An experimental study on the antileukemia effects of gypenosides in vitro and in vivo.

PURPOSE Gypenosides (Gyp), found in Gynostemma pentaphyllum Makino, have been used as folk medicine for centuries and have exhibited diverse pharmacological effects, including antileukemia effects in vitro and in vivo. In the present study, Gyp were used to examine effects on cell viability, cell cycle, and induction of apoptosis in vitro. They were administered in the diet to mice injected with WEHI-3 cells in vivo. EXPERIMENTAL DESIGN Effects of Gyp on WEHI-3 cells were determined by flow cytometric assay and Western blotting. RESULTS Gyp inhibited the growth of WEHI-3 cells. These effects were associated with the induction of G0/G1 arrest, morphological changes, DNA fragmentation, and increased sub-G1 phase. Gyp promoted the production of reactive oxygen species, increased Ca(2+) levels, and induced the depolarization of the mitochondrial membrane potential. The effects of Gyp were dose and time dependent. Moreover, Gyp increased levels of the proapoptotic protein Bax, reduced levels of the antiapoptotic proteins Bcl-2, and stimulated release of cytochrome c, AIF (apoptosis-inducing factor), and Endo G (endonuclease G) from mitochondria. The levels of GADD153, GRP78, ATF6-α, and ATF4-α were increased by Gyp, resulting in ER (endoplasmic reticular) stress in WEHI-3 cells. Oral consumption of Gyp increased the survival rate of mice injected with WEHI-3 cells used as a mouse model of leukemia. CONCLUSIONS Results of these experiments provide new information on understanding mechanisms of Gyp-induced effects on cell cycle arrest and apoptosis in vitro and in an in vivo animal model.