Metastatic choroidal melanoma. Hepatic binding protein reactivity toward a liver-metastasizing clone

A clone of B16 malignant melanoma cells with a preference for metastasis to the liver was isolated and characterized. The parent tumor cells (F1) were injected in the tail vein of C57BL/6 mice, and the resultant liver colonizing cells were isolated and then subcultured for two to three weeks. The cells were then reinjected into the next series of mice. After five such passages, a clone (L4) of melanoma cells was obtained that metastasized almost exclusively to the liver. A hepatic binding protein (HBP) was isolated from rabbit liver that agglutinated neuraminidase-treated F1 and L4 malignant melanoma cells. Different agglutination titers found between the parent and liver-metastasizing clone demonstrated differences in cell-surface properties between the parent tumor and the liver-metastasizing clone. These results demonstrate that malignant melanoma cells can be selected for preferential liver metastasis and can be recognized and agglutinated by specific HBPs. Metastasis from human uveal malignant melanoma may occur by similar mechanisms.