Astragalus saponins modulate cell invasiveness and angiogenesis in human gastric adenocarcinoma cells

Abstract

Aim of the study: We had reported that Astragalus saponins (AST) exert promising anti-tumorigenic effects by suppressing the growth of HT-29 human colon cancer cells and tumor xenograft. In the present study, we further investigated the anti-angiogenic property of AST in human gastric adenocarcinoma cells (AGS) and attempted to elucidate the underlying mechanism.

Materials and methods: Viability of AGS cells was measured by using the MTT reduction method. Western blotting was performed to examine the effect of AST on apoptotic- and cell growth-related protein expression. Effect of AST on cell cycle progression was also evaluated using PI staining. A Matrigel invasion assay was then employed to demonstrate the effect of AST on the invasiveness of gastric cancer cells. The expression of invasion-associated proteins (VEGF and MMPs) was also investigated.

Results: AST could induce apoptosis in AGS cells by activating caspase 3 with subsequent cleavage of poly(ADP-ribose) polymerase. Besides, cell cycle arrest at the G2/M phase had been observed in AST-treated cells, leading to substantial growth inhibition. The anti-proliferative effect of AST was associated with the regulation of cyclin B1, p21 and c-myc. Results indicate that the number of AGS cells invaded through the Matrigel membrane was significantly reduced upon AST treatment, with concomitant down-regulation of the pro-angiogenic protein vascular endothelial growth factor (VEGF) as well as the metastatic proteins metalloproteinase (MMP)-2 and MMP-9.

Conclusion: AST derived from the medicinal plant Astragalus membranaceus could modulate the invasiveness and angiogenesis of AGS cells besides its pro-apoptotic and anti-proliferative activities. These findings also suggest that AST has the potential to be further developed into an effective chemotherapeutic agent in treating advanced and metastatic gastric cancers.