Effects of the tumour promoter 12-O-tetradecanoylphorbol-13-acetate on junctional communication in intact mouse skin: persistence of homologous communication and increase of epidermal-dermal coupling.

12-O-Tetradecanoylphorbol-13-acetate (TPA) has been reported to inhibit junctional communication in some cell cultures. In view of the tumour-promoting activity of TPA in rodent skin, these results have interesting implications for the possible role of junctional communication in tumorigenesis. However, little is known about the effect of TPA on junctional communication in intact skin. Using the technique of iontophoretic injection of Lucifer Yellow CH, we have now studied the patterns of junctional communication in skin treated with TPA. In this paper we report results of such experiments showing that junctional communication in skin persists 4 h after treatment with TPA. In addition, TPA unexpectedly increases communication across the dermal-epidermal boundary. These effects of TPA can still be observed 24 h after treatment. In light of these results, we discuss the possible role of junctional communication in the control of proliferation of normal and pathological tissues.