Tumor prevention by a xanthate compound in experimental mouse-skin tumorigenesis.

The antiviral and antitumoral compound tricyclodecan-9-yl-xanthogenate (D609), which is an inhibitor of protein kinase C activation, has been used for tumor prevention in vivo. When applied chronically together with 12-O-tetradecanoylphorbol-13-acetate (TPA) in the classic initiation-promotion mouse-skin model, D609 prevented tumor induction in a dose-dependent manner. At the concentration that inhibited tumor formation by 97%, no toxic effects were detected and the TPA-induced hyperplasia remained unaffected. As D609 failed to prevent the activity of a chronically applied carcinogen, it is concluded that the observed tumor prevention achieved with D609 is tumor-promotion-specific and is not due to killing of tumor cells.