Expression of anionic sites on tumour cells at different stages of tissue invasion in vivo: a comparative study by...

Quantification of colloidal iron hydroxide (CIH) labelling by X-ray microanalysis was used to investigate anionic sites at the surface of Ehrlich carcinoma cells from different locations in the mouse host. Individual tumour cells from peritoneal ascites suspensions (pre-invasion stage) varied up to threefold in their ability to bind CIH and a similar degree of intra-tumour heterogeneity was observed in different experimental animals. Pretreatment of the cells with neuraminidase confirmed that binding was at least partly due to surface sialic acid. Invasive cells isolated from mesenteric tumour nodules were also heterogeneous with regard to the availability of surface anionic sites, as were tumour cells adhering to the surface of the mesentery; however, in both these populations CIH binding was significantly greater on average than for free ascites tumour cells. The results suggest that surface anionic sites are determinants of the invasiveness of malignant cells in vivo, and that both the number and topography of these sites may be important in modulating tumour cell behaviour.