Alterations of prostaglandin E2-9-ketoreductase activity in proliferating skin

The activity of an NADPH-dependent PGE2-9-ketoreductase has been demonstrated in rat and human skin. This activity is localized in the high speed supernatant fraction, indicating the presence of an active PGE2-9-ketoreductase associated with the cytoplasmic fraction of the skin. Transformation of PGE2 into PGF2alpha is enhanced by skin specimens from psoriatic plaques and EFA-deficient rats, both characterized by excessive cellular proliferation and increased NADPH production. Incubations of the 105,000 g supernatant fractions from normal and EFA-deficient rats demonstrated that the activity of the PGE2-9-ketoreductase was elevated in high speed preparations from EFA-deficient rats. Results from these studies suggest that the increased activity of PGE2-9-ketoreductase observed in skin from human psoriatic plaques and EFA-deficient rats may be due in part to the increased generation of NADPH by these tissues and in part to alteration of the PGE2-9-ketoreductase by the excessive proliferation of the tissues.