Scientists at Cancer Research UK have discovered that a single gene – known as FOXA1 – controls the oestrogen-fuelled growth of breast cancer cells.
Importantly, they have shown that the gene determines whether breast cancer cells respond to hormone treatments such as tamoxifen, which works by blocking oestrogen receptors found in some, but not all, breast cancer cells. These receptors would normally switch on genes that lead to cell growth. It remains one of the most effective breast cancer treatments for so-called “oestrogen receptor (ER) positive” breast cancers. However, about a third of women who take the drug will either fail to respond initially or will develop resistance to it over time. FOXA1 appears to be the key that allows oestrogen receptors to interact with the DNA inside breast cancer cells, switching on genes that trigger unchecked cell growth. Almost none of the genes normally switched on by oestrogen receptors interacting with the DNA were activated in breast cancer cells lacking FOXA1. The researchers believe that developing drugs to block FOXA1 could help women who are resistant to tamoxifen. Commenting on the findings, Dr Lesley Walker, director of cancer information at Cancer Research UK, said: “We know that some women with breast cancer stop responding to tamoxifen, making them more prone to relapsing. This discovery could one day lead to new drugs that help improve the outcome for these patients.”
