Antitumor activity of the water-soluble polysaccharide from Hyriopsis cumingii in vitro

As a freshwater pearl mussel, Hyriopsis cumingii is widely cultured in China to produce pearls. This study was made to explore the antitumor activity of water-soluble polysaccharide (WSP) frommantles ofH. cumingii. Cell viability of human hepatocarcinoma HepG2 cells was estimated by MTT method. Cell cycle analysis was deter-mined by flow cytometry. Apoptosis was observed under fluorescence microscopy and confirmed by DNA fragment assay. Reverse transcriptase-polymerized chain reaction (RT-PCR) and immunocytochemistry were carried to evaluate c-myc, bcl-2 and cyclinD1 gene expressions in HepG2 cells. Furthermore, intracellular reac-tive oxygen species (ROS) production was assessed by flow cytometry. After WSP treatment, the growth of HepG2 cells was inhibited and most of cells arrested in G0/G1 phage (p <.01); apoptotic changes in nucleus and cytoplasm were also observed in WSP-treated cells; percentage of apoptotic rate significantly increased in a dose-dependent manner (p < 0.001); DNA fragmentation was detected in treated HepG2 cells; The mRNA level and protein level of c-myc, bcl-2 and cyclinD1 were decreased in the treated HepG2 cells. ROS was sig-nificantly increased in a dose- and time-dependent manner as well. The results suggested that WSP has potent antitumor activity