The caspases-dependent apoptosis of hepatoma cells induced by an acid-soluble polysaccharide from Grifola frondosa

The edible mushroom Grifola frondosa has been used as a functional food for diseases prevention and therapy in Asian countries. In the present work, an acid-soluble polysaccharide (GFAP) was prepared from Grifola frondosa under room temperature and hydrochloric acid solution treatment, and its inhibitory effects on H22 and HepG2 cells were investigated. Results of MTT indicated that GFAP could effectively suppress proliferations of HCC cells, dose-dependently. Microscopic observation results demonstrated that GFAP-treated HCC cells showed apoptotic characteristics like membrane blebbing, chromatin condensed, nucleus pycnosis and fragmentation. Annexin V-FITC/PI staining and cell cycle distribution results showed that GFAP could induce the apoptosis of H22 and HepG2 cells via arresting them in G1 and S phases respectively. Rh123, JC-1 staining and western blotting results suggested that GFAP could significantly increase the permeability of mitochondrial membrane of HCC cells, and upregulated the expressions of Bax, cytochrome c, cleaved-caspase-3 and cleaved-caspase-9, which indicated that GFAP could trigger apoptosis of HCC cells through mitochondria apoptotic pathway in a caspases-dependent pattern. Our data demonstrated that GFAP holds great application prospect as a safe and effective antitumor drug for hepatocellular carcinoma therapy.