[Interaction of extracellular matrix macromolecules between host and metastatic tumor cells]

Tumor cell attachment to host endothelium appears to be one of the specific steps occurring during the formation of distant metastasis, in which interactions of extracellular matrix molecules between tumor cells and endothelial cells are greatly involved. From mouse mammary carcinoma cells with no apparent lung-colonizing capacity (FM3A P-O), Honma et al. (Gann, 72, 898-905, 1981) selected two variant sublines, P-15A and P-10, for their ability to form lung tumor colonies with relatively high and low efficiencies, respectively. Comparison of their extracellular matrix products indicated that the rate of hyaluronic acid synthesis in both metastatic variants was about 60 times the rate in the parent cells and that there was no apparent association between metastatic ability and the rate of synthesis of other extracellular matrix molecules. Further analysis of the variant cells in vivo and in vitro indicated that the highly metastatic P-15A cells were surrounded by a hyaluronic acid-rich pericellular coat whereas the intermediately metastatic P-10 cells were not, suggesting the involvement of accumulation of hyaluronic acid in the pericellular regions in the potential for metastasis. The extracellular matrix molecules in host endothelium having a capacity to interact with hyaluronic acid were also studied. Bovine pulmonary arterial endothelial cells were metabolically labeled with 35S-methionine. Extraction and subsequent biochemical characterization of the labeled molecules suggested that PG-M-like chondroitin sulfate proteoglycan participated in the binding. These results provide a basis for further investigation of the potential role of interactions of extracellular matrix molecules between host and tumor cells during metastatic processes.