title: Tumor-suppressive activity of retinoic acid receptor-beta in cancer.
abstract: Retinoids, a group of structural and functional analogs of vitamin A, are known to regulate a large number of essential biological processes and to suppress carcinogenesis. The effects of retinoids are mainly mediated by nuclear retinoid receptors, which include retinoic acid receptors (RARs) and retinoid X receptors (RXRs). Each receptor has three subtypes (alpha, beta, and gamma) and each subtype has different isoforms. Retinoic acid receptor-beta (RAR-beta) has four isoforms that have different affinities to retinoids and different biological functions. Loss of expression of RAR-beta(2) during cancer development is associated with tumorigenesis and retinoid resistance; induction of its expression, on the other hand, can suppress carcinogenesis. Expression of another isoform, RAR-beta(4), is increased in various types of cancer. RAR-beta(4) transgenic mice develop hyperplasia and neoplasia in various tissues, and induction of RAR-beta(4) expression increases the growth of tumor cells that do not express RAR-beta(2). Future studies will focus on molecular pathways involving RAR-beta(2) and the role of RAR-beta(4) in cancer development.
authors.affiliation: Department of Clinical Cancer Prevention, Unit 1360, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. xxumdanderson.org
authors.forename: Xiao-Chun
authors.initials: XC
authors.lastname: Xu
mesh_terms: D001483:Base Sequence; D015415:Biomarkers / Q000378:metabolism; D005544:Forecasting; D006801:Humans; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000378:metabolism* / Q000517:prevention & control; D020033:Protein Isoforms / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000502:physiology*
chemical_list: D015415:Biomarkers; D020033:Protein Isoforms; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta