Suppressive effects of MT1-MMP siRNA on TNF-α-induced endothelial apoptosis mediated via the phosphorylation of FoxO1.

<p>(<b>A–D</b>) Effect of knockdown of MT1-MMP by siRNA on TNF-α-induced endothelial cell apoptosis. ECs were incubated with or without TNF-α for 24 hours. Cell apoptosis was determined by TUNNEL staining. Photomicrographs are from an experiment representative of 4 independent experiments. Scale bars indicate 50 µm (lens x10). (<b>E</b>) Quantitative image analysis of cell apoptosis was performed by ImageJ. Data are expressed as means ± SD (n = 3, each group). ^**<i>P</i><0.005. (<b>F</b>) Effect of a specific pharmacological inhibitor of Akt on TNF-α-induced FoxO1 phosphorylation. ECs were treated with Akt inhibitor X and then stimulated by TNF-α. Bars are the means±SD of quantitative densitometric analyses from 4 separate experiments. ^*<i>P</i><0.05. (<b>G</b>) Effect of knockdown of MT1-MMP by siRNA on TNF-α-induced FoxO1 phosphorylation. ECs were incubated in the presence of TNF-α with or without transfection with siRNA to MT1-MMP, followed by Western blotting. Immunoblots are from an experiment representative of 4 similar experiments. Bars are the means±SD of quantitative densitometric analyses from 4 separate experiments. ^*<i>P</i><0.05. (<b>H</b>) Effect of knockdown of MT1-MMP by siRNA on TNF-α-induced caspase-3 activation. ECs were incubated in the presence of TNF-α with or without transfection with siRNA to MT1-MMP, followed by Western blotting. Immunoblots are from an experiment representative of 4 similar experiments. Bars are the means ±SD of quantitative densitometric analyses from 4 separate experiments. *P<0.05, **P<0.005.