Filtering out Cancer from the Bloodstream

Professor Michael King (Credit: Cornell University)

The most deadly feature of the cancer cells is their ability to spread around the body (metastasize), using the bloodstream and create new tumors. Therefore, one of the crucial tasks of cancer research is to find a way to stop or stall this process. Recently, Michael King conducted a research study at the University of Rochester showing that two naturally occurring proteins can partner together to capture and kill up to 30 percent of tumor cells traveling in the bloodstream, doing so without causing any harm to healthy cells. King created a tiny device shaped like a tube with a protein covered surface. The device could be implanted into a peripheral blood vessel to filter out and destroy cancer cells flowing through the bloodstream.

The proteins used to capture the tumor cells are selectin molecules, which are proteins that normally appear on the surface of blood vessel cells (epithelium) in case of infection or injury. These molecules recruit white blood cells (leukocytes) to fight the infection. The leukocytes, which also have selectins on their surfaces, roll along the blood vessel using selectin interaction. This creates an inflammatory response but also attracts cancer cells, which sometimes mimic the adhesion and rolling process. The cancer cells that get attached to the selectins on the microtube’s surface are then an easy target.

A version of the device used in King’s experiments. In the body, the inlet and outlet would connect to an artery and vein, respectively (Credit: Cornell/Kuldeep Rana)

King exposed these cells to a previously researched protein called TRAIL (Tumor Necrosis Factor Related Apoptosis-Inducing Ligand), which in turn binds two receptors that induce the process of apoptosis and the cancer cell destroys itself. The cells are then detached from the TRAIL and drift back to the bloodstream to die. The device itself becomes free to capture new cancer cells.

A schematic of the two-receptor cancer neutralization concept. Cancer cells present in blood stick and roll on the selectins on the surface of the device. While rolling they bind to TRAIL and accumulate the self-destruct signal. Once they detach from the surface and leave the device, they will die 1-2 days later. (Credit: Cornell/Kuldeep Rana)

King’s group tested the device on prostate and colon cancer cells, but they are sure that it can be altered to fight other cancer types, if other peptides or proteins are added to the tube’s surface. “And if you could reduce or prevent metastasis, pretty much any cancer would be treatable,” he said.