Cells carrying mutations can out compete early tumours in the mouse oesophagus, so they never make it into cancers, new research has shown.
Normal human oesophagus is a patchwork of cells containing mutations, known as mutant clones. This new research, from the Wellcome Sanger Institute, the University of Cambridge, and collaborators, used state of the art 3D imaging techniques and mouse models to visualise microscopic tumours at an earlier stage of development than was previously possible, allowing researchers to uncover an unexpected role that mutant clones play in tumour prevention.
The paper, published today (13th October 2021) in Nature, shows that these high mutant clone burden creates a highly competitive environment in which microscopic early tumours struggle to grow before they are swept out of the tissue by the surrounding mutant cells. Despite this, a few early tumours survive and may develop into oesophageal cancer.
Understanding the mechanisms that prevent the majority of these newly formed microscopic tumours from becoming cancer will give new insights into the prevention of this disease.
All tissues in the human body accumulate mutations over an individual’s life. In the oesophagus, there is a high density of these mutant clones, which compete for space in order to survive in the tissue.
While most mutant clones contain mutations that have been associated with the development of cancer, the rate of tumour formation is not as common as expected*, suggesting that there are other factors preventing the growth of cancer.
In this research, the teams from the Wellcome Sanger Institute, the University of Cambridge, and other collaborators, were able to show that early tumours − up to approximately 100 cells − struggle to grow in the competitive environment created by the presence of highly competitive mutant clones carrying more advantageous mutations.
This research shows that the survival of early tumours in mice does not depend solely on the mutations they carry, but also on the mutations within the neighbouring normal tissue. In addition to this, it shows that while some mutations can be the cause of cancer, other mutant clones can have a tumour suppressive role, which is independent of the body’s immune system. These findings help to explain how there is a relatively low rate of cancers compared with the very high number of mutant cells*.
Further studies into whether the same interactions are seen in human tissue, which mutations lead to cancer cells being successful in this aggressive environment, and the mechanisms behind this, are needed to gain further understanding about the development of oesophageal cancer.
Dr Bartomeu Colom, first author and Senior Staff Scientist at the Wellcome Sanger Institute, said: “Studying the highly competitive environment of the oesophagus and how cells interact and evolve to survive here has given us new insight into how the surrounding cells impact the ability of early tumours to progress in mice. If we understand these interactions fully, it could lead to new ways to prevent early tumours from growing into cancers.”
Dr Albert Herms, author and Postdoctoral Fellow at the Wellcome Sanger Institute, said: “Adult tissues have multiple barriers that cancer cells need to overcome in their route from the initial accumulation of mutations until the development of cancer. In this study we uncovered a new mechanism of protection against cancer that oesophageal tissues use, which is the competition for the space between cancer-driving cells and their neighbour mutant cells.”
Dr Phil Jones, senior author and Senior Group Leader at the Wellcome Sanger Institute and the MRC Cancer Unit at the University of Cambridge, said: “Before our research, it wasn’t understood how the cells in the oesophagus could contain so many cancer-driving mutations and not have a higher rate of tumours. Our study unravels part of this mystery by showing, in single-cell resolution, that these clones can engulf and remove early tumours in mice, leading to a protective effect. Future research can continue to build on this to try to uncover why some of these tumours develop into cancer.”
Notes to Editors:
Oesophageal cancer is the 14th most common cancer in adults, with around 9,200 people being diagnosed in the UK each year.
Cancer Incidence from Cancer Intelligence Statistical Information Team at Cancer Research UK. (2015 - 2017 UK average). Available at https://www.cancerresearchuk.org/about-cancer/oesophageal-cancer/about Accessed September 2021
* Martincorena, I. et al. Somatic mutant clones colonize the human esophagus with age. (2018).Science, 911-917.
B. Colom, A. Herms, M.W.J Hall, et al. Mutant clones in normal epithelium outcompete and eliminate emerging tumours. (2021). Nature. DOI 10.1038/s41586-021-03965-7
This research was funded by Wellcome, Cancer Research UK, the UK Medical Research Council, EMBO, Harrison Watson Fund, the Royal Society, the European Bioinformatics Institute EMBL-EBI, and the Chan Zuckerberg Initiative. For more information, please see the full paper.
About the University of Cambridge
The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 107 affiliates of the University have won the Nobel Prize.
Founded in 1209, the University comprises 31 autonomous Colleges, which admit undergraduates and provide small-group tuition, and 150 departments, faculties and institutions. Cambridge is a global university. Its 19,000 student body includes 3,700 international students from 120 countries. Cambridge researchers collaborate with colleagues worldwide, and the University has established larger-scale partnerships in Asia, Africa and America.
The University sits at the heart of the ‘Cambridge cluster’, which employs 60,000 people and has in excess of £12 billion in turnover generated annually by the 4,700 knowledge-intensive firms in and around the city. The city publishes 341 patents per 100,000 residents. www.cam.ac.uk
The Wellcome Sanger Institute
The Wellcome Sanger Institute is a world leading genomics research centre. We undertake large-scale research that forms the foundations of knowledge in biology and medicine. We are open and collaborative; our data, results, tools and technologies are shared across the globe to advance science. Our ambition is vast – we take on projects that are not possible anywhere else. We use the power of genome sequencing to understand and harness the information in DNA. Funded by Wellcome, we have the freedom and support to push the boundaries of genomics. Our findings are used to improve health and to understand life on Earth. Find out more at www.sanger.ac.uk or follow us on Twitter, Facebook, LinkedIn and on our Blog.
Wellcome supports science to solve the urgent health challenges facing everyone. We support discovery research into life, health and wellbeing, and we’re taking on three worldwide health challenges: mental health, global heating and infectious diseases. https://wellcome.org/
Mutant clones in normal epithelium outcompete and eliminate emerging tumours.
Article Publication Date