The regulation of matrix metalloproteases by NHE1 in non‐small lung cancer cells

Abstract

The Na+‐H+ exchanger isoform‐1 (NHE1) has plays a major role in the coordination of cell migration and cancer metastasis. One possible mechanism is based on a family of proteases, matrix metalloproteases (MMPs), which degrade the extracellular matrix allowing cells to escape tumors and migrate. Studying three non‐small cell lung carcinoma cell lines (NCI‐H358, ‐H460, ‐1299) we have demonstrated using zymogen gels that stimulation with urokinase plasminogen activator (uPA) leads to an increase in MMP9 activity. Additionally, when NHE1 is inhibited with ethylisopropyl amiloride (EIPA), MMP9 activity decreases. Here we investigated whether the increase in MMP9 activity was due to increased activation or increased expression of MMP9. We hypothesized that NHE1 drives an intracellular alkalization that promotes MMP‐9 expression. To determine this action, stimulated and EIPA inhibited cells were analyzed for the level of RNA transcription measured by qPCR. Expression of MMP9 in H460 and H358 show a 3‐4 fold increase in transcription while H1299 displays a 100 fold increase in MMP‐9 transcription when stimulated with uPA. MMP1 transcription displays a 14 and 66 fold increase in H460 and H358 under NHE1 inhibition, but the H1299 showed no increase in MMP‐1 with EIPA treatment. This work was supported by NIH grant 1R15CA135616‐01, and NSF grant MCB‐0817784.