Growth inhibition and cell-cycle arrest of human gastric cancer cells by Lycium barbarum polysaccharide

Lycium barbarum polysaccharide (LBP) is extracted from the traditional Chinese herb Lycium barbarum, and has potential anticancer activity. However, the detailed mechanisms are largely unknown. The purpose of this study was to observe the anticancer effect of LBP on human gastric cancer, and its possible mechanisms. Human gastric cancer MGC-803 and SGC-7901 cells were treated with various concentrations of LBP for 1-5 days, and cell growth was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide assay. Distribution of the cell cycle was analyzed by flow cytometry. Western blotting was used to indicate changes in the level of cyclins and cyclin-dependent kinases (CDKs). LBP treatment inhibited growth of MGC-803 and SGC-7901 cells, with cell-cycle arrest at the G0/G1 and S phase, respectively. We believe that this is the first study to show that LBP arrested different cell lines from the same types of cancer at different phases. The changes in cell-cycle-associated protein, cyclins, and CDKs were consistent with the changes in cell-cycle distribution. This study suggests that induction of cell-cycle arrest participates in the anticancer activity of LBP on gastric cancer cells.