imaging was performed on 61 NSCLC patients to evaluate the clinical significance of FAP. CAFs and normal fibroblasts (NFs) were isolated from patient tissues. Bioinformatic analysis and qRT-PCR were employed to screen and validate miRNAs. Functional assays (CCK-8, collagen contraction, wound healing, transwell co-culture) were utilized to investigate the role of miR-624-5p in regulating fibroblast activation and the effects on the metastatic potential of NSCLC cells. The targeting relationship between miR-624-5p and FAP was validated using FISH, dual-luciferase assay, and Western blotting. RESULTS: (68)Ga-FAPI-04 uptake was higher in advanced NSCLC (p < 0.001) and correlated with tumor size, lymph node metastases, and distant metastases (p < 0.05). Isolated primary CAFs significantly enhanced the migration and invasion of A549 and PC9 cells compared to NFs (p < 0.001). We identified miR-624-5p as a significantly downregulated miRNA in CAFs (p < 0.001). Functionally, miR-624-5p overexpression inhibited CAF proliferation and collagen contraction (p < 0.01) and reduced the proliferation, migration, and invasion capabilities of A549 and PC9 cells (p < 0.001). Mechanistically, miR-624-5p bound to FAP mRNA and negatively regulated FAP expression (p < 0.001), thus suppressing CAF activation and tumor metastasis. CONCLUSIONS: Our findings establish miR-624-5p as a novel upstream regulator that suppresses FAP expression, consequently inhibiting CAF activation and its pro-metastatic function. Targeting the miR-624-5p/FAP axis represents a promising therapeutic strategy for NSCLC metastasis.