Urokinase plasminogen activator receptor induced non‐small cell lung cancer invasion and metastasis requires NHE1 transporter expression and transport activity

Abstract

In this study we investigate the relationship between urokinase plasminogen activator (uPA)/uPA receptor (uPAR) signaling and Na+/H+ exchanger (NHE1). 10nM uPA increased the carcinogenic potential of three NSCLC cell lines. Including an increase in cell proliferation, the percentage of cells displaying stress fibers, and an increase in anchorage‐independent growth. NHE1 inhibitor EIPA blocked these effects. To further evaluate the role of uPA/uPAR and NHE1 in tumor progression we assessed signaling events using full‐length uPA and uPA amino terminal fragment (ATF). We found that both uPA and ATF increased stress fiber formation approximately 2 fold, while uPA increased MMP9 activity 5.44 fold compared to 2.81 fold for ATF. Using two cell lines, one with reduced NHE1 expression (NHE1 K/D) and one with reduced uPAR expression (uPAR K/D), neither uPA nor ATF could stimulate stress fiber formation or MMP9 activity in cells with dramatically decreased NHE1 or uPAR expression. Finally, using in vivo tumor formation studies showed that when mice were injected with H460 cells 80% of mice formed tumors. This was compared to 20% of H460 uPAR K/D injected mice forming tumors and 10% of NHE1 K/D injected mice forming tumors. These data demonstrate that uPA/uPAR‐mediated tumor progression and metastasis requires NHE1 and suggests a potential therapeutic approach to blocking cancer progression. NIH Grant 1 R15 HL074924‐01A1