An RNA Aptamer Targeting PAI-1 That Restores tPA Activity, Unexpectedly Suppresses Cancer Cell Progression

Plasminogen activator inhibitor-1 (PAI-1), the primary physiological inhibitor of tissue-type plasminogen activator (tPA), is a key regulator of fibrinolysis. Elevated levels of PAI-1 are linked to thrombotic disorders and correlate with poor prognosis across various cancers. In this study, we further characterize the RNA aptamer R10-4, previously shown to bind PAI-1 with high affinity and inhibit its antiproteolytic activity. While R10-4's role in modulating fibrinolysis is established, its influence on cancer cell behavior remains unclear. Here, we demonstrate that intracellular transfection of R10-4 in triple negative breast cancer cells significantly impairs migration and invasion without affecting proliferation, mirroring the effects observed with other PAI-1-specific RNA aptamers. Moreover, conditioned media from R10-4 transfected cells suppress endothelial tube formation and exhibit reduced secretion of the pro-angiogenic chemokine (C-C) motif ligand 5 (CCL5). Collectively, these findings reveal that R10-4 restores fibrinolytic balance and disrupts PAI-1-mediated tumor progression, positioning it as a promising multifunctional candidate for therapeutic development.