Role of retinoids and their cognate nuclear receptors in breast cancer chemoprevention.

Retinoids are natural and synthetic compounds related to retinoic acid that act through interaction with two basic types of nuclear receptors: retinoic acid receptors (RARalpha, RARbeta and RARgamma) and retinoid X receptors (RXRalpha, RXRbeta and RXRgamma) as ligand-activated, DNA-binding, transacting, transcription-modulating proteins involved in a general molecular mechanism responsible for transcriptional responses in target genes. Function of retinoids in organisms affecting broad spectrum of various biochemical and molecular biology reactions is unimaginable without fully functional nuclear receptors--retinoid inducible transcription factors. Retinoic acids exert tumour-suppressive activity due to their antiproliferative and apoptosis-inducing effects. A number of novel retinoids and rexinoids acting through cognate nuclear receptors have been tested both in vitro and in vivo, using cell culture or animal models for breast cancer. This article briefly summarizes the role and properties of nuclear retinoid/rexinoid receptors as well as selected effects of retinoic acids or selected synthetic retinoids and rexinoids with respect to their potential use in chemoprevention of breast cancer.