An Underlying Viral Cause to Prostate Cancer?

An unfortunate draw-back to being a man is the seemingly unavoidable risk of developing prostate cancer. Statistically, one in six men in the U.S. will be diagnosed with having prostate cancer in their lifetime; one in thirty-four of those men will die because of the cancer. Though the cause of prostate cancer has baffled researchers, a new study may have finally discovered the answer to this elusive problem.

Many theories and factors have been contributed to increasing the risk of prostate cancer, such as: age, race, and diet, but new research argues that prostate cancer may be linked to a virus. Researcher’s noticed the gammaretrovirus called Xenotropic Murine Leukemia Virus (XMRV) present within nearly one-fourth of cancerous prostate cells, and merely six percent of control cells. The findings suggest a possible correlation between the presence of XMRV and prostate cancer. Furthermore, a co-author of the study, Dr. Ila Singh, presented her conclusion that the presence of the virus denotes a more aggressive prostate cancer.

This finding is not the first time a virus has been attributed to cancer however. It has long been accepted that some cancers have a link to certain viruses, including: cervical cancer, lymphoma and sarcomas. In fact, Dr. Joseph DeRisi, a professor at UCSF and investigator at the Howard Hughes Medical Institute, states that 15 percent of cancers are actually known to be linked to viruses. In an entirely independent analysis a few years prior to Singh’s report, DeRisi also, noted the presence of XMRV in prostate cancer cells; however, a lack of adequate samples and a benign control group prevented a definitive relation.

Gammaretroviruses, such as XMRV, have been known to cause cancer in animals like rodents, cats and monkeys, but had previously been overlooked because they have never been found in humans until recently. Singh explains that retroviruses sometimes integrate onto the chromosomes of a host, and can cause a tumor by landing on a cellular gene; causing the gene to become overactive. Singh’s research team also managed to conclude that XMRV is not linked to a genetic mutation, a prevalent theory, meaning all men are potential carriers.

The study included a larger experiment, testing 233 cancer cell samples and 101 control samples, and Singh’s team did confirm that XMRV was indeed present. Singh’s next step is to determine whether the discovered correlation of XMRV and prostate cancer is in actuality the cause of the cancer, and she admits that it’s “going to take a long time and a lot of work to resolve”.

At the moment, the virus XMRV is the only viral link with the possibility of being attributed to prostate cancer. Unfortunately, researchers are still unsure of the all the systems at work in XMRV and how it is transmitted in the first place. DeRisi points out that what is of importance at the moment is discovering “whether XMRV is something all people are exposed to”.

Due to the prevalence of this particular cancer, the findings of Singh’s team may herald the first step in preventing a cancer that infects one-third of the world’s male population. Ultimately, if the underlying cause of prostate cancer is a virus, the possibility of a simple vaccination, similar to that being used to fight off Human Papillomavirus (HPV), could be employed world-wide; a phase Singh “hopes” her team can make a reality.

http://www.scientificamerican.com/article.cfm?id=retrovirus-linked-prostate-cancer
http://www.webmd.com/prostate-cancer/guide/prostate-cancer-risk-factors

Joshua Mott
VTPP 434-501