Solute exchange through gap junctions lessens the adverse effects of inactivating mutations in metabolite-handling genes

Abstract

Growth of cancer cells in vitro can be attenuated by genetically inactivating selected metabolic pathways. However, loss-of-function mutations in metabolic pathways are not negatively selected in human cancers, indicating that these genes are not essential in vivo. We hypothesize that spontaneous mutations in 'metabolic genes' will not necessarily produce functional defects because mutation-bearing cells may be rescued by metabolite exchange with neighboring wild-type cells via gap junctions. Using fluorescent substances to probe inter-cellular diffusion, we show that colorectal cancer (CRC) cells are coupled by gap junctions assembled from connexins, particularly Cx26. Cells with genetically inactivated components of pH regulation (SLC9A1), glycolysis (ALDOA), or mitochondrial respiration (NDUFS1) could be rescued through access to functional proteins in co-cultured wild-type cells. The effect of diffusive coupling was also observed in co-culture xenografts. Rescue was largely dependent on solute exchange via Cx26 channels, a uniformly and constitutively expressed isoform in CRCs. Due to diffusive coupling, the emergent phenotype is less heterogenous than its genotype, and thus an individual cell should not be considered as the unit under selection, at least for metabolite-handling processes. Our findings can explain why certain loss-of-function mutations in genes ascribed as 'essential' do not influence the growth of human cancers.

Data availability

Fig 1 - original sequencing data is available from the reference given in text. A tabulated form of 1E is given as a supplementary Table.All original data generated or analysed during this study are included in the manuscript and supporting file; Source Data files have been provided.

The following previously published data sets were used

Article and author information

Author details

  1. Stefania Monterisi

    Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
    For correspondence
    stefania.monterisi@dpag.ox.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
  2. Johanna Michl

    Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Alzbeta Hulikova

    Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Jana Koth

    Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Esther M Bridges

    Department of NDM Experimental Medicine, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  6. Amaryllis E Hill

    Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  7. Gulnar Abdullayeva

    Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4961-3671
  8. Walter F Bodmer

    Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  9. Pawel Swietach

    Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
    For correspondence
    pawel.swietach@dpag.ox.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9945-9473

Funding

European Research Council (723997)

  • Pawel Swietach

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

Ethics

Animal experimentation: This study was performed in accordance with the provisions of the Animals (Scientific Procedures) Act 1986 and recommendations set by the Biomedical Services unit at Oxford University. All work involving mice obtained approval of ethics and welfare board instructions, and was authorized by Project Licence PPL P01A04016 issued by the UK Home Office. All surgery was performed under anesthesia, and appropriate post-recovery care was provided to minimize suffering.

Reviewing Editor

  1. Jean X Jiang, The University of Texas Health Science Center at San Antonio, United States

Publication history

  1. Received: March 7, 2022
  2. Accepted: September 13, 2022
  3. Accepted Manuscript published: September 15, 2022 (version 1)

Copyright

© 2022, Monterisi 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.

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  1. Stefania Monterisi
  2. Johanna Michl
  3. Alzbeta Hulikova
  4. Jana Koth
  5. Esther M Bridges
  6. Amaryllis E Hill
  7. Gulnar Abdullayeva
  8. Walter F Bodmer
  9. Pawel Swietach
(2022)
Solute exchange through gap junctions lessens the adverse effects of inactivating mutations in metabolite-handling genes
eLife 11:e78425.
https://doi.org/10.7554/eLife.78425

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