Scientists Are Testing Out Nanoparticles that Can Stop Cancer in Its Tracks

Cancer cells take advantage of one of our immune system’s defense mechanism to spread through the body, but these nanoparticles might be able to stop them.

Oct 19 2016, 6:00pm

Cancer cells. Image: Wikipedia

The future is here; We now live in a world where researchers can send tiny, manmade particles into the body to blast apart cells that help cancer spread. Well, at least in mice.

Though it's still at an early stage of research, this nanotechnology is helping us get a better understanding of how cancer spreads—and how to stop it.

When cancer spreads to different parts of the body, it's considered metastatic or stage four—and once it spreads, it's much more difficult to control and treat. But researchers in the US recently discovered one tool that cancer cells use to spread throughout the body, and created a nanoparticle that breaks that tool apart, according to research published Wednesday in Science Translational Medicine.

Neutrophil extracellular traps, appropriately shortened to NETs, are traps that neutrophils—a type of white blood cell that usually eats up intruding bacteria—set up as an immune defense in the body.

"What happens is the enzymes that normally work inside neutrophils to digest bacteria are put on DNA, and the DNA is used as a scaffold to keep these enzymes in check so they don't diffuse," explained Mikala Egeblad, a cancer researcher at Cold Spring Harbor Laboratory and co-author of the paper. "At the same time, the DNA is pretty sticky, so it physically traps the bacteria and keeps them next to the digestive enzymes."

But cancer cells use these structures to their advantage: the NETs break down small amounts of tissue, creating holes that allow the cancer space to spread. It's not the only way cancer can metastasize, but it's such a handy tool that cancer cells even send out chemical signals to prompt neutrophils to create these NETs.

What's even trickier is that when cancer patients undergo chemotherapy, it can drastically reduce the number of neutrophils in the body. This puts them at risk for potentially life-threatening infections, so patients often take neutrophil-boosting medication. Egeblad said this could potentially be making it easier for the cancer to spread.

A high magnification of an intact neutrophil (yellow arrow) and a NET (white arrow). Image: Park et al., Science Translational

Medicine To try to disrupt this pattern, Egeblad and her colleagues designed a nanoparticle made of medically-safe materials that were coated with DNAse 1, an enzyme that can destroy the NETs before the cancer cells exploit them. They injected the nanoparticles into mice with breast cancer and found that three of the nine mice that had the nanoparticle treatment showed no signs of the cancer spreading, compared to all 10 mice in the control group.

"It's possible we didn't get a high enough dose of the nanoparticles in all of the mice, because it limited metastasis even in the ones that still got metastasis—so it wasn't as if there was no effect," Egeblad said.

The results are promising and merit more research, but it's still too soon to know if this treatment could work in humans. For one, there's concerns about safety: just as chemotherapy wiping out neutrophils puts people at risk of infection, these nanoparticles targeting NETs may have the same effect. Egeblad said they'll be doing more animal trials to better understand how the NETs and cancer cells function together, and to determine if there's any safety risk.

They also want to refine how we detect NETs—since it's not the only way cancer spread, this kind of treatment would be better targeted to cancers where NETs have been exploited.

But the research represents an innovative combination of technology and biology, and gives us a glimpse of the very progressive treatments that may not be so far off in the future.