Retinoids: present role and future potential

Vitamin A and its biologically active derivatives, retinal and retinoic aci d (RA), together with a large repertoire of synthetic analogues are collect ively referred to as retinoids. Naturally occurring retinoids regulate the growth and differentiation of a wide variety of cell types and play a cruci al role in the physiology of vision and as morphogenic agents during embryo nic development. Retinoids and their analogues have been evaluated as chemo prevention agents, and also in the management of acute promyelocytic leukae mia. Retinoids exert most of their effects by binding to specific receptors and modulating gene expression. The development of new active retinoids an d the identification of two distinct families of retinoid receptors has led to an increased understanding of the cellular effects of activation of the se receptors. In this article we review the use of retinoids in chemopreven tion strategies, discuss the cellular consequences of activated retinoid re ceptors, and speculate on how our increasing understanding of retinoid-indu ced signalling pathways may contribute to future therapeutic strategies in the management of malignant disease.