Apoptosis of human gastric carcinoma MGC-803 cells induced by a novel Astragalus membranaceus polysaccharide via intrinsic mitochondrial pathways.

In our previous study, a novel cold-water-soluble polysaccharide (APS4) was isolated from Astragalus membranaceus. This study aimed to evaluate the proliferation inhibition and apoptosis-induced effects of APS4 on human gastric carcinoma MGC-803 cells and to investigate its potential molecular mechanism. It was found that APS4 could significantly suppress the proliferation of MGC-803 cells in a concentration- and time-dependent manner. Morphologic observations and Annexin V-FITC/PI staining showed that APS4-treated MGC-803 cells exhibited typical morphological characteristics of apoptosis. Cell cycle detection revealed that APS4 could arrest MGC-803 cells in S phase of the cell cycle. Additionally, APS4 treatment could induce the mitochondria-dependent apoptosis, which was closely related to the accumulation of intracellular ROS, the collapse of mitochondrial membrane potential, the increase of the pro-apoptotic/anti-apoptotic (Bax/Bcl-2) ratios, the release of cytochrome c, further activating the expression of caspase-9/-3 and the cleavage of poly-ADP-ribose polymerase (PARP) in MGC-803 cells. Taken together, our results suggested that APS4 had observable apoptosis-induced effects on MGC-803 cells via arresting the cell cycle in S phase and inducing the intrinsic mitochondrial apoptosis pathway.