[Metabolism of vitamin A and retinoids]

Dietary vitamin A is stored in the liver as ester derivatives; after hydrolysis it is transported through the organism bound to a Retinol Binding Protein-Prealbumin complex. Intracellular metabolism is complex and involves the binding to specific receptors for retinol (CRBP) and retinoic acid (CRABP) followed by a nuclear translocation. In addition, retinol can be phosphorylated and implicated in glycosylation processes. Retinoids are characterized by their action on cellular growth and differentiation. Such properties result in anticancer activities which have been clearly put in evidence in vitro and begin to be applied in human oncology. Nevertheless there is always a need for a better comprehension on fundamental mechanisms of natural or synthetic retinoids.