Benzoyl peroxide activation of protein kinase C activity in epidermal cell membranes

We have investigated the effects of various tumor promoting agents on protein kinase C activity in adult female SENCAR mice. Topical application of benzoyl peroxide increased the calcium-independent activity of protein kinase C in the particulate fraction of basal epidermal cells while decreasing protein kinase C activity in the soluble fraction of basal epidermal cells isolated from the mice. Benzoyl peroxide apparently altered protein kinase C indirectly, as it had no direct effect on the activity of protein kinase C partially purified from bovine brain. Topical application of 12-O-tetradecanoyl phorbol-13-acetate to mouse skin resulted in increased protein kinase C activity associated with the particulate fraction of the epidermal cells with no change in the calcium-dependence of the enzyme. Since the proliferative agent ethylphenylpropiolate had no effect on protein kinase C in epidermis from SENCAR mice, the ability of benzoyl peroxide to influence protein kinase C activity in mouse skin may reflect its tumor promoting capabilities rather than its ability to induce hyperplasia.