Acid-base transporters and pH dynamics in human breast carcinomas predict proliferative activity, metastasis, and survival

  1. Nicolai J Toft
  2. Trine V Axelsen
  3. Helene L Pedersen
  4. Marco Mele
  5. Mark Burton
  6. Eva Balling
  7. Tonje Johansen
  8. Mads Thomassen
  9. Peer M Christiansen
  10. Ebbe Boedtkjer  Is a corresponding author
  1. Aarhus University, Denmark
  2. Regionshospitalet Randers, Denmark
  3. University of Southern Denmark, Denmark

Abstract

Breast cancer heterogeneity in histology and molecular subtype influences metabolic and proliferative activity and hence the acid load on cancer cells. We hypothesized that acid-base transporters and intracellular pH (pHi) dynamics contribute inter-individual variability in breast cancer aggressiveness and prognosis. We show that Na+,HCO3--cotransport and Na+/H+-exchange dominate cellular net acid extrusion in human breast carcinomas. Na+/H+-exchange elevates pHi preferentially in estrogen receptor-negative breast carcinomas, whereas Na+,HCO3--cotransport raises pHi more in invasive lobular than ductal breast carcinomas and in higher malignancy grade breast cancer. HER2-positive breast carcinomas have elevated protein expression of Na+/H+-exchanger NHE1/SLC9A1 and Na+,HCO3--cotransporter NBCn1/SLC4A7. Increased dependency on Na+,HCO3--cotransport associates with severe breast cancer: enlarged CO2/HCO3--dependent rises in pHi predict accelerated cell proliferation; whereas enhanced CO2/HCO3--dependent net acid extrusion, elevated NBCn1 protein expression, and reduced NHE1 protein expression predict lymph node metastasis. Accordingly, we observe reduced survival for patients suffering from Luminal A or Basal-like/triple-negative breast cancer with high SLC4A7 and/or low SLC9A1 mRNA expression. We conclude that the molecular mechanisms of acid-base regulation depend on clinicopathological characteristics of breast cancer patients. NBCn1 expression and dependency on Na+,HCO3--cotransport for pHi regulation, measured in biopsies of human primary breast carcinomas, independently predict proliferative activity, lymph node metastasis, and patient survival.

Data availability

- In order to comply with the ethical approval, we share the human data presented in Figure 1-8 and corresponding Figure Supplements (data on acid-base transport activity, intracellular pH, and protein expression of transporters linked to clinicopathological information) in de-identified form. Following consultation with the legal team at the Regional Committee on Health Research Ethics, we have generated dataset files where restricted information is grouped in intervals each consisting of no less than five individuals. To provide the reader with the best possible data insight, we also show Figure Supplements with more detailed and advanced plots of the data and include the corresponding de-identified dataset.- The meta analyses presented in Figure 9, 10, and corresponding figure supplements (data on RNA expression linked to patient survival) are based on data that have previously been published by other investigators (references 28-34), as detailed in the manuscript and the dataset list.

The following previously published data sets were used

Article and author information

Author details

  1. Nicolai J Toft

    Department of Biomedicine, Aarhus University, Aarhus C, Denmark
    Competing interests
    No competing interests declared.
  2. Trine V Axelsen

    Department of Biomedicine, Aarhus University, Aarhus C, Denmark
    Competing interests
    No competing interests declared.
  3. Helene L Pedersen

    Department of Pathology, Regionshospitalet Randers, Randers, Denmark
    Competing interests
    No competing interests declared.
  4. Marco Mele

    Department of Surgery, Regionshospitalet Randers, Randers, Denmark
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8156-7804
  5. Mark Burton

    Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark
    Competing interests
    No competing interests declared.
  6. Eva Balling

    Department of Surgery, Regionshospitalet Randers, Randers, Denmark
    Competing interests
    No competing interests declared.
  7. Tonje Johansen

    Department of Pathology, Regionshospitalet Randers, Randers, Denmark
    Competing interests
    No competing interests declared.
  8. Mads Thomassen

    Department of Clinical Genetics, University of Southern Denmark, Odense, Denmark
    Competing interests
    No competing interests declared.
  9. Peer M Christiansen

    Department of Surgery, Regionshospitalet Randers, Randers, Denmark
    Competing interests
    No competing interests declared.
  10. Ebbe Boedtkjer

    Department of Biomedicine, Aarhus University, Aarhus C, Denmark
    For correspondence
    eb@biomed.au.dk
    Competing interests
    Ebbe Boedtkjer, is an inventor on patents covering NBCn1 as target for cancer therapy (EP 3271402)..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5078-9279

