Effect of compound K, a metabolite of ginseng saponin, combined with gamma-ray radiation in human lung cancer cells in vitro and in vivo.

Pretreatment of NCI-H460 human lung cancer cells with compound K produced by intestinal bacteria enhances gamma-ray radiation-induced cell death. Increases in apoptosis induced by combined treatment are made apparent in the observation of nuclear fragmentation, loss of mitochondrial membrane potential (Deltapsi), and activation of caspase 3. Apoptosis induced by compound K and gamma-ray radiation is associated with reactive oxygen species (ROS) generation. Furthermore, compound K, in combination with gamma-ray radiation, has an enhanced effect in the regression of NCI-H460 tumor xenografts of nude mice. These results suggest that compound K has possible application for cancer therapy when used in combination with gamma-ray radiation.