Metastasis is the main cause of cancer death. It is described as the transfer of cancer cells from the original tumour to distant organs via the blood stream.
The new findings add significantly to the understanding of metastasis, and may lead to the development of anti-cancer drugs in the future.
Led by Prof. Yosef Yarden of the Institute's Biological Regulation Department, the researchers mapped all of the genetic changes that occur in the cell when it receives a signal from a growth factor, a substance that orders cells to "prepare to move".
As they sifted through the enormous amount of data they received, including details on every protein level that went up or down, one family of proteins stood out. Tensins, as they are called, are proteins that stabilize the cell structure. But to the scientists' surprise, the amounts of one family member rose dramatically while, at the same time, the levels of another dropped.
When the scientists conducted experiments with genetically engineered cells, they found that the growth factor directly influences levels of both proteins, and that these, in turn, control the cells' ability to migrate.
While blocking the production of the short tensin protein kept cells in their place, its overproduction increased their migration.
Upon conducting tests on tumour samples taken from around 300 patients with inflammatory breast cancer, which is associated with elevated growth factor levels, the scientists discovered a strong correlation between high growth factor activity and levels of the 'plug' protein.
High levels of the protein were associated with cancer metastasis to the lymph nodes, the first station of migrating cancer cells as they spread to other parts of the body.
The scientists also examined the effects of drugs that block the growth factor receptors on the cell walls. The harmful 'plug' proteins disappeared from the cancer cells when patients were given these drugs.
"The mechanism we identified is clinically important. It can predict the development of metastasis and possibly how the cancer will respond to treatment," Nature magazine quoted Prof. Yarden as saying.