2000/10/24 by Minna K. Tikkanen, Damien J. Carter, Alana Harris +4 · 2 citations
Biochemistry, Genetics and Molecular Biology · Pharmacology, Toxicology and Pharmaceutics · Medicine · #Estrogen and related hormone effects #Bioactive Compounds and Antitumor Agents #Inflammatory mediators and NSAID effects
paper · doi:10.1073/pnas.220427297
openalex publication_date 2000/10/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Coactivators are believed to mediate estrogen-induced gene responses via interaction with estrogen receptors (ER). Currently, a major challenge is to determine the importance of each coactivator in a specific cell type and promoter context in response to a particular ligand. The potential of ER to interact with a growing list of coactivators has been shown in a variety of in vitro and gene transfer assays, yet very few data have demonstrated the interaction of endogenous coactivators with ER in intact cells. We report here a ligand-specific interaction of endogenous human ER (hER) and the AIB1 coactivator in MCF-7 human breast cancer cells by using immunoprecipitation analyses. Complexes between endogenously expressed hER and AIB1 were detected in estradiol-treated cells and to a much lesser extent in cells treated with the partial agonist, monohydroxytamoxifen. We were unable to detect an hER-SRC-1 complex in our immunoprecipitations from MCF-7 cells. The in vitro-binding affinity for mouse ER interaction with AIB1 was estimated to be 40-120 nM. We conclude that AIB1 is a major coactivator for hER in MCF-7 human breast cancer cells.