title: Limiting effects of RIP140 in estrogen signaling: potential mediation of anti-estrogenic effects of retinoic acid.
abstract: The receptor interacting protein 140 (RIP140) belongs to a unique subclass of nuclear receptor coregulators with the ability to bind and repress the action of a number of agonist-bound hormone receptors. We have previously demonstrated that all-trans-retinoic acid (RA) induction of RIP140 constitutes a rate-limiting step in the regulation of retinoid receptor signaling. Here we demonstrate that RIP140 is also a limiting regulator of estrogen receptor signaling. Overexpression of RIP140 dose dependently inhibits estrogen-dependent reporter activity in human breast cancer cells. Furthermore, small interfering RNA to RIP140 enhances estrogen-dependent signaling. Our previous studies indicate that RIP140 is a direct target of RA. We report here that RA can abrogate estrogen-mediated cell cycle re-entry. In addition, RA treatment of estrogen-dependent breast cancer cells opposes estrogen receptor-dependent reporter activity, implying that a proportion of RA effects are anti-estrogenic. We provide evidence for a role for RIP140 in mediating anti-estrogenic effects of RA. RIP140 small interfering RNA blocks RA-mediated repression of estrogen receptor activity and provides a growth advantage to estrogen-dependent cells. Together these data implicate a regulatory role for RIP140 in mediating anti-estrogenic effects of RA in estrogen-dependent breast cancer cells and suggest that acute regulation of coregulator expression may be a general mechanism to integrate diverse hormone signals.
authors.affiliation: Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
authors.forename: Kristina A
authors.initials: KA
authors.lastname: White
authors.forename: Mark M
authors.initials: MM
authors.lastname: Yore
authors.forename: Dexin
authors.initials: D
authors.lastname: Deng
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Spinella
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015152:Blotting, Northern; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000378:metabolism*; D020868:Gene Silencing; D017930:Genes, Reporter; D006801:Humans; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology*; D000078723:Nuclear Receptor Interacting Protein 1; D034741:RNA, Small Interfering / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014212:Tretinoin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004967:Estrogens; D008024:Ligands; C000627127:NRIP1 protein, human; D009687:Nuclear Proteins; D000078723:Nuclear Receptor Interacting Protein 1; D034741:RNA, Small Interfering; D011960:Receptors, Estrogen; D014212:Tretinoin; D008156:Luciferases