bafilomycin-a1 and Fibrosarcoma

Binding of tissue inhibitor of metalloproteinase-2 (TIMP-2) to pro-MMP-2 and mature membrane type-1 MMP (MT1-MMP) on the cell surface is required for activation of MMP-2. It has been reported that following binding to cell surface receptors, TIMP-2 undergoes endocytosis and extensive degradation in lysosomes. The purpose of this study was to reexamine the fate of TIMP-2 following binding to transfected HT1080 cell surface MT1-MMP at 4 degrees C. Following 37 degrees C incubation, 125I-TIMP-2 release, endocytosis, and degradation were characterized under varying conditions. More than 85% of the total 125I-TIMP-2 bound to cells was released as intact functional molecules; <15% was degraded. Transfection of HT1080 cells with dominant negative mutant dynamin cDNA resulted in delayed endocytosis and release of 125I-TIMP-2 from cells. Pharmacologic agents that induce clustering of cell surface receptors (concanavalin A) and interfere with endosomal/lysosomal function (bafilomycin A(1)) resulted in enhanced binding of 125I-TIMP-2 to cell surface receptors. Abrogation of activation of proMT1-MMP with a furin inhibitor prevented binding and endocytosis of 125I-TIMP-2. Biotinylation of cell surface MT1-MMP followed by Western blotting confirmed the presence of mature MT1-MMP on the cell surface and degraded MT1-MMP in the intracellular compartment. In conclusion, these studies demonstrate that TIMP-2 is released from cells primarily as an intact functional molecule following binding to MT1-MMP on the cell surface.

Topics: Animals; Cell Line, Tumor; Cell Membrane; Chlorocebus aethiops; Concanavalin A; COS Cells; Endocytosis; Endosomes; Enzyme Activation; Enzyme Inhibitors; Enzyme Precursors; Epithelial Cells; Fibrosarcoma; Humans; Kinetics; Macrolides; Matrix Metalloproteinases, Membrane-Associated; Metalloendopeptidases; Receptors, Cell Surface; Temperature; Tissue Inhibitor of Metalloproteinase-2

Pericellular matrix degradation during cancer invasion and inflammation is dependent on activation of progelatinase A by membrane type 1-matrix metalloproteinase (MT1-MMP); a stoichiometric concentration of tissue inhibitor of metalloproteinase-2 (TIMP-2) is required. Activation of progelatinase A has generally been considered to be a slow process occurring as a result of enhanced expression of MT1-MMP. We herein report that ConA treatment of HT1080 fibrosarcoma cells is followed by MT1-MMP-induced activation of progelatinase A on the cell surface within 1 hour. Cell surface biotinylation, immunohistochemistry, and (125)I-labeled TIMP-2 binding to cell surface MT1-MMP were used to characterize the appearance and function of MT1-MMP on the plasma membrane. Treatment of HT1080 cells with ConA resulted in increased specific binding of (125)I-labeled TIMP-2 to cell surface receptors within 5 minutes. TIMP-2 binds almost exclusively to activated MT1-MMP on the surface of HT1080 cells. MT1-MMP function at the cell surface was also accelerated by treatment of cells with cytochalasin D, an inhibitor of actin filaments, PMA, a stimulator of protein kinase C, and bafilomycin A(1), an inhibitor of lysosome/endosome function. A functional pool of intracellular MT1-MMP available for trafficking to the cell surface was demonstrated by repetitive ConA stimulation. ConA-induced expression of MT1-MMP mRNA (Northern blot analysis) in HT1080 cells was a delayed event (>6 hours). These data suggest that presynthesized MT1-MMP is sorted to a transient storage compartment (trans-Golgi network/endosomes), where it is available for rapid trafficking to the plasma membrane and cell surface proteolytic activity.

Topics: Anti-Bacterial Agents; Cell Membrane; Concanavalin A; Cytochalasin D; Enzyme Activation; Enzyme Precursors; Fibrosarcoma; Fluorescein-5-isothiocyanate; Gelatinases; Humans; Macrolides; Matrix Metalloproteinases, Membrane-Associated; Metalloendopeptidases; Protein Transport; Receptors, Cell Surface; Tetradecanoylphorbol Acetate; Tissue Inhibitor of Metalloproteinase-2; Tumor Cells, Cultured