Radiation therapy is currently one of the best treatments we have for cancer, but it could benefit from being more targeted at healthy cells. Now researchers in Japan have developed nanoparticles that can penetrate tumors and kill them from the inside after they have been activated by external X-rays.
Radiation therapy usually works by damaging the cancer cells’ DNA, and part of that damage comes from the creation of reactive oxygen species. However, this requires oxygen, which can be scarce in the center of tumors and limit the effectiveness of the treatment.
For the new study, scientists from Kyoto University and colleagues investigated another way of using 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 another method – the photoelectric effect, in which a material emits electrons in response to electromagnetic radiation.
The nanoparticles are made of organosilica and carry iodine in their pores. There iodine is the active ingredient that releases electrons at relatively low levels of radiation. The electrons then cause double-strand breaks in the nuclear DNA of the cancer cells, which trigger cell death.
To test the idea, the team distributed the nanoparticles through 3D models of healthy and cancerous cells. They found that the nanoparticles tended to cluster just outside the cancer cells’ nuclei, and 30 minutes of X-rays were enough to wipe them out within three days. The best results were achieved with radiation values of 33.2 keV.
“Our study is an important example of the application of a quantum physical phenomenon in a cancer cell,” says Kotaro Matsumoto, co-author of the study. “It appears that a cloud of low-energy electrons is generated near the DNA, causing difficult-to-repair double-strand breaks that ultimately lead to programmed cell death.”
The basic concept of killing cancer with the help of nanoparticles that are activated by external radiation is not new, but there are different forms. Previous studies have used nanoparticles that kill cancer from the inside by heating up, changing acidity, releasing drugs or reactive oxygen species, or depriving them of nutrients. Now it seems like the release of electrons could be a new weapon in the arsenal.
But of course the course is still at the very beginning. So far, the technology has only been tested on cell cultures grown in the laboratory and not yet on animals, let alone humans. Mouse tests are the next steps, say the researchers.
The study was published in the journal Scientific Reports.
Source: Kyoto University