Dynamic assembly of the urokinase-type plasminogen activator signaling receptor complex determines the mitogenic activity of urokinase-type plasminogen activator.
The urokinase-type plasminogen activator (uPA) receptor (uPAR) functions in concert with co-receptors, including integrins, FPR-like receptor-1/lipoxin A4 receptor, and the epidermal growth factor receptor (EGFR), to initiate cell signaling. uPAR co-receptors may be dynamically organized into a multiprotein signaling receptor complex. In Chinese hamster ovary-K1 (CHO-K1) cells, uPA-binding to uPAR activates ERK/MAP kinase, even though these cells do not express the EGFR; however, when CHO-K1 cells are transfected to express the EGFR, ERK activation becomes EGFR-dependent. In this study, we demonstrate that ERK activation in response to uPA follows equivalent biphasic kinetics in EGFR-expressing and -deficient CHO-K1 cells. In both cell types, the response is pertussis toxin-sensitive; however, uPA promotes cell proliferation exclusively in the EGFR-expressing cells. uPA-induced mitogenic activity requires activation of both STAT5b and ERK. STAT5b was tyrosine-phosphorylated, in response to uPA, only in EGFR-expressing cells. uPA-induced cell proliferation was blocked by dominant-negative MEK1, dominant-negative STAT5b, and by expression of an EGFR that is mutated at Tyr-845, which is essential for STAT5b activation. In two cell culture models of uPA-stimulated breast cancer growth, MDA-MB 468 cells treated with uPA and MCF-7 cells treated with uPA-plasminogen activator inhibitor-1 complex, proliferation was completely inhibited when EGFR expression or activity was blocked. We conclude that expression and assembly of uPAR co-receptors in a specific cell type determines the response to uPA. The EGFR selectively cooperates with uPAR to mediate mitogenesis.
Jo
Minji
M
Department of Pathology, University of California San Diego School of Medicine, La Jolla, California 92093, USA.
Thomas
Keena S
KS
Marozkina
Nadzeya
N
Amin
Tanay J
TJ
Silva
Corinne M
CM
Parsons
Sarah J
SJ
Gonias
Steven L
SL
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D016466:CHO Cells; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004396:Coloring Agents / Q000494:pharmacology; D006224:Cricetinae; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D007700:Kinetics; D008894:Milk Proteins / Q000378:metabolism; D009154:Mutation; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D011379:Prognosis; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
D004396:Coloring Agents; D004268:DNA-Binding Proteins; D008894:Milk Proteins; D034741:RNA, Small Interfering; D050799:STAT5 Transcription Factor; C494095:STAT5B protein, human; D013778:Tetrazolium Salts; D013844:Thiazoles; D015534:Trans-Activators; D049452:Green Fluorescent Proteins; D014443:Tyrosine; D004247:DNA; D037342:Pertussis Toxin; D066246:ErbB Receptors; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D014568:Urokinase-Type Plasminogen Activator; C022616:thiazolyl blue; D001973:Bromodeoxyuridine