Antitumor effects of Ninjin-youei-to and its mechanisms

Some Chinese herbal medicines have been reported to have immunomodulating activities, which may have antitumor effects. In the present study, we examined the antitumor effect of Ninjin-youei-to in mice receiving implantation of tumor cells. In C57BL/6 mice, Ninjin-youei-to was mixed with chow and one week after initiation of the experiment, they received intradermal transplantation with 2 X 10⁵ cells of the Lewis lung tumor cell line into the right hind leg. The mean tumor size was significantly (p<0.05) suppressed at 2 and 3 weeks after the transplantation in the group treated with Ninjin-youei-to (n=7) compared with the group treated with solvent alone (n=7). In order to understand the action mechanism of Ninjin-youei-to, blood was collected and the spleen was excised followed by measurement of NK cell activity, Lyt-land Lyt-2. In the group treated with Ninjin-youei-to, NK cell activity, Lyt-land Lyt-2 were significantly (p<0. 05) elevated at 0 and 2 weeks after the transplantation. The antitumor effect of combined treatment of Ninjin-youei-to and cisplatin (CDDP) was also investigated using Lewis lung tumor-bearing mice. The combined use of CDDP with Ninjin-youei-to resulted in significant augmentation of the antitumor activity at 1 (p<0.003) and 2 weeks (p<0.001)after the transplantation compared with CDDP alone. In addition, the combined treatment significantly (p=0.021) prolonged the survival rate compared with CDDP alone. Although there were significant differences in NK cell activity, Lyt-land Lyt-2 (p=0.008, 0.037 and 0.042, respectively) in blood and spleen cells obtained at 1 week after the transplantation, no significant difference was observed thereafter.