ostaglandin E2 (PGE2) receptor subtype EP2, which is coupled to cAMP metabolism, is known to mediate proliferation of primary human keratinocytes in vitro. The effect of gain or loss of EP2 receptors in immortalized human keratinocytes (HaCat cells) was examined. HaCat keratinocytes were transfected with sense or anti-sense constructs of the EP2 receptor. Loss or gain of EP2 expression was documented by immunoblot and associated changes in agonist-stimulated cAMP production. Loss or gain of EP2 receptor expression correlated with alterations in plating efficiencies but with modest affects on growth. When cell lines were studied in an organ culture model, antisense clones were highly invasive compared with vector controls and sense transfectants. A marked increase in prostaglandin production is commonly seen in malignant lesions. Because prostaglandin receptors are known to undergo ligand-induced receptor down-regulation, we sought to determine whether EP2 receptor down-regulation results in increased invasiveness. In vector controls, invasiveness was reproduced by ligand-dependent EP2 receptor down-regulation as assessed by immunohistochemistry. In addition, loss of EP2 receptor expression was associated with decreased paxillin expression, a critical component of focal adhesion assembly. Thus, downregulation of EP2 receptors represents a potential mechanism for neoplastic progression to an invasive phenotype.
ASJC Scopus subject areas
- Pathology and Forensic Medicine