title: Anacardic acid inhibits estrogen receptor alpha-DNA binding and reduces target gene transcription and breast cancer cell proliferation.
abstract: Anacardic acid (AnAc; 2-hydroxy-6-alkylbenzoic acid) is a dietary and medicinal phytochemical with established anticancer activity in cell and animal models. The mechanisms by which AnAc inhibits cancer cell proliferation remain undefined. AnAc 24:1(omega5) was purified from geranium (Pelargonium x hortorum) and shown to inhibit the proliferation of estrogen receptor alpha (ERalpha)-positive MCF-7 and endocrine-resistant LCC9 and LY2 breast cancer cells with greater efficacy than ERalpha-negative primary human breast epithelial cells, MCF-10A normal breast epithelial cells, and MDA-MB-231 basal-like breast cancer cells. AnAc 24:1(omega5) inhibited cell cycle progression and induced apoptosis in a cell-specific manner. AnAc 24:1(omega5) inhibited estradiol (E(2))-induced estrogen response element (ERE) reporter activity and transcription of the endogenous E(2) target genes pS2, cyclin D1, and cathepsin D in MCF-7 cells. AnAc 24:1(omega5) did not compete with E(2) for ERalpha or ERbeta binding, nor did AnAc 24:1(omega5) reduce ERalpha or ERbeta steady-state protein levels in MCF-7 cells; rather, AnAc 24:1(omega5) inhibited ER-ERE binding in vitro. Virtual screening with the molecular docking software Surflex evaluated AnAc 24:1(omega5) interaction with ERalpha ligand binding (LBD) and DNA binding (DBD) domains in conjunction with experimental validation. Molecular modeling revealed AnAc 24:1(omega5) interaction with the ERalpha DBD but not the LBD. Chromatin immunoprecipitation experiments revealed that AnAc 24:1(omega5) inhibited E(2)-ERalpha interaction with the endogenous pS2 gene promoter region containing an ERE. These data indicate that AnAc 24:1(omega5) inhibits cell proliferation, cell cycle progression, and apoptosis in an ER-dependent manner by reducing ER-DNA interaction and inhibiting ER-mediated transcriptional responses.
authors.affiliation: Department of Biology, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Schultz
authors.forename: Nalinie S
authors.initials: NS
authors.lastname: Wickramasinghe
authors.forename: Margarita M
authors.initials: MM
authors.lastname: Ivanova
authors.forename: Susan M
authors.initials: SM
authors.lastname: Isaacs
authors.forename: Susan M
authors.initials: SM
authors.lastname: Dougherty
authors.forename: Yoannis
authors.initials: Y
authors.lastname: Imbert-Fernandez
authors.forename: Albert R
authors.initials: AR
authors.lastname: Cunningham
authors.forename: Chunyuan
authors.initials: C
authors.lastname: Chen
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Klinge
mesh_terms: D048729:Anacardic Acids / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects*; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D047628:Estrogen Receptor alpha / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D017930:Genes, Reporter / Q000187:drug effects; D006801:Humans; D011485:Protein Binding / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D048729:Anacardic Acids; D000972:Antineoplastic Agents, Phytogenic; D047628:Estrogen Receptor alpha; C088115:anacardic acid; D004247:DNA