Plasminogen activator inhibitor-1 and -3 increase cell adhesion and motility of MDA-MB-435 breast cancer cells.
Plasminogen activator inhibitor-1 (PAI-1), an inhibitor of urokinase plasminogen activator, is paradoxically associated with a poor prognosis in breast cancer. PAI-1 is linked to several processes in the metastatic cascade. However, the role of PAI-1 in metastatic processes, which may be independent of protease inhibitory activity, is not fully understood. We report herein that PAI-1, when added exogenously to or stably transfected in human MDA-MB-435 breast carcinoma cells, had disparate effects on adhesion to extracellular matrix proteins and motility in vitro. Specifically, exogenously added PAI-1 inhibited cell adhesion to vitronectin but not fibronectin, in agreement with the literature. By contrast, stably transfected PAI-1 stimulated adhesion to both proteins. Wild-type PAI-1 was required for this stimulation, because expression of a non-protease inhibitory P14 (T333R) PAI-1 mutant failed to enhance adhesion. Compared with non-inhibitory PAI-1, wild-type PAI-1 also increased cell motility in chemotaxic assays. Furthermore, stable transfection of a related serine protease inhibitor, plasminogen activator inhibitor-3 (PAI-3, or protein C inhibitor) gave results similar to wild-type PAI-1. The stimulatory activity of PAI-3 was not seen with a non-protease inhibitory P14 PAI-3 mutant (T341R). We show that a downstream effect of endogenous wild-type PAI-1 and PAI-3 overexpression, but not their non-inhibitory counterparts, was the altered expression of alpha(2), alpha(3), alpha(4), alpha(5), and beta(1) integrin subunits. Additionally, blocking antibodies to beta(1) integrin inhibited PAI-1-induced adhesion. Our data provide experimental support for the stimulatory and inhibitory effects of PAI-1 in metastasis and introduce PAI-3 as another serpin potentially important in malignant disease.
Palmieri
Diane
D
Department of Pathology and Laboratory Medicine, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27759-7035, USA.
Lee
Jung Weon
JW
Juliano
Rudy L
RL
Church
Frank C
FC
D001483:Base Sequence; D001943:Breast Neoplasms / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects*; D002633:Chemotaxis / Q000187:drug effects*; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D016023:Integrins / Q000502:physiology; D017395:Plasminogen Activator Inhibitor 1 / Q000494:pharmacology*; D018046:Protein C Inhibitor / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D016023:Integrins; D017395:Plasminogen Activator Inhibitor 1; D018046:Protein C Inhibitor