Scientists discover how cancer spreads

They have discovered that a key protein molecule - called Src - helps to loosen the structure of tissues surrounding a tumour, opening the way for cancer cells to spread around the body.

The discovery at Glasgow's Beatson Institute could lead to new drugs that block this action and prevent cancer spreading.

Src was the first ever molecule to be implicated in the development of cancer, in particular bowel cancer.

However, until now nobody knew exactly what it did.

Cells in healthy tissues are bound together by a number of molecules that work as a set of scaffolding.

During the development of cancer the scaffolding breaks down and tissues become loose and disorganised.

Src seems to play a key role in this process.

The molecule is vital for maintaining the flexibility of healthy tissues and making sure there's plenty of space for future growth.

But during the development of cancer it becomes over active and begins to disrupt a tissue's normal structure.

Vital component

Lead researcher Professor Margaret Frame said: "We were pretty sure that Src played an important role in bowel cancer, but untangling the precise nature of that role has taken a long time.

"We've now found that the molecule triggers several different chemical signals, affecting cells in a variety of ways.

"Designing drugs to intercept these signals could be an important way of preventing bowel cancer from spreading."

Professor Frame and her colleagues found that Src sends out instructions for the removal of a molecule called E-cadherin from the surface of cells.

E-cadherin is a vital component of the scaffolding that holds cells together and without it a tissue's structure becomes disrupted.

Src appears to work with another set of molecules - called integrins - to form a new and much looser type of tissue structure that helps bowel cancer cells to move and spread.

Chance of success

Professor Frame said: "Improving our understanding of how cancer spreads should help in the development of drugs to block the process.

"If we could confine cancer cells to the original tumour it would give surgery a much greater chance of success and reduce the risk of the disease reappearing in other parts of the body."

When detected early bowel cancer is often curable, since most of the cancer cells remain within the original tumour, where they can be removed by surgery.

But over time, cells start to move away from the tumour into the bloodstream and lymphatic system, which act as highways to the rest of the body.

Once bowel cancer has spread, the chances of successful treatment are much lower.

The research is published in the journal Nature Cell Biology.