Body’s Radiation Response Can Aid Cancer Spread

Researchers at the Francis Crick Institute have uncovered how a process involved in the regeneration of tissue damaged by radiation can aid in the spread of cancer. By blocking signals from particular immune cells, the team was able to lower development of secondary tumors in mice with lung cancer.

“The relationship between cancer cells, the immune system and the organ where cancer takes hold is highly complex,” says Ilaria Malanchi, author and group leader of the Tumour-Host Interaction Laboratory at Francis Crick Institute. “And it’s by untangling aspects of this web that we can better understand why cancer is able to spread, what predisposes organ to the arrival of cancer cells and ultimately how we can try to stop this.”

The team first exposed healthy mouse lungs to a high dose of radiation to damage the tissue. They then tested the potential of breast cancer cells to grow in the damaged area compared to uninjured lungs. More cancer cells spread to the lungs and began forming secondary tumors in mice that had been injured by radiation compared to the mice who had not.

Further experiments revealed that this is due to the signaling of neutrophils, a type of immune cell that helps repair tissue damage. When the researchers blocked signaling from the neutrophils in the injured lungs, secondary tumors were greatly reduced.

The work highlights pro-tumorigenic activity of neutrophils, which is likely linked to their tissue regenerative functions.

 “This is a situation where tissue damage sets the stage for the spread of cancer and, in trying to repair the damaged tissue, the immune system inadvertently aids the cancer,” says Emma Nolan, first author and postdoc in the Tumour-Host Interaction Laboratory at the Crick. “This role of neutrophils in supporting cancer spread is something which needs further research and could potentially help to identify new ways to treat the disease.”

The radiation administered to the mice was at higher doses and targeted larger proportions of tissue than would be given in clinical settings. Better technology means exposure to radiation is restricted to cancerous tissue, and radiotherapy remains a powerful weapon to control cancer disease.  “Unrevealing the new responses of neutrophils to radiation we described here, could further enhance the efficacy of this highly-regarded treatment for cancer,” Ilaria adds.

The study, entitled “Radiation exposure elicits a neutrophil-driven response in healthy lung tissue that enhances metastatic colonization,” was published recently in Nature Cancer.