Polysaccharides from Rhizopus nigricans mycelia induced apoptosis and G2/M arrest in BGC-823 cells

In this study, we reported that polysaccharides (RPS) from the mycelia of liquid-cultured Rhizopus nigricans inhibited the proliferation and clonogenic potential of human gastric cancer BGC-823 cells. Results of acridine orange/ethidium bromide and Hoechst 33258 staining showed that treated cells displayed typical morphological characteristics of apoptosis such as condensation of chromatin, nuclear pyknosis and formation of apoptotic bodies. Flow cytometry analyses and colorimetric assay indicated that RPS induced mitochondria-mediated apoptosis which was associated with collapse of mitochondrial membrane potential, activation of caspase-9 and caspase-3, generation of intracellular reactive oxygen species and elevation of intracellular calcium in BGC-823 cells. Moreover, cell-cycle analysis revealed that RPS arrested cells in the G2/M phase of the cell cycle. These results provided further insights into the potential use of RPS as an anti-cancer agent against human gastric cancer.