Article Text

Original research
PI3K-driven HER2 expression is a potential therapeutic target in colorectal cancer stem cells
  1. Laura Rosa Mangiapane1,
  2. Annalisa Nicotra1,
  3. Alice Turdo2,
  4. Miriam Gaggianesi1,
  5. Paola Bianca1,
  6. Simone Di Franco1,
  7. Davide Stefano Sardina1,
  8. Veronica Veschi1,
  9. Michele Signore3,
  10. Sven Beyes4,
  11. Luca Fagnocchi4,
  12. Micol Eleonora Fiori5,
  13. Maria Rita Bongiorno2,
  14. Melania Lo Iacono1,
  15. Irene Pillitteri1,
  16. Gloria Ganduscio1,
  17. Gaspare Gulotta1,
  18. Jan Paul Medema6,7,
  19. Alessio Zippo4,
  20. Matilde Todaro2,
  21. Ruggero De Maria8,9,
  22. Giorgio Stassi1
  1. 1Department of Surgical, Oncological and Stomatological Sciences, Università degli Studi di Palermo, Palermo, Italy
  2. 2Department of Health Promotion Sciences, Internal Medicine and Medical Specialties, Università degli Studi di Palermo, Palermo, Italy
  3. 3Core Facilities, Istituto Superiore di Sanità, Roma, Italy
  4. 4Department of Cellular, Computational, and Integrative Biology (CIBIO), University of Trento, Trento, Italy
  5. 5Department of Oncology and Molecular Medicine, Istituto Superiore di Sanita, Roma, Italy
  6. 6Laboratory for Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, University of Amsterdam, Amsterdam, Noord-Holland, The Netherlands
  7. 7Oncode Institute, University of Amsterdam, Amsterdam, Noord-Holland, The Netherlands
  8. 8Institute of General Pathology, Universita Cattolica del Sacro Cuore Facolta di Medicina e Chirurgia, Roma, Italy
  9. 9Policlinico A Gemelli, Roma, Lazio, Italy
  1. Correspondence to Professor Giorgio Stassi, Department of Surgical, Oncological and Stomatological Sciences, Università degli Studi di Palermo, Palermo, Italy; giorgio.stassi{at}; Professor Ruggero De Maria, Institute of General Pathology, Università Cattolica del Sacro Cuore, Rome, Italy; ruggero.demaria{at}


Objective Cancer stem cells are responsible for tumour spreading and relapse. Human epidermal growth factor receptor 2 (HER2) expression is a negative prognostic factor in colorectal cancer (CRC) and a potential target in tumours carrying the gene amplification. Our aim was to define the expression of HER2 in colorectal cancer stem cells (CR-CSCs) and its possible role as therapeutic target in CRC resistant to anti- epidermal growth factor receptor (EGFR) therapy.

Design A collection of primary sphere cell cultures obtained from 60 CRC specimens was used to generate CR-CSC mouse avatars to preclinically validate therapeutic options. We also made use of the ChIP-seq analysis for transcriptional evaluation of HER2 activation and global RNA-seq to identify the mechanisms underlying therapy resistance.

Results Here we show that in CD44v6-positive CR-CSCs, high HER2 expression levels are associated with an activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, which promotes the acetylation at the regulatory elements of the Erbb2 gene. HER2 targeting in combination with phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase kinase (MEK) inhibitors induces CR-CSC death and regression of tumour xenografts, including those carrying Kras and Pik3ca mutation. Requirement for the triple targeting is due to the presence of cancer-associated fibroblasts, which release cytokines able to confer CR-CSC resistance to PI3K/AKT inhibitors. In contrast, targeting of PI3K/AKT as monotherapy is sufficient to kill liver-disseminating CR-CSCs in a model of adjuvant therapy.

Conclusions While PI3K targeting kills liver-colonising CR-CSCs, the concomitant inhibition of PI3K, HER2 and MEK is required to induce regression of tumours resistant to anti-EGFR therapies. These data may provide a rationale for designing clinical trials in the adjuvant and metastatic setting.

  • colorectal cancer
  • stem cells
  • drug resistance
  • antibody targeted therapy

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See:

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  • LRM and AN contributed equally.

  • Correction notice This article has been corrected since it published Online First. The funding statement has been amended.

  • Contributors LRM, AN, RDM and GS conceived and designed the project. Experiments were conducted by LRM, AN, AT, MG, PB, SDF, VV, MS, SB, LF, MEF, MLI, IP, GGa and MT. Data provision and bioinformatic analysis were carried out by DSS, MS, SB, JPM and AZ. Pathology support, tissue provision and intellectual input were from MEF, MRB and GGu. RDM and GS wrote the manuscript.

  • Funding This work was supported by AIRC 5x1000 (9979) to GS and RDM, AIRC IG (22911) to AZ, RF2018-12367044 to MT and RDM, AIRC IG (21445) and PRIN (2017WNKSLR) to GS.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available in a public, open access repository. All data relevant to the study are included in the article or uploaded as supplementary information. The data that support the findings of this study are available from the corresponding author (GS) upon reasonable request. RNA sequencing data of CR-CSphCs have been deposited in a public, open access GEO repository, under accession number GSE162104 (link to data:

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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