Welsh scientists uncover role of female hormones in breast cancer spread

Oestrogen can help breast cancer cells invade the blood stream and spread around the body, according to a new study¹ by Cancer Research UK scientists in Wales.

Dr Wen Jiang and his team in Cardiff studied the effect of oestrogen on cells that line our blood vessels. They found the hormone made the vessels leaky, making it easier for cancer cells to slip through.

And they believe designing treatments to counteract the effect of oestrogen and strengthen the blood vessel wall could stop rogue cancer cells from getting into circulation and reaching other organs in the body.

Cancer spreads to other parts of the body when a cell breaks away from the primary tumour and enters a surrounding blood vessel.

Dr Jiang from the University of Wales College of Medicine in Cardiff, says: “We already knew oestrogen could help some breast cancers to develop by stimulating the growth of cells. As a tumour develops the chance of a cell breaking away and travelling to another part of the body increases. But this is the first study to show that oestrogen affects the cells which line our blood vessels.”

In the lab, researchers created a mini-wall of blood vessel cells. Using a fluorescent chemical they visualised how much of it leaked from one side of the wall to the other. When they added oestrogen and repeated the experiment the cells became substantially more leaky.

They think the hormone makes blood vessel cells more permeable by stopping structures, called tight junctions, from working properly. Tight junctions act like glue sealing our cells together.

To test their theory the team analysed the levels of the glue-like structures in blood vessel cells and found they dropped after oestrogen was added.

Scientists believe without this glue, the links between blood vessel cells are weaker, making it easier for cancer cells to get through.

At the end of last year Dr Jiang’s team found breast cancer patients with low levels of the glue are more prone to disease spread.

Dr Jiang says: “It seems that oestrogen disrupts these glue-like structures that lie between the cells in our blood vessels, creating opportunities for breast cancer to spread to other parts of the body.

“We are currently looking at ways to boost the levels of tight junctions in patients to see if this can help halt the rapid spread of the disease.”

Professor Robert Souhami, Director of Clinical Research at Cancer Research UK, says: “There are currently very effective methods to manage cancer confined to the breast but treatment becomes more difficult when abnormal cells spread to other parts of the body.

“This study has provided us with valuable clues on how it might be possible to contain the disease in its early stages and improve the chances of successful treatment.”

ENDS