Sulfation of a squid ink polysaccharide and its inhibitory effect on tumor cell metastasis

This paper is the first to report the preparation, characterization, and potential biological activities of a chemically sulfated polysaccharide isolated from the ink of the squid, Ommastrephes bartrami. The squid ink polysaccharides (SIPs) were firstly sulfated with the pyridine–sulfur-trioxide complex in dimethyl sulfoxide. Structural characterization of sulfated SIP using nuclear magnetic resonance indicated that sulfation mainly occurred at the 4,6-position of GalNAc. The effects of the sulfated SIP (TBA-1) on tumor cell growth, invasion, and migration were examined in vitro, and its effects on angiogenesis were measured in vivo using the chick embryo chorioallantoic membrane (CAM) assay. TBA-1 did not have any obvious effects on the proliferation of HepG2 tumor cells, but induced the dose-dependent suppression of cell invasion and migration in HepG2. Moreover, TBA-1 obviously inhibited angiogenesis in a CAM model. Thus, our results indicate that TBA-1 is a potential candidate compound for the prevention of tumor metastasis.