A team of scientists at Cancer Research UK’s Cambridge Research Institute examined breast cancer cells to determine the relationship between two receptors called retinoic acid-alpha and oestrogen receptor-alpha when cells are exposed to the hormone oestrogen.
Dr Jason Carroll, lead author and group leader at the Cancer Research UK Cambridge Research Institute, said: “Given that up to 70 per cent of breast cancers are oestrogen receptor positive and require oestrogen for the growth of the tumour, it is important that we better understand how oestrogen receptors function in breast cancer. This knowledge will help us develop better treatments.”
Receptors are the parts of the cell that receive molecular ‘messengers’ with instructions for the cell to behave in a certain way. Oestrogen-receptor-positive breast cancer means that oestrogen receptors have been found in the cancer cells. The area on the oestrogen receptor is like an antenna that can pick up the oestrogen signal to drive breast cancer.
It was previously known that the growth of some breast cancers can be slowed by molecules called retinoids, which bind to retinoid alpha receptors – although the reasons for this have been unclear.
The team found for the first time that these two sets of receptors – oestrogen and retinoic – ‘speak’ to each other in breast cancer cells in order for the oestrogen ‘signal’ to have an effect.
This research suggests that retinoids in breast cancer cells interrupt the two different receptors ‘conversing‘. This lack of conversation may prevent oestrogen receptors functioning properly in breast cancer, thereby blocking the oestrogen’s ability to fuel breast cancer.
Dr Carroll, added: “We’re excited about these findings. We have discovered that in breast cancer cells, oestrogen receptors have a ‘conversation’ with retinoid receptors in order for the oestrogen receptor to work as well as possible.
“It appears that the oestrogen receptor can also work with other similar receptors – the parts of the cell which receive instructions from molecules – suggesting that the role of oestrogen receptor in breast cancer cells may be more complex than we currently believe.”
“These findings have been carried out in cancer cells and are therefore preliminary. The next stage is to confirm the interplay between oestrogen receptors and retinoic acid receptors in primary breast cancer tissue.”
Breast cancer is now the most common cancer in the UK with more than 45,500 women diagnosed with the disease each year – around 125 women a day. Each year in the UK just less than 12,000 women die from the disease.
Dr Lesley Walker, Cancer Research UK’s director of cancer information said: “These important findings add to our understanding of new potential ways in which breast cancer could be stopped – and will help scientists to develop more treatments to beat the disease.
“Since peaking in the late 1980s, breast cancer death rates have fallen by a third and it is thanks to research like this that Cancer Research UK will continue to improve survival.”
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Cooperative interaction between retinoic acid receptor-alpha and estrogen receptor in breast cancer. Ross-Innes et al. Genes and Development. January 2010.