“Sticky Balls” and Cancer Therapy

Macrophages killing cancer cells

Macrophages killing cancer cells. Credit: Wikimedia commons

There have been several reports of a new ‘breakthrough’ cancer therapy that uses nanoparticles tagged with cancer killing proteins. What exactly does this mean, and how realistic is it to expect this treatment to reach patients anytime soon?

Let’s go over the findings first.

✤ Scientists at Cornell University first created nanoparticles (in this case, tiny lipid droplets that were measured to be just over 100 nm diameter). Next, they attached two proteins to these nanoparticles.

✤ The first was a protein known as TRAIL. TRAIL is basically a “DIE RIGHT NOW!” signal to any cell that comes in contact with it; it induces a cellular suicide program known as apoptosis. The second protein was E-selectin, which is a cell adhesion molecule. Think of it as a sticky bit of velcro for certain types of cells to stick to other types of cells.

✤ Cancer cells have TRAIL receptors on their surface; when TRAIL binds to this receptor, the suicide program is activated in the cell. So the theory is, when cancer cells migrating in the blood stream encounter these TRAIL-bound nanoparticles, they kill themselves. This is important because cancers spread through the blood stream, and the ability to kill invasive cancer cells could dramatically improve patient prognosis.

✤ So the researchers created the TRAIL-bound nanoparticles, and then tested them in human blood that was mixed with circulating tumor cells. They found that the TRAIL nanoparticles were extremely effective at killing the cancer cells.

✤ Since this was just an in vitro experiment (i.e. done in a cell culture dish), next they tested it on a mouse. The scientists injected tumor cells into mice, along with the TRAIL nanoparticles. Again, they showed that the TRAIL nanoparticles were able to kill the tumor cells in the mice.

✤ TRAIL’s cancer killing abilities have already been used on patients in clinical trials. But this is the first time TRAIL nanoparticles were used in this manner, and it is exciting to consider the possibility that these nanoparticles may be able to zap cancer cells into oblivion as they circulate in the bloodstream during metastasis.

But, that’s still a while away. It is important to remember that this has only been done in a petri dish and in mice. It hasn’t been tested in humans. That might be a few more years down the line. For now, it’s not available to patients and should not be viewed as a cure for metastatic cancers.

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