Department of Dermatology, University of Rochester Medical Center, Rochester, NY 14642, U.S.A.

Correspondence: Alice P. Pentland, Department of Dermatology, University of Maryland Baltimore, 601 Elmwood Ave., Rochester, NY 14642, U.S.A. Email: alice_pentland@urmc.rochester.edu

Received 23 July 2001; Revised 6 June 2002; Accepted 17 June 2002.

Abstract

Secretory phospholipase A₂ and cycloxygenase-2 are coexpressed in activated primary keratinocytes. These proteins are known to be functionally linked, mediating proliferation of human keratinocytes during epidermal wound repair. Primary human keratinocytes grown at low densities (15–30%; nonconfluent) produce high levels of prostaglandin E₂ important for proliferation and are a good model for studying activated keratinocytes after injury. In this study, we used this model to assess the role of secretory phospholipase A₂ and cycloxygenase-2 in keratinocyte motility. Initial work showed 24 h pretreatment with 20 ng pertussis toxin per ml, an inhibitor of the inhibitory G-protein, decreased prostaglandin E₂ production and both secretory phospholipase A₂ and cycloxygenase-2 protein expression. This suggested that inhibitory G-protein may be involved in mediating expression of these proteins. Pertussis toxin also caused changes in cell morphology, actin organization, and keratinocyte motility. Pretreatment with 5 M 12-epi-scalaradial, a secretory phospholipase A₂ inhibitor, caused similar changes in cell motility and actin organization; however, the specific cycloxygenase-2 inhibitor, SC-58236 (20 nM) was much less effective. These results suggested that secretory phospholipase A₂ plays a part in keratinocyte motility that is independent of its functional linkage to cycloxygenase-2 and prostaglandin E₂ biosynthesis.