title: The role of estrogen receptor-β in breast cancer.
abstract: The discovery of a second estrogen receptor (ER), ERβ, has led to a reevaluation of estrogen action. The widespread expression of ERβ-like proteins in normal and neoplastic mammary tissues suggests a role of ERβ in the breast. Little progress has been made in elucidating this role or roles, but the presence of two ERs and variant isoforms in breast cancers presents challenges and opportunities to tease out complexities in understanding the estrogen signaling pathway in breast tissues. Identification of two groups of ERβ-expressing tumors in vivo, and the possibility of differential function, has already raised expectations that targeting ERβ may offer new treatment options for breast cancer patients where previously only aggressive chemotherapies were available. This supports continued efforts to understand the nature and function of ERβ in breast cancer, but it also suggests that ER status may need to be redefined to include an assessment of ERβ isoforms in addition to ERα.
authors.affiliation: Department of Biochemistry and Medical Genetics and the Manitoba Institute of Cell Biology, University of Manitoba and CancerCare Manitoba, Winnipeg, Manitoba, Canada. lcmurph@cc.umanitoba.ca
authors.forename: Leigh C
authors.initials: LC
authors.lastname: Murphy
authors.forename: Etienne
authors.initials: E
authors.lastname: Leygue
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D042361:Mammary Glands, Human / Q000187:drug effects / Q000378:metabolism; D058990:Molecular Targeted Therapy; D009363:Neoplasm Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000819:agonists / Q000235:genetics / Q000378:metabolism
chemical_list: D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D047629:Estrogen Receptor beta; D004967:Estrogens; D009363:Neoplasm Proteins; D020033:Protein Isoforms