Scientists show how 'dormant virus' causes cancer

Cancer Research UK

Cancer Research UK scientists have revealed how a dormant virus triggers a type of cancer found in young people, according to research published in PLoS Pathogens* today (Friday).

Burkitt's lymphoma** - a type of non-Hodgkin's lymphoma - affects around 200 young adults aged between 13 and 24 each year in the UK and is more common in children living in equatorial Africa.

The cancer is triggered by a genetic accident in cells of the immune system, called B lymphocytes.

But once that accident has happened, the chances of the cancer developing are greatly increased if those same cells are infected with a common virus, called the Epstein-Barr virus (EBV).

Scientists at the University of Birmingham have now identified a subset of Burkitt's lymphomas in which EBV triggers a viral protein that keeps the tumour cells alive.

Interestingly, this EBV protein behaves like a cellular protein, called bcl2, whose job is to keep normal cells alive.

The virus' ability to mimic the cell's own bcl2 appears to be an important factor in the development of Burkitt's lymphoma.

Professor Alan Rickinson, lead author based at Cancer Research UK's Institute for Cancer Studies at the University of Birmingham, said: "EBV is carried by most of us as a 'dormant' virus - but in a very small proportion of people it can have devastating effects. Precisely how EBV helps to cause Burkitt's lymphoma has remained a mystery.

"Now our study suggests that in some tumours it does so by switching on a protein that is usually inactive when the virus is dormant."

Around 90 per cent of adults in the UK are infected with EBV, most of them as young infants. Most infected people show no ill-effects, although a minority will develop glandular fever. Very rarely, the virus can trigger cancers, such as Burkitt’s lymphoma and Hodgkin’s lymphoma.

Burkitt's lymphoma was discovered in 1958 by Denis Burkitt, a British scientist studying tumours that were common in African children. Scientists now know that this cancer is more prevalent in Africa because having to deal with other infections like malaria reduces people’s ability to naturally control EBV.

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "Cancer Research UK scientists have played a leading role in EBV research - from the discovery of the virus to immunotherapy for EBV-related lymphoma - and this is another first for us.

"This interesting research sheds light on how this rare type of cancer might develop. Understanding each step in the chain of events that leads to the development of cancer is crucial to learning how to improve treatments and even prevent the disease."

ENDS

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References

Kelly, G., Long, H., Stylianou, J., Thomas, W., Leese, A., Bell, A., Bornkamm, G., Mautner, J., Rickinson, A., & Rowe, M. (2009). An Epstein-Barr Virus Anti-Apoptotic Protein Constitutively Expressed in Transformed Cells and Implicated in Burkitt Lymphomagenesis: The Wp/BHRF1 Link PLoS Pathogens, 5 (3) DOI: 10.1371/journal.ppat.1000341

Notes to Editor

* An Epstein-Barr Virus Anti-Apoptotic Protein Constitutively Expressed in Transformed Cells and Implicated in Burkitt Lymphomagenesis: The Wp/BHRF1 Link. Kelly et al. PLoS Pathogens. Friday 13 March 2009.

** About Burkitt lymphoma

Burkitt lymphoma is a type of non-Hodgkin lymphoma arising in cells of the immune system called B lymphocytes. How the disease develops remains unclear but research has shown that the Epstein-Barr virus (EBV), a virus that naturally infects B lymphocytes, is often involved. In equatorial countries where Burkitt lymphoma is most common, all cases of the cancer involve EBV; in UK, where Burkitt lymphoma is rarer, only some cases involve the virus.