Inhibition of tumor invasion and metastasis by aqueous extract of the radix of Platycodon grandiflorum

Platycodon grandiflorum is a traditional oriental herbal medicine that is known for its immunostimulatory and anti-tumor effects. This study examined the anti-metastatic activities of an aqueous extract from the root of P. grandiflorum (Changkil: CK) using in vitro and in vivo metastasis assays. CK inhibited the invasion of B16-F10 melanoma cells through a reconstituted basement membrane (Matrigel)-coated filter, and strongly inhibited the adhesion of B16-F10 melanoma cell to extracellular matrices such as Matrigel, fibronectin and laminin substrates. CK also inhibited an experimentally induced lung cancer and prolonged the survival time in vivo. In addition, CK augmented NK cell activity. These results show that CK can reduce the extent of a lung metastasis of B16-F10 melanoma cells by inhibiting the adhesion of tumor cells to the basement membrane possibly and activating NK cells.