New research published in PLoS Biology finds a link between a protein essential for milk production and an increased metastasis of breast cancer. The protein in question appears to aid breast cancer’s advance through two separate pathways.

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ELF5 is a protein responsible for switching on milk production. It may also assist the spread of breast cancer.

Breast cancer is the most common cancer to affect American women. In 2012, the Centers for Disease Control and Prevention (CDC) report that 224,147 women in America were diagnosed with breast cancer and 41,150 died as a result.

Figures like these constantly fuel research into the mechanisms at work in breast cancer. How breast cancer begins and how it spreads are complicated questions we are only beginning to answer.

Any new potential targets for drugs to attack are investigated thoroughly in the hope that more successful defenses can be built against this most prevalent of cancers.

A recent study, carried out by the Garvan Institute of Medical Research in New South Wales, Australia, looks in detail at the mechanisms of a particular protein – ELF5.

ELF5 is a transcription factor, and as such, it switches on targeted genes at certain times, in response to specific signals. ELF5 activates a number of genes, most of which are involved in epithelial roles.

Importantly, for the purposes of this research, ELF5 is partly responsible for switching on mammalian milk production.

During pregnancy, hormone changes drive the mammary glands to produce milk. The processes involved in this switch are complex and relatively unknown. However, ELF5 appears to be an important player.

ELF5 drives certain cells to develop into milk-secreting alveolar cells in response to specific hormone levels.

Research has shown that if mice are bred without ELF5, they do not grow a milk-secreting epithelium during pregnancy. Conversely, if ELF5 is over-expressed in virgin mice, they begin to express milk.

This most recent study, led by Dr. David Gallego-Ortega, investigates the role of ELF5 in cancerous breast tissue.

The team observed that ELF5 switches from a life-nourishing role to that of a deadly rabble rouser. In response to a tumor, it recruits immune cells to surround the area and encourages the growth of new blood vessels.

These new vessels become “leaky,” allowing cancer cells to escape into the blood and then the lungs. Once in the lungs, the tumor can fix itself and continue its harmful activities. Dr. Gallego-Ortega says:

We show that ELF5 drives the spread of breast cancer to the lungs in a model of breast cancer, and it also predicts early metastasis in patients with luminal A breast cancer.”

This research is not the first time the Garvan Institute of Medical Research has investigated ELF5. Previous studies uncovered a secondary pathway in breast cancer that involves ELF5.

The team found that ELF5 causes breast cancer to switch to a more aggressive form. This more resilient type of cancer lacks sensitivity to estrogen and does not respond to tamoxifen and other anti-estrogen therapies.

It seems that ELF5 is responsible for making breast cancer more resistant to treatment and also allows it to spread with ease to the lungs. Increased levels of ELF5 have been found in breast cancer patients whose disease rapidly worsened. In the words of Dr. Gallego-Ortega:

It’s intriguing that immune cells – which are supposed to defend us from disease – are promoting the spread of cancer.”

It goes without saying that the more biological targets science has to aim treatments at, the better. ELF5 offers a novel route for drug advancements. Perhaps in time, once the complex processes of milk production have been unravelled, ELF5-based treatments might save or, at least, prolong lives.

Another intriguing advancement recently covered by Medical News Today involves links between periodontal disease and breast cancer.