Fucoidan from brown algae Laminaria japonica trigger apoptosis in colon cancer cells

In many cases, cancer cells develop resistance to chemotherapy and other cancer treatments. Therefore, there is a need for new therapeutic agents using naturally derived compounds that are expected to have low toxicity and fewer side effects. Fucoidan is a sulfated polysaccharide found in brown algae such as kelp and wakame seaweed. Many previous reports have shown that fucoidan exerts anti-bacterial, anti-viral, antioxidant, immunomodulatory effects, and anti-tumor effects. The antitumor and antiviral effects of fucoidan have been reported to vary depending on its origin, as they are influenced by sulfate content and molecular weight. Therefore, it is important to investigate the antitumor effects of various species of fucoidan, but there are few reports on the effects of fucoidan derived from Laminaria japonica on colorectal cancer. In this study, we evaluated the effects of fucoidan from Laminaria japonica on apoptosis in five human colon cancer cells. The apoptotic cell population was significantly increased in fucoidan-treated cells. In addition, the expressions of Bax, Bak, PARP, caspase-8, -9 and -3 were upregulated. The necroptosis-related molecule RIP and MLKL were degraded indicates that necroptosis was not involved in this fucoidan-treated cell death. These results suggest that fucoidan-treated cells showed induction of apoptosis via mitochondrial intrinsic pathway, but not necroptosis via caspase-8. Fucoidan-induced apoptosis may prove useful in the therapeutic protocol of colon cancer.