Tumour cells may ‘hijack’ white blood cells to help spread

White blood cells that usually help fight infections could be co-opted by cancer cells to help tumours spread, a US study has found. 

Researchers at Cold Spring Harbor Laboratory found that neutrophils – the most common type of white blood cell – can be ‘hijacked’ by cancer cells and used to aid the spread of breast tumours to the lungs in mice. 

The study, which was published in Science Translational Medicine, also shows a possible way of preventing this process, which could have implications for the development of new cancer treatments. 

Neutrophils are important components of the immune system that help destroy potentially harmful invaders, such as bacteria.  

One way that the cells do this is by releasing meshes of DNA when they detect a threat. These form dense web-like structures outside the cell called NETs. 

These NETs are studded with tiny toxic molecules that can break down and digest the invaders.

Using imaging techniques in mice with breast cancer, the researchers showed that cancer cells caused neutrophils to release their NETs “even when no infection or invader was present,” said lead researcher Professor Mikala Egeblad. 

The NETs, Egeblad added, encouraged breast cancer cells to spread in the mice, possibly by creating small holes in tissues that the cancer cells can squeeze through. 

In an attempt to prevent this process the researchers treated the mice with tiny particles carrying molecules that can break down DNA. 

The experimental nanoparticle treatment reduced the spread of breast cancer to the lungs in the mice. 

Dr Ilaria Malanchi, from the Francis Crick Institute, part-funded by Cancer Research UK, described the study as “elegant,” adding that it “shows a potential way to stop particular immune cells from helping tumours spread.” 

This promising discovery, Malanchi said, could have relevance for treating patients.

“The researchers found aggressive breast cancer cells trick neutrophils into producing DNA traps, which help the cancer cells spread to the lungs in mice. 

“Importantly, they also identified a possible way to target this neutrophil activity using nanoparticles, which could be developed into a new treatment.

“But further research is needed to see if this approach will work in cancer patients.”