Effect of sulfated polysaccharides on blood-borne pulmonary metastasis in rats

The inhibitory effect of sulfated polysaccharides on blood-borne metastasis was examined. As a model of blood-borne metastasis, the ascitic form of hepatoma AH-109A tumor was injected intravenously into Donryu strain rats. Examination of the pulmonary metastatic nodules developed 2 weeks later showed inhibitory effect of the five sulfated polysaccharides tested. Xylan sulfate was the most inhibitory, and exerted its inhibitory effect when the tumor cells were in the pulmonary capillary beds. However, fromthe rapid disappearance of radioactivity from the lungs after injection of 125IUDR-labeled AH-109A cells, tumor cells seemed to be retained in the lungs for only a very short time. Measurement of the anticoagulative and fibrinolytic activities of three sulfated polysaccharides showed that the inhibitory effect of these compounds on blood-borne metastasis was proportional to their anticoagulative and fibrinolytic activities, xylan sulfate showing the highest activities. These results suggest that sulfated polyaccharides may inhibit blood-borne pulmonary metastasis by inhibiting the lodging of tumor cells in the pulmonary capillary beds.