Cell Invasion Is Affected by Differential Expression of the Urokinase Plasminogen Activator/Urokinase Plasminogen Activator Receptor System in Muscle Satellite Cells from Normal and Dystrophic Patients

Abstract

SUMMARY:The aim of this study was to evaluate the differential expression and the function in cell movement and proliferation of the urokinase plasminogen activator (u-PA) system in muscle satellite cells (MSC) of normal individuals and patients with Duchenne muscular dystrophy (DMD). By immunoenzymatic, zymographic, and radioligand binding methods and by quantitative polymerase chain reaction of the specific mRNA we have shown that both normal and DMD MSC produce u-PA and the plasminogen activator inhibitor-1 and express u-PA receptors (u-PAR). During the proliferation phase of their growthdifferentiation program, MSC from DMD patients show more u-PAR than their normal counterpart, produce more plasminogen activator inhibitor-1, and release low amounts of u-PA into the culture medium. By Boyden chamber Matrigel invasion assays we have shown that normal MSC are more prone than DMD cells to spontaneous invasion but, when subjected to a chemotactic gradient of u-PA, DMD MSC sense the ligand much better and to a greater extent than normal MSC. u-PA also stimulates proliferation of MSC, but no difference is observable between normal and DMD patients. Antagonization of u-PA/u-PAR interaction with specific anti-u-PA and anti-u-PAR monoclonal antibodies and with antisense oligonucleotides inhibiting u-PAR expression indicates that u-PA/u-PAR interaction is required in spontaneous and u-PA-induced invasion, as well as in u-PA-induced proliferation. (Lab Invest 2001, 81:27-39).

The urokinase-type plasminogen activator receptor is not required for skeletal muscle inflammation or regeneration

“…Previous studies have demonstrated that antibodies against uPA or uPAR impaired satellite cell migration and fusion in vitro (5,12,15). In the present study, isolated satellite cells from WT and uPAR Ϫ/Ϫ neonatal mice were induced to fuse in differentiation medium for 72 h. The resulting myotubes were stained and the percentage of nuclei in myotubes with Ն3 nuclei were counted (Fig.…”

“…In addition, treatment of monocytes with an anti-uPAR antibody suppressed chemotaxis induced by fMLP in vitro (19), and peritoneal macrophages collected from uPAR Ϫ/Ϫ mice failed to promote plasminogen activation (7). In vitro experiments with muscle satellite cells or myoblasts demonstrated that antibodies against uPA or uPAR impaired cell proliferation, migration, and fusion (5,12,15,31,47). uPAR may contribute to these processes through different mechanisms.…”

Urokinase-type plasminogen activator increases hepatocyte growth factor activity required for skeletal muscle regeneration

“…Our data are consistent with prior reports in which uPA was shown to stimulate proliferation of human myoblasts in a dose-dependent manner. 26,39 Furthermore, a blocking antibody against uPA inhibited basic fibroblast growth factor-induced proliferation, indicating that uPA may mediate proliferation induced by fibroblast growth factor. 26,39 Studies on vascular smooth muscle cells produced similar findings that uPA induces proliferation of these cells and may mediate growth factor-induced proliferation.…”

“…26,39 Furthermore, a blocking antibody against uPA inhibited basic fibroblast growth factor-induced proliferation, indicating that uPA may mediate proliferation induced by fibroblast growth factor. 26,39 Studies on vascular smooth muscle cells produced similar findings that uPA induces proliferation of these cells and may mediate growth factor-induced proliferation. [40][41][42] Our data demonstrated that (1) intact uPA but not the aminoterminal fragment, which lacks the proteolytic domain, stimulated myoblast proliferation; (2) the specific proteolytic inhibitor PAI-1 blocked uPA-mediated myoblast proliferation; (3) the HGFblocking antibody reduced uPA stimulation of myoblast proliferation; and (4) both the PI3K inhibitor LY and the MEK1 inhibitor PD98059 reduced uPA-mediated myoblast proliferation.…”

Shikonin, Acetylshikonin, and Isobutyroylshikonin Inhibit VEGF-induced Angiogenesis and Suppress Tumor Growth in Lewis Lung Carcinoma-bearing Mice

“…14) A549 cells were plated at 5×10 5 cells/well in 6 well plates for 24 h. The cells were treated with various concentrations of shikonin and its derivatives for 24 h. Total RNA was prepared from A549 cells by using Trizol reagent. Total RNA (1.0 mg) was reverse transcribed by using oligo poly (dT) and MMLV reverse transcriptase.…”