Role of sialylglycoconjugate(s) in the initial phase of metastasis of liver-metastatic RAW117 lymphoma cells

To elucidate the early events of blood-borne metastasis under actual blood flow, real-time trafficking of RAW117 large cell lymphoma cells, namely par ental RAW117-P and liver-metastatic RAW117-H10 cells, was investigated usin g positron emission tomography (PET), Both types of cells accumulated in th e liver immediately after injection via the portal vein, and were eliminate d from the liver time-dependently. The elimination rate of RAW117-H10 cells , however, was slower than that of RAW117-P cells, suggesting that RAW117-H 10 cells interact more strongly with hepatic sinusoidal endothelium than th e parental cells. This result correlated with the metastatic potential of t hese cells: RAW117-H10 cells metastasized in the liver to a greater extent than RAW117-P cells after injection via this route. To investigate the role of sialylglycoconjugates in the interaction of RAW117-H10 cells with the h epatic endothelium after injection via the portal vein, the trafficking of RAW117-H10 cells was examined after the cells had been treated with sialida se, The elimination rate of RAW117-H10 cells from liver was observed to be greatly accelerated by sialidase treatment. To elucidate what kind of sialy lglycoconjugates is related to this phenomenon, we analyzed the distributio n of sialyl Lewis A and sialyl Lewis X antigens of both sublines of RAW117 by using flow cytometry. RAW117-H10 cells were found to express a much high er level of sialyl Le,vis A than RAW117-P cells, whereas the amount of sial yl Lewis X did not differ significantly. These findings suggest that some s ialylglycoconjugates, perhaps sialyl Lewis A in particular, play an importa nt role in the initial interaction of RAW117-H10 cells with the hepatic end othelium, leading to metastasis.