Viruses can kill healthy cells, grow cancerous ones: study

Scientists have long known that viruses can lead to certain cancers, such as Hodgkin's and non-Hodgkin's lymphoma, cervical cancer and cancer of the throat and liver.

Now, researchers at the University of Pittsburgh School of Medicine have discovered how viruses contribute to the development of cancer.

Their findings are published in the Oct. 24 issue ofjournal PLoS ONE.

Researchers have found that viruses can cause healthy cells to die while promoting the growth of cells with cancerous properties. A process that is repeated over and over, it can lead to the rapid growth of abnormal cells and the onset of cancer.

"We believe a separate mechanism may be at play in which a cellular insult, such as infection with a virus, selects a few pre-existing mutated clones of cells, promotes their further growth and multiplication, eventually leading to the emergence of fully cancerous cells," said Dr. Preet Chaudhary, a professor of medicine at the University of Pittsburgh School of Medicine, in a release.

"Consequently, similar to the role played by natural selection during evolution, excessive cell death, rather than its absence, may be a defining force that drives the initial emergence of cancer."

Chaudhary has named the process the Phoenix Paradigm, because the cancerfiguratively rises from the ashes of dead cells.

The scientists examined cells infected with Kaposi's sarcoma, a cancer associated with herpesvirus that causes patches of abnormal tissue to grow under the skin, in the lining of the mouth, nose and throat, or in other organs. Theytook particular interest ina gene called K13 that activates a pathway that has previously been shown to lead to cancer.

Cells with low K13 expression allowed herpesvirus to replicate, and these cells subsequently died off, the researchers noted. Cells with higher expression of K13 emerged after replication of herpesvirus and showed defective expression of two key proteins that are known to promote cancer.