Ganoderma Lucidum Polysaccharides Target a Fas/Caspase Dependent Pathway to Induce Apoptosis in Human Colon Cancer Cells

Ganoderma lucidum polysaccharides (GLP) extracted from Ganoderma lucidum have been shown to inducecell death in some kinds of cancer cells. This study investigated the cytotoxic and apoptotic effect of GLP onHCT-116 human colon cancer cells and the molecular mechanisms involved. Cell proliferation, cell migration,lactate dehydrogenase (LDH) levels and intracellular free calcium levels ([Ca2+]i) were determined by MTT,wound-healing, LDH release and fluorescence assays, respectively. Cell apoptosis was observed by scanningand transmission electron microscopy. For the mechanism studies, caspase-8 activation, and Fas and caspase-3expression were evaluated. Treatment of HCT-116 cells with various concentrations of GLP (0.625-5 mg/mL)resulted in a significant decrease in cell viability (P< 0.01). This study showed that the antitumor activity ofGLP was related to cell migration inhibition, cell morphology changes, intracellular Ca2+ elevation and LDHrelease. Also, increase in the levels of caspase-8 activity was involved in GLP-induced apoptosis. Western blottingindicated that Fas and caspase-3 protein expression was up-regulated after exposure to GLP. This investigationdemonstrated for the first time that GLP shows prominent anticancer activities against the HCT-116 humancolon cancer cell line through triggering intracellular calcium release and the death receptor pathway.