Polysaccharide from Rhizopus nigricans inhibits the invasion and metastasis of colorectal cancer.

Polysaccharide (EPS1-1) extracted from fermentation liquor of Rhizopus nigricans possesses antitumor and immune-enhancing activities. The study was the first to investigate the anti-metastasis effects of EPS1-1 in vitro and in vivo. Results suggested that EPS1-1 dose-dependently suppressed the migration, invasion and adhesion abilities of CT26 cells. Furthermore, EPS1-1 dramatically inhibited the enzyme activity and expression levels of matrix metalloproteinases (MMPs) in CT26 cells, as well as the tube formation of HUVECs. Similar results were observed in the lung metastasis mice which were administrated with EPS1-1 for 14 d. EPS1-1 could inhibit angiogenesis by decreasing the expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in lung tissue. Moreover, vimentin, as a marker molecule in epithelial-mesenchymal transition (EMT) which is closely related to metastasis, was found to be down expression by EPS1-1 in CT26 cells and lung tissue. These results suggested that EPS1-1 could suppress metastasis in vitro and in vivo by inhibiting invasion and angiogenesis, which provides potential application to against colorectal cancer metastasis.