Fig. 3.

Microglial MT1-MMP activation of glioma-derived MMP-2 and the impact of glioma MT1-MMP expression on cell survival. (A) MT1-MMP shRNA blocks the GCM-stimulated MT1-MMP activity in microglia. The activity is measured with an enzymatic assay and is normalized to controls (i.e., the baseline activity was measured in non-stimulated microglia). (B) The gelatin zymography demonstrates that activation of MMP-2 is diminished in microglia transfected with an shRNA for MT1-MMP. (C) Forced expression of MT1-MMP in glioma cells induces cell death. The GL261 (mouse) and U373 (human) glioma cells were transfected with empty vector-pGL3, human MT1-MMP vector (hMT1), or mouse MT1-MMP vector (mMT1). Forty-eight hours after transfection, the cells were stained with propidium iodide (which labels dead cells) and Hoechst dye (which labels all cells). The rate of cell death was expressed as percentage of total cells.