Hormone found to influence breast cancer development

In collaboration with the Press Association

Italian researchers have found that the hormone leptin, which is produced by fat tissue, significantly influences the development and progression of breast cancer in mice.

Speaking at Experimental Biology 2007 in Washington DC, Dr Sebastiano Ando, a researcher at the University of Calabria's department of cellular biology, said that the finding may have unravelled a new mechanism for the accepted link between obesity and breast cancer in post-menopausal women.

Leptin is known to alert the body when it is full, a process which is thought to malfunction in some obese people.

It has also been shown to be involved in the development of breast cancer by increasing the amount of a form of oestrogen in breast tissue, and has been detected in the large majority of breast cancers.

In the recent study, published in the journal Cancer Research, researchers grafted human breast cancer tissue into mice which had been bred to be unable to reject tumours. They also studied laboratory-grown cancer cells in Petri-dishes.

In both cases, the addition of leptin and oestrogen caused the cancer cells to grow faster and to become more 'sticky' and clump together - a hallmark of cancer progression.

They found that this effect was caused by the production of a molecule called E-cadherin, known to be involved in cell growth and 'stickiness'.

Significantly, blocking the action of E-cadherin prevented these effects from occurring, suggesting that blocking this pathway could lead to new treatments for breast cancer.

Dr Kat Arney, Senior Science Information Officer at Cancer Research UK, said: "Although we know that obesity increases the risk of several types of cancer, relatively little is known about how the two are linked.

"These results are intriguing, as they provide evidence for a new connection between the fat hormone leptin and breast cancer, at least in mice. Now the researchers need to find out if this pathway works in human cancers."