2013 Volume 30 Issue 1 Pages 19-26
We have focused on the effects of Kampo medicines on cancer metastasis for some time, and 10 years ago we began to assess the medicines in terms of their ability to protect against cancer metastasis. Cancer cell motility is thought to be closely associated with metastatic processes; therefore, we tried to screen Kampo medicines for an inhibitor of cancer cell motility. The samples used for screening were sera from mice given a Kampo medicine such as juzentaihoto, hochuekkito, or maoto. The number of migrated cells was significantly reduced in serum obtained from mice given maoto, and the spontaneous metastasis of cancer cells in mice was significantly decreased by the oral administration of maoto. These results suggested that maoto suppresses cancer metastasis through the prevention of cancer cell motility. Furthermore, we investigated the effect of human sera after the intake of maoto on the motility of cancer cells. The sera collected from 10 volunteers after the intake of maoto showed inhibitory activity against cancer cell motility, indicating that maoto may be a novel inhibitor of cancer metastasis suitable for application in humans. To clarify the molecular mechanism by which maoto suppresses cancer cell motility, we focused on the effects of maoto on hepatocyte growth factor (HGF)-c-Met signaling because HGF is one of the growth factors in serum, and it stimulates cell migration through tyrosine phosphorylation of the HGF receptor, c-Met. Maoto prevented HGF-induced cancer cell motility through the inhibition of the phosphorylation of c-Met, and this effect of maoto was derived from its major component, Ephedrae herba. Taken together, these results suggest that maoto may be a candidate drug for protecting patients from the recurrence and metastasis of cancer that expresses c-Met.
