Prostate Cancer Linked to a Virus Infection

Cancer researchers have identified a virus in human prostate cancer cells that is strikingly similar to a type of virus known to cause leukemia and sarcomas in animals.

Investigators from the University of Utah (Salt Lake City, USA) used both quantitative polymerase chain reaction (PCR) and a specific immunoassay to screen 334 consecutive prostate resection specimens and more than 100 samples of normal prostate tissue.

The investigators reported in the September 8, 2009 online edition of the journal Proceedings of the [U.S.] National Academy of Sciences (PNAS) that 27% of the prostate cancer samples were infected with XMRV (xenotropic murine leukemia virus-related virus), a gamma-retrovirus similar in protein composition and particle ultrastructure to Moloney murine leukemia virus (MoMLV), another gamma-retrovirus known to cause cancer in animals.

XMRV proteins were found primarily in malignant epithelial cells, suggesting that retroviral infection may have been directly linked to development of tumors. XMRV infection was associated with prostate cancer, especially higher-grade cancers.

"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 Dr. Ila R. Singh, associate professor of pathology at the University of Utah. "We still do not know that this virus causes cancer in people, but that is an important question we are going to investigate."

Results of earlier studies had limited XMRV infection to individuals with a mutation in the RNASEL gene. However, the current study found evidence to refute these findings, and the authors suggest that all individuals may be at risk of becoming infected. Confirmation that the virus causes prostate cancer would encourage the development of diagnostic tests, vaccines, and therapies for treating the disease.

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