Protein destroys migrating cancer cells on contact

Metastasis is where cancer cells from a first tumor detach and spread to other parts of the body.

Surgery and radiation are usually quite effective for treating primary tumors, but once cancer cells start migrating the chances of successful treatment worsen considerably, partly because they are difficult to track down. The vast majority of deaths from cancer are due to metastasis.

Now, a new study suggests it is possible not only to locate these migrating cancer cells, but to annihilate them before they have a chance to set up secondary tumors.

Cancer cells 'kill themselves' when in contact with TRAIL-coated white blood cells. Together the two proteins formed a sticky coating around leukocytes - white blood cells found everywhere in the bloodstream. They found that once cancer cells came into contact with the sticky white blood cells, they imploded.

One surprising factor was that the chaotic environment of a flowing medium, the bloodstream, actually improved the chances this would happen. When they tested the approach in a still medium, it was not as effective. And targeting the cancer cells directly with proteins, was not as effective either. It seems the best way was to turn the white blood cells into sticky carriers of the killer TRAIL protein. 

For instance, when they targeted the cancer cells in saline directly with the proteins, the success rate was 60%. But when they tried again with a model of flowing blood that has forces, mixing and other conditions similar to the human body, the kill rate shot up to 100%.They discovered that by knocking out a protein in a class of cells that leads the migration, they could render them incapable of carrying out the first crucial step of metastasis.