In vitro effects of fucans on MDA-MB231 tumor cell adhesion and invasion.

Fucans are sulphated polysaccharides extracted from brown seaweed, which display a wide scale of activities including inhibition of tumour cell invasion. Like several sulphated polysaccharides, they have been shown to be potent inhibitors of experimental metastasis. However, their mechanism of action is not fully understood Using standard adhesion and chemoinvasion assays, we demonstrated that fucans can inhibit MDA-MB231 cell invasion through matrigel. This effect is correlated with a direct interaction of the fucans with laminin that leads to an inhibition of cell adhesion. It depends upon the sulphate content and the molecular weight of the fucans. Moreover, chromogenic assays allowed us to bring to the fore an increase of u-PA activity in the MDA-MB231 culture medium when tests were performed in the presence of fucans. Since tumour cell adhesion is a prerequisite step in the invasion process, our results suggest that the inhibitory effect of fucans on MDA-MB231 cell invasion is caused, at least in part, by the blockage of tumour cell adhesion to the extracellular matrix and by the increase of the proteolysis of the extracellular membrane.