Murine melanoma: a model for intracranial metastasis.

A variant subline (B16-F10-B2) selected from the B16-F10 melanoma cell line, shows greater metastatic capacity and preferential growth in the brain after i.v. injection into C57BL/6 mice. Several biological properties of these two cell lines have been compared, in an effort to determine the mechanisms responsible for this non-random metastatic pattern. No differences in cell morphology, in vitro growth rates or exposed cell-surface proteins were detected. Quantitative analysis of tumour-cell arrest and distribution using 125IUdR-labelled cells indicated that, although initial arrest patterns of the cell lines were very similar, B16-F10-B2 cells survived in the lungs to a greater cell line had a higher mean number of chromosomes than the parent line, whereas the variance of chromosome distribution was less. We suggest that the selection of a brain-colonizing variant represents the emergence of a pre-existing subpopulation of cells, and provides a useful model for studying mechanisms of intracranial metastasis.