In vitro studies (human cell lines)
Induction of apoptosis in human gastric epithelial AGS cancer cells by an aqueous extract of Agaricus blazei has been demonstrated. It was found that an Agaricus blazei extract could inhibit cell growth in a dose-dependent manner, which was associated with the arrest of G2/M phase and the induction of apoptotic cell death via caspase3 activation (Jin et al., 2006).
An exopolysaccharide produced from the medicinal mushroom Fomes fomentarius, has been reported to have a direct anti-proliferative effect in vitro on SGC-7901 human gastric cancer cells in a dose- and time-dependent manner (Chen et al., 2008).
A water-soluble extract of Grifola frondosa has been shown to inhibit the proliferation of four human gastric cancer cell lines (TMK-1, MKN28, MKN45 and MKN74) in a time-dependent manner. The inhibition was most pronounced in TMK-1 cells, which exhibited up to 90% inhibition after treatment with 10% extract for 3 days. Induction of apoptosis was confirmed by fluorescence-activated cell sorting analyses, while Western blot analyses of TMK-1 cells after treatment with the extract revealed increases in intracytoplasmic cytochrome c and cleavage of caspase-3 and poly(ADP-ribose) polymerase, but no expression of p21 or Bax. The caspase-3 protease activities in lysates of TMK-1 cells treated with 1% or 10% of the extract were approximately 3-fold higher than in control cells. The data suggest that this extract from Grifola frondosa produces potential antitumour effects on gastric cancer via an induction of apoptosis of TMK-1 cells by caspase-3-dependent and -independent pathways (Shomori et al., 2009).
Animal model (mouse) studies
The effects of natural polysaccharides isolated from Phellinus gilvus (PG) in vitro and in vivo against gastric cancer have been evaluated. PG decreased cell proliferation and increased cell apoptosis in a dose-dependent manner in vitro and also led to a marked inhibition of tumour growth and significant decrease in the incidence of peritoneal carcinomatosis. Histological analysis of the tumour confirmed a significant increase in tumour cell apoptosis by PG, indicating reduced tumour cell proliferation. The data showed that polysaccharides isolated from PG significantly inhibited tumour growth and metastasis in an orthotopic model of human gastric adenocarcinoma, without detectable adverse effects (Bae et al., 2006).
Toth and co-workers have recently reported the inhibition of intestinal cancer by a hot water extract of the Coriolus versicolor (Turkey Tail) mushroom in C57bl/6j-Apc(Min) mice (Toth et al., 2007).