EVALUATION OF THE USE OF THE LUCIFERASE-REPORTER-GENE SYSTEM FOR GENE-REGULATION STUDIES INVOLVING CYCLIC AMP-ELEVATING AGENTS

The effects of cyclic AMP (cAMP)-elevating agents on the activity of cis-acting gene promoter sequences are frequently studied using the luciferase-reporter-gene system. The aim of the present study was to assess whether cAMP-elevating agents induce any changes in the level of luciferase activity independently of a transcriptional activation of promoter elements. Chloramphenicol acteyltransferase (CAT) and luciferase reporter genes under the control of the same promoter elements were transiently expressed in primary cultures of human vascular smooth-muscle cells. Transfected cells were treated with a cell-permeable and non-hydrolysable cAMP analogue, 2'-O-monobutyryl-8-bromo cAMP, or with the cAMP-elevating agents forskolin and prostaglandin E(1) (PGE(1)). Forskolin and PGE(1) induced a significant increase in the level of luciferase activity, but had no effect on CAT activity. Conclusions based solely on the use of the luciferase-reporter-gene system in studies involving promoter activation by cAMP-elevating agents could therefore be misleading.