Antimetastatic effect of amiloride in an animal tumour model.

The diuretic Amiloride competitively inhibits the catalytic activity of the urokinase-type plasminogen activator on plasminogen in vitro. This effect was tested on a rat adenocarcinoma model and its invasive potential in the host lung. While the inhibitory effect on intact cell cultures of the tumour was slight, continuous exposure of tumour-injected animals to the drug completely prevented the formation of lung metastasis.