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

Abstract

The interaction of metastatic cells with their environment is mediated to a large extent by the cell surface^1–5. Although several biochemical differences beteen tumour cells with low or high metastatic potentials have been reported^6–10, 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-F10^Lr) or high (B16-F10) lung colonisation potentials^11,12 is their propensity to aggregate in vitro with other tumour cells (homotypic clumping)^13,14, or with host cells (heterotypic clumping)^15,16. The initial sites for membrane–membrane recognition, contact and subsequent interaction are thought to be associated with dense membrane anionic sites^17–20. 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.