Preventive effect of green tea catechins on experimental tumor metastasis in senescence-accelerated mice.

Successful avoidance of the immune surveillance system is critical for the development of a blood-borne metastasis. Previous findings suggest that experimental tumor metastasis was enhanced in senescence-accelerated mice prone 10 (SAMP10) due to a reduction in immune surveillance potential with age. In the present study, water containing green tea (GT)-catechins was freely given to SAMP10 mice, and the chemopreventive effect of GT-catechin intake on tumor metastasis was examined.

Enhanced experimental tumor metastasis with age in senescence-accelerated mouse.

Tumor metastasis is affected by the host immune surveillance system. Since aging may attenuate the host immune potential, the experimental tumor metastasis may be enhanced with age. In the present study, we investigated this alteration of experimental tumor metastasis with age.

Chemoprevention of tumor metastasis by liposomal beta-sitosterol intake.

To investigate chemopreventive effect of liposomal beta-sitosterol on tumor metastasis, we prepared liposomal beta-sitosterol composed of egg yolk phosphatidylcholine for oral delivery. Although orally administered beta-sitosterol (4 micromol as beta-sitosterol/mouse) was not absorbed into plasma, the amount of immune response cytokines such as IL-12 and IL-18 was increased in the small intestine after the liposome intake. Moreover, after daily oral administration of the liposome for 7 d, natural killer (NK) cell activity in the mice was increased, suggesting that the immune surveillance activity of mice was enhanced by the liposomal beta-sitosterol intake.