Researchers at Peter MacCallum Cancer Centre have advanced biological understanding of the early cellular development of breast tissue.

The world-first research, published overnight in the journal Stem Cell Reports, shows that there is a rare sub-set of cells within the mammary stem cell compartment that are estrogen receptor (ER) positive – meaning they can directly receive estrogen signalling which is the hormone required for growth and expansion of the breast.

Mammary biologists had previously thought that mammary stem cells were estrogen receptor-negative – meaning they do not directly rely on estrogen to grow.

Studies had previously suggested that these stem cells responded to estrogen via their more mature neighbouring cells which develop during puberty.

Study author, Peter Mac’s Dr Kara Britt, says the research provides a new and deeper insight into why abnormal estrogen exposure might lead to breast cancer in some women.                                                                                                            

“It is known that abnormal exposure to estrogen at a very young age can lead to an increased risk of developing breast cancer later in life.

“However, it has never been well understood why some people would develop breast cancer in their sixties from something that happened at such a young age.

“The presence of these estrogen-receptor positive stem cells in the mammary gland could be the key to understanding how estrogens can affect a person’s breast cancer risk from the very start of life.

“Having now discovered that there are estrogen-receptor positive mammary stem-cells, it’s possible we may not have been looking early enough in previous work to understand their impact on the development of a normal, or otherwise, mammary gland.

PhD student and lead author, Dr Genevieve Dall says the next stage of their research involves exploring the role of this rare sub-set of cells in earlier stages of mammary gland development and susceptibility to breast cancer – in particular ER-positive breast cancer which accounts for around 80 percent of breast cancers in Australia.

“Should we find a link between these cells and breast cancer initiation, hormone treatments could be developed to alter the number of these estrogen receptor-positive stem cells to safer levels – potentially lowering a person’s risk of developing breast cancer.” 

This Peter Mac-led research was jointly funded by the National Health and Medical Research Council and the National Breast Cancer Foundation.

Experts from across the globe including: the National Institute of Environmental Health Services in the US, the MRC Centre for Inflammation Research in Edinburgh, the Institute of Cancer Sciences at the University of Glasgow as well as researchers at The Florey Institute and Monash University in Melbourne were all involved in providing supporting evidence for this research.

Media Release.