Sunday, February 22, 2009


King's approach uses a tiny tubelike device coated with the proteins that could hypothetically be implanted in a peripheral blood vessel to filter out and destroy free-flowing cancer cells in the bloodstream. To capture the tumor cells in the blood, King used selection molecules proteins that move to the surface of blood vessels in response to infection or injury. Selectin molecules normally recruit white blood cells which "roll" along their surfaces and create an inflammatory response but they also attract cancer cells, which can mimic the adhesion and rolling process. Once the cancer cells adhered to the selectin on the microtube's surface, King exposed them to a protein called TRAIL (for Tumor Necrosis Factor Related Apoptosis-Inducing Ligand), which binds to two so-called "death receptors" on the cancer cells' surface, setting in motion a process that causes the cell to self-destruct. The TRAIL then releases the cells back into the bloodstream to die; and the device is left free to work on new cells.It's a little more sophisticated than just filtering the blood, because we're not just accumulating cancer cells on the surface. King's research showed that the device can capture and kill about 30 percent of cancer cells flowing past it a single time, with the potential to kill more in the closed-loop system of the body. Used in combination with traditional cancer therapies, King said, the device could remove a significant proportion of metastatic cells ,and give the body a fighting chance to remove the rest of them.
The team also showed that a system in which the cancer cells "roll" over the target molecules presenting their entire surface to the molecules is four times more effective than a static setup in which the cells and proteins make contact at a single point. King's group tested the device on prostate and colon cancer cells, but noted that it could also be customized with additional peptides or other proteins to target other types of cancer cells and if you could reduce or prevent metastasis, pretty much any cancer would be treatable. But translating the research into a clinical application will take time, and is still likely years away.
A version of the device used in King's experiments is shown below. In the body, the inlet and outlet would connect to an artery and vein, respectively

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