Water Soluble <i>Pleurotus ostreatus</i> Polysaccharide Down-Regulates the Expression of MMP-2 and MMP-9 in Caco-2 Cells
AbstractMany polysaccharides and polysaccharide-protein complexes isolated from mushrooms have immunomodulatory and anti-cancer effects. Our aim was to study the regulatory mechanisms of Caco-2 cell response to water soluble P. ostreatus polysaccharide extract up to 72 hours. Specific enzymatic activities were assessed by kinetic measurements. The reduced glutathione content and the lipid peroxidation level were also analyzed. Protein expression of several heat shock proteins, Bcl-2 and metalloproteinases 2 and 9 were revealed by Western blot. Gelatin zymography assay was used to evaluate the MMP-2 and MMP-9 activities. Until the third day of exposure the total SOD activity decreased continuously by 30%, whereas GST and GR ones diminished by 17% respectively 30.5% compared to control. No significant changes were observed in CAT and G6PDH specific activities as well as in GSH and MDA concentration. After the third day of exposure a significant up-regulation of Hsp60 and Hsp90 expression and a down-regulation of Hsp70 one were registered. Bcl-2 protein levels were down-regulated by 50% in the first day of treatment but increased after 3 days. MMP-2 and 9 secretion in the culture medium was significantly reduced suggesting a diminished ability of invasion of colon cancer cells. Our data revealed that in vitro treatment with P. ostreatus aqueous polysaccharide extract does not induce apoptosis in Caco-2 cell line but it could inhibit the invasion of colon cancer cells through the basement membrane.
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