A cold-water soluble polysaccharide isolated from Grifola frondosa induces the apoptosis of HepG2 cells through mitochondrial passway

Grifola frondosa is a widely eaten and medicinal fungus. In this study, we extracted a cold-water-soluble polysaccharide from Grifola frondosa (cGFP) and investigated its effects on the proliferation and apoptosis of human hepatoma HepG2 cells. MTT assay showed that cGFP induced apoptosis of HepG2 cells in a dose-dependent manner. Flow cytometry analysis showed that cGFP induced apoptosis in HepG2 cells through S phase arrest. The distribution of cells at different apoptotic stages was determined by Annexin V-FITC and Propidium Iodide (PI) staining. Scanning electron microscopy (SEM) results indicated that cGFP induced typical apoptotic morphological features in HepG2. Mitochondrial membrane potential was reduced according to the screening of JC-1 staining. And western blot analysis of Bax, Bcl-2, cytochrome C (Cyto-c), caspase-3, and caspase-9 further demonstrated that the cGFP-induced apoptosis effect functioned through the mitochondrial pathway. Further analysis by qRT-PCR showed that Bax expression increased and Bcl-2 expression decreased. These findings suggested that cGFP could inhibit the proliferation of HepG2 cells and induce apoptosis mainly through the intrinsic activation mitochondrial pathway.