Abstract
BACKGROUND: Lung cancer is the leading cause of cancer-related mortality worldwide. Although immune checkpoint inhibitors (ICIs), chemotherapy, and molecular targeted therapies have improved survival rates, therapeutic resistance remains a major barrier to curative outcomes. Recently, plasminogen activator inhibitor-1 (PAI-1) has been implicated in lung cancer progression and treatment resistance. MATERIAL AND METHODS: This review summarizes the recent evidence from preclinical and clinical studies on the role of PAI-1 in the progression and treatment resistance in lung cancer, focusing on its contribution to tumor aggressiveness and resistance to therapy. As limited evidence is available regarding its role in small cell lung cancer, this review focuses on the findings reported to date for non-small cell lung cancer (NSCLC). RESULTS: PAI-1 promoted tumor invasion, angiogenesis, and epithelial-mesenchymal transition (EMT), thereby facilitating cancer progression. Elevated PAI-1 expression in tumor tissues and plasma is correlated with advanced disease stages and poor prognosis. Genetic polymorphisms such as A15T, which affect PAI-1 stability, are also associated with unfavorable outcomes. PAI-1 contributes to radiotherapy resistance through the hypoxia-induced upregulation of AKT/ERK signaling, chemotherapy by activating cancer-associated fibroblasts, and targeted therapies via integrin-mediated EMT. Moreover, it enhances immune evasion by promoting programmed cell death-ligand 1 expression and creating an immunosuppressive tumor microenvironment. CONCLUSIONS: PAI-1 is a key regulator of tumor progression and therapeutic resistance in NSCLC. Targeting PAI-1 may offer a novel strategy to overcome resistance to multiple treatment modalities, and future research should focus on developing PAI-1-based biomarkers and therapeutic combinations for both NSCLC.