Attaching a cancer-killer protein to white blood cells annihilates metastasizing cancer cells traveling throughout the bloodstream, new research shows.
Metastasis is the spread of a cancer cells to other parts of the body. Surgery and radiation are effective at treating primary tumors, but difficulty in detecting metastatic cancer cells has made treatment of the spreading cancer problematic.
“These circulating cancer cells are doomed,” says Michael King, professor of biomedical engineering at Cornell University 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.”
For the new study published in Proceedings of the National Academy of Sciences, the researchers injected human blood samples, and later mice, with two proteins: E-selectin (an adhesive) and TRAIL (Tumor Necrosis Factor Related Apoptosis-Inducing Ligand).
The TRAIL protein joined together with the E-selectin protein stick to leukocytes—white blood cells—that are ubiquitous in the bloodstream.
When a cancer cell comes into contact with TRAIL, which becomes unavoidable in the chaotic blood flow, the cancer cell essentially kills itself.
Surprising and unexpected
“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,” the authors write.
In the laboratory, King and colleagues tested the concept’s efficacy. When treating cancer cells with the proteins in saline, they found a 60 percent success rate in killing the cancer cells.
In normal laboratory conditions, the saline lacks white blood cells to serve as a carrier for the adhesive and killer proteins. Once the proteins were added to flowing blood, which models forces, mixing, and other human-body conditions, however, the success rate in killing the cancer cells jumped to nearly 100 percent.
The National Cancer Institute (Physical Sciences-Oncology program) of the National Institutes of Health funded the research through Cornell’s Center for the Microenvironment and Metastasis.
Source: Cornell University