A study presented at the American Association for Cancer Research International Conference on Frontiers in Basic Cancer Research has elucidated a mechanism of action by which fucoidan, a sulfated polysaccaride extracted from brown seaweeds, exerts chemopreventive effects. Fucoidan has been reported to exhibit anticancer activities. In the study, fucoidan from Laminaria cichorioides, a type of brown algae, was shown to inhibit neoplastic cell transformation induced by epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate (a tumor promoter), but had less cytotoxic effect on JB6 mouse epidermal cells. Extensive testing demonstrated that fucoidan directly interacted with epidermal growth factor, apparently preventing the binding of epidermal growth factor to its cell surface receptor. This could explain fucoidan's anticarcinogenic effect. The authors affirm that the study findings are the first to reveal a molecular basis for the anticancer action of fucoidan, which may partially account for the reported chemopreventive effects of brown seaweeds.