Purification, partial characterization and inducing tumor cell apoptosis activity of a polysaccharide from Ganoderma applanatum

In this study, a homogeneous polysaccharide (designated as GAP-3S) with an average molecular weight of 6.82 × 105 Da was purified from Ganoderma applanatum. GAP-3S was composed of glucose, galactose, fucose and xylose in the molar ratio of 7.1:2.6:1.1:1. It could significantly inhibit the proliferation of MCF-7 cells in a dose- and time-dependent manner. Flow cytometry analysis indicated that GAP-3S could also induce cell apoptosis. Treatment of MCF-7 cells with GAP-3S lead to the collapse of mitochondrial membrane potential and the accumulation of ROS, up-regulated expression of Bax, cleavage of PARP, p-p38 and p-JNK, and the down-regulated expression of Bcl-2, PARP and p-ERK. The activities of caspase-3 and caspase-9 were also increased in GAP-3S-treated MCF-7 cells compared to untreated cells. These findings suggested that GAP-3S probably induced apoptosis in MCF-7 cells through intrinsic mitochondrial apoptosis and MAPK signaling pathways.