Effect of Urokinase on Growth and Metastases of Rabbit V2 Carcinoma

Effect of urokinase on the tumor growth and metastasis formation of rabbit V2 carcinoma, having low thromboplastic and high fibrinolytic activities, was examined. Weight of the tumor and lymphogenous metastases tended to increase, but the number of metastatic foci in the lungs was unchanged by the administration of urokinase. Diminution of fibrin deposits and connective tissue reaction in association with increase in the pattern of invasive growth was recognized at the advancing border of the tumors in the urokinase-treated group. In the intravenously induced pulmonary metastases, the number of metastatic foci decreased significantly in the urokinase-treated group. Fibrin was demonstrated at the site of tumor cell embolism by the conjugated anti-rabbit fibrinogen antibody. The growth of metastatic foci in the lungs was not affected by the treatment with urokinase. Enhancing effect of urokinase on fibrin resolution might promote the local tumor growth and release of tumor cells into the vessels, but interfere with the lodgement of tumor cells in remote organs.