[5-fluorouracil inhibits bacterial collagenase and the collagenolytic system of a human rhabdomyosarcoma].

Protease inhibitory activity of eight cytostatic drugs on 5 proteases was tested by applying an immunoelectrophoretic system, a rhabdomyosarcoma's collagenolytic activity was investigated and inhibition studies were performed. We found 5-fluorouracil stopping collagenolytic activity of clostridial origin and the enzyme released by the tumor. No other cytostatic drug showed protease inhibition. The collagenolysis of the rhabdomyosarcoma was examined for its origin. Negative inhibition studies with ethylene-diamine-tetraacetate make the leukocyte origin highly improbable so that one can suggest that the hydrolytic enzyme derived from the tumor. Our findings could contribute to characterize the enzyme released by the tumor. We suggest its role as a mediator of invasion and metastasis and on the other hand we detected its relatively specific inhibitor, 5-fluorouracil, which could influence tumorous and normal growth, regeneration and the intermediary protein metabolism.