A cold-water extracted polysaccharide-protein complex from Grifola frondosa exhibited anti-tumor activity via TLR4-NF-κB signaling activation and gut microbiota modification in H22 tumor-bearing mice

Grifola frondosa polysaccharide-protein complex (G. frondosa PPC) is a polymer which consists of polysaccharides and proteins/peptides linked by covalent bonds. In our previous ex vivo research, it has been demonstrated that a cold-water extracted G. frondosa PPC has stronger antitumor activity than a G. frondosa PPC extracted from boiling water. The main purpose of the current study was to further evaluate the anti-hepatocellular carcinoma and gut microbiota regulation effects of two PPCs isolated from G. frondosa at 4 °C (GFG-4) and 100 °C (GFG-100) in vivo. The results exhibited that GFG-4 remarkably upregulated the expression of related proteins in TLR4-NF-κB and apoptosis pathway, thereby inhibiting the development of H22 tumors. Additionally, GFG-4 increased the abundance of norank_f__Muribaculaceae and Bacillus and reduced the abundance of Lactobacillus. Short chain fatty acids (SCFAs) analysis suggested that GFG-4 promoted SCFAs production, particularly butyric acid. Conclusively, the present experiments revealed GFG-4 has the potential of anti-hepatocellular carcinoma growth via activating TLR4-NF-κB pathway and regulating gut microbiota. Therefore, G. frondosa PPCs could be considered as safe and effective natural ingredient for treatment of hepatocellular carcinoma. The present study also provides a theoretical foundation for the regulation of gut microbiota by G. frondosa PPCs.