Selenium-lentinan inhibits tumor progression by regulating epithelial-mesenchymal transition.

Background: Selenium supplementation can be used to treat tumors. However, inorganic selenium is highly toxic, and natural organic selenium is extremely rare. Polysaccharides can improve drug bioavailability and targeting. Lentinan is a polysaccharide that has been approved as an anti-cancer drug in Japan and China.

Methods: Lentinan, an antitumor polysaccharide extracted from Lentinus edodes, was conjugated with seleninic acid to be transformed into ester (Se-lentinan) and utilized as drug carrier. The enhancement of the anti-tumor effects of Se-lentinan was evaluated by cell viability, cell cycle, migration, and transwell assays and animal xenograft models. The effects of Se-lentinan on the expression levels of epithelial-mesenchymal transition (EMT) markers were determined through immunofluorescence, Western blot, and immunohistochemistry analyses.

Results: Se-lentinan inhibited the invasiveness of B16-BL6 and HCT-8 cells by suppressing EMT. In vivo, Se-lentinan significantly inhibited tumor growth and metastasis of the transplanted melanoma and colon cancer cells and showed less toxicity than sodium selenite. Moreover, Se-lentinan reduced the accumulation of selenium in the liver and kidney tissues of mice and exhibited low organ toxicity.

Conclusion: The antitumor activity of selenium was enhanced greatly, and its side effects were reduced with the use of lentinan as drug carrier.