A polysaccharide from Grifola frondosa fruit body induces HT-29 cells apoptosis by PI3K/AKT-MAPKs and NF-κB-pathway

Background: A neutral polysaccharide was isolated from the fruiting body of a mushroom Grifola frondosa (GFP-A). The tumor suppressive activity of GFP-A on protein expressions of PI3K/Akt, MAPKs, nuclear factor κB and Caspase pathways in HT-29 cells were investigated.

Methods: The inhibitory effect and mechanism of GFP-A on the HT-29 cells were investigated. The cell viability was examined by MTT. Scanning electron microscopy analysis and flow cytometry were conducted to examine the Apoptosis of cells. The protein expressions of PI3K/Akt, MAPKs, nuclear factor κB and Caspase pathways were analyzed using western blot.

Results: The results of MTT assay showed that GFP-A of 180 μg/mL could significantly inhibit the proliferation of HT-29 cells. Western blotting results showed that GFP-A decreased the protein expression of PI3K and Akt, enhanced the phosphorylation of c-Jun N-terminal kinase (JNK), p38 MAPK and inhibited the phosphorylation of ERK1/2 and the translocation of nuclear factor-κB (NF-κB) into the nucleus. In the meanwhile, GFP-A could up-regulate the ratio of Bax to Bcl-2, increase the release of cytochrome C to cytoplasm, ultimately lead to the activation of caspase-9.

Conclusions: The above results confirmed that GFP-A promoted the Apoptosis of HT-29 cells through PI3K/AKT-MAPKs-NF-κB and Caspase signaling pathways.