203 Hypoxia-inducible Factor-1 Regulates Matrix Metalloproteinase-14 Expression: Underlying Effects of Hypoxia and Statins

Introduction Matrix metalloproteinase-14 (MMP14) plays an important role in atherosclerosis and angiogenesis. There is evidence indicating that hypoxia and inflammatory stimuli up-regulate MMP14 expression whereas statins have an opposite effect. However, the molecular mechanism by which these factors modulate MMP14 expression is unclear. We sought to investigate whether it involves the transcription factor hypoxia-inducible factor-1 (HIF1). Methods and Results A bioinformatics analysis of the MMP14 gene promoter identified two regions matched with the consensus sequence of HIF1-responsive element (HRE). In vitro DNA-protein interaction assay demonstrated the ability of these sequences to complex with HIF1α/HIF1β, and chromatin immunoprecipitation showed HIF1 binding to the MMP14 promoter in vascular endothelial cells under hypoxia. Cell transfection and promoter-reporter assays demonstrated that augmenting HIF1α/HIF1β expression increased MMP14 gene promoter activity and this effect was abolished by mutating the HREs in the MMP14 promoter. MMP14 mRNA and protein assays showed that hypoxia increased MMP14 expression in endothelial cells but this effect diminished in endothelial cells with HIF1α knockdown or knockout. HIF1α knockdown/knockout or MMP14 inhibition by a blocking antibody attenuated hypoxia-induced endothelial cell proliferation/migration and angiogenesis. Simvastatin reduced HIF1α in endothelial cells and mitigated hypoxia- or HIF1-induced MMP14 expression, endothelial cell proliferation/migration, and angiogenesis. Conclusions The results of this study indicate that hypoxia increases MMP14 expression in vascular endothelial cells by inducing HIF1 binding to HREs in the MMP14 gene promoter, and this action is attenuated by simvastatin.