Distribution of membrane anionic sites on B16 melanoma variants with differing lung colonising potential.

The interaction of metastatic cells with their environment is mediated to a large extent by the cell surface. Although several biochemical differences between tumour cells with low or high metastatic potentials have been reported, the specific surface characteristics associated with metastasis have not yet been identified. One distinctive feature of murine B16 melanoma variants with low (B16-F1, B16-F10Lr) or high (B16-F10) lung colonisation potentials is their propensity to aggregate in vitro with other tumour cells (homotypic clumping), or with host cells (heterotypic clumping). The initial sites for membrane-membrane recognition, contact and subsequent interaction are thought to be associated with dense membrane anionic sites. In the experiments reported here we determined that the distribution of cell-surface dense anionic sites, examined ultrastructurally with the use of cationised ferritin (CF), is correlated with tumour cell aggregation in vitro and/or production of pulmonary tumour colonies following intravenous (i.v.) injection into syngeneic recipients.