title: The Role of MicroRNAs as Predictors of Response to Tamoxifen Treatment in Breast Cancer Patients.
abstract: Endocrine therapy is a key treatment strategy to control or eradicate hormone-responsive breast cancer. However, resistance to endocrine therapy leads to breast cancer relapse. The recent extension of adjuvant tamoxifen treatment up to 10 years actualizes the need for identifying biological markers that may be used to monitor predictors of treatment response. MicroRNAs are promising biomarkers that may fill the gap between preclinical knowledge and clinical observations regarding endocrine resistance. MicroRNAs regulate gene expression by posttranscriptional repression or degradation of mRNA, most often leading to gene silencing. MicroRNAs have been identified directly in the primary tumor, but also in the circulation of breast cancer patients. The few available studies investigating microRNA in patients suggest that seven microRNAs (miR-10a, miR-26, miR-30c, miR-126a, miR-210, miR-342 and miR-519a) play a role in tamoxifen resistance. Ingenuity Pathway Analysis (IPA) reveals that these seven microRNAs interact more readily with estrogen receptor (ER)-independent pathways than ER-related signaling pathways. Some of these pathways are targetable (e.g., PIK3CA), suggesting that microRNAs as biomarkers of endocrine resistance may have clinical value. Validation of the role of these candidate microRNAs in large prospective studies is warranted.
authors.affiliation: Department of Pathology, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011 Stavanger, Norway. nina.gran.egeland@sus.no.|Department of Mathematics and Natural Sciences, University of Stavanger, 4036 Stavanger, Norway. nina.gran.egeland@sus.no.
authors.forename: Nina G
authors.initials: NG
authors.lastname: Egeland
authors.affiliation: Department of Breast and Endocrine Surgery, Stavanger University Hospital, 4011 Stavanger, Norway. siri.lunde@sus.no.
authors.forename: Siri
authors.initials: S
authors.lastname: Lunde
authors.affiliation: Department of Pathology, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011 Stavanger, Norway. kristin.jonsdottir@sus.no.
authors.forename: Kristin
authors.initials: K
authors.lastname: Jonsdottir
authors.affiliation: Department of Breast and Endocrine Surgery, Stavanger University Hospital, 4011 Stavanger, Norway. tone.hoel.lende@sus.no.|Department of Clinical Science, University of Bergen, Postboks 7804, 5020 Bergen, Norway. tone.hoel.lende@sus.no.
authors.forename: Tone H
authors.initials: TH
authors.lastname: Lende
authors.affiliation: Department of Clinical Epidemiology, Aarhus University, Science Center Skejby, Olof Palmes Allé 43, Aarhus N, 8200 Aarhus, Denmark. dc@clin.au.dk.
authors.forename: Deirdre
authors.initials: D
authors.lastname: Cronin-Fenton
authors.affiliation: Department of Haematology and Oncology, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011 Stavanger, Norway. bjornar.gilje@sus.no.
authors.forename: Bjørnar
authors.initials: B
authors.lastname: Gilje
authors.affiliation: Department of Pathology, Stavanger University Hospital, Gerd Ragna Bloch Thorsens Gate 8, 4011 Stavanger, Norway. emilius.adrianus.maria.janssen@sus.no.|Department of Mathematics and Natural Sciences, University of Stavanger, 4036 Stavanger, Norway. emilius.adrianus.maria.janssen@sus.no.
authors.forename: Emiel A M
authors.initials: EA
authors.lastname: Janssen
authors.affiliation: Department of Breast and Endocrine Surgery, Stavanger University Hospital, 4011 Stavanger, Norway. havard.soiland@sus.no.|Department of Clinical Science, University of Bergen, Postboks 7804, 5020 Bergen, Norway. havard.soiland@sus.no.
authors.forename: Håvard
authors.initials: H
authors.lastname: Søiland
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics*; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D035683:MicroRNAs; D011960:Receptors, Estrogen; D013629:Tamoxifen
keywords: biomarker; breast cancer; endocrine resistance; microRNA; tamoxifen