A virus turns lymph vessel cells into a cancer that affects people with weakened immune systems, according to research published today in Nature Genetics.
A Cancer Research UK team based at University College London have discovered that Kaposi sarcoma – which is common in people who are HIV positive or have had an organ transplant – first develops in the inner cell lining of lymph vessels, the transport network for the body's immune system.
The findings indicate that drugs arresting the development of cells lining lymph vessels could prove powerful against Kaposi sarcoma. They could also yield a test for doctors to predict which patients are likely to develop this cancer.
Kaposi sarcoma typically appears as coloured lesions or blotches on the skin, although it can spread to internal organs.
The sarcoma is the most common cancer in individuals with HIV or AIDS and for that reason is the most common cancer in many Sub-Saharan African countries. It is also one of the most common cancers in patients who have had their immune system suppressed to lower the likelihood that their bodies will reject a transplanted organ.
Professor Boshoff, who is joint Director of the Cancer Research UK Viral Oncology Group at UCL, says: "The cell type in which Kaposi sarcoma first develops has been a mystery since it was discovered in 1872.
"We analysed the genetic makeup of Kaposi sarcoma cells and found they are most similar genetically to cells of the inner lining of lymph vessels, known as lymphatic endothelial cells."
The research was funded by Cancer Research UK, with additional funding from the Medical Research Council and the Wellcome Trust.
The team also found that the virus that causes Kaposi sarcoma – the Kaposi sarcoma herpes virus (KSHV) – can turn the endothelial cells that line blood vessels into cancerous lymphatic endothelial cells.
Professor Boshoff adds: "We have shown for the first time that a virus can genetically reprogramme blood vessel endothelial cells into lymphatic endothelial cells, and that it is these lymphatic cells that develop into Kaposi sarcoma."
"Now that we know in which type of cell Kaposi sarcoma originates, we should be able to identify new ways to treat the condition. The findings could also yield new clues about other cancers that are triggered by viruses, such as cervical cancer."