Despite the familial similarity, the team found a significant difference between them. The protein that drops off has two arms: One arm attaches to the protein fibers forming the skeleton, and the other anchors itself to the cell membrane. This action is what stabilizes the cells structure. The protein that increases, on the other hand, is made up of one short arm that only attaches to the anchor point on the cell membrane. Rather than structural support, this protein acts as a kind of plug, blocking the anchor point, and allowing the skeletal protein fibers to unravel into the threads that push the cells apart. The cell is then free to move, and, if its a cancer cell, to metastasize to a new site in the body.
In experiments with genetically engineered cells, the scientists showed that the growth factor directly influences levels of both proteins, and that these, in turn, control the cells ability to migrate. Blocking production of the short tensin protein kept cells in their place, while overproduction of this protein plug increased their migration.
Next, the scientists carried out tests on tumor samples taken from around 300 patients with inflammatory breast cancer, a rare but swift and deadly form of the disease, which is associated with elevated growth factor levels. The scientists found a strong correlation between high growth factor activity and levels of the 'plug' protein. High levels of this protein, in turn, were associated with cancer metastasis
Contact: Yivsam Azgad
Weizmann Institute of Science