Sodium Hydrogen Exchanger 1 is required for Matrix Metalloproteinase 9 activity by Phenylephrine

Abstract

Matrix metalloproteinases (MMP) are a group of enzymes that play a critical role in digesting the extracellular matrix. Degradation of the extracellular matrix by MMP in migrating cells provides a vital function for tumor metastasis and angiogenesis. The link between extracellular MMP activity and the sodium hydrogen exchanger (NHE) has been suggested but not yet identified. We studied the relationship between NHE and MMP activity in CCL39 fibroblasts containing NHE1, PS120 cells (NHE1 null derived from CCL39 cells) and PS127 cells (PS120 cells expressing NHE1). Initial studies with CCL39 cells found resting cells had moderate MMP9 activity. This activity increased 2.5 fold after 12 hour phenylephrine (PE) stimulation. Western blot analysis of culture media identified MMP9. We found MMP9 activity to be dependent upon the expression and activation of NHE1. In both CCL39 and PS127 cells, MMP9 was activated in the presence of 100 μM PE. In PS120 cells no MMP was activated in the presence of PE. Incubation of cells with amiloride prior to PE addition also resulted in a notable decrease in MMP9 activation compared to control cells. Incubation of cells with 0.5% butanol prior to PE stimulation decreased MMP9 activity similar to the control level, while expression of either dominant negative phospholipase D1 or 2 caused a decrease in MMP9 activity less than untransfected cells. This work, for the first time, describes an agonist-induced relationship between NHE1 and MMP and a new potential role for NHE1 in tumor formation. This work was supported by a grant from the NIH, Award number 1 R15 HL074924-01A1.