Abstract
Plasminogen activator inhibitor-1 (PAI-1) is a serine protease inhibitor that plays a critical role in cancer progression, particularly in skin cancers. PAI-1 is widely recognized for its role in inhibiting fibrinolysis; however, emerging evidence suggests that it also contributes to tumor progression through multiple mechanisms, including tumor angiogenesis, immunomodulation, and stromal cell regulation. In the tumor microenvironment (TME), PAI-1 influences tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs), promoting an immunosuppressive environment that supports cancer growth and therapy resistance. Furthermore, PAI-1 has been implicated in the regulation of programmed death-ligand 1 (PD-L1) expression via the JAK/STAT signaling pathway, thereby influencing immune evasion in various skin cancers. The significance of PAI-1 as a therapeutic target has been demonstrated in melanoma and other cutaneous malignancies, where inhibition of PAI-1 has shown promise in overcoming resistance to immune checkpoint inhibitors. Additionally, clinical trials evaluating PAI-1 inhibitors, such as TM5614, highlight its potential as an adjunctive therapy for melanoma and cutaneous angiosarcoma. This review comprehensively explores PAI-1's role in skin cancer progression, its influence on tumor-stromal interactions, and its potential as a therapeutic target.