Forskolin: a potential antimetastatic agent.

Forskolin, a diterpene from the roots of an Indian plant, Coleus forskohlii, is a potent platelet aggregation inhibitor and has been examined for its effects on (a) tumor-induced human platelet aggregation and (b) pulmonary tumor colonization in mice. These studies employed a subline of B16 murine melanoma, B16-F10 (highly metastatic to lungs). Forskolin (2 microM) strongly inhibits the melanoma cell-induced human platelet aggregation. A single dose of forskolin (82 micrograms/mouse) administered intraperitoneally 30 or 60 min prior to tail vein injection of cultured B16-F10 cells (2 or 3 X 10(5) cells/mouse) reduced tumor colonization in the lungs by more than 70%. Similar results were obtained in three separate experiments. These findings raise the possibility that forskolin could prove of value in the clinic for the prevention of cancer metastasis.