• A Corrigendum to this article was published on 26 May 2017

This article has been updated


Tumor evolution is shaped by many variables, potentially involving external selective pressures induced by therapies1. After surgery, patients with estrogen receptor (ERα)-positive breast cancer are treated with adjuvant endocrine therapy2, including selective estrogen receptor modulators (SERMs) and/or aromatase inhibitors (AIs)3. However, more than 20% of patients relapse within 10 years and eventually progress to incurable metastatic disease4. Here we demonstrate that the choice of therapy has a fundamental influence on the genetic landscape of relapsed diseases. We found that 21.5% of AI-treated, relapsed patients had acquired CYP19A1 (encoding aromatase) amplification (CYP19A1amp). Relapsed patients also developed numerous mutations targeting key breast cancer–associated genes, including ESR1 and CYP19A1. Notably, CYP19A1amp cells also emerged in vitro, but only in AI-resistant models. CYP19A1 amplification caused increased aromatase activity and estrogen-independent ERα binding to target genes, resulting in CYP19A1amp cells showing decreased sensitivity to AI treatment. These data suggest that AI treatment itself selects for acquired CYP19A1amp and promotes local autocrine estrogen signaling in AI-resistant metastatic patients.

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  • 31 January 2017

    In the version of this article initially published online, the names of authors Hermannus Kempe and Pernette J. Verschure were spelled incorrectly. These errors have been corrected in the print, PDF and HTML versions of this article.


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We thank all participants and their families. We thank A. Bardelli for his comments. We thank D. Patten for help with the exemestane study. We thank L. Watson for her help with the manuscript. We thank J.Bean for support. For these studies, S.M. and G.P. were supported by Associazione Italiana Ricerca sul Cancro (AIRC) (5x1000 campaign). L.M. was supported by the Imperial College Junior Research Fellowship. S.-P.H. was supported by Cancer Research UK (CRUK) grant C37/A18784. Y.P. was supported by CRUK PhD studentship P55374. G.C. was supported by the EpiPredict project (European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement 642691).

Author information

Author notes

    • Luca Magnani
    •  & Gianmaria Frigè

    These authors contributed equally to this work.


  1. Department of Surgery and Cancer, Imperial College London, London, UK.

    • Luca Magnani
    • , Raffaella Maria Gadaleta
    • , Giacomo Corleone
    • , Sung-Pil Hong
    • , Ylenia Perone
    •  & Simak Ali
  2. Department of Experimental Oncology, European Institute of Oncology, Milan, Italy.

    • Gianmaria Frigè
    •  & Saverio Minucci
  3. Hematology Unit, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.

    • Sonia Fabris
    •  & Antonino Neri
  4. Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands.

    • Hermannus Kempe
    •  & Pernette J Verschure
  5. Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.

    • Iros Barozzi
  6. Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy.

    • Valentina Vircillo
  7. Division of Stem Cells and Cancer, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.

    • Massimo Saini
    •  & Andreas Trumpp
  8. Institute for Stem Cell Technology and Experimental Medicine GmbH, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany.

    • Massimo Saini
    • , Andreas Trumpp
    •  & Giancarlo Pruneri
  9. Division of Pathology, European Institute of Oncology and University of Milan, School of Medicine, Milan, Italy.

    • Giuseppe Viale
  10. Department of Oncology and Hemato-oncology, University of Milano, Milan, Italy.

    • Antonino Neri
  11. Division of Medical Senology, European Institute of Oncology (IEO), Milan, Italy.

    • Marco Angelo Colleoni
  12. Department of Biosciences, University of Milano, Milan, Italy.

    • Saverio Minucci


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L.M. conceived the study and wrote the manuscript. L.M., S.M. and G.P. planned and supervised all experiments. L.M., G.F., S.-P.H., Y.P., R.M.G., S.F., H.K., and V.V. performed experiments. G.C. and I.B. performed bioinformatics analyses. P.J.V., G.V., A.N., M.S., A.T., S.A. and M.A.C. provided reagents, samples and intellectual contribution. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Luca Magnani or Giancarlo Pruneri or Saverio Minucci.

Integrated supplementary information

Supplementary information

PDF files

  1. 1.

    Supplementary Text and Figures

    Supplementary Figures 1–11 and Supplementary Note

Excel files

  1. 1.

    Supplementary Table 1

    Estimation of CYP19A1 amplification in primary cancers using SNP arrays SNP array-based CNV analysis of several cancer studies has been performed using http://cistrome.org/CaSNP/ (see Online Methods). A summary of the results is shown.

  2. 2.

    Supplementary Table 2

    Probe lists for mutational profiling using Ion Torrent technology BEDFILE containing the genomic coordinates of the probes used for the AmpliSeq custom panel.

  3. 3.

    Supplementary Data 1

    Ion Torrent called mutations in patients treated with tamoxifen Report summaries for each patient treated with single adjuvant tamoxifen were generated using Ion Reporter (https://ionreporter.thermofisher.com/ir/). Each tab contains the results from paired analyses (normal-metastasis). Labeling of each patient is concordant with the labeling from the main text.

  4. 4.

    Supplementary Data 2

    Ion Torrent called mutations in patients treated with aromatase inhibitors Report summaries for each patient treated with single adjuvant aromatase inhibitors were generated using Ion Reporter (https://ionreporter.thermofisher.com/ir/). Each tab contains the results from paired analyses (normal-metastasis). Labeling of each patient is concordant with the labeling in the main text.

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