Scientists have discovered how a key protein helps cancerous cells spread through the body in a finding that could pave the way for new drugs to slow down the progression of the disease.
The molecule, called Src, loosens the tissue around a tumour and allows cancerous cells to metastasise, or grow in other organs.
Scientists at Glasgow's Beatson Institute, who figured out how it works, believe drugs designed to block the action of the molecule could prevent cancer from spreading.
"We discovered what it is actually doing in human cancer cells. It is important in the molecular understanding of how cancer cells spread," Professor Margaret Frame, who headed the research team, said in an interview on Monday.
Cancer develops when the control signals in the cell go wrong and an abnormal cell forms. Instead of destroying itself the mutated cell divides and multiplies and forms a lump or tumour.
When cells escape from a tumour they can invade nearby parts of the body or travel to other organs. A breast cancer cell, for example, can travel to the lymph nodes and then to the bones or liver where it can set up a secondary growth, or tumour.
Surgeons are skilled at removing cancerous tumours but if cells have broken off from the original site and set up other tumours the disease becomes much more serious. Most deaths from cancer result from the uncontrollable spread of cells from the tumour to other sites.
Src is the oldest known cancer-causing molecule but until now scientists did not know how it was involved in the disease.
While studying colon cancer, Frame and her colleagues discovered that the molecule becomes over-active and breaks down the tissue's normal structure.
Src sends out signals for the removal of a molecule, called E-cadherin, which is needed to hold cells together. It also works with integrins, another set of molecules, to form a new and much looser type of tissue structure that allows cancerous cells to move and spread.
"We've now found that the molecule triggers several different chemical signals in a variety of ways. Designing drugs to intercept these signals could be an important way of preventing bowel cancer from spreading," said Frame, whose research is reported in the science journal Nature Cell Biology.
The molecule works in a similar way in many of the commonest cancers, including breast, prostate and ovarian, so a drug that blocks its action could have potential in treating different cancer.
"Hopefully we can slow down the disease in patients," Frame added.
She is confident that drugs that either prevent the cancer from spreading from the original tumour or slow down its progression if it has already started could be developed in the next few years.
"Improving our understanding of how cancer spreads should help in the development of drugs to block the process," she said. "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."