Figure 8.

Inhibition of plasmin or the removal of uPAR by PI-PLC decreases transmigration of U251N cells in invasion assays. Lac-Z U251N cells (25,000 cells) cocultured with astrocytes (10,000 cells) resulted in a high number of glioma cells transmigrating through the Matrigel-coated Boyden invasion chambers by 68 hr (A). The addition to the coculture of α2-antiplasmin (B) or PI-PLC (C; with PI-PLC replenished at 24 and 48 hr) significantly decreased the number of U251N cells invading through the chamber. This experiment was replicated three times. Values are the mean ± SEM of triplicate samples; Student's t test, ***p < 0.001. D, E, Representative micrographs of U251N cells, identified after staining for β-galactosidase, that have invaded across Matrigel in a control coculture (D) or in a coculture treated with inhibitors (E). The holes in D and E are the 8 μm pores present in the filter that supports the Matrigel barrier. F, Control experiment to indicate that the Lac-Z transfectants (U251N Lac-Z) indeed are behaving in a similar manner to the parent line (U251N) with respect to the activation of MMP-2 in glioma–astrocytes cocultures.