Differential expression of fibronectin in a rat histiocytoma: possible role of fibronectin in tumor cell adhesion.

The specific role of fibronectin in tumor cells has been investigated using the transplantable histiocytic tumor line AK-5 [A. Khar (1986) J. Natl. Cancer Inst. 76, 871]. These cells, capable of growth as both ascites and solid tumors in rats, can be separated into four subpopulations by buoyant density centrifugation on Percoll. These subpopulations are shown to contain different amounts of fibronectin on the cell surface when studied by immunofluorescent staining followed by cytofluorometric analysis. Cells which contain high amounts of fibronectin can grow both as ascites and as solid tumors while those cells which contain low amounts of fibronectin cannot grow as solid tumors but can grow as ascitic tumors. Pretreatment of high-fibronectin-containing cells with anti-fibronectin antibody abolished their capacity to grow as solid tumors; however, the cells retained their capacity to grow as ascitic tumors. These results have been discussed with reference to the specific role of fibronectin in tumor-forming cells.