Coleusin factor exerts cytotoxic activity by inducing G0/G1 cell cycle arrest and apoptosis in human gastric cancer BGC-823 cells

Coleusin factor (CF), a kind of diterpenoids, is isolated and purified from the root of a Chinese tropical plant Coleus forskohlii by our laboratory. Our previous studies have demonstrated that CF significantly inhibits growth in some kinds of cancer cell lines. Here, we found that CF remarkably inhibited growth in human gastric cancer BGC-823 cells by decreasing cell proliferation, inducing G(0)/G(1) cell cycle arrest and apoptosis. CF also decreased the mitochondrial membrane potential in BGC-823 cells. Immunoblotting analysis revealed that CF significantly decreased the expressions of cyclinD1, Bcl-2, and Bcl-x(L), increased the expressions of cytosol cytochrome c, p53, p21, and Rb. In addition, CF significantly increased the expressions and activities of caspase-3 and -9. More importantly, CF potently inhibited the growth of BGC-823 cells xenografted in athymic nude mice with negligible body weight loss and damage towards the spleen. These results indicate that CF exerts a cytotoxic effect on BGC-823 cells by inducing cell cycle arrest and apoptosis.