Radiation therapy is currently one of the best treatments we have against cancer, but it could benefit from being more targeted to spare healthy cells. Now, researchers in Japan have developed nanoparticles that can penetrate tumors and kill them from within, after being activated by external X-rays.
Normally, radiation therapy works by damaging the DNA of the cancer cells, and part of that damage comes from the generation of reactive oxygen species. But this requires oxygen, which can be scarce at the center of tumors and limit the effectiveness of the treatment.
So for the new study, scientists at Kyoto University and colleagues investigated a different way to use radiation to kill cancer cells. They designed nanoparticles that infiltrate tumors, and once inside, they can be activated by X-rays to destroy the cells using a different method – the photoelectric effect, where a material emits electrons in response to electromagnetic radiation.
The nanoparticles are made of organosilica and carry iodine in their pores. The iodine is the active ingredient there, releasing electrons when irradiated at relatively low levels. The electrons then cause double-strand breaks in the nuclear DNA of the cancer cells, which triggers cell death.
To test out the idea, the team dispersed the nanoparticles through 3D models of healthy and cancerous cells. They found that the nanoparticles tended to congregate just outside the nuclei of the cancer cells, and 30 minutes of X-ray radiation was enough to wipe them out within three days. The best results were achieved with radiation levels of 33.2 keV.
“Our study represents an important example of employing a quantum physics phenomenon inside a cancer cell,” says Kotaro Matsumoto, co-author of the study. “It appears that a cloud of low-energy electrons is generated close to DNA, causing double strand breaks that are difficult to repair, eventually leading to programmed cell death.”
The basic concept of killing cancer using nanoparticles, activated by outside radiation, isn’t new, but it comes in a range of forms. Previous studies have used nanoparticles that kill cancer from within by heating up, altering the acidity, releasing drugs or reactive oxygen species, or starving them of nutrients. Now it seems like releasing electrons could be a new weapon in the arsenal.
But of course, it’s still very early days for the study. The technique has only been tested in lab-grown cell cultures and not yet animals, let alone humans. Mouse tests are the next steps, the researchers say.
The study was published in the journal Scientific Reports.
Source: Kyoto University
