Selective distribution of fibronectin to a tumor-cell line

Distribution of plasma fibronectin in Yoshida sarcoma-bearing rats was studied. Fibronectin from human plasma labelled with 125I was administered intravenously to the tumor bearing-rats. The ratios of specific radioactivity (cpm/g) of the tumor to that of blood or liver increased in the time course after the administration. Consequently, 48 h later, the tumor/blood and the tumor/liver ratios were estimated to be 4.6 and 2.8, respectively. In contrast, the liver/blood ratio did not increase during the experimental period. Similar results were also obtained by the administration of fibronectin from rat plasma. Whole-body autoradiography also suggested such a selective distribution. However, 125I-labelled albumin was not localized in the tumor.