Protein Kinase A-induced tamoxifen resistance is mediated by anchoring protein AKAP13

BMC Cancer

Research Article

Els Berns¹  Maurice Jansen¹  Rob Michalides²  Jacques Neefjes²  Marleen Kok³  Cristiane Bentin Toaldo³  Wilbert Zwart³  Xanthippi Alexi³  Karin Beelen³  Sabine Linn⁴  Michael Hauptmann⁵ 

[1] Department of Medical Oncology, Josephine Nefkens Institute and Cancer Genomics Center, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands;Division of Cell Biology, the Netherlands Cancer Institute, Amsterdam, The Netherlands;Division of Molecular Pathology, the Netherlands Cancer Institute, Amsterdam, The Netherlands;Division of Molecular Pathology, the Netherlands Cancer Institute, Amsterdam, The Netherlands;Department of Medical Oncology, the Netherlands Cancer Institute, Amsterdam, The Netherlands;Division of Psychosocial Research and Epidemiology, the Netherlands Cancer Institute, Amsterdam, The Netherlands;

关键词: Tamoxifen;    Breast Cancer Patient;    Fluorescence Resonance Energy Transfer;    Fulvestrant;    Tamoxifen Resistance;   

DOI  :  10.1186/s12885-015-1591-4

 received in 2014-09-11, accepted in 2015-08-03,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundEstrogen Receptor alpha (ERα)-positive breast cancer patients receive endocrine therapy, often in the form of tamoxifen. However, resistance to tamoxifen is frequently observed. A signalling cascade that leads to tamoxifen resistance is dictated by activation of the Protein Kinase A (PKA) pathway, which leads to phosphorylation of ERα on Serine 305 and receptor activation, following tamoxifen binding. Thus far, it remains elusive what protein complexes enable the PKA-ERα interaction resulting in ERα Serine 305 phosphorylation.MethodsWe performed immunohistochemistry to detect ERαSerine 305 phosphorylation in a cohort of breast cancer patients who received tamoxifen treatment in the metastatic setting. From the same tumor specimens, Agilent 44 K gene expression analyses were performed and integrated with clinicopathological data and survival information. In vitro analyses were performed using MCF7 breast cancer cells, which included immunoprecipitations and Fluorescence Resonance Energy Transfer (FRET) analyses to illustrate ERα complex formation. siRNA mediated knockdown experiments were performed to assess effects on ERαSerine 305 phosphorylation status, ERα/PKA interactions and downstream responsive gene activity.ResultsStratifying breast tumors on ERα Serine 305 phosphorylation status resulted in the identification of a gene network centered upon AKAP13. AKAP13 mRNA expression levels correlate with poor outcome in patients who received tamoxifen treatment in the metastatic setting. In addition, AKAP13 mRNA levels correlate with ERαSerine 305 phosphorylation in breast tumor samples, suggesting a functional connection between these two events. In a luminal breast cancer cell line, AKAP13 was found to interact with ERα as well as with a regulatory subunit of PKA. Knocking down of AKAP13 prevented PKA-mediated Serine 305 phosphorylation of ERα and abrogated PKA-driven tamoxifen resistance, illustrating that AKAP13 is an essential protein in this process.ConclusionsWe show that the PKA-anchoring protein AKAP13 is essential for the phosphorylation of ERαS305, which leads to tamoxifen resistance both in cell lines and tamoxifen-treated breast cancer patients.

【 授权许可】

CC BY   
© Bentin Toaldo et al. 2015