OBJECTIVETo investigate the effect of ginsenoside-Rg3 on lung metastasis of ribonuclease inhibitor (RI) gene-transfected mouse B16 melanoma.

METHODSC57BL/6 mice were iv injected with parental or RI-transfected B16 melanoma cells. Lung metastasis was assessed by the number of surface tumor nodules. Mice were divided into 6 groups. Group I, II and III of mice were given parental, mock-transfected and RI-transfected B16 melanoma cells, respectively while in group IV, V and VI, Rg3 (1.5 mg/kg, iv q.o.d. x 10) was given to mice bearing parental, mock-transfected and RI-transfected B16 melanoma, respectively. Micovessel density (MVD) of the lung metastatic tumor was assessed by immunohistochemical staining of factor VIII-R expression.

RESULTSThe number of tumor nodules was significantly decreased in mice injected with RI-transfected B16 melanoma (Gp III, compared to Gp I and II). Rg3 treatment per se could also decrease the number of lung tumor nodules but to a lesser extent (Gp IV and V compared to Gp III). However, Rg3 synergized with RI transfection resulting in most significant inhibition of lung metastasis (Gp VI). Mice in Gp I and II died within 26 days of the experiment, whereas all the mice in Gp VI were alive during the observation period of one and one half month. MVD was significantly decreased in the lung tumor nodules in mice injected with RI-transfected B16 melanoma. It was further decreased when additional Rg3 was given (Gp VI).

CONCLUSIONTransfection of ribonuclease inhibitor gene significantly reduces the metastatic potential of B16 melanoma. Ginsenoside-Rg3 has a synergistic effect.