Funding

Sundhed og Sygdom, Det Frie Forskningsråd (7025-00050B)

  • Ebbe Boedtkjer

Novo Nordisk Fonden (NNF18OC0053037)

  • Ebbe Boedtkjer

Danish Cancer Society (R136-A8670)

  • Nicolai J Toft

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Caigang Liu, Shengjing Hospital of China Medical University, China

Ethics

Human subjects: All participants gave written informed consent. The Mid-Jutland regional division of the Danish Committee on Health Research Ethics (M-20100288) and the Danish Data Protection Agency (1-16-02-191-16) approved the procedures for tissue sampling and data handling, respectively.

Version history

  1. Received: March 16, 2021
  2. Accepted: July 2, 2021
  3. Accepted Manuscript published: July 5, 2021 (version 1)
  4. Version of Record published: July 15, 2021 (version 2)
  5. Version of Record updated: February 11, 2022 (version 3)
  6. Version of Record updated: March 3, 2023 (version 4)
  7. Version of Record updated: March 17, 2023 (version 5)

Copyright

© 2021, Toft et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 1,454
    Page views
  • 206
    Downloads
  • 20
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Nicolai J Toft
  2. Trine V Axelsen
  3. Helene L Pedersen
  4. Marco Mele
  5. Mark Burton
  6. Eva Balling
  7. Tonje Johansen
  8. Mads Thomassen
  9. Peer M Christiansen
  10. Ebbe Boedtkjer
(2021)
Acid-base transporters and pH dynamics in human breast carcinomas predict proliferative activity, metastasis, and survival
eLife 10:e68447.
https://doi.org/10.7554/eLife.68447

Share this article

https://doi.org/10.7554/eLife.68447

Further reading

    1. Cancer Biology
    2. Structural Biology and Molecular Biophysics
    Johannes Paladini, Annalena Maier ... Stephan Grzesiek
    Research Article

    Abelson tyrosine kinase (Abl) is regulated by the arrangement of its regulatory core, consisting sequentially of the SH3, SH2, and kinase (KD) domains, where an assembled or disassembled core corresponds to low or high kinase activity, respectively. It was recently established that binding of type II ATP site inhibitors, such as imatinib, generates a force from the KD N-lobe onto the SH3 domain and in consequence disassembles the core. Here, we demonstrate that the C-terminal αI-helix exerts an additional force toward the SH2 domain, which correlates both with kinase activity and type II inhibitor-induced disassembly. The αI-helix mutation E528K, which is responsible for the ABL1 malformation syndrome, strongly activates Abl by breaking a salt bridge with the KD C-lobe and thereby increasing the force onto the SH2 domain. In contrast, the allosteric inhibitor asciminib strongly reduces Abl’s activity by fixating the αI-helix and reducing the force onto the SH2 domain. These observations are explained by a simple mechanical model of Abl activation involving forces from the KD N-lobe and the αI-helix onto the KD/SH2SH3 interface.

    1. Biochemistry and Chemical Biology
    2. Cancer Biology
    Litong Nie, Chao Wang ... Junjie Chen
    Research Article

    Poly(ADP-ribose)ylation or PARylation by PAR polymerase 1 (PARP1) and dePARylation by poly(ADP-ribose) glycohydrolase (PARG) are equally important for the dynamic regulation of DNA damage response. PARG, the most active dePARylation enzyme, is recruited to sites of DNA damage via pADPr-dependent and PCNA-dependent mechanisms. Targeting dePARylation is considered an alternative strategy to overcome PARP inhibitor resistance. However, precisely how dePARylation functions in normal unperturbed cells remains elusive. To address this challenge, we conducted multiple CRISPR screens and revealed that dePARylation of S phase pADPr by PARG is essential for cell viability. Loss of dePARylation activity initially induced S-phase-specific pADPr signaling, which resulted from unligated Okazaki fragments and eventually led to uncontrolled pADPr accumulation and PARP1/2-dependent cytotoxicity. Moreover, we demonstrated that proteins involved in Okazaki fragment ligation and/or base excision repair regulate pADPr signaling and cell death induced by PARG inhibition. In addition, we determined that PARG expression is critical for cellular sensitivity to PARG inhibition. Additionally, we revealed that PARG is essential for cell survival by suppressing pADPr. Collectively, our data not only identify an essential role for PARG in normal proliferating cells but also provide a potential biomarker for the further development of PARG inhibitors in cancer therapy.