Fra-1: a novel target for retinoid action

Using a cDNA gene expression array system, we identified fra-1 as a novel t arget molecule for retinoid action in the human pancreatic carcinoma cell l ine Dan-G. Retinoid treatment resulted in a significant and time-dependent induction of the fra-1 expression on the post-transcriptional level. Supers hift assays revealed that fra-1 participates in the activator protein 1 com plex together with c-fos, c-jun and junB, Transient transfection experiment s using a reporter plasmid containing an activator protein site upstream of the CAT reporter gene revealed that the phorbolester-induced CAT activity, vas suppressed by retinoids, Since fra-1 lacks a transactivation function, we therefore suggest that the retinoid-mediated induction of fra-1 might fu nction as a negative regulator of the activator protein 1 activity in human pancreatic carcinoma cells. (C) 1999 Federation of European Biochemical So cieties.