Researchers find virus in malignant prostate cancer cells

Researchers have reported that a virus known to cause leukemia and sarcomas in animals has been found in malignant human prostate cancer cells.

If further investigation proves that the virus, XMRV (Xenotropic murine leukemia virus-related virus), causes prostate cancer in humans, it would open opportunities for developing diagnostic tests, vaccines, and therapies for treating the cancer, according to the authors of study, which is published online in the Proceedings of the National Academy of Sciences (Sept. 8, 2009).

"We found that XMRV was present in 27% of prostate cancers we examined and that it was associated with more aggressive tumors," said senior author Ila R. Singh, MD, PhD, of the University of Utah, Salt Lake City. "We still don’t know that this virus causes cancer in people, but that is an important question we're going to investigate."

Dr. Singh and colleagues examined more than 200 human prostate cancers and compared them with more than 100 non-cancerous prostate tissues. They found 27% of the cancers contained XMRV, compared with only 6% of the benign tissues. The viral proteins were found almost exclusively in malignant prostatic cells, suggesting that XMRV infection may be directly linked to the formation of tumors.

In another important finding of the study, Dr. Singh and colleagues also showed that susceptibility to XMRV infection is not enhanced by a genetic mutation, as was previously reported. If XMRV were caused by the mutation, only the 10% of the population who carry the mutated gene would be at risk for infection with virus. But the researchers found no connection between XMRV and the mutation, meaning the risk for infection may extend to the population at large.

While the study answers important questions about XMRV, it also raises a number of other questions, such as whether the virus infects women, is sexually transmitted, how prevalent it is in the general population, and whether it causes cancers in tissues other than the prostate.