Viral alert could pinpoint cancer cells for destruction

Cancer Research UK

Cancer Research UK scientists may be a step closer to a treatment that could help the body’s own immune system recognise and kill tumours, they report in the journal Nature1 today.

The team found that cells injected with a molecule produced by viruses were much more likely to trigger the body’s immune response.

The immune system readily recognises cells infected with bacteria or viruses and targets them for destruction. But it is less adept at spotting cancer cells, as they have very few distinguishing features that alert the body to their presence.

When a virus invades a cell, it makes many copies of itself that can then infect other cells. In the process, many types of virus make a genetic material called double stranded RNA (dsRNA). A large amount of dsRNA in a cell is a hallmark of viral infection and serves as an ‘alert’ signal to the immune system.

A research team based at Cancer Research UK’s London Research Institute found that putting artificial viral dsRNA into normal cells enabled the immune system to recognise them, and hopes the technique could form the basis of a therapy against cancer and other diseases.

Dr Caetano Reis e Sousa, who led the research team, explains: “The immune system is not good at recognising tumour cells.

“By making tumour cells seem as though they have been infected by viruses we hope to be able to make it easier for the immune system to spot and eliminate them.”

Putting cells containing viral dsRNA into mice mobilised the immune system. The number of immune cells called ‘killer T cells’ in the mice was greatly increased, and the injected cells were targeted and destroyed.

Dr Reis e Sousa adds: “We’ve been studying how the immune system is alerted to the presence of viruses for six years, with a view to harnessing the mechanisms for cancer therapy. Our new technique prompts the immune system to mount a response, just as it would if a real virus had infected the body.

“Using a real virus for therapy could be dangerous, as it could replicate and spread around the body. Marking cells for destruction using artificial viral dsRNA could allow doctors to avoid this problem.”

The team now hopes to test the method on cancer cells in mice.

Professor Robert Souhami, Cancer Research UK’s Director of Policy and Communication, says: “Dr Reis e Sousa and his team have found a new method to enable the immune system to recognise cancer cells. Extensive further research is needed to show whether this type of therapy could prove suitable for clinical trials in patients.”

ENDS

Notes to Editor

  1. Nature Advance Online Publication 13 February 2005 DOI: 10.1038/nature03326

The team used a synthetic form of dsRNA called poly inosinic:cytidilic acid.

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