Lycopene induces retinoic acid receptor transcriptional activation in mice

Scope Lycopene is a lipophilic carotenoid and provides the red colour to tomatoes and tomato product. Various studies indicated that lycopene and tomatoes/tomato products are able to positively influence various diseases associated with a chronic inflammation. The mechanism of action of lycopene to elicit these effects is partly unknown. A possible mechanism is that biological metabolites of lycopene may activate nuclear hormone receptors in mammalian cells. The aim of this study was to investigate the potential of orally administered lycopene and all-trans retinoic acid (ATRA) for the induction of the retinoic acid receptor (RAR) in a transgenic retinoic acid response-element (RARE)-reporter mouse system. Methods and results Orally administered lycopene (100 mg/kg bw in beadlets, n similar to= 6) and ATRA as an endogenous RAR ligand (50 mg/kg bw, n similar to= 6) for the induction of the retinoic acid receptor in male mice using a transgenic RARE-reporter mouse system. Conclusion Lycopene treatments induced RARE-mediated cell signalling indicated by quantified bioimaging, increased luciferase activity and up-regulated the retinoid target genes in selected organs of the mice. We conclude that lycopene can induce RAR-transcriptional activation in mice and lycopene might be a precursor of still non-identified biologically active metabolites.