Inhibition of 12-O-tetradecanoylphorbol-13-acetate-caused tumor promotion in benzo[a]pyrene-initiated CD-1 mouse skin by geniposide.

The effects of topical application of geniposide on 12-o-tetradecanoylphorbol-13-acetate(TPA)-induced promotion of skin tumors, hyperplasia, ornithine decarboxylase (ODC) and inflammation were evaluated in female CD-1 mice. Topical application of geniposide (0.2 to 1.0 mumol) with TPA (15 nmol) twice weekly for 20 weeks to mice previously initiated with benzo[a]pyrene (B[a]P) inhibited the number of TPA-induced tumor per mouse by 84 or 89%, respectively. Pre-application of the same amount of geniposide also afforded significant protection against TPA-induced hyperplasia in the ear skin. Topical application of geniposide inhibited tumor promoter-caused induction of epidermal ODC activity by TPA (5 nmol). The topical application of geniposide (0.2 or 1.0 mumol) inhibited TPA-induced edema of mouse ears by 41 or 43%, respectively. Pretreatment of mouse skin with various amounts of geniposide caused inhibition of hydrogen peroxide (H2O2) and myeloperoxidase (MPO) formation by TPA. These results indicate that geniposide possesses potential as a cancer chemopreventive agent against tumor promotion.