By adhering proteins to white blood cells, scientists are able to form an inescapable dragnet for cancer cells
Cancer – it’s a killer, everyone knows that. Localized cancer (in the breast, the prostate gland or the lungs, for instance) is bad enough, but at least it can be treated with targeted therapy. Things really get deadly when cancerous cells travel to other parts of the body, and until now doctors have fallen back on the “scorch the Earth” tactics of radiation and chemotherapy, because they didn’t have a better way to stop the spread. That might be changing. According to researchers at Cornell University, attaching a sticky ball of special proteins to white blood cells proves to be an effective method for eliminating metastasizing cancer cells.
“These circulating cancer cells are doomed,” said Michael King, Cornell professor of biomedical engineering and the study’s senior author. “About 90 percent of cancer deaths are related to metastases, but now we’ve found a way to dispatch an army of killer white blood cells that cause apoptosis – the cancer cell’s own death – obliterating them from the bloodstream. When surrounded by these guys, it becomes nearly impossible for the cancer cell to escape.”
The vigilante proteins responsible for the cancer termination are known as TRAIL (Tumor Necrosis Factor Related Apoptosis-Inducing Ligand) proteins, and they’re attached to white blood cells with another adhesive protein called E-selectin. As the newly adorned white blood cells spread throughout the bloodstream, it becomes impossible for cancer cells to avoid the TRAILs. Once the two come in contact, the cancer cell essentially kills itself, perhaps due to shame.
The tests have been replicated in both mice and human bloodstreams.
“The mechanism is surprising and unexpected in that this repurposing of white blood cells in flowing blood is more effective than directly targeting the cancer cells with liposomes or soluble protein,” say the authors. It’s essentially the difference between casting a wide net and taking aim at a moving target with a single shot.
The key to the success is the moving bloodstream. When the scientists attempted to treat the cancer cells in a stagnant saline environment, their success rate was around 60%. With the addition of white blood cells as carriers and the flowing bloodstream as a delivery mechanism, the success rate jumped to nearly 100%.
As Prof King told the BBC: “The data shows a dramatic effect: it’s not a slight change in the number of cancer cells. The results are quite remarkable actually, in human blood and in mice. After two hours of blood flow, they [the tumour cells] have literally disintegrated.”