Figure 8. TNF-α silencing blocks MMP-induced MMP-9 expression.
RAW264.7 macrophages transfected with nonspecific (NS) or TNF-α siRNA were suspended in DMEM-0.1% LE-BSA, and aliquoted into a 24-well plate. Following adherence, cells received media alone (Ctrl) or media containing 50 nM MMP-1, MMP-3 or LPS (10 ng/ml) and were incubated overnight. In addition, cells transfected with TNF-α siRNA were incubated with MMP-1, MMP-3 or LPS in the presence of exogenous TNF-α (50 ng/ml). Levels of MMP-9 in conditioned media, and Cox-2 and GAPDH in lysates were determined by Western blot. Levels of TNF-α mRNA were determined utilizing RT-PCR. The data are representative of two separate experiments.