Researchers at the University of Cambridge report they have created the world’s largest catalog of human breast cells, which has revealed early cell changes in healthy carriers of BRCA1 and BRCA2 gene mutations.
Their new study is published in Nature Genetics in an article titled, “A single-cell atlas enables mapping of homeostatic cellular shifts in the adult human breast.”
“Our results suggest that in carriers of BRCA mutations, the immune system is failing to kill off damaged breast cells—which in turn seem to be working to keep these immune cells at bay,” said Walid Khaled, PhD, a professor at the University of Cambridge’s department of pharmacology and Wellcome-MRC Cambridge Stem Cell Institute, and senior author of the study.
He added: “We’re very excited about this discovery because it opens up potential for a preventative treatment other than surgery for carriers of BRCA breast cancer gene mutations. Drugs already exist that can overcome this block in immune cell function, but so far, they’ve only been approved for late-stage disease. No one has really considered using them in a preventative way before.”
“The best way to prevent breast cancer is to really understand how it develops in the first place. Then we can identify these early changes and intervene,” said Khaled. “Late-stage breast cancer tends to be very unpredictable and hard to manage. As we make better and better drugs, the tumors just seem to find a way around it.”
The researchers used healthy breast tissue collected from 55 women across a range of ages, the researchers cataloged over 800,000 cells—including all the different types of breast cells.
Their Human Breast Cell Atlas is now available as a resource for other researchers to use and add to. It contains huge amounts of information on other risk factors for breast cancer including Body Mass Index (BMI), menopausal status, contraceptive use, and alcohol consumption.
“We’ve found that there are multiple breast cell types that change with pregnancy, and with age, and it’s the combination of these effects—and others—that drives the overall risk of breast cancer,” said Austin Reed, a PhD student in the University of Cambridge’s department of pharmacology and co-first author of the study.
He added: “As we collect more of this type of information from samples around the world, we can learn more about how breast cancer develops and the impact of different risk factors—with the aim of improving treatment.”
The researchers used “single cell RNA-sequencing” to characterize the many different breast cell types and states. Almost all cells in the body have the same set of genes, but only a subset of these are switched on in each cell—and these determine the cell’s identity and function.
“Breast cancer occurs around the world, but social inequalities mean not everyone has access to treatment. Prevention is the most cost-effective approach. It not only tackles inequality, which mostly affects low-income countries, but also improves disease outcome in high-income countries,” said Sara Pensa, PhD, senior research associate in the University of Cambridge’s department of pharmacology and co-first author of the study.
Their findings raise the possibility of early intervention to prevent the disease and present a potential preventative therapeutic approach that could pave the way for clinical trials in human carriers of BRCA1 and BRCA2 mutations.
